JPS60143380A - Liquid crystal display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention relates to a display device using a liquid crystal, and in particular to a liquid crystal element including a liquid crystal cell sealed with liquid crystal, and a lighting member provided behind the liquid crystal element to illuminate the liquid crystal element at night. ,
The present invention relates to a mounting structure of a circuit board for applying a signal voltage to the liquid crystal element.

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 due to voltage application, and displaying symbols such as predetermined characters or gauze letters depending on the electrode shape. A liquid crystal display device like this is used,
As this kind of liquid crystal display device, for example,
No. 680, No. 58-21115, No. 58-2] 116
There are numbers etc. In both of these liquid crystal display devices, light from a lamp or the like is emitted from a liquid crystal cell, which has a liquid crystal sealed between two glass plates, and near the rear of a liquid crystal element, which includes a polarizing plate provided as necessary. Is the lighting component made up of
this! The 1α1 member was installed on a circuit Mi provided with a drive circuit for applying a signal voltage to the liquid crystal element.

Therefore, there is a problem in that the noise of the power supply circuit is transmitted to the drive circuit, which increases the possibility of erroneous display. Zunawaji, the wiring pattern of the lighting 5B material is provided on the same plane of the circuit board in close proximity to the wiring pattern of the driving circuit II, which is composed of electronic components such as ICs and transistors that operate with minute currents. In conventional liquid crystal display devices, the wiring pattern of the lighting component is directly connected to an external power supply circuit such as a battery, and noise may be generated in the power supply circuit due to changes in load due to the use of headlights, horns, relays, etc. connected to the power supply. If this occurs, it will be transmitted directly to the wiring pattern of the lighting component, and will then jump to the wiring pattern of the nearby drive circuit, giving an abnormal signal to the drive circuit, making it impossible for the liquid crystal element to perform normal display, resulting in erroneous display. This is what you will do.

The present invention was devised by focusing on such conventional problems, and includes a circuit board provided with a drive circuit for applying a signal voltage to a liquid crystal element, and a circuit provided with a lighting member for illuminating the liquid crystal element. By separating the circuit board from the circuit board, noise from the power supply circuit can be suppressed from being transmitted to the drive circuit.
It is an object of the present invention to provide a highly reliable liquid crystal display device with improved reliability and stability of display operation.

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;
5 is a mask plate located in front of the liquid crystal display device 3 and made of colored polycarbonate I/resin plate, etc. to cover unnecessary parts for display inside the meter case 2; 5 is a mask plate located in front of the mask plate 4; This is a front panel formed from a translucent acrylic resin plate or the like so as to close the front of the meter case 2, and display symbols such as letters and scales are printed on the rear surface.

The liquid crystal display device 3 includes a frame member 6. made of super heat-resistant ABS resin or the like to serve as a reference member for mounting its component parts. A liquid crystal element 9 is placed and fixed on the front side of the frame member 6 by pressing at least its peripheral portion from the 011 direction by a cell presser 8, which is a presser member made of iron or the like, via a comb 7.
A liquid crystal element 9 is interposed between this liquid crystal element 9 and the frame member 6.
A semi-transparent reflector plate containing a filter element colored according to the display u1 location]0. A heat shielding member 11, which is interposed between the reflective plate 10 and the frame member 6, is made of glass fiber-containing paper or the like and has a cutout portion corresponding to the display area of the liquid crystal element 9. A light guide 12 is disposed within the frame of the frame member 6 and is formed from an acrylic resin plate or the like having a light intake portion on at least a portion of the side surface. Covering the front and side surfaces of this light guide 12 and a lighting member to be described later, and cutting out a portion corresponding to the display area of the liquid crystal element 9 at a portion covering the front surface of the light guide 12, and further covering the side surface of the lighting member. A heat dissipating member 13 formed of an aluminum slope or the like with at least a part of the structure vertically extended to the rear. Reflector plate 14 provided on the rear surface of the light guide 12.
16 fixed to the rear side of the frame member 6 with a hiss etc. and attached to the liquid crystal element 9.
The mounting leg member 17 is positioned between the two boards 16.19 and the lead wire 202 for electrically connecting the two boards 16.19 through the mounting leg member 7. A third circuit board 23. is fixed with screws or the like and is provided with an illumination member so that the light emitting portion faces the light intake portion 12a of the light guide 12. A conductive rubber 24 is disposed in a through hole 6a provided in a frame portion of the frame member 6 and makes an electrical connection between predetermined terminals between the electrodes of the liquid crystal element 9 and the terminals of the first circuit board 16. It is composed of.

The liquid crystal element 9 is connected to a liquid crystal cell 25 and this cell 2 as necessary.
5 is a front electrode substrate 28 made of a transparent insulating plate.
Characters to be displayed on the inner surface of this electrode substrate 28.

A first electrode 29 formed of a transparent conductive film so as to have a shape corresponding to symbols such as numbers and scales. A rear electrode substrate 31 formed of a transparent insulating plate is held at a constant distance from the front electrode substrate 28 via a spacer 30. A second electrode 3 formed of a transparent conductive material 19 or a reflective metal film is formed on the inner surface of this electrode substrate 31 to face the first electrode 29.
21 and a liquid crystal 33 sealed between both electrode substrates 28 and 31. The front electrode substrate 2 is drawn out from the electrodes 29 and 32 and formed.
8 and a terminal 34 formed on the rear surface of the terminal 8 and exposed to the outside.

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, or the long axes are aligned in one direction, and the electrode substrate 2
8.31 A P-type twisted immajinok liquid crystal whose inner surface is aligned 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 is used, and polarized light is used. When the plates 26 and 27 are attached so that the polarization axes that determine the polarization of transmitted light are orthogonal to each other, the electrodes 29 and 27 respond to the signal voltage applied to the terminal 34.
When a voltage higher than a predetermined level is not generated between the liquid crystal cells 32 and 32, the liquid crystal 33 maintains its initial molecular alignment, and when the light is polarized in one direction by the rear polarizing plate 27, it is transmitted through the liquid crystal cell 25. Since the polarization axis of the polarized light is twisted by 90 degrees and reaches the front polarizing plate 26, the polarization axis of the polarized light matches the direction of the polarization axis of the polarizing plate 26, and the light can pass through the liquid crystal element 9, making the whole bright. It becomes a visible unmarked stool. Also, ff;'1 child 3
When the signal voltage applied to the electrodes 29.4 changes and a voltage of the predetermined level or higher is generated between the predetermined overlapping portions of the electrodes 29.32, the voltage applied to the electrodes 29.32 where the voltage is generated is changed. The long axes of the molecules of only the liquid crystal 33 in a2g+ are aligned perpendicular to the electrode substrate 28 and 31 planes, and only the part of the liquid crystal 33 where this molecular arrangement has changed becomes polarized light with a unidirectional component by the rear polarizing plate 27. When the light passes through the liquid crystal cell 25, the polarization axis of the polarized light is not twisted and reaches the front polarizing plate 26, so that the polarization peak of the polarized light is orthogonal to the direction of the polarization axis of the light plate 26, and the light passes through the liquid crystal element. 9 cannot be transmitted through, a dark "figure" appears on a bright "ground" and a predetermined symbol is displayed in a positive manner. Incidentally, in the above description, the case where light traveling from the rear side 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, the 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 from behind the liquid crystal element 9. Therefore, the principle is the same, and furthermore, the circularly polarizing plates 2G, 27o) (((1:1 optical axis direction is parallel to each other so that the adhesion deviation is a bright 1 image on a dark ``ground'') The liquid crystal 33 may be a nematic liquid crystal having positive dielectric anisotropy, or may be a cholesteric liquid crystal, an optically active substance, a dichroic dye, etc. The so-called KEST post-type liquid crystal cell 25 may be used by adding dichroic dye.
When configuring the liquid crystal element 9 by arranging a plurality of layers in a layered manner, the polarizing plates 26 and 27 can be omitted.

Next, the assembly work of the components will be explained.

A heat shielding member 111 and a reflecting plate 10 are aligned and placed on the front side of the frame member 6, and a liquid crystal element 9 composed of polarizing plates 26 and 27 to which a liquid crystal cell 25 is attached is placed thereon. A cell presser 8 is fixed to the frame member 6 by screws, hooks, etc., and is pressed against the frame member 6 by coming into contact with at least the peripheral edge portion of the liquid crystal element 9 from the front.

Thereafter, 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. The front end of the conductive rubber 24 comes into contact with this.

Then, the light guide 12 disposed on the heat radiating member 13 is disposed within the frame tube of the frame member 6 so that the heat radiating 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 board 23, on which lamps 21, connectors 22, etc. are mounted.
are respectively arranged on the mounting leg members] 7, and the circuit board 16 is 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 toward the front. The rear end of the conductive rubber 24 comes into contact with this.

The assembly of the liquid crystal display device 3 is now complete, and by storing and fixing it inside the meter case 2 and attaching the mask plate 4 and the surface panel 5 to the front of the meter case 2, the liquid crystal meter device 1 for the vehicle can be assembled. Complete.

Furthermore, according to this embodiment, the lamp 21, which was conventionally mounted on the circuit board 16 or circuit board 19 provided with a drive circuit for applying a signal voltage to the liquid crystal element 9, is now mounted on a dedicated circuit board 23. The wiring pattern of the lamp 21, which is directly connected to the power supply circuit, is separated from the wiring pattern of the drive circuit, so that even if noise occurs in the power supply circuit due to fluctuations in the load connected to the power supply, it will not be transmitted to the wiring pattern of the drive circuit. , it is possible to suppress the occurrence of erroneous display. That is, the circuit board 16 provided with the drive circuit. Both the circuit board 19 and the circuit board 23 provided with the lamp 21 are connected to the power supply circuit, and the wiring pattern of the latter circuit board 23 is directly connected to the power supply circuit, and the noise generated in the power supply circuit is directly transmitted, whereas the former circuit board 23 is connected directly to the power supply circuit. Although the wiring pattern of the board 16 and 19 is not affected by the noise due to the noise countermeasure circuit provided in the drive circuit, etc., the circuit impedance is high because only a current of about several μ8 to several mA flows normally. If another wiring barrier that transmits noise from the power supply circuit is disposed near the wiring pattern of the drive circuit, the noise may be carried over. However, a circuit board 23 with a wiring pattern for the lamp 21 that transmits noise from the power supply circuit is provided exclusively, and a circuit board 16, 19 with a wiring pattern for the driving circuit of the liquid crystal element 9 is provided.
By separating it from the rewiring pattern, it is possible to widen the interval between the rewiring patterns, making it difficult for noise from the power supply circuit to be transmitted to the drive circuit side, and thereby suppressing the occurrence of erroneous display on the liquid crystal element 9. It is.

Also, when mounting the lamp 21 on the circuit board 16 or circuit board 19 for the drive circuit, if a common ground line is used, the resistance of the wiring pattern will be affected since a current of several hundred mA normally flows through the lamp 21. This causes the ground level of the drive circuit to rise relatively, and the output signal voltage of the drive circuit, which is determined by the relationship between this ground level and the human input signal voltage from the object under test, deviates from the normal state.
Although there has been a problem of erroneous display on the liquid crystal element 9, this embodiment can eliminate such a problem.

Furthermore, a plurality of circuit boards 16. 19.23 is a circuit board 16.19 for a drive circuit that is connected to the front bent portion 17a of a metal mounting leg member 17 having a substantially U-shaped cross section so that it is disposed in a fi layer state behind the liquid crystal element 9. Side bending part +7b
In addition, the circuit M [i23 for the lamp 21 is attached to the mounting leg member 1
Since the circuit board 16.7 is fixed to an intermediate bent portion 17c formed by bending a part of the middle portion of the circuit board 16.7 in the longitudinal direction, the circuit board 16.
A plurality of circuit boards 16, 19, 23 can be positioned and fixed at once by simply assembling the circuit boards 19, 23 in one piece. Moreover, the distance between the circuit board 23 provided with the lamp 21 and the liquid crystal element 9 side can be adjusted by adjusting the folded position of the intermediate bent portion 17c of the mounting leg member I7.
The light emitting portion of the lamp 2I can be set to face the light intake portion 12a of the light guide I2.

As described above, according to the present invention, it is possible to make it difficult for the noise of the power supply circuit to be transmitted to the drive circuit side, and it is possible to provide a highly reliable liquid crystal display device with improved reliability and stability of display operation.

In addition, the installation of the circuit board can be done easily, and the position of the lighting component that illuminates the liquid crystal element can be adjusted and set as desired, which is expected to improve the lighting effect. can.

[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 above liquid crystal meter device, and Fig. 3 is a front view of a liquid crystal meter device used in the above liquid crystal meter device. FIG. 4 is a sectional view of essential parts of the liquid crystal display device, and FIG. 5 is an exploded perspective view of the same liquid crystal display device.
FIG. 6 is an enlarged cross-sectional view of the main parts of the liquid crystal display device as described above, and FIG. FIG. 2 is a sectional view of a main part of a liquid crystal element. 1: Liquid crystal meter device for vehicles 3: Liquid crystal display device 6 frame member 8: Cell holder 9: Liquid crystal element 10: Reflector plate 11, shielding member 12: Light guide 13: Heat radiation member 14: Reflector plate 17: Mounting leg member 16 ．． 19.23 Circuit board 24
, conductive rubber 25: Liquid crystal cell Fig. 1 , 63 Fig. 2 / Fig. 5 Fig. 3 Fig. 6 Fig. 1 Nm- 7th U! J

Claims (1)

[Claims] 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, a drive circuit that applies a signal voltage to the liquid crystal element, and an illumination member that illuminates the liquid crystal element. and a circuit board on which the driving circuit is provided and a circuit board on which the lighting member is provided are separated and installed.
1. A liquid crystal display device characterized in that both substrates are fixed in a stacked state via metal mounting leg members and disposed behind the liquid crystal element.