JP2015169879A - Projector, image display apparatus and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the vibration of a light source or the like caused by the on/off switching of the light source.SOLUTION: A projector includes at least one light source, a light source control part which controls the output of light emitted from the light source by controlling power supplied to the light source by PWM, an image light-emitting part which emits image light representing an image corresponding to an image signal by using the light emitted from the light source, and a projection optical system which projects the image light. The light source control part repeatedly performs an operation for generating a plurality of PWM pulses whose periods are different in one frame period in synchronization with the frame period of the image signal, for each frame period, to control the power supplied to the light source.

Description

  The present invention relates to an image display device, a projector, and a control method thereof.

  2. Description of the Related Art In recent years, image display devices such as projectors and televisions have been developed that use a semiconductor light source such as a laser diode (LD) or a light emitting diode (LED) or a light source called a solid light source. . For adjusting the light emission luminance of the light source, a technique for controlling the power supplied to the light source by PWM (pulse width modulation) is usually used. For example, Patent Document 1 discloses a technique that makes scroll noise generated when PWM controlling a light source inconspicuous by changing the period of a PWM pulse with a predetermined width. Note that scroll noise is a phenomenon in which when a light source is PWM-controlled, a band-like bright portion and a dark portion extending in the horizontal direction of the screen move slowly or upwardly on the screen.

JP 2009-175627 A

  Here, when PWM control of the light source is performed, the light source and other associated circuits (hereinafter also referred to as “light source on (ON) / off (OFF) switching”) are repeatedly supplied and cut off (hereinafter also referred to as “light source on (ON) / off (OFF) switching”) (Hereinafter referred to as “light source or the like”), there is a problem that noise or image quality degradation may occur due to the generated vibration. In addition, patent document 1 does not have any description or suggestion regarding this problem.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the invention, a projector is provided. The projector uses at least one light source; a light source control unit that controls output of light emitted from the light source by controlling power supplied to the light source by PWM; and uses light emitted from the light source. And an image light emitting unit that emits image light representing an image corresponding to the image signal; and a projection optical system that projects the image light. The light source control unit repeatedly performs an operation for generating a plurality of PWM pulses having different periods in one frame period in synchronization with the frame period of the image signal, and supplies the light source to the light source. It is characterized by controlling electric power. According to the projector of this aspect, when the PWM pulse cycle fluctuates within the frame cycle, the supply of power to the light source (on) and the interruption (off) are repeatedly executed by the PWM pulse of power to the light source ( Switching) frequency can be dispersed. As a result, it is possible to suppress vibrations of the light source and the like that are generated by the on / off switching of the light source. Further, scroll noise can be suppressed by changing the PWM pulse cycle in synchronization with the frame cycle.

(2) The projector according to the above aspect may include a plurality of the light sources; and the light source control unit may vary the fluctuation state of the cycle of the plurality of PWM pulses for each of the light sources. In this way, it is possible to distribute not only the on / off switching frequency of the light source within the frame period but also the on / off switching frequency of the light source among the light sources. Thereby, in the case of a plurality of light sources, it is possible to more effectively suppress vibrations of the light sources and the like that are generated by switching on / off of the light sources.

(3) In the projector of the above aspect, the light source control unit may vary the combination of fluctuations in the period of the plurality of PWM pulses for each light source. In this way, since the fluctuation state of the frequency of on / off switching of the light source can be dispersed so as not to overlap between the light sources, the light source generated by the on / off switching of the light source can be more effectively performed. Can be suppressed.

(4) In the projector according to the aspect described above, the light source control unit may stop the generation of the PWM pulse in a certain period at the beginning or end of the frame period. In this way, it is possible to prevent the display of an image in which image quality degradation or the like has occurred due to a change in the image according to a change in the image signal when the frame period is switched.

Note that the present invention can be realized in various modes as described below.
(A) Projector and projector control method.
(B) Image display device and control method of image display device.

It is a schematic block diagram which shows the structure of the projector in 1st Embodiment. It is a schematic block diagram which shows the structure of a control part. It is explanatory drawing shown about the PWMY signal and PWMB signal which are produced | generated in a PWM signal production | generation part. It is explanatory drawing shown about the PWMY signal and PWMB signal in the case of light-emitting a light source intermittently in a frame period. It is explanatory drawing shown about the case where the fluctuation state of the period of several PWM pulse in a frame period differs with a PWMY signal and a PWMB signal. It is a schematic block diagram which shows the structure of the projector in 2nd Embodiment. It is a schematic block diagram which shows the structure of a control part. It is explanatory drawing shown about the case where the fluctuation state of the period of several PWM pulse in a frame period differs with the PWMR signal, PWMG signal, and PWMB signal which are produced | generated in a PWM signal generation part. It is explanatory drawing shown about the other example when the fluctuation state of the period of several PWM pulse in a frame period differs with the PWMR signal, PWMG signal, and PWMB signal which are produced | generated in a PWM signal generation part.

A. First embodiment:
A1. Projector configuration:
FIG. 1 is a schematic block diagram showing the configuration of the projector in the first embodiment. The projector 50 includes a blue light illumination device 51, a yellow light illumination device 52, a dichroic mirror 25, light guide optical systems 3R, 3G, and 3B, reflective liquid crystal panels 4R, 4G, and 4B, and red light. The optical sensor 36 </ b> R, the green light sensor 36 </ b> G, the blue light sensor 36 </ b> B, the cross dichroic prism 5, the projection optical system 6, and the control unit 63 are provided.

  As an example, the blue light illumination device 51 emits mainly P-polarized blue light LB. As an example, the yellow light illumination device 52 emits mainly P-polarized yellow light LY.

  The dichroic mirror 25 is an optical element in which a wavelength selection film that reflects a light beam in a predetermined wavelength region and transmits a light beam in another wavelength region is formed on a substrate. In the present embodiment, as an example, the dichroic mirror 25 transmits the red light LR having a wavelength longer than a predetermined reference wavelength among the yellow light LY emitted from the yellow light illumination device 52, and determines a predetermined reference. The green light LG having a wavelength shorter than the wavelength is reflected.

  The light guide optical system 3R guides S-polarized red light reflected by the polarization beam splitter 26 out of the red light LR transmitted through the dichroic mirror 25 to the red light optical sensor 36R. On the other hand, the light guide optical system 3R guides the P-polarized red light transmitted through the polarization beam splitter 26 out of the red light LR transmitted through the dichroic mirror 25 to the reflective liquid crystal panel 4R. The light guide optical system 3 </ b> R guides S-polarized red light reflected by the polarization beam splitter 26 out of the red light reflected from the reflective liquid crystal panel 4 </ b> R to the cross dichroic prism 5.

  The light guide optical system 3G guides the S-polarized green light reflected by the polarization beam splitter 27 out of the green light LG reflected by the dichroic mirror 25 to the green light optical sensor 36G. The light guide optical system 3G guides the P-polarized green light transmitted through the polarization beam splitter 27 out of the green light LG reflected by the dichroic mirror 25 to the reflective liquid crystal panel 4G. The light guide optical system 3G guides the S-polarized green light reflected by the polarization beam splitter 27 out of the green light reflected from the reflective liquid crystal panel 4G to the cross dichroic prism 5.

  The light guide optical system 3B guides the S-polarized blue light reflected by the polarization beam splitter 28 out of the blue light LB emitted by the blue light illumination device 51 to the blue light optical sensor 36B. The light guide optical system 3B guides the P-polarized blue light transmitted through the polarization beam splitter 28 out of the blue light LB emitted by the blue light illumination device 51 to the reflective liquid crystal panel 4B. The light guide optical system 3B guides S-polarized blue light reflected by the polarization beam splitter 28 out of the blue light reflected from the reflective liquid crystal panel 4B to the cross dichroic prism 5.

  The reflective liquid crystal panel 4R modulates the red light guided by the light guide optical system 3R according to an image signal, and emits image light representing a red image. Similarly, the reflective liquid crystal panel 4G modulates the green light guided by the light guide optical system 3G in accordance with the image signal, and emits image light representing a green image. Similarly, the reflective liquid crystal panel 4B modulates the blue light guided by the light guide optical system 3B according to the image signal and emits image light representing a blue image. The cross dichroic prism 5 combines the red image light guided by the light guide optical system 3R, the green image light guided by the light guide optical system 3G, and the blue image light guided by the light guide optical system 3B. The projection optical system 6 projects image light representing a color image synthesized by the cross dichroic prism 5 onto a projection surface such as a screen SCR.

  The red light optical sensor 36R detects the brightness of the S-polarized red light guided by the light guide optical system 3R (in this embodiment, the light intensity is an example). The red light optical sensor 36 </ b> R outputs a red light intensity signal indicating the detected light intensity of the red light to the control unit 63. Similarly, the blue light optical sensor 36B detects the brightness of the S-polarized blue light guided by the light guide optical system 3B (in this embodiment, the light intensity is an example). The blue light optical sensor 36 </ b> B outputs a blue light intensity signal indicating the detected light intensity of the blue light to the control unit 63. Similarly, the green light optical sensor 36G detects the intensity of S-polarized green light guided by the light guide optical system 3G. The green light sensor 36G outputs a green light intensity signal indicating the intensity of the detected green light to the control unit 63.

  The blue light illumination device 51 includes a blue laser diode array 53, a collimating lens 54, a condenser lens 55, a diffusion plate 56, a pickup lens 57, a collimating lens 58, a first lens array 9, A second lens array 10, a polarization conversion element 11, and a superimposing lens 12 are provided.

  The blue laser diode array 53 is, for example, a structure in which twelve blue laser diodes 59 are arranged in an array of 4 × 3. The same number of collimating lenses 54 as the individual blue laser diodes 59 are provided at positions corresponding to the individual blue laser diodes 59. The first lens array 9 has a plurality of first small lenses 13 for dividing the illumination light beam emitted from the collimating lens 58 into a plurality of partial light beams. The second lens array 10 has a plurality of second small lenses 14 corresponding to the plurality of first small lenses 13 of the first lens array 9. The polarization conversion element 11 converts each partial light beam from the second lens array 10 into approximately one type of linearly polarized light having a uniform polarization direction and emits the converted light. The superimposing lens 12 superimposes each partial light beam emitted from the polarization conversion element 11 in the illuminated area.

  The blue light LB emitted from the blue laser diode 59 is collimated by the collimating lens 54, then condensed by the condensing lens 55, and irradiated on the diffusion plate 56, thereby forming a point light source. Blue diffused light from each point light source on the diffusion plate 56 passes through the pickup lens 57 and is collimated by the collimating lens 58 and then enters the first lens array 9.

  The first lens array 9 has a function as a light beam splitting optical element that splits the parallel light from the parallelizing lens 58 into a plurality of partial light beams. The first lens array 9 has a configuration in which a plurality of first small lenses 13 are arranged in a matrix of a plurality of rows and a plurality of columns in a plane orthogonal to the illumination optical axis 51ax. Although not illustrated, the outer shape of the first small lens 13 is similar to the outer shape of the image forming region that emits image light of the reflective liquid crystal panel 4B.

  The second lens array 10, together with the superimposing lens 12, has a function of forming an image of each first small lens 13 of the first lens array 9 in the vicinity of the image forming area of the reflective liquid crystal panel 4B. Similar to the first lens array 9, the second lens array 10 has a configuration in which a plurality of second small lenses 14 are arranged in a matrix of a plurality of rows and a plurality of columns in a plane orthogonal to the illumination optical axis 51ax.

  The polarization conversion element 11 emits the polarization direction of each partial light beam divided by the first lens array 9 as approximately one type of linearly polarized light having the same polarization direction. Of the illumination light from the blue laser diode 59, the polarization conversion element 11 transmits one polarized light (for example, P-polarized light) and reflects the other polarized light (for example, S-polarized light) in a direction perpendicular to the illumination optical axis 51ax. A polarization separation layer that reflects the light having the other polarization component reflected by the polarization separation layer in a direction parallel to the illumination optical axis 51ax, and a light having one polarization component reflected by the polarization separation layer. And a retardation plate that converts light into light having the other polarization component. In addition, although the light which permeate | transmitted the polarization conversion element 11 turns into P polarization substantially, not all become P polarization, and S polarization is mixed.

  The superimposing lens 12 is an optical element for condensing a plurality of partial light beams that have passed through the first lens array 9, the second lens array 10, and the polarization conversion element 11 and superimposing them on the vicinity of the image forming area of the reflective liquid crystal panel 4B. is there. The superimposing lens 12 is disposed so that the optical axis of the superimposing lens 12 and the illumination optical axis 51ax of the blue light illumination device 51 substantially coincide. The superimposing lens 12 may be composed of a compound lens in which a plurality of lenses are combined.

  The yellow light illumination device 52 includes an excitation laser diode array 60, a collimating lens 54, a condensing lens 55, a phosphor substrate 61, a pickup lens 57, a collimating lens 58, and a first lens array 9. And a second lens array 10, a polarization conversion element 11, and a superimposing lens 12. For example, the excitation laser diode array 60 includes 30 excitation laser diodes 62 arranged in an array of 6 × 5. The excitation laser diode 62 emits ultraviolet light or blue light as excitation light for exciting the phosphor. The collimating lens 54 is provided corresponding to each excitation laser diode 62. The phosphor substrate 61 is a substrate in which a phosphor layer that emits yellow light upon receiving excitation light such as ultraviolet light or blue light is formed on the substrate.

  Each excitation light emitted from the excitation laser diode 62 is collimated by the collimating lens 54, then condensed by the condensing lens 55, and irradiated onto the phosphor substrate 61 to form a point light source. The The yellow light LY emitted from each point light source on the phosphor substrate 61 passes through the pickup lens 57 and is collimated by the collimating lens 58 and then enters the first lens array 9.

  The first lens array 9, the second lens array 10, the polarization conversion element 11, and the superimposing lens 12 in the yellow light illumination device 52 are respectively the first lens array 9 and the second lens array 10 in the blue light illumination device 51. Since the configuration is the same as that of the polarization conversion element 11 and the superimposing lens 12, the description thereof is omitted. However, the yellow light illumination device 52 is different in that the illumination optical axis 51ax of the blue light illumination device 51 is changed to the illumination optical axis 52ax.

  The light guide optical system 3B includes a condenser lens 32B, a first diaphragm (incident angle limiting member) 37, a polarization beam splitter (polarization separation element) 28, a second diaphragm 38, and a polarizing plate 34B. .

  The condensing lens 32B converts each partial light beam of the blue light LB collected by the superimposing lens 12 into a light beam substantially parallel to each principal ray. The first stop 37 stops the substantially parallel light beam converted by the condenser lens 32B. As a result, the blue light LB collected by the superimposing lens 12 enters the polarization beam splitter 28 via the condensing lens 32B and the first diaphragm 37. At this time, the illumination light beam from the blue light illumination device 51 is aligned by the polarization conversion element 11 to approximately one type of linearly polarized light (for example, P-polarized light) whose polarization direction is substantially aligned. The passed light passes through the polarization beam splitter 28 and is incident on the blue reflective liquid crystal panel 4B. The other condenser lens 32R and condenser lens 32G are configured in the same manner as the condenser lens 32B.

  The polarization beam splitter 28 is a plate-type polarization beam splitter, and has a configuration in which a polarization separation film is provided on a translucent substrate. The polarization beam splitter 28 has a function of transmitting one polarized light and reflecting the other polarized light. In the present embodiment, the polarization beam splitter 28 has a function of transmitting P-polarized light and reflecting S-polarized light as an example. The second stop 38 stops the S-polarized blue light beam reflected by the polarization beam splitter 28. Thereby, the light narrowed down by the second diaphragm 38 is guided to the blue light optical sensor 36B.

  The polarization beam splitter 28 reflects S-polarized blue light out of the blue light reflected from the reflective liquid crystal panel 4B and transmits P-polarized blue light. Thereby, the S-polarized blue light reflected by the polarization beam splitter 28 is guided to the polarizing plate 34B. The polarizing plate 34B allows only the light polarized in a predetermined direction out of the guided blue light. Thereby, blue light polarized in a predetermined direction is guided to the cross dichroic prism 5. The other polarization beam splitter (polarization separation element) 26 and polarization beam splitter (polarization separation element) 27 are also configured in the same manner as the polarization beam splitter 28 described above.

  As described above, the illumination light beam from the illuminating device 51 for blue light is substantially aligned with the P-polarized light by the polarization conversion element 11, and the blue P-polarized light is transmitted through the polarization beam splitter 28 and is reflected liquid crystal for blue light. Incident on panel 4B. However, in reality, not all the light transmitted through the polarization conversion element 11 is converted to P-polarized light, but S-polarized light is also mixed. Therefore, the S-polarized light incident on the polarization beam splitter 28 is reflected by the polarization beam splitter 28. A blue light optical sensor 36B is provided on the S-polarized light path reflected by the polarization beam splitter 28 in the blue light path.

  The light guide optical system 3R includes a condenser lens 32R, a first diaphragm 37, a polarization beam splitter (polarization separation element) 26, a second diaphragm (incident angle limiting member) 38, and a polarizing plate 34R. .

  The condenser lens 32R converts each partial light beam of the red light LR that has passed through the dichroic mirror 25 into a light beam that is substantially parallel to each principal ray. The first stop 37 stops the substantially parallel light beam converted by the condenser lens 32R. As a result, the red light LR that has passed through the dichroic mirror 25 enters the polarization beam splitter 26 via the condenser lens 32R and the first diaphragm 37. At this time, since the illumination light beam from the yellow light illumination device 52 is aligned with approximately one type of linearly polarized light (for example, P-polarized light) whose polarization directions are substantially aligned by the polarization conversion element 11, the condenser lens 32 </ b> R is provided. The passed light passes through the polarization beam splitter 26 and is incident on the reflective liquid crystal panel 4R for red light.

  The polarization beam splitter 26 has a function of transmitting P-polarized light and reflecting S-polarized light as an example. The second stop 38 stops the light beam of S-polarized color light reflected by the polarization beam splitter 26. Thereby, the light narrowed down by the second diaphragm 38 is guided to the red light optical sensor 36R.

  The polarization beam splitter 26 reflects S-polarized red light out of the red light reflected from the reflective liquid crystal panel 4R and transmits P-polarized red light. Accordingly, the P-polarized red light reflected by the polarization beam splitter 26 is guided to the polarizing plate 34R. The polarizing plate 34R allows only the light polarized in a predetermined direction out of the guided red light. Thereby, red light polarized in a predetermined direction is guided to the cross dichroic prism 5.

  The light guide optical system 3G includes a condenser lens 32G, a first diaphragm 37, a polarization beam splitter (polarization separation element) 27, a second diaphragm (incident angle limiting member) 38, and a polarizing plate 34G. .

  The condensing lens 32G converts each partial light beam of the green light LG reflected by the dichroic mirror 25 into a light beam substantially parallel to each principal ray. The first stop 37 stops the substantially parallel light flux converted by the condenser lens 32G. As a result, the green light LG reflected by the dichroic mirror 25 enters the polarization beam splitter 27 via the condenser lens 32G and the first diaphragm 37. At this time, the illumination light beam from the yellow light illumination device 52 is aligned with approximately one type of linearly polarized light (for example, P-polarized light) having substantially the same polarization direction by the polarization conversion element 11, so The passed light passes through the polarization beam splitter 27 and is incident on the green reflective liquid crystal panel 4G.

  For example, the polarization beam splitter 27 transmits P-polarized light and reflects S-polarized light. The second stop 38 stops the S-polarized green light beam reflected by the polarization beam splitter 27. Thereby, the light narrowed down by the second diaphragm 38 is guided to the green light optical sensor 36G.

  The polarization beam splitter 27 reflects S-polarized green light out of the green light reflected from the reflective liquid crystal panel 4G and transmits P-polarized green light. Thereby, the S-polarized green light reflected by the polarization beam splitter 27 is guided to the polarizing plate 34G. The polarizing plate 34G allows only the light polarized in a predetermined direction out of the guided green light. Thereby, green light polarized in a predetermined direction is guided to the cross dichroic prism 5.

  The reflective liquid crystal panel 4R, the reflective liquid crystal panel 4G, and the reflective liquid crystal panel 4B are light modulators that modulate illumination light according to an image signal and emit image light representing an image. The reflective liquid crystal panel 4 </ b> R and the reflective liquid crystal panel 4 </ b> G are light modulation units to be illuminated by the yellow light illumination device 52. The reflective liquid crystal panel 4 </ b> B is a light modulation unit to be illuminated by the blue light illumination device 51. The reflective liquid crystal panel 4R, the reflective liquid crystal panel 4G, and the reflective liquid crystal panel 4B correspond to the “image light emitting portion” of the present invention.

  The reflective liquid crystal panel 4R, the reflective liquid crystal panel 4G, and the reflective liquid crystal panel 4B include a pair of substrates that sandwich the liquid crystal layer and a reflective layer (or reflective electrode) that is disposed on the substrate side facing the light incident side substrate. ) And. Further, as shown in FIG. 1, on the surface opposite to the light incident side of the reflective liquid crystal panel 4R, the reflective liquid crystal panel 4G, and the reflective liquid crystal panel 4B, the radiation fins 33R, the radiation fins 33G, and the radiation fins 33B, respectively. Is arranged.

  The cross dichroic prism 5 is an optical element that combines image light modulated for each color light emitted from the polarizing plate 34R, the polarizing plate 34G, and the polarizing plate 34B to form image light representing a color image. The cross dichroic prism 5 has a substantially square shape in plan view in which four right angle prisms are bonded together, and a dielectric multilayer film is formed on the substantially X-shaped interface in which the right angle prisms are bonded together. The dielectric multilayer film formed at one of the substantially X-shaped interfaces reflects the blue light LB, and the dielectric multilayer film formed at the other interface reflects the red light LR. By these dielectric multilayer films, the blue image light and the red image light are bent and aligned with the traveling direction of the green image light that passes through the cross dichroic prism 5, thereby synthesizing the three color image lights. . The color image formed by the image light emitted from the cross dichroic prism 5 is enlarged and projected by the projection optical system 6 to form an image on the screen SCR.

  The control unit 63 emits a blue laser diode (BLD) 59 that is a point light source constituting the blue laser diode array 53 as a light source of blue (B) light in accordance with information set by a control signal (not shown). The adjustment of the amount of light is controlled, and the adjustment of the amount of light emitted by the excitation laser diode 62 which is a point light source constituting the excitation laser diode array 60 as a light source of yellow (Y) light is controlled. The control unit 63 controls the adjustment of the amount of light emitted by the blue laser diode 59 according to the intensity of light detected by the blue light sensor 36B, or the red light sensor 36R or the green light sensor. The adjustment of the light amount of the excitation laser diode 62 can also be controlled in accordance with the intensity of light detected by 36G. In addition, the control unit 63 controls the reflectance of each pixel of the reflective liquid crystal panels 4R, 4G, and 4B according to a video signal (not shown). The video signal input to the control unit 63 may be a plurality of image signals indicating images of successive frames or an image signal indicating an image of one frame.

  FIG. 2 is a schematic block diagram showing the configuration of the control unit of FIG. In the figure, in addition to the control unit 63 and the reflective liquid crystal panels 4R, 4G, and 4B, a blue laser diode (BLD) 59, which is a point light source that constitutes a blue (B) light source, and yellow (Y ) An excitation laser diode (excitation LD) 62, which is a point light source that constitutes a light source, is shown.

  The control unit 63 includes an image processing unit 64 and liquid crystal drive units 66R, 66G, and 66B as an image control unit, and a drive processing unit 65, a PWM signal generation unit 67, and an excitation laser diode as a light source control unit. A drive unit 68 and a blue laser diode drive unit 69 are provided. The output of the laser diode as the light source is, for example, brightness. The brightness corresponds to, for example, light intensity (light quantity).

  The image processing unit 64 applies various image quality correction processes to the received video signal, and outputs the signals after the image quality correction process to the liquid crystal driving units 66R, 66G, and 66B. Accordingly, the liquid crystal driving units 66R, 66G, and 66B are included in the video signal by controlling the reflectance of the reflective liquid crystal panels 4R, 4G, and 4B using the signals input from the image processing unit 64, respectively. The image light of the color according to the image signal of each color is emitted.

  The drive processing unit 65 executes processing and control for dimming control of the blue light source by the blue laser diode 59 and the yellow light source by the excitation laser diode 62 according to the received control signal. Here, the control signal is a signal including information relating to user settings input by the user or display of the color mode on a menu screen (not shown) displayed on the screen SCR (FIG. 1). Thereby, the light quantity of the light source 71 is controlled based on the user setting or the brightness and color setting linked with the color mode. Note that the drive processing unit 65A can also perform dimming control adapted to the brightness (gradation value) of the received video signal. It is also possible to perform dimming control according to the intensity of light detected by a red light sensor 36R, a green light sensor 36G, and a blue light sensor 36B (not shown).

  The drive processing unit 65 derives the excitation drive current value CY of the excitation laser diode 62 corresponding to the brightness setting value and the excitation duty value DutyY for PWM driving. Similarly, the drive processing unit 65 derives a blue drive current value CB for the blue laser diode 59 and a blue duty value DutyB for PWM drive.

  The PWM signal generation unit 67 performs PWM (corresponding to blinking of the excitation laser diode 62 from the excitation duty value DutyY based on the synchronization signal (vertical synchronization signal Vsync of the video signal) supplied from the image processing unit 64. A PWMY signal subjected to pulse width modulation is generated, and the generated PWMY signal is output to the excitation laser diode driving unit 68. Similarly, the PWM signal generation unit 67 generates a PWMB signal that is PWM (pulse width modulated) from the blue duty value DutyB so as to correspond to the blinking of the blue laser diode 59, and generates the generated PWMB signal. Is output to the blue laser diode driver 69.

  The excitation laser diode drive unit 68 performs ON / OFF control of the excitation laser diode 62 based on the waveform of the PWMY signal. When the excitation duty value DutyY is 100%, the excitation laser diode driving unit 68 performs constant current driving with the excitation drive current value CY without performing the ON / OFF control of the excitation laser 62. Can do. The blue laser diode driving unit 69 performs ON / OFF control of the blue laser diode 59 based on the waveform of the PWMB signal. When the blue duty value DutyB is 100%, the blue laser diode driving unit 69 can perform constant current driving with the blue driving current value CB without performing ON / OFF control of the blue laser diode 59. .

  As can be seen from the above description, the drive processing unit 65, the PWM signal generation unit 67, the excitation laser diode drive unit 68, and the blue laser diode drive unit 69 correspond to the light source control unit of the present invention.

A2. PWM signal:
The PWMY signal and the PWMB signal generated in the PWM signal generation unit 67 have the characteristics described below. Hereinafter, the PWMY signal and the PWMB signal are also simply referred to as “PWM signals” unless they are particularly distinguished.

  FIG. 3 is an explanatory diagram showing the PWMY signal and the PWMB signal generated by the PWM signal generation unit 67. FIG. 3A shows the waveform of the vertical synchronization signal Vsync included in the video signal, and FIG. 3B shows the supply to the reflective liquid crystal panels 4R, 4G, and 4B via the liquid crystal drivers 66R, 66G, and 66B. The waveform of the timing signal DY for driving the liquid crystal panel is shown. FIG. 3C shows the excitation duty value DutyY and the blue duty value DutyB. FIG. 3D shows the PWMY signal, and FIG. 3E shows the PWMB signal.

  The frequency fv of the vertical synchronization signal Vsync is 120 Hz. This is an example in which the image processing unit 64 converts a video signal based on a vertical synchronization signal of 60 Hz into a video signal based on a vertical synchronization signal of 120 Hz and processes it. The timing signal DY for driving the liquid crystal panel is 240 Hz, which is twice the frequency of the vertical synchronization signal Vsync, and the reflective liquid crystal panels 4R, 4G, 4B are driven at a refresh rate twice that of the vertical synchronization signal Vsync. The This is because the liquid crystal panel is driven twice with the positive polarity and the negative polarity with respect to the same video signal in one period (also referred to as “frame period”) of the vertical synchronization signal Vsync (also referred to as “frame period”). This is to suppress the burn-in of the liquid crystal panel.

  As an example, the PWM excitation duty value DutyY and the blue duty value DutyB are the same value and change from 30% to 50% at the generation timing of the vertical synchronization signal Vsync. When the image processing apparatus obtains an appropriate light amount for each frame based on the result of analyzing the video signal for each frame, the PWM duty value corresponding to the light amount is set as the excitation duty value DutyY and the blue duty value DutyB. can do.

  The PWMY signal and the PWMB signal are repeatedly turned on and off eight times in a frame period in which the frequency (also referred to as “frame frequency”) fv of the vertical synchronization signal Vsync is 120 Hz, and each frame period (also referred to as “frame period”). Are composed of eight PWM pulses P1 to P8. The PWM pulses P1 to P8 of the PWMY signal have frequencies f1 to f8 that are changed around a reference frequency f0 (= 120 Hz × 8 = 960 Hz) that is eight times the frame frequency fv (= 120 Hz), and an average of them. The value is the reference frequency f0, and the total period of each period T1 (= 1 / f1) to T8 (= 1 / f8) is set to coincide with the frame period. Note that the pulse widths of the PWM pulses P1 to P8 when the excitation duty value DutyY and the blue duty value DutyB are changed from 30% to 50% change according to the duty value, but the respective frequencies f1 to f1. There is no change in the periods T1 to T8 corresponding to f8. The PWM pulses P1 to P8 of the PWMB signal are also set to be the same as the PWMY signal. In this example, the frequency f1 of the first PWM pulse P1 is 1.0 times (reference, 0%), the frequency f2 of the second PWM pulse P2 is 1.1 times (+ 10%), and the third PWM pulse P3. The frequency f3 of the fourth PWM pulse is 1.2 times (+ 20%), the frequency f4 of the fourth PWM pulse is 1.05 times (+ 5%), and the frequency f5 of the fifth PWM pulse P5 is 1.0 times (reference, 0%) ), The frequency f6 of the sixth PWM pulse P6 is 0.9 times (−10%), the frequency f7 of the seventh PWM pulse P7 is 0.8 times (−20%), and the frequency of the eighth PWM pulse P8. f8 is set to 0.95 times (−5%). In the state where a certain duty value is set, even if the frequency of each pulse, that is, the cycle is set to be different as described above, the lighting (on) duty in each cycle is set. The duty value is set to be equal.

  As described in the conventional example, by changing the cycle (frequency) of the PWM pulse, it is possible to suppress scroll noise caused by PWM control of the light source. However, since the repetition period of the fluctuation of the PWM pulse period is not related to the drive period (frame period) of the liquid crystal panel, the frame frequency (frame period) and the repetition frequency of fluctuation of the PWM pulse period (variation repetition period) Similarly, scroll noise is generated on the screen due to the interference. On the other hand, in the case of the PWM signal, since the repetition cycle of the fluctuation of the PWM pulse cycle is synchronized with the frame cycle, it is between the frame frequency and the repetition frequency of the fluctuation of the PWM pulse cycle. It is possible to make scroll noise due to interference inconspicuous.

  Also, by changing the frequency of the PWM pulse within the frame period with respect to the reference frequency, the frequency of switching of the light source by the PWM pulse within the frame period can be dispersed, so that the energy of noise generated by the switching of the light source Can be dispersed. As a result, the vibration of the light source and other associated circuits (light source, etc.) generated by PWM control in which the switching of the light source is performed at the same frequency, as described in the problem, is suppressed, and the noise generated due to the vibration, image quality degradation, etc. Can be suppressed. In addition, noise energy concentration due to continuous generation of PWM pulses with the same frequency (period) and switching noise of the same frequency in time also causes vibration and noise due to vibration and image quality degradation. obtain. Therefore, it is preferable that the PWM pulse having the same frequency (cycle) has a variation pattern that does not occur continuously (adjacent in time).

  FIG. 4 is an explanatory diagram showing the PWMY signal and the PWMB signal when the light source is intermittently lit during the frame period. 4A to 4E show the vertical synchronization signal Vsync, the liquid crystal panel driving timing signal DY, the excitation duty value DutyY, and the blue duty, as in FIGS. 3A to 3E. A value DutyB, a PWMY signal for driving the excitation laser diode 62, and a PWMB signal for driving the blue laser diode 59 are shown. FIG. 4F shows an MSK signal indicating a non-lighting period of the excitation laser diode 62 and the blue laser diode 59 as light sources. As shown in FIG. 4F, the non-lighting period is set to a certain period from the beginning of the frame period (frame period) represented by the period of the vertical synchronization signal Vsync. During this non-lighting period, the PWMY signal and PWMB signal stop outputting PWM pulses, and the light source is not lighted. The PWMY signal in FIG. 4D and the PWMB signal in FIG. 4E show an example in which the output of the first PWM pulse P1 to the fourth PWM pulse P4 is stopped.

  As described above, based on the two-cycle timing signal DY generated in one frame period, display by driving the liquid crystal panel with the same video signal is executed twice. In the case of 3D display or moving image display, the first period of the timing signal DY is driven with a video signal that is different from the second period of the previous frame period. Crosstalk can occur. For example, in the case of 3D display, since the video for the left eye and the video for the right eye are switched every frame period, the video for the left eye and the video for the right eye in the first period of the timing signal DY at the beginning of the frame period. Video crosstalk can occur. Further, in the case of moving image display, since the video changes every frame period, video blur due to video crosstalk that changes in the first period of the timing signal DY at the beginning of the frame period may occur.

  Therefore, in the first period of the timing signal DY at the beginning of the frame period, the output of the PWM pulse is stopped and the light source is turned off in a certain period in which crosstalk can occur. Visible motion blur can be suppressed. In this example, among the eight PWM pulses P1 to P8 set to the same frequency as in FIG. 3, the output of the PWM pulses P1 to P4 corresponding to the non-lighting period is stopped. The frequency of the PWM pulse is set to a pattern in which the frequency of the PWM pulse is changed around the reference frequency f0 and the average value thereof becomes the reference frequency f0, and vibration of the light source or the like is effectively suppressed, Noise and image quality degradation caused by vibration may be suppressed.

  FIG. 5 is an explanatory diagram showing the case where the PWMY signal and the PWMB signal have different cycle fluctuation states of the plurality of PWM pulses within the frame period. 5 (a) to 5 (e) are similar to FIGS. 3 (a) to 3 (e) in that the vertical synchronization signal Vsync, the liquid crystal panel driving timing signal DY, the excitation duty value DutyY, and the blue duty A value DutyB, a PWMY signal for driving the excitation laser diode 62, and a PWMB signal for driving the blue laser diode 59 are shown. However, the eight PWM pulses P1 to P8 in one frame period of the PWMY signal in FIG. 5D have periods T1 to T8 (frequency f1 to f8), whereas the PWMB signal in FIG. Eight PWM pulses P1 to P8 in one frame period have periods T5 to T8 (frequency f5 to f8) in the first to fourth PWM pulses P1 to P4 and periods in the fifth to eighth PWM pulses P5 to P8. T1 to T4 (frequency f1 to f4). This can be said that the fluctuation state of the PWM pulse period of the PWMB signal is out of order of fluctuation with respect to the fluctuation state of the PWM pulse period of the PWMY signal. It can also be said that the variation state of the PWM pulse period of the PWMB signal is different from the variation state of the PWM pulse period compared to the variation state of the PWMY signal period. Specifically, in the PWMY signal, the first to fourth PWM pulses P1 to P4 have a cycle T1 to a cycle T4, and the fifth to eighth PWM pulses P5 to P8 have a cycle T5 to T8. On the other hand, the PWMB signal has the first to fourth PWM pulses P1 to P4 in the cycle T5 to the cycle T8, and the fifth to eighth PWM pulses P5 to P8 in the cycles T1 to T4. It is a combination of opposite fluctuations. In this case, for example, when focusing on the first to fourth PWM pulses P1 to P4, the PWMY signal is a pulse having a period T1 to T4, and the PWMB signal is a combination of pulses having a period T5 to T8. A combination of signal pulses forms eight types of pulses having a period T1 to T8. The same applies to the fifth to eighth PWM pulses P5 to P8.

  In the case of the PWMY signal and PWMB signal in FIG. 5, since the repetition cycle of the fluctuation of the PWM pulse cycle is synchronized with the frame cycle, similarly to the PWMY signal and PWMB signal in FIG. 3, the frame frequency and the PWM pulse cycle It is possible to make the scroll noise inconspicuous due to interference with the repetition frequency of the fluctuation. Further, since the switching frequency of the light source by the PWM pulse within the frame period can be dispersed, it is possible to suppress the vibration of the light source and the like, and to suppress noise and image quality degradation caused by the vibration. Furthermore, since the period (frequency) of the PWM pulse set in the same time is distributed so as to be different for each light source, the energy of the switching noise can be further distributed as compared with the case of FIG. As a result, it is possible to further suppress the vibration of the light source and the like, and to further increase the suppression effect of noise and image quality degradation caused by the vibration.

B. Second embodiment:
B1. Projector configuration:
FIG. 6 is a schematic block diagram showing the configuration of the projector in the second embodiment. The projector 50b includes a red light illumination device 51R, a green light illumination device 51G, a blue light illumination device 51B, condenser lenses 32bR, 32bG, and 32bB, a transmissive liquid crystal panel 4bR, 4bG, and 4bB, and a cross. A dichroic prism 5, a projection optical system 6, and a control unit 63b are provided. In addition, the same code | symbol is attached | subjected to the same structural member as the projector 50 of 1st Embodiment.

  The blue light illumination device 51B is the same as the blue light illumination device 51 (see FIG. 1) of the first embodiment. The red light illuminating device 51R is an illuminating device using a red laser diode in place of the blue laser diode 59 of the blue light illuminating device 51, and the green light illuminating device 51G is a blue laser diode 59 of the blue light illuminating device 51. It is an illuminating device using a green laser diode instead. The other configurations of the red light illumination device 51R and the green light illumination device 51G other than the laser diodes are exactly the same.

  The red illumination light emitted from the red light illumination device 51R is incident on the transmissive liquid crystal panel 4bR via the condenser lens 32bR. Similarly, the green illumination light emitted from the green light illumination device 51G is incident on the transmissive liquid crystal panel 4bG via the condenser lens 32bG. Similarly, the blue illumination light emitted from the blue light illumination device 51B is incident on the transmissive liquid crystal panel 4bB via the condenser lens 32bB.

  The transmissive liquid crystal panel 4bR is a light modulation unit that modulates incident red light according to an image signal, and emits image light representing a red image. Similarly, the transmissive liquid crystal panel 4bG is a light modulation unit that modulates incident green light according to an image signal, and emits image light representing a green image. Similarly, the transmissive liquid crystal panel 4bB is a light modulation unit that modulates incident blue light according to an image signal, and emits image light representing a blue image. The cross dichroic prism 5 receives red image light emitted from the transmissive liquid crystal panel 4bR, green image light emitted from the transmissive liquid crystal panel 4bG, and blue image light emitted from the transmissive liquid crystal panel 4bB. Synthesize. The projection optical system 6 projects image light representing a color image synthesized by the cross dichroic prism 5 onto a projection surface such as a screen SCR. The transmissive liquid crystal panels 4bR, 4bG, and 4bB correspond to the “image light emitting portion” of the present invention.

  FIG. 7 is a schematic block diagram showing the configuration of the control unit in FIG. In the figure, in addition to the control unit 63b and the transmissive liquid crystal panels 4bR, 4bG, and 4bB, a red laser diode (RLD) 59R of a red laser diode array 53R as a red light source, and a green light source as A green laser diode (GLD) 59G of the green laser diode array 53G and a blue laser diode (BLD) 59B of the blue laser diode array 53B as a blue light source are shown.

  The control unit 63b includes an image control unit and a light source control unit, similarly to the control unit 63 (see FIG. 2) of the first embodiment. Since the image control unit is the same as the control unit 63, the description thereof is omitted. Regarding the light source control unit, instead of the drive processing unit 65, the PWM signal generation unit 67, the excitation laser diode drive unit 68, and the blue laser diode drive unit 69 of the control unit 63, a drive processing unit 65b, a PWM signal generation unit 67b. , A red laser diode driver 69R, a green laser diode driver 69G, and a blue laser diode driver 69B.

  The blue laser diode drive unit 69B is the same as the blue laser diode drive unit 69, and performs ON / OFF control of the blue laser diode 59B based on the blue drive current value CB and the waveform of the PWMB signal. Similarly, the red laser diode driver 69R performs ON / OFF control of the red laser diode 59R based on the red drive current value CR and the waveform of the PWMR signal. Similarly, the green laser diode drive unit 69G performs ON / OFF control of the green laser diode 59G based on the green drive current value CG and the waveform of the PWMG signal.

  Similar to the PWM signal generation unit 67, the PWM signal generation unit 67b generates a PWMB signal from the blue duty value DutyB based on the synchronization signal, and further generates a PWMR signal from the red duty value DutyR and a green duty value DutyG. Generates a PWMG signal.

  Similarly to the drive processing unit 65, the drive processing unit 65b derives the blue drive current value CB of the blue laser diode 59B corresponding to the brightness setting value and the blue duty value DutyB for PWM drive. Further, the drive processing unit 65b derives the red drive current value CR of the red laser diode 59R corresponding to the brightness setting value and the red duty value DutyR for PWM driving, and the green color corresponding to the brightness setting value. A green driving current value CG of the laser diode 59G and a green duty value DutyG for PWM driving are derived.

B2. PWM signal:
FIG. 8 is an explanatory diagram illustrating a case where the PWMR signal, the PWMG signal, and the PWMB signal generated in the PWM signal generation unit 67b have different fluctuation states of the periods of the plurality of PWM pulses in the frame period. FIGS. 8A and 8B show the vertical synchronization signal Vsync and the timing signal DY for driving the liquid crystal panel, as in FIGS. 5A and 5B. FIG. 8C shows an example in which the red duty value DutyR, the green duty value DutyG, and the blue duty value DutyB are set to a constant 30%. FIG. 8D shows the PWMR signal, FIG. 8E shows the PWMG signal, and FIG. 8F shows the PWMB signal.

  The PWMR signal, the PWMG signal, and the PWMB signal are repeatedly turned on and off eight times during the frame period in which the frame frequency fv is 120 Hz, similarly to the PWMY signal in FIG. 5D and the PWMB signal in FIG. Each frame period (frame period) is composed of eight PWM pulses P1 to P8. Each PWM pulse P1 to P8 of the PWMR signal has frequencies f1 to f8 changed around the reference frequency f0 (= 960 Hz) as in the PWMY signal of FIG. 5D, and the average value thereof is the reference. The frequency is f0, and the total period of each period T1 (= 1 / f1) to T8 (= 1 / f8) is set to coincide with the frame period. On the other hand, the PWMG signal has a period T1 to T6 (frequency f1 to f6) in the third to eighth PWM pulses P3 to P8 and a period T7 and T8 (frequency in the first to second PWM pulses P1 and F6). f7, f8), and the order of variation is shifted by two pulses with respect to the PWMR signal. Similarly to the PWMB signal of FIG. 5 (e), the PWMB signal has first to fourth PWM pulses P1 with the fifth to eighth PWM pulses P5 to P8 having periods T1 to T4 (frequency f1 to f4). ~ P4 has a period T5 to T8 (frequency f5 to f8), the order of fluctuation is shifted by 4 pulses with respect to the PWMR signal, and the order of fluctuation is shifted by 2 pulses with respect to the PWMG signal. Yes. That is, the PWMR signal, the PWMG signal, and the PWMB signal are set such that the cycle variation states are shifted from each other.

  In the case of the PWMR signal, the PWMG signal, and the PWMB signal in FIG. 8, as in the case of the PWMY signal and the PWMB signal in FIG. 5, the repetition period of the fluctuation of the PWM pulse period is synchronized with the frame period. Scroll noise due to interference with the repetition frequency of the fluctuation of the PWM pulse cycle can be made inconspicuous. Further, since the switching frequency of the light source by the PWM pulse within the frame period can be dispersed, the vibration of the light source (or a light source device including other accompanying circuits) is suppressed, and noise and image quality deterioration caused by the vibration are suppressed. Etc. can be suppressed. Furthermore, since the period (frequency) of the PWM pulse set in the same time is different for each light source, the energy of the switching noise generated when each light source is in the same fluctuation state as shown in FIG. Can be further dispersed. Thereby, it is possible to further suppress the vibration of the light source (or the light source device including other accompanying circuits), and to further enhance the suppression effect of noise and image quality degradation caused by the vibration.

  FIG. 9 is an explanatory diagram illustrating another example in which the PWMR signal, the PWMG signal, and the PWMB signal generated by the PWM signal generation unit 67b are different in the variation state of the periods of the plurality of PWM pulses in the frame period. 9 (a) to 9 (f) are similar to FIGS. 8 (a) to 8 (f), the vertical synchronization signal Vsync, the timing signal DY for driving the liquid crystal panel, the red duty value DutyR, and the green duty value. DutyG, blue duty value DutyB, PWMR signal, PWMG signal, and PWMB signal are shown.

  The PWMR signal, the PWMG signal, and the PWMB signal are different from the PWMR signal, the PWMG signal, and the PWMB signal in FIGS. 8D to 8F, and the number of light sources (red in this example) in the frame period with a frame frequency fv of 120 Hz. The lighting device 51R for light, the lighting device 51G for green light, and the lighting device 51B for blue light (a total of three) are turned on and off 9 times as many times (3 times in this example), every frame period Are composed of nine PWM pulses P1 to P9. The PWM pulses P1 to P9 of the PWMR signal have frequencies f1 to f9 that are changed around the reference frequency f0 (= 120 × 9 = 1080 Hz), and their average value becomes the reference frequency f0, and each period T1 The total period of (= 1 / f1) to T9 (= 1 / f9) is set to coincide with the frame period. On the other hand, the PWMG signal includes the fourth to ninth PWM pulses P4 to P9 having the periods T1 to T6 (frequency f1 to f6) and the first to third PWM pulses P1 to P3 having the periods T7 to T9 (frequency). f7 to f9), and the order of fluctuation is shifted by 3 pulses from the PWMR signal. Further, the PWMB signal has the seventh to ninth PWM pulses P7 to P9 having the periods T1 to T3 (frequency f1 to f3) and the first to sixth PWM pulses P1 to P6 having the periods T4 to T9 (frequency f4 to f9). ), The order of variation is shifted by 6 pulses with respect to the PWMR signal, and the order of variation is shifted by 3 pulses with respect to the PWMG signal. Further, the PWMR signal, the PWMG signal, and the PWMB signal are set such that the fluctuation states of the periods are shifted from each other by the number of equally spaced pulses (three pulses in this example). It can be said that this setting is different in the combination of fluctuations in the period of the PWM pulse between the PWMR signal, the PWMG signal, and the PWMB signal. Specifically, the PWMY signal includes the first to third PWM pulses P1 to P3 in the periods T1 to T3, the fourth to sixth PWM pulses P4 to P6 in the periods T4 to T6, and the seventh to ninth. PWM pulses P7 to P9 have periods T7 to T9. On the other hand, the PWMG signal includes the first to third PWM pulses P1 to P3 in the periods T7 to T9, the fourth to sixth PWM pulses P4 to P6 in the periods T1 to T3, and the seventh to ninth. PWM pulses P7 to P9 have periods T4 to T6. The PWMB signal includes the first to third PWM pulses P1 to P3 in the periods T4 to T6, the fourth to sixth PWM pulses P4 to P6 in the periods T7 to T9, and the seventh to ninth PWM pulses. P7 to P9 are periods T1 to T3. In this case, for example, focusing on the first to third PWM pulses P1 to P3, the PWMR signal is a pulse having a period T1 to T3, the PWMG signal is a pulse having a period T7 to T9, and the PWMB signal is having a period T4 to T6. This is a combination of pulses, and the pulses of three PWM signals are combined to form pulses of nine types of periods T1 to T9. The same applies to the fourth to sixth PWM pulses P4 to P6 and the seventh to ninth PWM pulses P7 to P9.

  In the case of the PWMR signal, the PWMG signal, and the PWMB signal in FIG. 9 as well, the repetition cycle of the fluctuation of the PWM pulse cycle is synchronized with the frame cycle, so that the frame frequency and the PWM pulse cycle are the same. It is possible to make the scroll noise inconspicuous due to interference with the repetition frequency of the fluctuation. Moreover, since the switching frequency of the light source by the PWM pulse within the frame period can be dispersed, the vibration of the light source and other accompanying circuits (light source, etc.) is suppressed, and the noise and image quality deterioration caused by the vibration are suppressed. Etc. can be suppressed. Furthermore, since the period (frequency) of the PWM pulse set in the same time is different for each light source, the energy of the switching noise generated when each light source is in the same fluctuation state as shown in FIG. Can be further dispersed. As a result, it is possible to further suppress the vibration of the light source and the like, and to further increase the suppression effect of noise and image quality degradation caused by the vibration. The energy of the switching noise can be further dispersed than in the case of FIG. In particular, in the case of this example, the dispersion effect is higher than in the case of FIG. 8, and it is possible to further suppress the vibration of the light source and the like, and to further increase the suppression effect of noise and image quality degradation caused by the vibration. Become.

C. Variation:
(1) Modification 1
Note that the optical configuration of the above embodiment is not limited to the optical configuration of FIGS. For example, in the optical configuration of the first embodiment (FIG. 1), the three illumination devices of the red light illumination device, the green light illumination device, and the blue light illumination device are used as in the optical configuration of the second embodiment. In the optical configuration of the second embodiment (FIG. 5), yellow light is emitted using two illumination devices, a yellow light illumination device and a blue light illumination device, as in the optical configuration of the first embodiment. It is good also as an optical structure which isolate | separates into red light and green light. Further, for example, the phosphor substrate 61 of the yellow light illumination device 52 may be of a reflective type, and various optical configurations such as the presence / absence of a diffusion plate and the presence / absence of a polarization separation element are merely design matters. It is not limited to.

  Moreover, in the said embodiment, although it has set as the structure which used the laser diode as a solid light source (semiconductor light source), the structure using LED may be sufficient. Further, a configuration may be used in which one laser diode or one LED is used as a light source that emits white light, and the white light is separated into three colors of red, green, and blue by a dichroic mirror or the like. The light source that emits white light by the laser diode is, for example, yellow (Y) light obtained by exciting the phosphor substrate with blue light emitted by the blue laser diode, and blue (B) light that does not excite the phosphor substrate. , Can be realized. Moreover, although the light source which emits the light of a several color was demonstrated as an example for the some light source, it is good also considering all the plurality of light sources as a light source of white light or specific color light.

  Further, the light modulation unit (image light emitting unit) may be a DMD (Digital Mirror Device, digital mirror device) as well as a transmissive or reflective liquid crystal panel.

(2) Modification 2
In the PWM signal of the above embodiment, the case where the repetition period of the fluctuation of the plurality of PWM pulses coincides with the frame period has been described as an example. You may make it a frame period correspond. That is, it suffices if the repetition cycle of the fluctuations of the plurality of PWM pulses is synchronized with the frame cycle. However, the number of PWM pulses included in the frame period is between the frame frequency and the influence of flicker noise of illumination light generated due to the frequency of the PWM pulse and the repetition frequency of the fluctuation of the PWM pulse cycle. It is preferably set in consideration of the influence of scroll noise due to interference, the influence on the vibration of the light source (or other light source device including an accompanying circuit), and the like. It should be noted that the coincidence between the integer multiple of the repetition period of the variation of the period of the plurality of PWM pulses and the frame period is an allowable range up to an error corresponding to ± 2 Hz at the frequency represented by the reciprocal of each.

  Further, the fluctuation state of the period (frequency) of the plurality of PWM pulses is not limited to the above-described embodiment, and can be various patterns, which are changed around the reference period (reference frequency). In addition, it is only necessary that the average value thereof matches the reference frequency, and the sum of the periods of the respective PWM pulses is synchronized with the frame period.

(3) Modification 3
In FIG. 4 of the first embodiment, the output of the PWM pulse is stopped in a fixed period at the beginning of the frame period. For example, when changing the video signal in the second period of the timing signal DY, You may make it stop the output of a PWM pulse in the last fixed period of a frame period. Alternatively, the light source may be turned on by outputting a PWM pulse in a certain period at the beginning of the frame period, and the output of the PWM pulse may be stopped and the light source may be turned off in the subsequent period. That is, the output of the PWM pulse in a certain period of the frame period may be stopped. Note that the modification related to stopping the output of the PWM pulse can be similarly applied to the second embodiment.

(4) Modification 4
In the above embodiment, the laser diode drive unit drives the laser diode based on the drive current value output from the drive processing unit and the PWM signal generated by the PWM signal generation unit, but is output from the drive processing unit. The laser diode may be driven based on the drive voltage value and the PWM signal.

(5) Modification 5
The above embodiment has been described by taking a projector as an example, but it can also be applied to a general image display apparatus that does not include a projection optical system.

(6) Modification 6
Various controls of the control unit 63 and the control unit 63b are executed by recording a program for executing each process on a computer-readable recording medium, and causing the computer system to read the program recorded on the recording medium. It may be realized by doing so.

  Here, the “computer system” may include an OS and hardware such as peripheral devices. Further, the “computer system” includes a homepage providing environment (or display environment) if the WWW system is used. “Computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM, a writable non-volatile memory such as a flash memory, a portable medium such as a CD ROM, and a storage such as a hard disk built in a computer system. Refers to the device.

  Further, the “computer-readable recording medium” refers to a volatile memory (for example, DRAM (Dynamic) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. Random Access Memory)) that holds a program for a certain period of time is also included. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  The present invention is not limited to the above-described embodiments and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments and the modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

  3R, 3G, 3B Light guiding optical system 4R, 4G, 4B Reflective liquid crystal panel (light modulation unit, image light emitting unit) 4bR, 4bG, 4bB Transmission type liquid crystal panel (light modulating unit, image light emitting unit) 5 Cross dichroic Prism 6 Projection optical system 9 First lens array 10 Second lens array 11 Polarization conversion element 12 Superposition lens 25 Dichroic mirror 26, 27, 28 Polarization beam splitter (polarization separation element) 32R, 32G, 32B, 32bR, 32bG, 32bB Optical lens 34R, 34G, 34B Polarizing plate 36R Light sensor for red light 36G Light sensor for green light 36B Light sensor for blue light 37 First aperture (incident angle limiting member) 38 Second aperture (incident angle limiting member) 50 , 50b Projector 51 Blue light illumination device 5 R Red light illumination device 51G Green light illumination device 51B Blue light illumination device 52 Yellow light illumination device 53 Blue laser diode array 53R Red laser diode array 53G Green laser diode array 53B Blue laser diode array 54 Parallelizing lens 55 Optical lens 56 Diffuser plate 57 Pickup lens 58 Parallelizing lens 59 Blue laser diode 59R Red laser diode 59G Green laser diode 59B Blue laser diode 60 Excitation laser diode array 61 Phosphor substrate 62 Excitation laser diode 63, 63b Controller 64 Image Processing unit 65, 65b Drive processing unit 66R, 66G, 66B Liquid crystal driving unit 67, 67b PWM signal generation unit 68 Appointment laser diode driving unit 69 blue laser diode driving unit 69R red laser diode driving unit 69G green laser diode driving unit 69B blue laser diode driving unit

Claims (7)

A projector,
At least one light source;
A light source controller that controls output of light emitted from the light source by controlling power supplied to the light source by PWM; and
An image light emitting unit that emits image light representing an image according to an image signal using light emitted from the light source;
A projection optical system for projecting the image light;
With
The light source control unit repeatedly performs an operation for generating a plurality of PWM pulses having different periods in one frame period in synchronization with the frame period of the image signal, and supplies power to the light source. A projector characterized by controlling. The projector according to claim 1,
Comprising a plurality of the light sources,
The light source control unit varies a variation state of a cycle of the plurality of PWM pulses for each light source. The projector according to claim 2,
The light source control unit varies a combination of fluctuations in the period of the plurality of PWM pulses for each light source. It is a projector as described in any one of Claim 1- Claim 3, Comprising:
The light source control unit stops the generation of the PWM pulse in a certain period of the frame period. An image display device,
At least one light source;
A light source controller that controls output of light emitted from the light source by controlling power supplied to the light source by PWM; and
An image light emitting unit that emits image light representing an image according to an image signal using light emitted from the light source;
With
The light source control unit repeatedly performs an operation for generating a plurality of PWM pulses having different periods in one frame period in synchronization with the frame period of the image signal, and supplies power to the light source. An image display device characterized by controlling. And at least one light source, an image light emitting unit that emits image light representing an image corresponding to an image signal using light emitted from the light source, and a projection optical system that projects the image light. A projector control method,
When the power supplied to the light source is controlled by PWM, an operation of generating a plurality of PWM pulses having different periods in one frame period in synchronization with the frame period of the image signal is repeatedly performed for each frame period. A method for controlling a projector, comprising: controlling power supplied to the light source. An image display device control method comprising: at least one light source device; and an image light emitting unit that emits image light representing an image corresponding to an image signal using light emitted from the light source device. ,
When the power supplied to the light source is controlled by PWM, an operation of generating a plurality of PWM pulses having different periods in one frame period in synchronization with the frame period of the image signal is repeatedly performed for each frame period. A method for controlling an image display device, comprising: controlling power supplied to the light source.

Images