JP4489516B2 - Liquid crystal display device for small switches - Google Patents

Description

  The present invention relates to a liquid crystal display device for a small switch in which an IC chip is mounted inside a liquid crystal display device and the current / voltage of a light emitter can be controlled.

Conventionally, for example, when a liquid crystal display device is applied to a pushbutton switch, it is common to display a charge, the name of a product, and the like on the upper surface of the liquid crystal display unit to represent the function of the switch.
However, in that case, variations in luminance and hue of the light emitter in the liquid crystal display unit are one of the important problems. For example, there is a problem that the user cannot correctly recognize the display contents due to variations in the light emission hue, or that the user selects a different one from the intended purpose due to misidentification. Furthermore, with the increase in the number of functions of devices, the use of single-color light emission, multi-color light emission, and full-color light emission, the presence or absence of variations in luminance and hue has become an important determination factor for device quality. Therefore, in order to improve the variation in luminance and hue, a liquid crystal display device having an arrangement of light emitters of a plurality of colors has been developed (see Patent Document 1 below).
JP-A-10-223932

Further, when a plurality of light emitters are turned on by time-division driving, there are problems such as display brightness and hue differing depending on variations of individual light emitters, and display contents are misidentified.
The present invention provides a small switch liquid crystal display device for obtaining uniform light emission while suppressing variations in luminance and hue of individual light emitters when the liquid crystal display device is continuously used in the above situation. The purpose is to do.

In order to achieve the above object, the present invention provides
[1] In a liquid crystal display device for a small switch having a liquid crystal panel for displaying information such as characters and pictures on the upper surface of the main body and a printed circuit board on which an IC chip constituting a driving circuit of the liquid crystal panel is mounted, a display data generation source (51 ) And an external power source (52) are connected to a timing control circuit (41), a time-division drive circuit (61) connected to the timing control circuit (41), and a current / voltage setting unit (62). A current / voltage adjusting circuit (63) connected to the current / voltage adjusting circuit (63), and a backlight comprising a plurality of color light emitting diodes disposed in a holder (20) below the liquid crystal panel (33). (64), and the backlight (64) is turned on by applying a time-division voltage by the time-division drive circuit (61), and the current / voltage setting is Based on the current / voltage setting data stored in the unit (62) in advance, the current / voltage adjustment circuit (63) supplies the power adjusted to an appropriate current / voltage to the backlight (64). characterized that you correct the luminance and color variation of the light (64).

[2] In the liquid crystal display device for small switches described in [1], an antiferroelectric liquid crystal panel that is inexpensive, has a wide viewing angle, a high-speed response, and a high contrast is used.
[3] In the small switch liquid crystal display device according to [1], the printed circuit board including the liquid crystal panel disposed on a lower surface of the operation button and mounted with the IC chip constituting the driving circuit of the liquid crystal panel is provided. A push button switch including a switch main body provided with a contact mechanism portion that is disposed in the operation button and that opens and closes the electric circuit by the vertical movement of the operation button is provided .

  In the liquid crystal display device for a small switch of the present invention, a holder is disposed below the liquid crystal panel, and light emitters of a plurality of colors are disposed as backlight light sources on the upper surface of the holder, and the brightness of the light emitter within the IC chip. In addition to storing current and voltage setting data that make up the standard of LED, a lighting control circuit that drives the backlight source in a time-sharing manner and a current and voltage adjustment circuit that corrects variations in light emitters are built-in, so multiple liquid crystal displays Even when the devices are used close to each other, it is possible to provide a liquid crystal display device for a small switch that suppresses variations in luminance and hue between light emitters and enables uniform light emission display.

  Therefore, when adjusting the luminance and hue of the light emitters, it is not necessary to provide a current limiting resistor for each light emitter, and uniform light emission can be obtained. Furthermore, visual variation can be suppressed without selecting the light emitters based on luminance, forward voltage, and the like.

  The present invention stores current / voltage setting data that serves as a reference for the brightness of a light emitter in an IC chip in order to obtain uniform light emission while suppressing variations among light emitters of a plurality of colors as a backlight light source. In addition, it is possible to provide a small switch liquid crystal display device that incorporates a lighting control circuit that drives a light emitter in a time-sharing manner and a current / voltage adjustment circuit that corrects variations in the light emitter and enables uniform light emission display.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a block diagram showing a circuit configuration of a small switch liquid crystal display device according to an embodiment of the present invention.
As shown in this figure, a circuit 40 of a pushbutton switch with a liquid crystal display includes a backlight 64 made up of light emitting diodes (LEDs) arranged in an operation button, and a drive for driving the backlight 64. In addition, a current / voltage setting unit 62 that stores current / voltage setting data that defines the brightness of the light emitter in advance, a timing control circuit 41, a time-division drive circuit 61, and a current / voltage adjustment circuit 63 are provided. It is done. In other words, the backlight 64 is applied with the time-division voltage by the time-division drive circuit 61 and is controlled to be turned on, and the current and voltage setting data stored in the current / voltage setting unit 62 in advance -The electric power adjusted to the exact electric current and voltage in the voltage adjustment circuit 63 is supplied. Accordingly, variations in luminance and hue of the light emitter can be corrected, and uniform light emission display can be achieved.

The circuit 40 of the pushbutton switch with a liquid crystal display is also provided with a drive circuit for the antiferroelectric liquid crystal panel 33 disposed on the upper surface of the operation button. That is, a signal side reset signal generation circuit 42, a signal side voltage waveform generation circuit 43, a scanning side reset signal generation circuit 44, and a scanning side voltage waveform generation circuit 45 are provided, and the antiferroelectric liquid crystal panel 33 is driven. .
Furthermore, a switch mechanism 47 and switch terminals 48 and 49 are provided, and a display data generation source 51 and an external power source 52 are connected to the timing control circuit 41.

FIG. 2 is a sectional view of the main part of a pushbutton switch with a liquid crystal display showing an embodiment of the present invention, and FIG. 3 is an exploded perspective view of the pushbutton switch with a liquid crystal display.
In these drawings, reference numeral 1 denotes a switch body, and an operating shaft 2 is mounted at the center of the switch body 1. A recess 3 is formed on the left side of the switch body 1, and a connector 4 with a switch terminal 5 is provided below the recess 3. The connector 4 is connected to a circuit pattern 11A at one end of a flexible printed wiring board 10 described later.

  The flexible printed wiring board 10 is formed with through holes 12 through which the operating shaft 2 passes, and circuit patterns 11A and 11B and mounting holes 13 for fixing the printed circuit board 15 and the holder 20 are provided at both ends thereof. Plungers 6 are positioned at the upper end of the operating shaft 2 and protrusions 7 are formed at both ends thereof, to which the flexible printed wiring board 10 is attached. The circuit pattern 11 </ b> B at one end of the flexible printed wiring board 10 is connected and fixed to the back surface of the printed board 15. An IC chip 16 to be described later is mounted on the printed board 15. A holder 20 is provided on the printed circuit board 15, and a protrusion (not shown) on the lower surface of the holder 20 passes through the through hole 14 of the printed circuit board 15 and the attachment hole 13 for fixing the flexible printed wiring board 10. The printed circuit board 15 and the flexible printed wiring board 10 are fixed. Further, two pairs of multicolor (red, green, blue, etc.) light emitting diodes 21, 22, 23 and 24, 25, 26 are arranged on the holder 20. Connected to the pattern. The light emitting diode may have a shape in which a plurality of colors are integrated.

  Further, on the side of the holder 20 where the light emitting diodes 21 to 26 are not disposed, projecting portions 27 and 28 are formed facing both sides, and long holes 29A and 29B (not shown) are formed inside thereof. The Zebra connectors 31 and 32 are mounted on the circuit pattern on the upper surface of the printed board 15 through the long holes 29A and 29B, and an antiferroelectric liquid crystal panel 33 is disposed above the zebra connectors 31 and 32. . Further, inside the zebra connectors 31 and 32, the diffusing member 30 is disposed in a space between the light emitting diodes 21 to 26 disposed to face the holder 20. An operation button 34 is provided so as to cover the above-described assembly, and a display portion 35 made of a translucent member is formed at the center of the operation button 34.

The plunger 6 is also elastically fitted in the space of the operation button 34, and the operation button 34 accommodates the antiferroelectric liquid crystal panel 33 to the plunger 6 as described above.
A switch mechanism portion is provided in the switch body 1, and the operating shaft 2 that drives the switch mechanism portion projects, and the electric circuit is opened and closed by the vertical movement of the operation button 34.
The shaft 8 projecting downward from the plunger 6 and the operating shaft 2 are connected so as to be able to transmit an operating force. Furthermore, the flexible printed wiring board 10 is bent at the end of the plunger 6, the operating shaft 2 passes through the through hole 12 of the flexible printed wiring board 10, and the circuit pattern 11 </ b> A at one end of the flexible printed wiring board 10 is connected to the switch terminal 5. It is connected to the attached connector 4.

Further, in the assembly process, current / voltage setting data determined by the luminance and wavelength levels of the light emitting diodes 21 to 26 to be used are written into the IC chip 16.
With the above configuration, power is supplied from the switch terminal 5 of the connector 4 with the switch terminal 5 to the printed circuit board 15 via the flexible printed wiring board 10, and further, the light emitting diodes 21, 22, via the IC chip 16. Electric power is supplied to 23, 24, 25, 26 and the antiferroelectric liquid crystal panel 33. The drive control of the light emitting diodes 21, 22, 23, 24, 25, 26 and the antiferroelectric liquid crystal panel 33 is performed by the IC chip 16 to display various characters and pictures and change various colors. And uniform light emission with reduced variation.

FIG. 4 shows the applied voltage of the antiferroelectric liquid crystal panel showing the embodiment of the present invention and the change of the light transmittance with respect thereto. The antiferroelectric liquid crystal of the antiferroelectric liquid crystal panel 33 is 1 It has a sequential response in which the liquid crystal molecules are surely inverted by writing once, can operate at high speed, and is extremely inexpensive compared to TFT (thin film transistor) type liquid crystal.
In FIG. 4, the horizontal axis represents the applied voltage, and the vertical axis represents the relative light transmittance. Since the liquid crystal cell is in a dark state at an applied voltage of 0 V, when the applied voltage is increased in the positive direction, the arrangement of liquid crystal molecules starts to change, and changes to a bright state as the applied voltage increases. That is, the state changes from dark to bright as the applied voltage changes. Further, when the applied voltage is changed in the negative direction, the state changes from dark to bright as in the positive direction. In the present invention, both positive and negative voltages are applied alternately.

In this embodiment, the light emitters of a plurality of colors are arranged on both sides of the holder below the liquid crystal panel. However, the arrangement position of the light emitters is not limited to this, and the light emitter is arranged on the lower surface of the liquid crystal panel. On the holder which is located, it can be arranged at an arbitrary position where a clear display can be obtained.
The present invention is not limited to the above-described embodiments, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

  The liquid crystal display device for a small switch according to the present invention can obtain uniform light emission while suppressing variations in luminance and hue of the light emitter, and is suitable as a device for performing full color display for displaying information such as characters and pictures.

It is a block diagram which shows the circuit structure of the liquid crystal display device for small switches which shows the Example of this invention. It is principal part sectional drawing of the pushbutton switch with a liquid crystal display which shows the Example of this invention. It is a disassembled perspective view of the pushbutton switch with a liquid crystal display which shows the Example of this invention. It is a figure which shows the applied voltage of the antiferroelectric liquid crystal panel which shows the Example of this invention, and the change of the light transmittance with respect to it.

DESCRIPTION OF SYMBOLS 1 Switch body 2 Actuation shaft 3 Recess 4 Connector with switch terminal 5 Switch terminal 6 Plunger 7 Protrusion 8 Axis 10 Flexible printed wiring board 11A, 11B Circuit pattern 12, 14 Through hole 13 Mounting hole 15 Printed circuit board 16 IC chip 20 Holder 21 , 22, 23, 24, 25, 26 Light emitting diode 27, 28 Protruding part 29A, 29B Long hole 30 Diffusion member 31, 32 Zebra connector 33 Antiferroelectric liquid crystal panel 34 Operation button 35 Display part 40 Pushbutton switch with liquid crystal display Circuit 41 timing control circuit 42 signal side reset signal generation circuit 43 signal side voltage waveform generation circuit 44 scanning side reset signal generation circuit 45 scanning side voltage waveform generation circuit 47 switch mechanism 48, 49 switch terminal 51 display data generation source 52 external power source 6 Backlight comprising a time division driver 62 current-voltage setting unit 63 Current-voltage regulator circuit 64 a plurality of colors of light emitting diodes

Claims (3)

In a liquid crystal display device for a small switch having a liquid crystal panel that displays information such as characters and pictures on the top surface of the main body and an IC chip that constitutes a driving circuit for the liquid crystal panel, a display data source and an external power source are connected Timing control circuit, a time-division drive circuit connected to the timing control circuit, a current / voltage adjustment circuit connected to a current / voltage setting unit, and the current / voltage adjustment circuit connected to the liquid crystal panel A backlight composed of light emitting diodes of a plurality of colors arranged in a lower holder , and the backlight controls lighting by applying a time-division voltage by the time-division driving circuit, and the current / voltage Electric power adjusted to an accurate current / voltage in the current / voltage adjustment circuit based on current / voltage setting data stored in advance in the setting unit The backlight supplies, the backlight small switching liquid crystal display comprising a Turkey to correct the variation in the luminance and the hue of the.   2. The liquid crystal display device for a small switch according to claim 1, wherein the liquid crystal panel is an antiferroelectric liquid crystal panel.   2. The small switch liquid crystal display device according to claim 1, wherein the liquid crystal panel is disposed on a lower surface of the operation button, and the printed circuit board on which the IC chip constituting the driving circuit of the liquid crystal panel is mounted is disposed in the operation button. A liquid crystal display device for a small switch, characterized in that it is a pushbutton switch comprising a switch body provided with a contact mechanism portion that opens and closes an electric circuit by vertically moving the operation button.

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