JPH0214708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device using a liquid crystal that is effective as a display means for a vehicle instrument, and particularly to a liquid crystal element including a liquid crystal cell sealed with liquid crystal, and a display device provided at the rear of the liquid crystal element. The present invention relates to a lighting member for illuminating a liquid crystal element at night, etc., and a mounting structure for a heat dissipating member for dissipating heat generated by the lighting member to the outside of a display device.

In recent years, it has been used as a display device for vehicle instruments such as automobiles and motorcycles, controlling the transmission or non-transmission of light by changing the arrangement of liquid crystal molecules when voltage is applied, and displaying symbols such as predetermined letters and numbers according to the electrode shape. Liquid crystal display devices of this type are used, and examples of this type of liquid crystal display device include Utility Model Application No. 16680, No.
There are No. 21115, No. 58-21116, etc. In all of these liquid crystal display devices, an illumination member consisting of a light source such as a lamp is arranged behind a liquid crystal cell containing liquid crystal sealed between two glass plates and a liquid crystal element including a polarizing plate provided as necessary. Therefore, if the light source is left on for a long time, the heat emitted from this light source will heat up the liquid crystal in the liquid crystal cell of the liquid crystal element, making it impossible to maintain the desired molecular alignment, resulting in incorrect display or no display at all. I had a problem with it.

The present invention was devised by focusing on such conventional problems, and includes a liquid crystal element and an illumination member having at least a heat generating light source for illuminating the liquid crystal element. A heat dissipation member made of a material with good thermal conductivity is disposed between the illumination member, and the heat dissipation member is provided with an opening corresponding to the shape displayed by the liquid crystal element and directs the heat generated by the illumination member to the atmosphere. By having a heat dissipation part extending to a position that is not close to the liquid crystal element for dissipating heat inside, it is possible to suppress the heat transferred to the liquid crystal cell of the liquid crystal element even if the light source is turned on for a long time, resulting in a stable display. It is an object of the present invention to provide a highly reliable liquid crystal display device that improves the reliability and stability of display operations by making it possible to obtain liquid crystal molecular alignment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a liquid crystal meter device for a vehicle having a liquid crystal display device 3 according to the present invention housed and fixed in a meter case 2, and 4 is located in front of the liquid crystal display device 3 and is unnecessary for display inside the meter case 2. 5 is a surface panel formed from a translucent acrylic resin plate or the like so as to close the front surface of the meter case 2 in front of the mask plate 4. There are display symbols such as letters and scales printed on the back.

The liquid crystal display device 3 is mounted from the front by a cell presser 8, which is a presser member made of iron or the like, through a frame member 6 made of ultra-heat-resistant ABS resin, etc., and a rubber packing 7, which serves as a reference member for mounting its component parts. A liquid crystal element 9 that is placed and fixed on the front side of the frame member 6 with at least its peripheral edge pressed; a filter that is interposed between the liquid crystal element 9 and the frame member 6 and colored according to the display area of the liquid crystal element 9; A semi-transparent reflector plate 10 containing elements, and a shield made of glass fiber-containing paper or the like, which is interposed between the reflector plate 10 and the frame member 6 and has a cutout portion corresponding to the display area of the liquid crystal element 9. Thermal member 11, a light guide 12 formed of an acrylic resin plate or the like, which is disposed within the frame of the frame member 6 and has a light intake portion on at least a part of the side surface, and covers the front and side surfaces of the light guide 12. An opening 1 provided so as to correspond to the shape displayed by the liquid crystal element 9 at a portion covering the front surface of the light guide 12
3a, and a heat dissipating portion 13b extending from at least a part of a portion covering the side of the lighting member, which will be described later, to a position as far away from the liquid crystal element 9 as possible, that is, drawn out into the outside air. A drive circuit consisting of a heat dissipating member 13, a reflecting plate 14 provided on the rear surface of the light guide 12, and an electronic component 15, etc., is fixed to the rear surface of the frame member 6 with screws or the like and for applying a signal voltage to the liquid crystal element 9. A first circuit board 16, a connector 18, etc., which is fixed to the circuit board 16 with screws or the like via a mounting leg member 17 made of iron or the like, and is connected to an external battery (not shown) via a switch or the like. 2 circuit board 19, a lead wire 20 for electrically connecting both boards 16 and 19,
A lamp 21, which is a light source (not shown), is fixed to the mounting leg member 17 with screws or the like so as to be located between both substrates 16 and 19, and its light emitting portion faces the light intake portion 12a of the light guide 12. A third circuit board 23 is provided with a connector 22 etc. that is connected to an external battery via a switch or the like, a terminal of an electrode of a liquid crystal element 9 disposed in a through hole 6a provided in a frame portion of a frame member 6, and a first conductive rubber 24 for electrically connecting predetermined terminals with the terminals of the circuit board 16.

The illumination member includes at least the lamp 21, which is a heat source as well as a light source. In other words, the lighting member defined in the present invention can be defined as a heat generating light source. In the case of this embodiment, the light guide 12
The heat emitted from the lamp 12 is transmitted through the light guide 12, and the light guide 1
If heat generation is also recognized from 2, the light guide 12 is also considered to be an illumination member.

The liquid crystal element 9 consists of a liquid crystal cell 25 and polarizing plates 26 and 27 that are attached to the front and rear surfaces of the liquid crystal cell 25 as necessary and are capable of transmitting only polarized light of a unidirectional component. A front electrode substrate 28 formed from a metal plate, a first electrode 29 formed from a transparent conductive film so as to have a shape corresponding to symbols such as letters, numbers, scales, etc. displayed on the inner surface of this electrode substrate 28, and a front electrode. A rear electrode substrate 31 formed of a transparent insulating plate held at a constant distance via a substrate 28 and a spacer 30;
1, a second electrode 32 formed of a transparent conductive film or a reflective metal film so as to face the first electrode 29, a liquid crystal 32 sealed between both electrode substrates 28, 31, and the electrodes 29, 32. The terminal 34 is formed to be exposed to the outside on the rear surface of the front electrode substrate 28 drawn out from the front electrode substrate 28.

To explain the display operation of this liquid crystal element 9, for example, the liquid crystal 33 has positive dielectric anisotropy and the distribution of the center of gravity of the molecules is spatially random, but the long axes are aligned in one direction, and the inner surfaces of the electrode substrates 28, 31 A P-type twisted nematic liquid crystal is used which is parallel to the electrode substrates 28 and 31 and whose axial direction is twisted by 90 degrees while going from one electrode substrate 28 to the other electrode substrate 31 due to alignment treatment, and the polarizing plates 26 and 27 When the liquid crystal 33 is attached so that the directions of the polarization axes that determine the polarization to be polarized are perpendicular to each other, the liquid crystal 33 maintains the initial molecular arrangement,
When the light that has been polarized in one direction by the rear polarizing plate 27 passes through the liquid crystal cell 25, the polarizing axis of the polarized light is twisted by 90 degrees and reaches the polarizing plate 26, so that the polarizing axis of the polarized light and the polarizing plate 26 are Since the light can pass through the liquid crystal element 9 in the same direction as the polarization axis of the liquid crystal element 9, a non-display state is created in which the entire image appears bright. Further, when the signal voltage applied to the terminal 34 changes and a voltage of the predetermined level or more is generated between the predetermined overlapping portions of the electrodes 29 and 32, only the liquid crystal 33 between the portions of the electrodes 29 and 32 where the voltage is generated is generated. The long axis of the molecule is the electrode substrate 28,
Only the part of the liquid crystal 33 where the molecular arrangement has changed is aligned perpendicularly to the 31 plane, and when the light is polarized as a unidirectional component by the rear polarizing plate 27, when it passes through the liquid crystal cell 25, the polarization axis of the polarized light is twisted. Front polarizing plate 2
6, the polarization axis of the polarized light and the direction of the polarization axis of the polarizing plate 26 are perpendicular to each other, and the light cannot pass through the liquid crystal element 9. Therefore, a dark "figure" appears on a bright "ground" and the predetermined symbol is not displayed. It will be in the state of positive display. Incidentally, in the above description, the case where light traveling from the rear of the liquid crystal element 9 is used is assumed, that is, the case where the liquid crystal element 9 is used as a transmissive type. In other words, even when the liquid crystal element 9 is used as a reflective type, light from the front of the liquid crystal element 9 passes through the liquid crystal element 9 and then passes through the liquid crystal element 9 again at the rear of the liquid crystal element 9. are the same, and if the polarizing plates 26 and 27 are attached so that their polarization axes are parallel to each other, a bright "figure" will appear on a dark "ground" and a predetermined symbol will be displayed in a negative manner. As the liquid crystal 33, in addition to a nematic liquid crystal having positive dielectric anisotropy, a cholesteric liquid crystal, an optically active substance, a dichroic dye, etc. may be added as necessary, and a dichroic dye may be used. When the liquid crystal element 9 is constructed by arranging a plurality of doped so-called guest-host type liquid crystal cells 25 in a stacked manner, the polarizing plate 2
6, 27 can be abolished.

Next, the work of assembling the component parts will be explained.

A heat shielding member 11 and a reflecting plate 10 are provided on the front side of the frame member 6.
A liquid crystal element 9 consisting of a liquid crystal cell 25 and polarizing plates 26 and 27 attached to the liquid crystal cell 25 as necessary is placed on top of the liquid crystal cell 25. A cell presser 8 that contacts at least the peripheral edge portion of the element 9 and presses against the frame member 6 is fixed to the frame member 6 by screws, hooks, or the like.

After that, the frame member 6 is turned over, and the conductive rubber 24 is placed in the through hole 6a provided in the frame portion of the frame member 6. , dielectric rubber 24 to this
The front ends of the two are in contact with each other.

The light guide 12 disposed on the heat dissipating member 13 is disposed within the frame portion of the frame member 6 so that the heat dissipating member 13 is on the front side, and the reflecting plate 14 is disposed on the rear surface of the light guide 12.

Next, a first circuit board 16 on which electronic components 15 etc. are mounted, a second circuit board 19 on which connectors 18 etc. are mounted, and a third circuit on which the liquid crystal element 9 illumination lamp 21 and connector 22 etc. are attached. The circuit boards 23 are respectively arranged on the mounting members 17, and the circuit boards 16 are fixed to the rear side of the frame member 6, but the terminals provided on the first circuit board 16 are located in the through holes 6a facing forward. The rear end of the conductive rubber 24 comes into contact with this.

The assembly work of the liquid crystal display device 3 is completed above, and it is housed and fixed in the meter case 2, and the mask plate 4 and the surface panel 5 are attached to the front of the meter case 2, thereby completing the liquid crystal meter device 1 for a vehicle. .

Conventionally, the lamp 21 that illuminates the liquid crystal element 9 is placed too close to the liquid crystal element 9.
However, according to this embodiment, heat is generated between the liquid crystal element 9 and the lamp 21. By interposing the heat dissipation member 13 made of a material with good conductivity, most of the heat emitted from the lamp 21 is transferred to the liquid crystal display device 3 from the heat dissipation portion 13b of the heat dissipation member 13, which is provided to be drawn out into the outside air. The liquid crystal element 9 is emitted to the surroundings.
Transfer of heat to the sides can be suppressed, and stable molecular alignment of the liquid crystal 5 can be maintained. in this case,
By making the heat radiating portion 13b of the heat radiating member 13 have an uneven shape with a large surface area, the heat radiating effect can be further enhanced.

Therefore, the lamp 21 does not need to be provided far from the liquid crystal element 9, and therefore the thickness of the liquid crystal display device 3 can be reduced. In this case, the liquid crystal meter device 1 can be made thinner, and the vehicle instrument panel can be made thinner. Installation is easy because only a small installation space is required.

Furthermore, in the embodiment described above, the heat dissipation member 13 also includes the front and side surfaces of the lamp 21 and the front and side surfaces of the light guide 12 that takes in the light emitted from the lamp 21 and irradiates it to the liquid crystal element 9 side as a surface light source. Since it is covered, light is emitted from the front surface of the light guide 12 facing the display area of the liquid crystal element 9 through the opening 13a of the heat dissipation member 13, while facing the area that does not contribute to the display of the liquid crystal element 9. No light is emitted from the front of the light guide 12 because the heat dissipation member 13 blocks the light.
The light at this location is returned to the inside of the light guide 12, is repeatedly reflected around the light guide 12, and then exits from the opening 13a of the heat radiating member 13. Therefore, the heat dissipation member 13 also functions as a mask for the light guide 12 and a reflection member, that is, it irradiates light only to the portions of the liquid crystal element 9 that require illumination, eliminating the need for illumination of the liquid crystal element 9. Since the light is not irradiated to the location and the light that is originally irradiated to this location can be used as light for illuminating the location of the liquid crystal element 9 that requires illumination, the illumination efficiency can be improved. In this case, the illumination effect can be further enhanced by treating the inner surface of the heat dissipating member 13, that is, the surface facing the light guide 12, with good reflectivity, such as applying white paint.

Note that the side surface of the light guide 12 may be surrounded by silver tape or the like if necessary, or nothing may be attached to it. You don't have to cover it.

As described above, according to the present invention, even if the light source is turned on for a long time, it is possible to suppress the heat transmitted to the liquid crystal cells of the liquid crystal element, and it is possible to obtain stable liquid crystal molecular alignment, which improves the reliability of display operation. It is possible to provide a highly reliable liquid crystal display device with improved stability and stability.

Furthermore, since the light source can be disposed closer to the liquid crystal element than in the past, it is possible to provide a thinner liquid crystal display device, and the entire liquid crystal meter device can also be made thinner.

In addition, it is possible to use a configuration in which the light that originally illuminates areas of the liquid crystal element that do not require illumination can be used as light to illuminate areas that require illumination, thereby increasing lighting efficiency. In comparison, a small lamp can be used as a light source, making it more convenient to use as a display means for instruments in vehicles such as automobiles and motorcycles where power supply capacity is limited.

[Brief explanation of drawings]

FIG. 1 is a front view of a liquid crystal meter device for a vehicle equipped with a liquid crystal display device according to the present invention, FIG. 2 is a sectional view of a main part of the same liquid crystal meter device, and FIG. 3 is a front view of a liquid crystal meter device used in the same liquid crystal meter device as above. FIG. 4 is an exploded perspective view of a liquid crystal display device according to the above, FIG. 4 is a sectional view of a main part of the same liquid crystal display device, FIG. FIG. 7 is a perspective view illustrating the shape of the heat dissipation plate used, and is a sectional view of a main part of the liquid crystal element used in the liquid crystal display device. 1: Liquid crystal meter device for vehicles, 3: Liquid crystal display device, 6: Frame member, 8: Cell holder, 9: Liquid crystal element, 10: Reflector, 11: Heat shield member, 12: Light guide, 13: Heat dissipation member , 13a: opening, 13b:
Heat radiation part, 14: Reflector, 16, 19, 23: Circuit board, 24: Conductive rubber, 25: Liquid crystal cell.

Claims (1)

[Claims] 1 comprising a liquid crystal element that performs display by controlling the transmission of light by changing the alignment direction of liquid crystal molecules by applying a signal voltage; and an illumination member having at least a heat-generating light source that illuminates the liquid crystal element; A heat dissipation member made of a material with good thermal conductivity is disposed between the liquid crystal element and the lighting member, and this heat dissipation member is provided with an opening corresponding to the shape displayed by the liquid crystal element, and the heat dissipation member is provided with an opening corresponding to the shape displayed by the liquid crystal element. A liquid crystal display device characterized by having a heat dissipating section extending to a position not adjacent to the liquid crystal element for dissipating heat generated into the atmosphere.