JPS6217238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device that performs analog display using liquid crystal.

For example, devices using liquid crystals have been developed as display devices for various meters such as automobile speedometers and tachometers, but conventional liquid crystal display devices have adopted a digital display method that combines multiple segments, and each It has drawbacks such as extremely complicated and expensive segment wiring combination circuits.

The present invention is intended to address the above-mentioned problems, and provides a display device that uses a liquid crystal or the like to perform analog display at a low cost using simple measures.

The present invention will be explained below with reference to embodiments shown in the accompanying drawings.

Normally, a liquid crystal display device is constructed by sealing liquid crystal between two transparent electrodes facing each other, and when a voltage is applied to the transparent electrodes, a liquid crystal effect (for example, it becomes opaque) appears in the liquid crystal between the electrodes. In this way, a predetermined display is performed, and the relationship between the applied voltage waveform and the liquid crystal effect waveform in such a liquid crystal display device is as shown in FIG.

That is, in FIG. 1, the solid line a indicates the applied voltage waveform, and the dotted line b indicates the liquid crystal effect waveform. As is clear from this figure, liquid crystals have different response speeds in rise and fall times, and are characterized by a particularly long fall time. This is because the opposing transparent electrodes of a display device using liquid crystal are extremely close together (10
This is because the liquid crystal serves as a type of dielectric and forms a capacitor.

When a differential pulse obtained by differentiating a rectangular wave is applied as an applied voltage to a display device using a liquid crystal as described above, the length of the fall time mentioned above is promoted and the repetition frequency is increased.
Flicker-free display can be achieved even at around 10Hz.

By utilizing the characteristics of the liquid crystal effect as described above and configuring a liquid crystal display device as shown in FIG. 2, it is possible to obtain a device that displays an analog variation amount, such as the speed of an automobile, in an analog manner.

That is, in the present invention, as shown in FIG. 2, transparent electrodes 3,
4 are each finely divided to form a plurality of opposing electrode groups, and a liquid crystal 5 is sealed between them, and each of the divided transparent electrodes 3 and 4 is connected to a resistor R1, R2, R3, . R′1,
The divided transparent electrodes 3 are sequentially connected via R'2, R'3, . . . to form a cascade connection circuit.
At the end of and 4, the transparent electrodes 3 and 4 are connected via the end resistor R (the terminals 7 and 7' in A and B in FIG. 2 are connected). Note that in the figure, 6 indicates a spacer.

Normally, the distance between the two glass plates 1 and 2 in a liquid crystal device, that is, the distance between the liquid crystals is about 10μ.
The thickness of the transparent electrode is 0.3 to 0.5μ. Therefore, the resistors R1, R2, ......, in the device of the present invention,
R′1, R′2, etc. are about 10KΩ, and when printed on glass plates 1 and 2, the thickness is 5~
Since it is about 8μ, in order to obtain an analog display, the width of the counter electrodes is made small and even if the number of counter electrodes is increased, the resistors R1, R2, . . .
..., R'1, R'2, . . . can be printed within the distance between the two glass plates 1 and 2.

The equivalent circuit of the liquid crystal part of the device shown in Fig. 2 above is the third
As shown in the figure, each divided counter electrode is designated as A, B, C, . . . sequentially.

Here, a case will be described in which the present liquid crystal display device is applied to, for example, a vehicle speedometer of an automobile.

If a DC voltage is applied to the liquid crystal, a type of electrolysis will occur, so it is necessary to apply an alternating current.

Therefore, when using this device as a vehicle speedometer as described above, by passing the rectangular wave generated by the pulse generator as shown in Fig. 5 (a) and Fig. 6 (a) through a differentiating circuit, This is applied to the liquid crystal device as a differential pulse as shown in Figure B, and the pulse voltage is applied to each counter electrode by changing the resistance value of the end resistor R (variable resistor) shown in Figure 3 according to the vehicle speed. It is possible to perform analog display using a liquid crystal device.

This is shown in a block diagram in FIG. 7, in which a indicates a pulse generating circuit, b a differential circuit, and c a liquid crystal device.

When a pulse voltage from the pulse generator passes through the differential circuit and is applied to the liquid crystal device, that is, the circuit shown in FIG. 3, the pulse voltage itself is applied to the counter electrode A, but the pulse voltage applied to the counter electrode B is R ₁ +R′ ₁ ) and resistance (R ₂ +R ₃ +R ₄ +R′ ₂ +
Since the voltage is divided by the resistance ratio of R' ₃ +R' ₄ +R), it is smaller than the pulse voltage applied to the counter electrode A. Thereafter, in the same manner, the pulse voltages (i.e. charging voltages) applied to each opposing electrode section are sequentially decreased in the order of A, B, C, etc. from the voltage application side as shown in Fig. 4 A to E, and the pulse voltage A perfect liquid crystal effect is obtained up to the counter electrode portion where the effective value of is equal to the threshold voltage of the liquid crystal, but no change in the liquid crystal occurs in the counter electrode portion to which a pulse voltage lower than that is applied.

During discharging, when the next applied pulse voltage becomes lower than the peak value, the charge accumulated on the counter electrode A becomes the resistance (R ₁ +R ₂ +R ₃ +R ₄ +R' ₁ +R' ₂ +R' ₃ +R' ₄
+R), whereas the counter electrode B
The accumulated charge is the resistance (R ₂ + R ₃ + R ₄ + R′ ₂ +
R' ₃ +R' ₄ +R), the resistance value is smaller than that of the counter electrode A. Similarly, during discharge, the resistance value sequentially decreases in the order of A, B, C, etc., and the discharge waveform changes.

In the equivalent circuit shown in Figure 4, the internal resistance within the liquid crystal is several hundred kilohms, and the resistances R1, R2,...
It is assumed that the internal resistance is so large that it can be ignored compared to R'1, R'2, ......, R.

As described above, the energy that causes the liquid crystal effect accumulated in each counter electrode A, B, C...... decreases in sequence, so by changing the resistance value of the end resistor R in proportion to the vehicle speed, A liquid crystal effect is obtained up to the counter electrode portion where the amount of energy is above a certain level, but no change occurs in the counter electrode portion where the energy amount is below that level. Therefore, the boundary between the presence and absence of the liquid crystal effect changes according to the change in the resistance value of the end resistance R, and the counter electrode A,
B, C...... for example, 15cm, which is the normal display width.
If the space is divided into 60 or more equal parts, a display almost similar to analog display can be obtained.

Generally, the liquid crystal effect occurs in proportion to the energy present inside the liquid crystal, and becomes visible at the threshold level.

This existing energy per unit time is the electrode part x
Assuming that the voltage at the point is V(x) and the current I(x), and the number of pulses generated per unit time is f(x), W(x) = V(x)・I(x)・f(x) It is expressed as (1). If two of the above V, I, and f are fixed and one is changed, W(x) will change proportionally. It is clear from equation (1) above that this W(x) is controlled by the change in the resistance value of the end resistance R.
By configuring the resistance value to change in accordance with the amount of change to be displayed, such as vehicle speed, the amount of change can be displayed in an analog manner.

As is clear from the graph in Figure 8, the end resistance R
When the resistance value of is a certain value Rc, the opposing electrodes A, B,
C.... is in a display state, D is in a non-display state, and is clearly interrupted at the Rc section.

As described above, according to the present invention, non-contact analog display is possible, and as shown in FIG. Since it can be provided in any shape, it is very inexpensive and has extremely practical effects.

[Brief explanation of the drawing]

Fig. 1 is a waveform diagram showing the relationship between the liquid crystal effect and the applied voltage, Fig. 2 shows an example of the liquid crystal display device according to the present invention, and Figs. Figure 3 is a plan view, and figure C is a cross-sectional view of the assembled state. Figure 3 is an equivalent circuit diagram of the device shown in Figure 2, and Figures 4A to 4E are equivalent circuits of the device shown in Figure 2 when voltage is applied, charging and discharging waveforms, and equivalent circuits when discharging, respectively. It shows. 5 and 6 are diagrams for explaining liquid crystal power supply waveforms, and in each figure, A shows a rectangular wave, and B shows a differential waveform of A, respectively. FIG. 7 is a block diagram of the liquid crystal drive circuit according to the present invention, FIG. 8 is a graph showing the relationship between the energy present in the liquid crystal per unit time and the resistance value of the end resistance, and FIG. FIG. 3 is a front view showing an example of use for display. 1, 2... Glass, 3, 4... Transparent electrode, 5...
...Liquid crystal, 6...Spacer, 7, 7'...Connection terminal, R1-R4, R'1-R'4...Resistor, R...
End resistance, A, B, C, D, E... counter electrode set.

Claims (1)

[Claims] 1. A large number of display element parts each having a liquid crystal sealed between transparent electrodes are successively provided, and each display element part is successively connected in parallel via a resistor to form a cascade connection circuit. One end of the connection circuit is connected by an end resistor, and a pulse obtained by differentiating a rectangular wave is applied as a power source from the other end, and the resistance value of the end resistor is proportional to the amount of change to be displayed. A display device characterized in that the display device is configured to change the display device. 2. The display device according to claim 1, wherein the resistor connected between each display element portion is printed on an electrode holding plate so that the resistor is present in the liquid crystal together with the transparent electrode.