JP2000131760A - Projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To observe sufficiently clear projected picture even under a bright and wide condition without reducing the service life of a lamp while reducing the power consumption by increasing the driving voltage of the lamp at the point of time when the emitted light quantity of the lamp becomes a prescribed value. SOLUTION: A control section 50 obtains the data of an illuminating section from an emitted light quantity data holding section 51 which holds the data of emitted light quanties at the beginning and the end of a service life as the data of the illuminating section. The section 50 control a first power supply 53 so that the power supply 53 applies a normal voltage to a lamp 1. An emitted light quantity monitor 52 detects the emitted light quantity of the lamp 1, which is kept on, and transmits the detected data to the section 50. The section 50 switches a driving power supply circuit so that a second power supply 54, which supplies larger power than the power supply 53, applies a voltage to the lamp 1 when the emitted light quantity of the lamp 1 being transmitted from the monitor 52 becomes equal to a prescribed value. The value is set to the value which is less than the middle value between the emitted light quantity at the beginning and the emitted light quantity at the end of the service life.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector for illuminating a display means with illumination means comprising a lamp and a reflector to generate a projection image.

[0002]

2. Description of the Related Art Projectors have various uses and conditions for use. For example, it is used for the purpose of being projected on a large screen in a lecture and being observed by a large number of people in a large space, or displayed on a kitchen wall etc. during cooking to observe the cooking method etc. Some are used for the purpose of being performed. As described above, the use of the projector and conditions such as brightness and area are various, and it is desirable that a projected image with sufficient brightness is observed even under special conditions such as bright and wide.

A conventional projector that changes a lamp driving voltage according to the size of a screen is disclosed. According to this projector, even when a projected image is projected over a wide area over a large screen, an image of sufficient brightness can be observed because control is performed to increase the amount of light emission by increasing the driving voltage of the lamp. You.

[0004]

However, it is not economical in terms of power consumption not only to shorten the life of the lamp but also to shorten the life of the lamp, if the driving voltage is changed indiscriminately or the lamp is driven at a high voltage for a long time. .

SUMMARY OF THE INVENTION The present invention provides a projector capable of changing a drive voltage so that a projected image having sufficient brightness can be observed even under special conditions such as a bright or wide area without shortening the life and minimizing power consumption. The purpose is to provide.

[0006]

In order to achieve the above object, the present invention comprises a display means for spatially modulating illumination light based on a video signal to form an optical image for projection, a lamp and a reflector. In a projector having an illumination unit that generates the illumination light, and a projection optical system that projects the optical image on a projection screen, a detection unit that detects a light emission amount of the lamp, and a detection unit that detects a light emission amount of the lamp based on a detection result of the detection unit. When the light emission amount of the lamp becomes a predetermined value lower than an intermediate value between the initial light emission amount at the rated voltage and the light emission amount at the end of the life, control means for controlling to increase the drive voltage is provided.

In the above configuration, the predetermined value is set to a value lower than the intermediate value between the initial light emission amount at the rated voltage and the light emission amount at the end of the life. Even if it is performed, the period of driving at a high voltage does not become extremely long. Therefore, by high voltage driving,
The effect on lamp life and power consumption is small.

[0008]

FIG. 1 is a horizontal sectional view of a projector according to an embodiment of the present invention, which includes an optical axis of a projection lens. The projector 14 includes a lighting unit, a display unit, and a projection unit. The illumination unit performs uniform illumination on the display unit. The display unit outputs illumination light in three colors of red (R), green (G), and blue (B).
After being separated into illumination light of each color and converting the illumination light of each color into an optical image of each color, the optical images of these three colors are combined. The projection unit projects the synthesized optical image.

The display unit includes liquid crystal panels 11R, 11G, and 11B for converting illumination light of each color into an optical image, field lenses 10R, 10G, and 10B provided on the front surface of each of the liquid crystal panels 11R, 11G, and 11B. It has dichroic mirrors 6a and 6b that transmit only light in the region, folding mirrors 7a, 7b and 7c, condenser lens 8, relay lens 9, and cross dichroic prism 12.

The dichroic mirror 6a transmits only the R light. The dichroic mirror 6b transmits only the B light. The R light transmitted through the dichroic mirror 6b is reflected by the return mirror 7a, and illuminates the liquid crystal panel 11R after transmitting through the field lens 10R. The G light reflected by the dichroic mirrors 6a and 6b passes through the field lens 10G, and then passes through the liquid crystal panel 11G.
To illuminate. The B light reflected by the dichroic mirror 6a and transmitted through the dichroic mirror 6b passes through the condenser lens 8, the return mirror 7b, the relay lens 9,
The liquid crystal panel 11B is illuminated via the return mirror 7c and the field lens 10B.

Since the distance between the liquid crystal panel 11B and the light source is different from the distance between the liquid crystal panels 11R and 11G and the light source, the illumination state of the liquid crystal panel 11B is changed using the condenser lens 8 and the relay lens 9 to the liquid crystal panels 11R and 11G. The lighting conditions are the same. Field lens 10R, 10
The liquid crystal panels 11R, 11G, and 11B are telecentricly illuminated by G and 10B.

A bonding surface 12a of the cross dichroic prism 12 is provided with a dichroic coat that reflects only B light, and a bonding surface 12b is provided with a dichroic coat that reflects only R light. Each liquid crystal panel 11R, 1
In 1G and 11B, R, G, and B optical images are formed, respectively. The image light of these optical images is incident on the cross dichroic prism 12, the R light is reflected by the joint surface 12b, and the B light is reflected by the joint surface 12a to be synthesized to form a projection system. Provided to the lens 13. The projection lens projects the incident image light on a screen (not shown).

Next, the lighting section will be described. The illuminating part includes a metal hydrid lamp 1 as a light source, a reflector 2 composed of a spheroidal reflecting mirror that reflects light emitted by the lamp 1 and converts the light into substantially parallel light, and a plurality of lens cells arranged in a matrix. The first lens array 3 and the second
, And a superimposed lens 5.

The first lens array 3 includes a liquid crystal panel 11
R, 11G, and 11B have an optically conjugate relationship. Each lens on the second lens array 4 has an optically conjugate relationship with the lamp 1.

The white light emitted from the lamp 1 is reflected by the reflector 2 and is incident on the first lens array 3. Then, after being split into a plurality of light beams by the first lens array 3, the light beams are incident on the second lens array 4 to form a plurality of light source images. That is, each lens of the second lens array 4 is a secondary light source.

A plurality of light beams emitted from the second lens array 4 are superimposed by a superimposing lens 5 and provided to a display unit. The light beams divided as described above are superimposed on each other to form liquid crystal panels 11R, 11G, and 11B.
, The liquid crystal panels 11R, 11G, and 11B are illuminated with a uniform light amount distribution. Therefore, a color image is projected with a uniform illuminance distribution.

The control section of the projector of this embodiment has voltage switching means for switching the voltage applied to the lamp 1 of the illumination section. Hereinafter, the voltage switching means will be described. FIG. 2 shows a circuit block diagram of a portion related to the voltage switching means. The control unit 50 acquires the data of the light emission amount at the initial and the lifetimes from the light emission amount data holding unit 51 that holds the data of the lighting unit. The light emission amount data holding unit 51 may be configured in the control unit 50. The light emission amount data holding unit 51 may store data of the lighting unit in advance, or may hold data of the lighting unit input by the user.

When the user gives an instruction to turn on the power, the control unit 50 controls the first power supply 53 to apply a voltage to the lamp 1 based on the rated output, and the lamp 1 is turned on. . The light emission amount monitor 52 detects the light emission amount during lighting of the lamp 1 at predetermined intervals, and outputs the detected data to the control unit 5.
Send to 0.

The control unit 50 controls to increase the value of the voltage applied to the lamp 55 when the light emission amount of the lamp 1 transmitted from the light emission amount monitor 52 reaches a predetermined value. Specifically, the driving power supply circuit is switched so that a voltage is applied to the lamp 1 by the second power supply 54 that supplies a power larger than the first power supply 53.

FIG. 3 shows how the amount of light emission changes with the power-on time under the above control. The horizontal axis represents time, and the vertical axis represents the amount of light detected by the light emission monitor 52. The initial light amount is L1, the light amount at the end of the life is L2, and the predetermined value is L4. It is assumed that L3 is a value equal to (L1 + L2) / 2. After the power is turned on, the light emission amount gradually decreases, starting from the initial light emission amount L1. The value of this light emission amount is L
At time t1 when the predetermined value L4 becomes smaller than 3, the control unit 5
0 is a power supply for supplying power to the lamp 1
To the second power source 54.

When switching to the second power supply 54, the applied voltage increases and the amount of light emission increases. Due to the characteristics of the lamp,
As the driving voltage increases, the amount of decrease in the amount of light emission with respect to time increases. Therefore, the slope of the graph of the light emission amount is the first.
Becomes larger than when the power supply 53 is turned on. However, as a result, when driving at a constant voltage without increasing the driving voltage,
In contrast to the case where the lifetime light emission amount is reached at t2, when the control as in the present embodiment is performed, the lifetime light emission amount is reached at t3 longer than t2, and the use time of the lamp becomes longer by t3−t2. .

As for the timing of switching the power supply circuit, if the light emission amount is switched at a time point greater than the intermediate value L3, the time required to reach the lifetime light emission amount becomes earlier by that much, and the life when the power supply circuit is not switched is shortened. May be earlier than the time t2 to reach. In this case, the advantage obtained by switching the power supply circuit is reduced. Therefore, in the present embodiment, the predetermined value L4 is set to a value equal to or less than the intermediate value L3.

In this embodiment, the control is performed using the initial light emission amount and the lifetime light emission amount. However, in a general lamp, the lifetime light emission amount is reduced to half of the initial light emission amount. And the value of Therefore, control may be performed using only the initial light emission amount. In this case, L2
= 1/2 × L1, and L3 = (L1 + L2) / 2 =
(1/2 × L1 + L1) / 2 = 3/4 × L1.

[0024]

According to the projector of the present invention, a bright projected image can be obtained even under special conditions by controlling the driving voltage of the lamp. Further, according to the control in the present invention, since the high voltage driving is not performed for a long time, the influence of the high voltage driving on the life and power consumption of the lamp is small. Conversely, the life of the lamp can be extended. Therefore, it is possible to project a bright image at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a projector according to an embodiment.

FIG. 2 is a circuit block diagram of a portion related to a voltage switching unit of the projector according to the embodiment.

FIG. 3 is a diagram illustrating a state of a change in a light emission amount with respect to a power-on time based on control of a voltage switching unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lamp 2 reflector 6 a, 6 b dichroic mirror 11 RR display panel 11 GG display panel 11 BB display panel 12 cross dichroic prism 13 projection lens 50 control unit 51 luminescence data storage unit 52 luminescence monitor 53 first power supply 54 Second power supply

Continuation of the front page (72) Inventor Masayuki Ueyama 2-3-13 Azuchicho, Chuo-ku, Osaka City Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Akira Kawabata 2-3-13 Azuchicho, Chuo-ku, Osaka Osaka Kokusai Building Minolta Co., Ltd.

Claims (1)

[Claims] 1. A display means for spatially modulating illumination light based on a video signal to form an optical image for projection, an illumination means comprising a lamp and a reflector to generate the illumination light, and a projection screen for displaying the optical image. A projector having a projection optical system for projecting the light on the top thereof, a detecting means for detecting a light emission amount of the lamp, and a light emission amount of the lamp based on a detection result of the detection means. And a control unit for increasing the drive voltage when the light emission amount becomes a predetermined value lower than the intermediate value of the light emission amount.