JPS6025767B2 - LCD display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display method, and more particularly to a liquid crystal display method using a liquid crystal display cell comprising a resistive layer provided on the opposing surfaces of opposing substrates.

Display devices using liquid crystals have the advantage of being resistant to mechanical vibrations as they do not have rotating or moving parts, compared to analog displays using mechanical display devices such as ammeters, and are also compact. Since it is lightweight, requires low applied voltage, and consumes little power, a variety of devices and display methods have been proposed in recent years.

Among these conventional methods, there is a method in which, for example, the applied voltage is converted from analog to digital and this digital signal is applied to divided electrodes in order to convert the magnitude of the applied voltage to the position of the display surface. This method has the disadvantage that the circuit is complicated and the number of wirings is large, which is cumbersome.

In addition, as an improvement to these methods, the following method of directly displaying an analog signal in analog form has also been proposed. In other words, in some cases, the magnitude of the electric field between opposing electrodes is a function of distance, so the electrodes are arranged at unequal intervals, and the location where the liquid crystal operates differs depending on the magnitude of the applied voltage. It is something. Another display method is to connect functional elements with different threshold characteristics to each of the divided electrodes, and to apply a voltage to the external connection common terminal of the functional elements, the operation threshold changes depending on the magnitude of the voltage. This is based on the idea that the voltage position can be directly displayed by turning on the functional element that exceeds the voltage value and turning on the liquid crystal display connected to the functional element. Furthermore, a display method has also been proposed based on the idea of applying a voltage distribution to the liquid crystal display section by dropping the voltage through a resistor, and applying the voltage distribution directly to the liquid crystal display operation.

In these display methods, the display method uses a liquid crystal cell with two electrodes placed opposite each other at unequal intervals to display the position of the voltage. Because it has a sufficiently large resistance value, there is almost no voltage distribution between the opposing electrodes, and the voltage applied to the liquid crystal layer remains constant. An electric field is applied depending on the distance between the electrodes, resulting in an electric field strength distribution, but in actual liquid crystal operation, the operating point is determined by the voltage generated at the interface between the electrodes and the liquid crystal, rather than depending on the electric field strength within the liquid crystal layer. Therefore, in terms of phenomena, the operating threshold of the liquid crystal tends to be such that the entire display area operates with a constant voltage, regardless of the location of the unevenly spaced electrodes.

However, in this case, the rising response of the liquid crystal operation and the falling response due to voltage removal differ greatly depending on the uneven distances.
However, since the rising response changes depending on the magnitude of the voltage, there may be cases where the position indication is apparently indicated depending on the magnitude of the applied voltage.

However, in this display method, the display position changes depending on time when a voltage exceeding a threshold value is applied, and it is difficult to obtain reproducibility of the display position. In addition, these devices have many problems, such as it is difficult to keep the manufacturing conditions constant, and at the same time, they are highly temperature dependent, so it is necessary to eliminate the influence of ambient temperature during operation. . Additionally, there is a method of connecting functional elements that operate differently depending on the voltage to the liquid crystal element without using the original characteristics of the liquid crystal, but although this method is essentially problem-free in principle, it is complicated in practice. It is expensive and cannot be said to be a good product from a commercial standpoint.

On the other hand, a display method based on the idea of applying different voltage distributions to the liquid crystal layer to operate it is possible in principle, and it is also possible to simplify the equipment, so it is the display method that is most desired to be realized. This is a method, and in fact, there have been proposals to embody this display method until now, such as Tokuseki 46-3642 and Jitsoseki 46-3642.
9-145644 Several inventions have been proposed.

In addition, a device has been proposed in which a film resistor is connected to the divided electrodes and a similar effect is expected (Tokukan Sho 47-210).
Invention described in Publication No. 97).

However, these methods have various problems as described below, and the reality is that they have not yet reached the stage of practical application.

That is, in the above invention, a liquid crystal having a dynamic scattering effect (hereinafter abbreviated as DSM) is used. First, when DSM is used, the DSM is a state change between transparent and cloudy. Therefore, essential color display is not possible.

Secondly, DSM cannot provide a sufficiently large contrast because the state changes between transparent and cloudy. Thirdly, the dark value characteristic of DSM is inherently slow, and the display boundary area becomes unclear.
Furthermore, in the case where a doping agent such as an electrolyte is added to the liquid crystal for the purpose of improving this, a large amount of current flows through the liquid crystal layer, resulting in operational restrictions and a shortened lifespan. Furthermore, in the display method that attempts to clearly distinguish the boundary area using divided electrodes, one of the problems is that the display is no longer a continuous position change display, but is a step-by-step display, which limits the display stage. receive.

Second, the method of subdividing segmented electrodes in an attempt to provide an apparently continuous display suffers from drawbacks that essentially result from the problem of blurring of the boundary areas. Furthermore, in terms of manufacturing, processing finely divided electrodes requires advanced technology, and there are many commercial disadvantages such as an increase in the number of manufacturing steps. A fourth point that can be improved is the temperature dependence of the threshold value. This is because the boundary position moves depending on the temperature even for the same applied voltage, and this is remarkable in the conventional method. Therefore, in order to avoid this effect, auxiliary means such as temperature compensation are required, which leads to the complexity of the device, resulting in an increase in the number of manufacturing steps and an increase in cost, which is not a desirable display method. It is. The present invention has been made in view of the above points, and has excellent reproducibility of display position and display width, temperature dependence is practically negligible, contrast is extremely good, and continuous position changes are displayed. The object of the present invention is to provide a liquid crystal display method in which the boundary between a display area and a non-display area can be clearly distinguished.

In the liquid crystal display method of the present invention, a first resistance layer is provided on the surface of one of two transparent substrates facing each other, and a second resistance layer is provided on the surface of the other substrate facing the resistance layer. and applying voltage to the first resistive layer of a liquid crystal display cell which is arranged between two polarizing plates with a liquid crystal sandwiched between at least the first resistive layer and the second resistive layer. The voltage at which the sum of the voltage and the voltage applied to the second resistance layer is a constant value is set to the first resistance layer.
and the second resistance layer, and the potential gradient of the voltage applied to the first resistance layer and the potential gradient of the voltage applied to the second resistance layer are opposite to each other. This is a characteristic feature. By doing so, the above-mentioned object is achieved. Therefore, according to the liquid crystal display method of the present invention, the desired high contrast can be easily obtained, and either negative or positive display can be selected arbitrarily. The boundaries of the display area can be identified by clear contrast. Displays including analog calculation functions can be performed using two or more control voltages. The basic structure of a liquid crystal cell is that the electrodes are simply placed on the substrate surface, which is negligible, but has many advantages over current operation in terms of life span and electrode structure because it is essentially an electric field operation. It is extremely easy to manufacture.

This method has many advantages over conventional liquid crystal display methods, such as (no need for alignment of upper and lower electrodes, no need for masks for forming subdivided electrodes, etc.), and is also extremely effective. Hereinafter, the liquid crystal display method of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an example of the basic configuration of a liquid crystal cell used in the liquid crystal display method of the present invention.

1 is a first polarizing plate, 2 is a first substrate, 3 is a first resistance layer formed on the substrate 2, 4 is a space filled with nematic liquid crystal exhibiting an electric field effect, and 6 is a second substrate. board, 5 is board 6
The second resistive layer 7 formed thereon is a second polarizing plate.

FIG. 2a is a plan view of the substrate 2, in which a resistance layer 3 is formed on the substrate 2, and highly conductive electrode portions (terminal electrodes) 3a and 3b are formed in at least two separate regions of the resistance layer 3. ing.

FIG. 2b is a plan view of the substrate 6. Similar to FIG. 2a, a resistance layer 5 is formed on the substrate 6, and a highly conductive electrode portion (terminal electrode) 5a is formed in at least two separate regions. ,5b
have.

In the display method of the present invention, these two substrates are
A liquid crystal cell is used in which the peaks are arranged parallel to each other with a gap about the size of a Buddha, a nematic liquid crystal exhibiting an electric field effect is sandwiched in the space between them, and the terminal electrodes are hermetically sealed in a state where they can be connected to an external circuit.

A liquid crystal cell having such a four-terminal configuration is connected to a drive circuit for driving the cell as shown in FIG. 3. Figure 3a
LC within the dotted line is a liquid crystal cell having the structure explained in FIGS. 1 and 2, and E, E2 are voltage power supplies.

In FIG. 3a, if a voltage V is applied to the first resistance layer 3 and a voltage V2 is applied to the second resistance layer, the resistance layers 3 and 5 will have the following properties:
Potential gradients are generated as shown by the gradients of straight lines AB and CD in FIG. 3b, respectively.

Therefore, the voltage difference V applied to the liquid crystal layer in each area of the entire display area 1 of the liquid crystal cell LC is shown by the arrow between the straight line AB and the straight line CD in FIG. (The potential difference voltage V is shown by the arrow in the textbook in the figure, but it actually changes continuously within one region).Now, if the electro-optical threshold voltage of the liquid crystal of the liquid crystal cell LC is Vth, then , potential difference voltage V
The liquid crystal layer in region a where is less than the V ratio maintains the initial teardrop orientation state, and the liquid crystal layer outside region a changes from the initial wobbling orientation state to an isotropic state. When the polarization directions are perpendicular to each other, the area a appears bright because it transmits the incident light, and the area outside the area a appears dark because it blocks the incident light. That is, as shown in FIG. 3c}, the liquid crystal cell L
On the display surface of C, a band-shaped area of a bright area (1) (hereinafter referred to as a display area (1)) with a dark area (0) as a background is observed.

Of course, it goes without saying that the relationship between brightness and darkness in this case is a negative-positive relationship that is reversed when the polarization directions of the aforementioned polarizing plates are parallel to each other. Here, the display section (1) can be positioned at any position on the display surface of the liquid crystal cell LC with any band width by appropriately changing the voltages applied to the resistance layers 3 and 5. As an analog display such as a position display, the band width of the display section (1) must be constant regardless of the display position, except for changing it as desired.
In this sense, in the present invention, the total display width 1 in FIG. V, resistance layer 5
If the voltage applied to V2 is v. V and V2 are set so that 10v2 = aircraft carrier = blood ship tant.

That is, as will be described later, by an appropriate control means, (V, 10V
2) are changed in conjunction with each other so that V and V2 remain constant. In other words, the midpoint of the display width a is the display area (
1), where the points at both ends of the entire display area 1 of the liquid crystal cell LC are A and 0, and the distance from point A to the midpoint is m, then m; 1- (Flow) v, = (Flow) (Empty half - v・) = (Second flow) V2, and the position of the display part (1) is proportional to the size of V2, and is at one end of the entire display area 1 of the liquid crystal cell LC. It can continuously move from A to the other end D in a constant width.

The above point will be further explained based on FIG. 9.

In Figure 9, voltages ○ and V are applied to both ends of the first resistive layer having a width of 1, and voltages of V2 and 0 are applied to the second resistive layer so that the potential gradients intersect. When the voltage is applied, one end of the first resistance layer is marked as ◯, the length direction is taken as the x axis, and the coordinates are shown with the voltage as the vertical axis.

At this time, the potential distribution of the first resistance layer V,(x) and the potential distribution of the second resistance layer are expressed as V2(x). LCD function value Vth
, the length of the display section located between both resistor layers and within the threshold value is indicated by a. The sum of V and V2 is constant, and this is designated as V.
V, 10V2=V Find the value of a for any V, (or V2).

At this time, since V, (x) and V2 (x) have opposite slopes, V, (x) and V2 (x) are expressed by the following formula. V.(X)=hand vl, v2(X)=cow v2 The first point where the potential difference between one resistance layer is Vth is set as X, and the second point is set as equal.

V2(X)-V・(X)=1,000v2kiv,=V2-child(
V.10V2) =V2-Vth> Since this is a position that produces a potential difference of Vth at the first point x, Vth: V21,000V ~ Sanshi (V2-Vth).

Similarly, regarding the second point, V・■−V2■=sheep w. Twelve sheep v2 Vth=V2 cross V Snake Warrior (V20Vth) becomes.

Since the distance of uniform x, is a, a = & ~ = 2nd grade = 2nd place becomes.

Therefore, if V and V2 are set to constant values, the value of a (display width) will be constant regardless of the variable x and the value of the turret (display position).

FIG. 4a is a modification of FIG. 3a, in which there is a resistance R between AA.
, , DD'.

The gradient of the voltage applied to the resistance layers 3 and 5 at this time is the third
If expressed in the same way as shown in Figure b, the fourth
It will look like Figure b.

b represents the display width of the display section (1). In the case of FIG. 4a, compared to the case of FIG. 3b, the display section (1) can be moved arbitrarily from one end of the display wall 1 of the liquid crystal cell LC to the other end without relatively increasing the potential at point B or point C. can be moved to
Therefore, the liquid crystal cell LC can be easily driven.

FIG. 5 is an example of a specific circuit diagram for changing V, , V2 so that (V, V2) becomes constant, and this is done by using two interlocking variable resistors VR, , VR2.

Now, if R3 and R4 are resistors with the same value, and VR and VR2 are variable resistors with the same value, the power supply voltage V of the voltage power source E is divided into R3 and VR as V3 and V4, respectively. The voltage is divided into R4 and VR2 as V4 and V3, respectively.

Therefore, the voltage V, applied to the resistance layer 3 is equal to V4,
The voltage V2 applied to the resistance layer 5 becomes equal to V3, and (
V, 10V2) (V40V3)=V, and such a device can be applied as a voltmeter, for example. However, (resistance of resistance layer 3) >> VR,, (resistance layer 5
(resistance)》R4. FIG. 6 is an example of a circuit diagram when the display method of the present invention is applied to a side light meter.

In Fig. 6, the interlocking variable resistor VR in Fig. 5 is shown.
,,Instead of VR2, a light receiving element (
For example, CdS light-receiving elements (PC, PC2) are used to control the amount of light.

The operating principle in this case is the same as that in Fig. 5, but the resistance of the photodetectors PC, PC2 cannot change to zero, so
When trying to display in full display mode of the liquid crystal cell LC,
It is necessary to insert resistors R5 and R6 at the positions shown in the figure in order to apply a potential gradient as shown in FIG. 4b to the resistance layers 3 and 5 of the liquid crystal cell. This is also true in the following circuit diagrams to which the display method of the present invention is applied, so no special explanation will be given hereafter. FIG. 7 is a circuit diagram of yet another application example, which is an improved version of the circuit diagram shown in FIG. 6. In FIG. However, in the example shown in FIG. 7, it is possible to operate with one light receiving element PC3.
The amplifier 8 provides the value divided by the resistors 9 and 9' as a reference voltage. Photodetector PC3 connected to resistor 9″
Assuming that the potential at point F changes by △VF due to a change in the amount of received light, this is detected by the detector 10' and transmitted to the feedback control section 11, and the output value of the detector 10 and the resistance value of the resistor 9'' are combined. Based on the relationship, the amplifier 8 operates so that the output potential changes by (1 AVF).In this case, the voltage applied to the resistance layer 3 changes by (1△VF), and the voltage applied to the resistance layer 5 changes by △ VF changes and satisfies the condition that (V, +V2) remains constant.8th
The figure is a circuit diagram showing an example of a circuit to which still another display method of the present invention is applied, and is a partially modified version of the circuit of the example shown in FIG.

In the figure, 14 is SPC (SmconPhotoCel
1), compression diodes 12 and 13 are connected in place of the resistors 9' and 9^ shown in FIG. 7, since the characteristics with respect to light are different from those of the CdS light receiving element. The operating principle is the same as that shown in FIG. As described above in detail with specific examples, the liquid crystal display method of the present invention not only can be realized with a circuit configuration that is cheaper than the conventional one, but also can display an arbitrary position with a fixed display width and can be used as needed. The display width can be changed accordingly, and it has many advantages such as a clear boundary between the display area and non-display area and good contrast.

[Brief explanation of drawings]

1 and 2 are schematic diagrams showing the basic configuration of a liquid crystal cell used in the liquid crystal display method of the present invention, FIG. 3a is a basic circuit diagram for realizing the display method of the present invention, and FIG. Figure 3b
, c are explanatory diagrams of the display principle, FIG. 4 a is a modified circuit diagram of FIG. 3 a, FIGS. 4 b and c are explanatory diagrams, and FIGS. 5 to 8
The figure is a circuit diagram showing an example of a circuit to which the display method of the present invention is applied. FIG. 9 is an explanatory diagram showing coordinates in which the x axis is the length direction of the entire display area width 1 of the liquid crystal element used in the present invention, and the vertical axis is the voltage applied to the two resistance layers. 1,7...
Polarizing plate, 2, 6...Substrate, 3, 5...
Resistance layer, 4...Gap, 3a, 3b, 5a, 5b
...Terminal electrode, 8...Amplifier, 9,9
', 9''...Resistance, 10...Detector,
11... Return control section, 12, 13...
...Compression diode, 14...SPC. Grandson 1 Figure Group 2 Figure 3 Fist Figure 4 Mochiku Figure Grandchild Figure 5 Figure 7 Figure 8 Man? figure

Claims (1)

[Claims] 1 A first resistance layer is provided on the surface of one of two transparent substrates facing each other, a second resistance layer is provided on the surface of the other substrate facing the resistance layer, and at least the first resistance layer is provided on the surface of the other substrate facing the resistance layer. A voltage applied to the first resistance layer and the second resistance layer of a liquid crystal display cell in which a liquid crystal is sandwiched between a resistance layer and the second resistance layer and arranged between two polarizing plates. A voltage is applied to the first resistance layer and the second resistance layer such that the sum of the voltages applied to the voltage becomes a constant value, and a potential gradient of the voltage applied to the first resistance layer and the second resistance layer are applied to the first resistance layer and the second resistance layer. A liquid crystal display method characterized in that the potential gradients of the voltages applied to the layers are opposite to each other.