JPS6111786A - 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 [Field of Application of the Invention] The present invention relates to a liquid crystal display device, and particularly to a liquid crystal display device for automobiles.

[Background of the invention]

Automobile meters that use liquid crystals have become more popular recently because they have many advantages, such as being easily visible even under direct sunlight, allowing free display patterns to be created, and being able to be made smaller. It has become. For example, JP-A-58-9
Publication No. 5714 has S2 support ↓ ゛ text shown in red Request 1
Yes.

On the other hand, since a liquid crystal is a non-light-emitting element, a light source is required for display, and all liquid crystal display devices used as meters are those in which illumination light is directly applied to the liquid crystal display from the rear, or a light source is used. The light is guided through a light guide plate to indirectly illuminate the liquid crystal element.

However, all of these methods have drawbacks such as preventing the device from becoming thinner and making it impossible to provide uniform illumination.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that can make the entire device thinner and display images with uniform illuminance.

[Summary of the invention]

In order to achieve this object, according to the present invention, electroluminescence is used as a light source for illuminating the liquid crystal display element, and the display pattern of the liquid crystal display element and the emission pattern of the electroluminescence are made to match, thereby reducing the thinness of the device. to achieve uniformity, uniformity of lighting, and high efficiency.

[Embodiments of the invention]

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

FIG. 1 is an exploded perspective view showing an embodiment of the invention.

According to the figure, a liquid crystal display element 1, a color filter 2, an illumination light source 3, a printed circuit board 4, a conductive rubber 5, and a masking panel 6 are shown.

In the liquid crystal display element 1, when a voltage is applied between opposing electrodes (not shown) formed within the element, the alignment direction of liquid crystal molecules changes), the light transmittance changes, and a desired display can be obtained.

The color filter 2 is disposed on the back surface of the liquid crystal display element 1, and has a color scheme to make transmitted light easier to see.

An illumination light source 3 illuminates the element 1 with electroluminescence through a filter 2.

The printed circuit board 4 is equipped with a circuit for driving and controlling the element 1, a circuit for processing signals sent from each sensor required for display, and the like.

The conductive rubber 5 electrically connects each circuit of the printed circuit board 4 to the element 1 or the light source 3.

The masking panel 6 is placed in front of the liquid crystal display element 1 and has predetermined characters, symbols, etc. printed thereon.

Next, an example of display contents of the liquid crystal display element 1 will be shown with reference to FIG.

The seven-segment display 20 in the center is a speed display, and the speed can be switched between 1/h and Mite/h.

The bar-shaped display 21 at the bottom of the speed display 20 (7) is a speed warning display.

Further, on the left side of the speed display 20, a fuel gauge 22 indicating the remaining fuel level is formed in the form of a bar graph, and on the right side of the speed display 20, a thermo gauge 23 indicating the water temperature of the radiator is also provided. It is formed into a graph.

FIG. 3 shows the electroluminescent illumination light source 3 of FIG.

The light emitting parts 30 to 33 each correspond to the speed display 20 in FIG.
, speed alarm display 21, fuel gauge 22, and thermo gauge 23.

With this configuration, each display portion 20 in FIG.
Since the light from the light source 3 does not exist in areas other than ~23, the contrast of the display is high and it is easy to see, and since only the necessary areas are illuminated and there is no unnecessary light emission, the efficiency of using the power applied to the light source 3 is improved. It gets expensive. Furthermore, since the light source 3 itself has the property of emitting light uniformly, uniform illumination is possible compared to those using conventional incandescent lamps or light guide plates.

FIG. 4 shows a cross-sectional structure of the electroluminescent device of FIG.

According to the figure, a transparent electrode 42 is laid on a protective plastic film 41, and an insulating layer 4 on top of this electrode 42 is shown.
A light-emitting layer 44 is formed within 5. An aluminum electrode 43 having a pattern to emit light is formed on the insulating layer 45 including the light emitting layer 44, and the entire surface thereof is covered with a protective plastic film 46.

Therefore, the light emitting portion 30 shown in FIG.
A pattern consisting of ~33 is formed to obtain a desired light emitting surface. Such electroluminescence 3 can have a thickness of less than IW, contributing to making the entire device thinner.

Incidentally, the pattern of the electroluminescence 3 may be as shown in FIG.

That is, the entire surface of the electroluminescent device 3 is made to emit light, and the area other than the portion 51 that requires display is covered with the optical mask 50.

This method is more wasteful than the method shown in FIG. 3 in terms of effective use of power consumption.

However, since there is no need to form a pattern for the luminescence 3, the price of the luminescence 3 itself can be reduced, and the mask 50 can be easily processed and any pattern can be formed at low cost, making it possible to increase the economic efficiency of the entire device. . The lighting effect is no different from that shown in Figure 3.

FIG. 6 shows another pattern 60 of electroluminescence 3.

That is, the light emitting pattern 60 corresponds to the liquid crystal display element 1 of FIG.
matches the displayed content. Each of the light emitting segments 61 to 64 of the pattern 60 should be individually and independently controlled to turn on and off, and is appropriately controlled by a drive circuit described below.

FIG. 7 is a system diagram showing a control circuit mounted on the printed circuit board 4 of FIG. 1.

The figure shows an arithmetic and control unit 70, a vehicle speed sensor 71, a remaining fuel amount sensor 72, a water temperature sensor 73, an AD converter 74, and a
One drive circuit '15.7'l is shown. Note that blocks 1 and 60 respectively represent the liquid crystal display element in FIG. 2 and the electroluminescence device in FIG. 6.

The arithmetic and control device 70 is, for example, a microcomputer, and based on the outputs of the respective sensors 71 to 73, an eighth
Processing according to the flowcharts shown in Figures 1 to 10 is executed.

The vehicle speed sensor t71 detects the vehicle speed by generating a pulse signal corresponding to the vehicle speed. The remaining fuel amount sensor 72 is installed in the fuel tank of the vehicle and detects the remaining amount of fuel.

Water temperature sensor 73 detects the water temperature inside the radiator.

Drive circuits 75 and 77 drive the liquid crystal display element 1 and the electroluminescent device 3, respectively, based on output signals from the arithmetic and control unit 70.

Next, the operation of this control circuit will be explained with reference to FIGS. 8 to 10.

FIG. 8 shows the processing of the main routine.

First, the arithmetic processing unit 70 is initialized (80
), and then the analog output signals of the sensors 72 and 73 are converted into digital signals by the AD converter 74 (81).

In step 82, it is determined whether the counting of the number of vehicle speed pulses obtained from the vehicle speed sensor 71, which will be described later, has been completed. If the counting of the number of vehicle speed pulses has not been completed, step 83
If the process has ended, the process advances to step 84.

At step 84 when the counting is completed, the digital display value is converted to display the vehicle speed, and the display of the electroluminescence 60 is also changed at the same time so that it matches the vehicle speed display value.

Thereafter, it is determined whether or not the AD conversion in step 81 has been completed (83). If not, the process from step 81 is repeated, and if it has been completed, the process proceeds to step 85.

Following the determination of the end of AD conversion ffi (83), a change in the display of the Zhuer meter (85) and a change in the display of the thermometer (86) are executed in sequence. These display changes are performed by synchronizing the liquid crystal display element 1 and the electroluminescence 3.

After the change process, the process returns to step 81 and the same process is repeated.

FIG. 9 shows a timer interrupt routine for changing the display at regular intervals.

First, the vehicle speed time is counted in order to set a reference time for counting the output vehicle speed pulses of the vehicle speed sensor 71 for a certain period of time (90). According to this count, it is determined whether the count value has reached a predetermined reference time (91), and if it has reached the predetermined reference time, the vehicle speed count ends at 7.
Set the lugs (92). After this, the main routine (
Return to Figure 8).

FIG. 10 shows a counter interrupt process in which an interrupt is generated by a vehicle speed pulse from the vehicle speed sensor 71.

In other words, every time an interrupt occurs, the counter should be updated to count the vehicle speed pulse.
, return to main routine processing.

If the timer interrupt shown in Figure 9 and the counter interrupt shown in Figure 10 occur at the same time, for example, if the configuration is such that the interrupt processing on the counter side takes priority over the interrupt processing on the timer side, the vehicle speed pulse Counting mistakes can be prevented.

〔Effect of the invention〕

According to the present invention, by having the configuration as described above, it is possible to provide a liquid crystal display device having the following effects.

(1) By using electroluminescence, uniform illumination and therefore uniform display are possible.

(2) Similarly, by electroluminescence,
Since the lit portion and the non-lit portion can be clearly separated, the contrast of the display can be increased and visibility is excellent.

(8) Since the electroluminescence pattern can be made to match the pattern of the liquid crystal display element, electroluminescence light emission can be utilized with extremely high efficiency. Therefore, there is no waste of power consumption.

(4) By combining a low power consumption liquid crystal element with highly efficient electroluminescence, the liquid crystal display element consumes less power than conventional devices, where the light source consumes many times as much power as the liquid crystal element. You can take advantage of it.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention, FIGS. 2 to 4 are a plan view and a sectional view showing essential parts of the embodiment of FIG. 1, and FIGS. 5 and 6 are respectively 3 is a plan view showing a modification of FIG. 3, FIG. 7 is a system diagram showing other essential parts of the embodiment of FIG. 1, and FIGS. 8 to 1θ are flow charts showing the operation of FIG. 7. DESCRIPTION OF SYMBOLS 1... Liquid crystal display element, 2... Filter, 3... Electroluminescence, 4... Printed circuit board, 5...
...Conductive rubber, 6...Mask, 30-33...Light emitting part.

Claims (1)

[Claims] 1. A liquid crystal display device in which a liquid crystal display element in which liquid crystal segments are arranged in a pattern corresponding to a required display, and a light source for illumination disposed on the back side of this element to illuminate this element are visible. A liquid crystal display device, wherein the illumination light source is an electroluminescent device having a pattern in which only portions corresponding to the arrangement of the segments emit light. 2. A liquid crystal display device according to claim 1, wherein the electroluminescence pattern is obtained by forming an electroluminescence light emitting portion into a predetermined shape. 3. A liquid crystal display device according to claim 1, wherein the electroluminescent pattern is formed by a light-shielding mask placed on the electroluminescent light emitting surface.