JP2008193486A - Image display module - Google Patents

Abstract

Disclosed is a flat-type image display module that is small and thin and can be heard with clear sound while observing a display of good quality despite having a speaker.
A sound source unit 4 is disposed in a bottom plate recess 511 in an outer case 5, and a surface emitting backlight 3 and a liquid crystal display panel 2 are sequentially fitted and housed thereon. The sound source unit 4 is a C-type double-sided adhesive spacer in which a piezoelectric diaphragm 41 having a laminated structure in which a piezoelectric ceramic film 411 is sandwiched between a pair of circular electrodes 412 and 413 is disposed over a predetermined range along the periphery together with a holding case 43 that accommodates the piezoelectric diaphragm 41. In a state of being fixed to the light reflecting sheet 35 on the back surface of the surface emitting backlight 3 by 44, it is installed apart from the outer case bottom surface 51. The opening 441 of the C-type double-sided adhesive spacer 44 communicates with the sound guide path 6.
[Selection] Figure 2

Description

  The present invention relates to a planar image display module including a speaker.

  2. Description of the Related Art In recent years, flat image display panels (hereinafter referred to as FPD (Flat Panel Display)) that are convenient for miniaturization and thinning, such as liquid crystal display panels and organic EL displays, are widely used as displays for mobile devices such as mobile phones.

  On the other hand, mobile phones are evolving from simple telephones to multi-function devices having functions such as TVs and PDAs (Personal Data Assistants), and as a display used in such multi-function mobile devices, simply display images. There is also a need for a speaker that emits sound.

As an example of an FPD of a mobile device provided with a speaker, a vehicle-mounted liquid crystal display panel as disclosed in Patent Document 1 is known.
Japanese Patent Laid-Open No. 62-231847

  In the above-described in-vehicle liquid crystal display panel, a video display and a speaker are arranged in parallel on the front surface of the device. If the speakers are arranged in parallel on the video display on the front side of the device in this way, the area of the entire device increases, which goes against the demand for downsizing, and mobile devices that require both thinness and downsizing like mobile phones. Not suitable as a device display.

  In view of this, a display module has been proposed in which a speaker is installed on the back of the video display to avoid an increase in the overall area. In this case, a display defect is likely to occur because the back of the display is vibrated. However, since sound waves are emitted to the back side of the display module, there is a problem in that clear and sufficient sound cannot be provided to a display observer positioned on the front side of the display (front side of the display module).

  An object of the present invention is to provide a flat-type image display module capable of listening to a desired clear sound while observing a display having a small size and a thin shape and good quality in spite of having a speaker.

  An image display module according to a first aspect of the present invention is provided on an image display unit including a flat image display panel, and on a back side opposite to an observation side of display of the image display unit. A piezoelectric sound source element composed of a piezoelectric diaphragm that vibrates in response to the sound, and a sound guide path that houses the image display unit and the piezoelectric sound source element and guides sound waves oscillated from the piezoelectric sound source element to the viewing side of the display And a predetermined range between the back surface of the image display unit and the peripheral edge of the front surface of the piezoelectric diaphragm facing the back surface, and the piezoelectric diaphragm is separated from the exterior case. And an adhesive interposition member that is fixed to the back surface of the image display panel and that surrounds and forms a space communicating with the sound guide path between the back surface and the piezoelectric diaphragm. .

  The image display module according to claim 2 is the image display module according to claim 1, wherein the piezoelectric diaphragm is accommodated in a state where a front surface is opened, and the image is provided together with the piezoelectric diaphragm by the adhesive interposed member. It further has a holding case fixed to the back surface of the display unit.

  The image display module according to claim 3 is the image display module according to claim 1 or 2, wherein the image display panel is a liquid crystal display panel in which a liquid crystal is sandwiched between a pair of substrates. The display unit further includes a surface-emitting backlight that irradiates light in a planar shape on the back surface of the liquid crystal display panel.

  According to the image display module of the present invention, sound waves are efficiently oscillated while suppressing energy loss of sound waves and guided through the sound guide path to the front side of the module, and clear and sufficient while observing a good quality display. It is possible to listen to the sound of the volume.

  FIG. 1 is a perspective view showing a liquid crystal display module as an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II, and FIG. 3 is an exploded perspective view thereof.

  As shown in FIG. 3, the liquid crystal display module of this embodiment is generally composed of a liquid crystal display unit 1 including a liquid crystal display panel 2 and a surface emitting backlight 3, a sound source unit 4, and an exterior case 5. .

  As shown in FIG. 2, the liquid crystal display panel 2 includes a pair of rectangular glass substrates 21 and 22 on which electrodes (not shown) are formed, and frame-shaped sealing materials ( A liquid crystal display element formed by bonding liquid crystal (not shown) between glass substrates 21 and 22 surrounded by a frame-shaped sealing material is accommodated in a panel case 23. It is configured. The panel case 23 is provided with a window 231 for observing the display. As shown in FIG. 1, a flexible wiring board 24 for supplying a control signal voltage for driving liquid crystal from an external drive control circuit board (not shown) is conductively bonded to the liquid crystal display element. ing.

  A surface emitting backlight 3 is installed on the back side opposite to the viewing side of the display of the liquid crystal display panel 2. As shown in FIG. 3, the surface-emitting backlight 3 is a light source plate 31 that is a substantially transparent rectangular plate and a light source element that is disposed to face one end surface (light incident end surface) of the light guide plate 31. LED (Light-Emitting Diode) 32, a circuit board 33 on which a power supply wiring circuit for the LED 32 is formed, and an optical sheet laminated body that is laminated on the light emitting surface of the light guide plate 31 (front surface facing the liquid crystal display panel 2) 34, and a light reflecting sheet 35 disposed on the rear surface of the light guide plate 31. In the present embodiment, the three LEDs 32 are disposed so as to be evenly opposed to the light incident end face of the light guide plate 31, and these three LEDs 32 are directly mounted on the circuit board 33. Further, as shown in FIG. 2, the optical sheet laminate 34 includes two prism sheets 341 and 342 that align the light emission direction and a light diffusion sheet 343 that are sequentially stacked on the light emission surface of the light guide plate 31. It becomes.

  A sound source unit 4 is mounted on the back surface of the surface emitting backlight 3. The sound source unit 4 includes a disk-shaped piezoelectric vibration plate 41 in which circular electrodes 412 and 413 are attached to both front and back surfaces of a piezoelectric ceramic film 411 having a thin disk shape, and both the circular electrodes 412 and 413, respectively. An L-shaped sound source signal input flexible wiring board 42 provided with a pair of lead wires 422 and 423 to be electrically connected, a holding case 43 for accommodating and holding the piezoelectric diaphragm 41, and the piezoelectric diaphragm 41 are provided. And a double-sided adhesive spacer 44 that is fixed to the back surface of the surface emitting backlight 3 together with a holding case 43 that houses the surface emitting backlight 3.

  The flexible wiring board for sound source signal input 42 is formed by using an insulating resin film such as a polyimide film as a base film 421, and two wirings 422 and 423 are formed on one surface of the base film 421 by patterning a copper foil by photolithography. ing. Connection terminals 4221 and 4222 and connection terminals 4231 and 4232 are formed at both ends of each wiring 422 and 423, respectively. Each of the connection terminals 4221 and 4231 of the wirings 422 and 423 is electrically connected to a pair of circular electrodes 412 and 413 sandwiching the piezoelectric ceramic film 411 (see FIG. 2). The sound source signal input flexible wiring board 42 is disposed on the back side thereof in such a manner that the wiring forming surface faces the surface emitting backlight 3.

  The holding case 43 has a substantially horseshoe shape in plan view, and includes a storage hole 431 for storing the piezoelectric diaphragm 41 and a strip plate portion 432. A through hole 4311 having an inner diameter smaller than the outer diameter of the piezoelectric vibration plate 41 is formed at the bottom of the storage hole 431. A slit 4313 is formed by cutting out a part of the peripheral wall 4312 of the storage hole 431. From this slit 4313, the flexible wiring board 42 that is conductively connected to the piezoelectric diaphragm 41 loaded in the accommodation hole 431 is drawn out. The holding case 43 is molded using, for example, an injection method using a resin material having a relatively high hardness.

  The double-sided adhesive spacer 44 has a C-shape in which an outer diameter is larger than the outer diameter of the piezoelectric diaphragm 41 and an inner diameter is smaller than about 1/3 of an annular ring. This double-sided adhesive spacer 44 is formed by laminating adhesive layers made of an acrylic adhesive on both the front and back sides of a foamed butyl rubber sheet, and has necessary and sufficient adhesive force and vibration buffering ability. Therefore, according to the double-sided adhesive spacer 44 having such a configuration, as shown in FIG. 2, one adhesive layer of the double-sided adhesive spacer 44 has a peripheral wall 4312 of the holding case 43 that accommodates it from the periphery of the piezoelectric diaphragm 41. Since it adheres over the upper surface, the piezoelectric diaphragm 41 is securely fixed in a state of being accommodated in the holding case 43, and is firmly fixed to the back surface of the liquid crystal display unit 1, that is, the light reflecting sheet 35 of the surface emitting backlight 3 by the other adhesive layer. Has been.

  The liquid crystal display panel 2 and the surface emitting backlight 3 having the sound source unit 4 mounted on the back are housed in an outer case 5 as the liquid crystal display unit 1. The outer case 5 of the present embodiment is formed in a rectangular box shape with an open top surface that has a planar outer shape that is formed by processing a sheet metal material and can be fitted and housed with the liquid crystal display panel 2 and the surface emitting backlight 3. A rectangular concave portion 511 extending over the entire length in the longitudinal direction is formed at the center portion of the bottom plate 51 of the exterior case 5. The sound source unit 4 is accommodated in one end of the recess 511.

  In the bottom plate 51 at one end of the recess 511, in the present embodiment, five pores 512 are formed in a cross arrangement. These pores 512 are formed in an area facing the piezoelectric diaphragm 41 of the sound source unit 4 accommodated and installed, and quickly dissipate unnecessary sound waves emitted from the rear surface of the piezoelectric diaphragm 41 to the outside of the outer case 5. It is provided for. Thereby, unnecessary sound waves can escape to the space outside the outer case 5 (the surplus space of the present module installation space in the applied device) and be absorbed and attenuated. As a result, the sound emitted from the sound source unit 4 becomes clearer.

  Of the four side plates of the outer case 5, the short side plate 52 close to the sound source unit 4 is formed with a convex portion 521 for forming a sound guide path for guiding sound waves. The convex portion 521 is provided so as to correspond to one end portion of the concave portion 511 of the bottom plate 51, and thus both spaces of the concave portion 511 and the convex portion 521 communicate with each other.

  Note that two openings 531 and 532 are respectively formed over a predetermined length in one side plate 53 of the pair of longitudinal side plates. These openings 531 and 532 are openings for pulling out the flexible wiring board 24 bonded to the liquid crystal display panel 2 and the sound source signal input flexible wiring board 42 of the sound source unit 4 to the outside of the outer case 5.

  In the exterior case 5 configured as described above, as shown in FIG. 2, the surface emitting backlight 3 having the sound source unit 4 mounted on the back surface and the liquid crystal display panel 2 are sequentially fitted and housed. In this state, the strip plate portion 432 provided in the holding case 43 of the sound source unit 4 is fitted and inserted into the bottom portion of the convex portion 521, and the convex portion 521 of the side plate 52 and the stored surface emitting back surface. A sound guide path 6 is surrounded by the light 3 and the corresponding side end faces of the liquid crystal display panel 2. The sound guide path 6 is provided to guide useful sound waves oscillated from the front surface of the piezoelectric diaphragm 41 when it vibrates from the opening 441 of the double-sided adhesive spacer 44 to the front surface (module front surface) of the liquid crystal display panel 2. It has been. Accordingly, the sound wave oscillated from the front surface of the piezoelectric diaphragm 41 according to the input signal voltage propagates into the sound guide path 6 from the opening 441 of the double-sided adhesive spacer 44, and passes through the sound guide path 6. While propagating, the sound pressure (volume) is amplified to some extent and released to the display surface (front surface) side of the liquid crystal display panel 2. As a result, the viewer of the present liquid crystal display module can observe the video displayed on the liquid crystal display panel 2 and listen to clear sound related thereto.

  As described above, in the liquid crystal display module of the present embodiment, the sound source unit 4 is mounted on the back surface of the liquid crystal display unit 1 in which the surface emitting backlight 3 and the liquid crystal display panel 2 are superposed and emitted from the sound source unit 4. Since the sound guide path 6 that guides the generated sound wave to the front side of the liquid crystal display unit 1 is formed on the side of the module, an increase in the area of the entire liquid crystal display module due to the provision of the speaker can be minimized. As a result, an applied product such as a cellular phone on which the liquid crystal display module with a speaker is mounted can be reduced in size and thickness.

  The piezoelectric diaphragm 41 is fixed to the light reflecting sheet 35 on the rear surface of the surface emitting backlight 3 by the double-sided adhesive spacer 44 together with the holding case 43 that accommodates the piezoelectric diaphragm 41 and is separated from the bottom surface 51 of the outer case and accommodated in the recess 511. Therefore, the propagation of the vibration of the piezoelectric diaphragm 41 to the outer case 5 is substantially avoided, and thereby, the sound wave with sufficient sound pressure is efficiently oscillated while suppressing the energy loss. Combined with the sound pressure amplification effect, it is possible to emit sound with a sufficient volume to the front side of the module. In addition, since the vibration of the outer case 5 is suppressed, a problem that static electricity is generated in the outer case 5 is prevented.

  In addition, since the periphery of the front surface of the piezoelectric diaphragm 41 is fixed to the light reflecting sheet 35 on the back surface of the surface emitting backlight 3 via the double-sided adhesive spacer 44 having an opening 341 made of a vibration buffer material, the vibration of the piezoelectric diaphragm 41 is Is suppressed from propagating to the light reflecting sheet 35, whereby the sound wave is efficiently oscillated from the front surface of the piezoelectric diaphragm 41, and the oscillated sound wave smoothly proceeds to the sound guide path 6 from the widely opened opening 441. In addition, since the resonance of the light reflecting sheet 35 due to the vibration of the piezoelectric diaphragm 41 is suppressed, the display quality of the liquid crystal display unit 1 is prevented from being deteriorated.

  Further, the strip plate portion 432 of the holding case 43 is fitted to the bottom of the case convex portion 521 forming the sound guide path 6, and unnecessary sound waves oscillated from the rear surface of the piezoelectric diaphragm 41 enter the sound guide path 6. In addition, five pores 512 are formed in a portion of the case bottom 51 facing the piezoelectric vibration plate 41 so that unnecessary sound waves emitted from the rear surface of the piezoelectric vibration plate 41 are outside the outer case 5. Since it is configured to quickly dissipate, mixing of unnecessary sound waves oscillated from the rear surface to useful sound waves oscillated from the front surface of the piezoelectric diaphragm 41 is substantially prevented, and a desired clear sound can be transmitted through the sound guide path. 6 is discharged to the front of the module.

  As a result, the viewer of the liquid crystal display module of the present embodiment has a high quality in which the occurrence of display defects due to the vibration of the piezoelectric diaphragm 41 propagating to the liquid crystal display unit 1 on the front side of the liquid crystal display module is prevented. While observing the display, it is possible to listen to clear sound without noise at a sufficient volume.

  Further, since the sound source signal input flexible wiring board 42 is arranged with the rear surface opposite to the wiring formation surface facing the exterior case 5, wiring exposed portions such as the connection terminals 4221 and 4231 of the wirings 422 and 423 are provided. Is prevented from leaking into the outer case 5 formed of a conductive sheet metal, and the reliability of the display module is improved.

In addition, this invention is not limited to said embodiment.
For example, in the above embodiment, the piezoelectric diaphragm 41 is fixed to the light reflecting sheet 35 on the back surface of the liquid crystal display unit 1 with the double-sided adhesive spacer 44 in a state where the piezoelectric diaphragm 41 is accommodated in the holding case 43. If the bottom of 6 is shielded by a method such as changing the shape of the case, the holding case 43 may be omitted and the piezoelectric diaphragm 41 may be directly fixed to the light reflecting sheet 35 by the double-sided adhesive spacer 44. Thereby, the structure is simplified, the number of parts is reduced, and the cost of the liquid crystal display module is reduced.

  The present invention is not limited to a liquid crystal display module with a backlight, but a reflective liquid crystal display module without a backlight, or various other flat image display modules such as an organic EL (Electro Luminescence) display and a plasma display. Of course, the present invention can be widely applied.

It is a perspective view which shows the liquid crystal display module as one Embodiment of this invention. It is typical sectional drawing which cut | disconnects and shows the said liquid crystal display module by the II-II line | wire of FIG. It is a disassembled perspective view of the said liquid crystal display module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display unit 2 Liquid crystal display panels 21 and 22 Glass substrate 211 Display window 23 Panel case 24 Flexible wiring board (for liquid crystal drive)
3 Surface-emitting backlight 31 Light guide plate 32 LED
34 Optical sheet laminate 35 Light reflection sheet 4 Sound source unit 41 Piezoelectric diaphragm 411 Piezoelectric ceramic film 412, 413 Circular electrode 42 Flexible wiring board (for sound source signal input)
421 Lead wiring 43 Holding case 44 Double-sided adhesive spacer 5 Exterior case 51 Bottom plate 511 Concave portion 52 Side plate 521 Convex portion 6 Sound conducting path

Claims (3)

An image display unit having a flat image display panel;
A piezoelectric sound source element comprising a piezoelectric diaphragm installed on the back side opposite to the viewing side of the display of the image display unit and vibrating in accordance with an applied voltage;
An outer case that houses the image display unit and the piezoelectric sound source element, and that forms a sound guide path that guides sound waves oscillated from the piezoelectric sound source element to the observation side of the display;
The back surface of the image display panel is interposed over a predetermined range between the back surface of the image display unit and the peripheral edge of the front surface of the piezoelectric diaphragm facing the back surface, and the piezoelectric diaphragm is separated from the exterior case. And an adhesive interposition member that surrounds and forms a space communicating with the sound guide path between the back surface and the piezoelectric diaphragm.   The piezoelectric vibration plate is accommodated in a state where the front surface is opened, and further includes a holding case fixed to the back surface of the image display unit together with the piezoelectric vibration plate by the adhesive interposed member. The image display module according to claim 1.   The image display panel is a liquid crystal display panel in which a liquid crystal is sandwiched between a pair of substrates, and the image display unit further includes a surface emitting backlight that irradiates light on the back surface of the liquid crystal display panel. The image display module according to claim 1, wherein the image display module is an image display module.

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