JPS59211085A - System of driving electrooptic display - 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 Ta) Technical Field of the Invention The present invention relates to an electronic display device, particularly a relatively large type display device that displays characters or images by selectively driving display elements such as incandescent light bulbs arranged in a matrix. The present invention relates to an electronic display device.

(Background of BL technology) As a display device in a stadium or other large display device aimed at a large number of spectators, for example, display elements such as incandescent light bulbs are arranged in a matrix, and the incandescent light bulbs are selectively turned on. There are so-called electronic display devices that display text information or images.

In this type of display device, electromagnetic relays have been used as switches for controlling the on/off of driving power for the incandescent light bulbs, etc. Recently, due to the advantages of reliability, miniaturization, cost, etc. Semiconductor devices such as these are increasingly being used. In particular, when it is necessary to frequently rewrite display information or when displaying a moving image, a high writing speed of display information is required, and a method using semiconductor elements is also advantageous for this purpose.

(C1 Prior Art and Problems In the electronic display device as described above, after the display information for one screen is written, it is necessary to hold the display information until the display information for the next screen is written. However, a method is generally adopted in which an external memory is provided for each display element, and display information for each display element is held using this external memory.

Since Cyrisk has a self-holding function, it can be used not only as a drive power switch as described above but also as a display information holding function, but conventionally there was no need to detect a self-holding voltage for this purpose. Instead of utilizing this function, the thyristor 1 as shown in FIG.
Flip-flop (FF) 3 connected to gate 2 of
hold the write signal (X), or the same figure (B
), a Hall element 4 is connected to the gate 2 of the thyristor 1.
is connected, and a write signal (X) is applied to the coil 5, thereby magnetizing the magnetic body 6 around which the coil 5 is wound to control the Hall element 4 and holding the write signal. For external connection, a method using memory was adopted.

In addition, in FIG. 1, 7 is a display element such as an incandescent light bulb.

As mentioned above, with the method of providing external memory for each individual display element, the number of elements increases and the cost of the device inevitably increases.As a result, the X-Y matrix drive method is adopted. However, the advantages of external devices are not significant, and the write drive speed of external devices is limited depending on the type of memory element, making them unsuitable for high-speed display, especially for displaying moving images.

(Object of the Invention) An object of the present invention is to reduce device costs by effectively utilizing the self-holding function of Cyrisk, and to provide a drive system capable of high-speed display.

(e1 Structure of the Invention The present invention is an electronic display device that uses a thyristor as an on/off switch for a display element, and the basic feature is that display information is retained using the self-holding function of the thyristor. , when implementing this, the first feature is that a write signal is applied to the gate of the cyrisk after a predetermined time based on the zero-crossing point of the power supply voltage,
In this case, the second feature is that the write signal is sequentially applied to the gates of the plurality of cyrisks within a certain period from a predetermined time after the zero-crossing point of the power supply voltage as a reference to the next zero-crossing point. The third feature is that the gate of the thyristor is always at a negative potential during periods other than the thyristor.Furthermore, an AND circuit is provided at the gate of the thyristor, and the input of the AND circuit is connected to the X line write signal and the Y line write signal. The fourth feature is that X-Y matrix driving is possible by directly applying a line write signal, and in this case, the X line write address is alternately up-counted and down-counted every half cycle of the power supply voltage. is the fifth characteristic.

(Example of fi invention Embodiments of the present invention will be described below with reference to the drawings.

The driving method of the present invention is based on the fact that a pulsating current obtained by full-wave rectification of a commercial alternating current voltage is directly used as display element driving power as a power source.

That is, when a pulsating current as shown in Fig. 2 obtained by full-wave rectification of a commercial AC voltage (for example, 200 volts, 50 Hz) is applied between the anode and cathode of Cyrisk, the voltage of the pulsating current is By passing an appropriate current through the gate of the SIRISK during a period exceeding the holding voltage (Vs) of the SIRISK, the SIRISK becomes conductive and remains conductive until the applied voltage becomes smaller than the holding voltage (Vs).

Now, by adding a write signal to all of the predetermined sirisks during the hatched period (Tw) of the pulsating flow shown in FIG. 2, the sirisks retain the write signals for at least the period Td, and A display element such as an incandescent light bulb, which is controlled on/off by the cyrisk, lights up. Therefore, it is possible to display fixed information or to display a moving image by refreshing the sirisk so that a predetermined write signal is added every half cycle of the AC power supply (τ2: that is, one cycle of the pulsating current). It becomes possible.

As is clear from the above, the smaller the Tiy/Td ratio is, the smaller the difference in timing between the individual display elements turning on, and the smaller the difference in brightness. By the way, it is possible to set the turn-on speed of Cyrisk to 1 to 2 μsec, and the above τ% is 10 m when the power frequency is 50 Hz.
It is 5ec. Therefore, when a write signal is sequentially applied to 100 cyrisks, the difference in brightness between the display element lit first and the display element lit last becomes 2% or less. This brightness difference can be eliminated by a method described below that forms part of the present invention.

In the present invention, the timing for writing to a predetermined thyristor is determined based on the zero-crossing point of the AC voltage (the point where the peak value of the pulsating current in FIG. 2 becomes zero). In other words, since the point at which the pulsating current reaches the holding voltage (Vs) of Cyrisk is determined by the voltage value and frequency of the commercial AC power supply, the time from when the zero-crossing point is detected is measured by a counter or a CR integration circuit. So you can decide by that.

Further, in the present invention, as shown in FIG. 3, the gate 2 of the thyristor 1 is set to a negative potential by the voltage -νb except during writing (that is, when the voltage Viv is zero). There is. As a result, the thyristor 1, to which no write signal can be applied, is kept completely non-conductive. In other words, when the wiring distance between the write signal source and Thyristor 1 is long, the noise voltage may cause Thyristor 1 to become conductive, resulting in a false display, but the above method can reduce the noise margin for the write signal. It can be made thicker. In addition, in Fig. 3, R3 is a resistor for generating the gate threshold voltage of the thyristor.
The size of the noise margin can be set by this value, and cl is a capacitor for noise limit.

FIG. 4 is a block diagram showing an example of an XY matrix type drive circuit to which the above method is applied.

In the same figure (A), the display information from the control unit 8 is stored in the display information memory 9, and the Y-line write signal is sent to each Y-line, Yl, Y2, y3, . . . via the Y-driver 0.
・, are output in parallel to Yn.

On the other hand, when the zero-crossing detector 11 detects the zero-crossing point of the commercial AC power supply 12, the address counter 3 uses this detection time as a reference to adjust the peak value of the pulsating current that is the output of the rectifier 14 to the holding voltage (Vs) of the thyristor. Count the time until you reach it. The switching unit 15 switches the address bus to the address counter 12 side at this point or after a predetermined period of time has elapsed after this point. As a result, the output of the address counter 13 is input to the display information memory 9. The output of the address counter 13 is also sent to the decoder 16,
In synchronization with this, from the Xl- line of the X-driver 17
Each driver up to the i-line is selected in turn.

As a result of the above, the display information stored in the display information memory 9 is changed to
- Lines are read out line by line. That is, first, the display information at the intersection of the Xl-line and the Y-line is read, and thereby the X-line write signal and the Y-line write signal are transmitted to each display element block 18 on the xl-line. Next, the display information at the intersection of the X2-line and the Y-line is read out, and each display element block 18 on the Blocks 18 are written sequentially.

FIG. 2B shows a detailed configuration example of the display element block 18, in which a pulsating current, which is the output of the rectifier 14, is applied to both ends of the thyristor 1 and the display element 7, which are connected in series. The pulsating flow flows through all display element blocks 1
8 in parallel). The gate 2 of the thyristor 1 is provided with an AN comprising, for example, two diodes D1 and D2.
A diode DI is connected to the Y-line, while a diode D2 is connected to the X-line, and the gate 2' is connected only when a write signal is applied to both lines at the same time. When a positive voltage is applied, the thyristor 1 becomes conductive, and the display element 7 lights up. When a write signal is not applied to one or both of the diodes D1 and D2, the gate 2 is at a voltage of -
The thyristor 1, which has a negative potential due to vb and is not written, is kept completely non-conductive. Note that the resistors R1 and R3 and the capacitor CI in the same figure are the third
It has the same purpose as in the figure, and the resistor R2 is inserted for the same purpose as the resistor R1. Also, i and j in Xi of the X-line and 'IJ of the Y-line are respectively 1 to m.
and line numbers from 1 to n.

1 When performing X-Y matrix driving as shown in Figure 4,
When the display element blocks 18 on each X-line are sequentially written from the Xl-line to the Xm-line during the writing time Tw shown in FIG. 2, the maximum TIv between each line as described above. /m, and a maximum Tw difference in lighting start time occurs between the Xl-line and the Xm-line, and this is recognized as a luminance difference.

In the present invention, in order to eliminate this brightness difference, the count by the address counter 13 after a predetermined time after detecting the zero crossing point is changed to The amp count will be down-counted for the next 7%.
Adopt an alternating and repeating method. This gives us a certain half period τ
The X-line to which writing was performed the latest in 2 is the earliest to be written in the next half cycle τ2, and the writing timings for all X-lines are averaged. As a result, the timing delay in the start of lighting is averaged out,
It becomes possible to eliminate the brightness difference based on the timing shift.

2. The method of the present invention can also be applied to electric display devices other than incandescent light bulbs that use light emitting diodes and other display elements that operate by controlling on/off control of relatively large currents, and can also be applied to electric display devices that use display elements that operate by controlling on/off of relatively large currents. The element is not limited to Cyrisk, and it is obvious that it can be applied to electronic display devices that perform similar operations using other switch elements.

(a) Effects of the Invention According to the present invention, a cyrisk is used as a switching element to turn on/on a display element such as an incandescent light bulb, display information can be directly written and held in the cyrisk, and X-Y matrix driving is possible. As a result, it is possible to provide a relatively low-cost electronic display device that can be driven at high speed and is suitable for displaying moving images.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an external memory used in a conventional electronic display device, and FIGS. 2, 3, and 4 are display element drive voltage waveform diagrams of the drive method according to the present invention, respectively. , a diagram for explaining Principle 3 of expanding the noise margin, and a drive circuit diagram. In the figure, 1 is Sirisk, 2 is a gate, 3 is a flip-flop, 4 is a Hall element, 5 is a coil, 6 is a magnetic material, 7 is a display element, 8 is a control unit, 9 is a display information memory, 1
0 is a Y-drion, 11 is a zero-cross detection section, 12 is a commercial AC power supply, 13 is an address counter, 14 is a rectifier, 15 is a switching section, 16 is a decoder, 17 is an X-driver, 18 is a display element pro-7 It is. 4 Dormitory 1 town also Z dark ¥ - 4 songs

Claims (6)

[Claims] (1) An electric display device driving method characterized in that, in an electric display device using Cyrisk as an on/off switch for a display element, display information is retained using a self-holding function of the Cyrisk. (2) The electronic display device driving method according to claim 1, wherein a write signal is applied to the gate of the cyrisk after a predetermined time based on the zero-crossing point of the power supply voltage. (3) Claim 2, characterized in that the write signal is sequentially applied to the gates of the plurality of cyrisks within a certain period from a predetermined time after a zero-crossing point of the power supply voltage as a reference to the next zero-crossing point. The electronic display device driving method described. (4) The electronic display device driving method according to claim 1, wherein the gate of the cyrisk is always kept at a negative potential during periods other than during writing. (5) Provide an AND circuit at the gate of Cyrisk, and
2. The electro-optical display device driving method according to claim 1, wherein x-y matrix driving is performed by directly applying an X-line write signal and a Y-line write signal to the input of the D circuit. (6) The electro-optical display device driving method according to claim 5, characterized in that the X-line write address is alternately subjected to amplifier counting and down-counting every half cycle of the power supply voltage.