JPS629917B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a gas discharge type display device that displays characters, graphics, etc. using discharge, and a method for driving the same. A typical DC discharge type display device is a self-scanning type called Burroughs type, and its electrode configuration consists of three types of electrode groups: two types of display matrix electrode groups and a scanning electrode group. has. In contrast, the present inventors have
In the specification of the present invention, a display device constructed of only two types of display matrix electrodes as shown in FIG. 1 was proposed. In this device, between two glass plates 1 and 2,
Y-direction electrode group 3', 3 operated as a cathode,
The two types of electrode groups of the X-direction electrode group 4 to be operated as anodes are arranged perpendicularly to each other, and the discharge space is divided by the elongated strip-shaped dielectric layer 5 provided in parallel to each anode 4, and a discharge is generated inside. It has a two-electrode group structure filled with a gas whose main component is a rare gas that emits light by Note that 3' is a cathode for reset. FIG. 2 is a cross-sectional view of the display device taken along the cathode line 3 in FIG. , a space 6a and a space 6b, the space 6a is used to sequentially transfer pilot discharge along the anode line 4, and the space 6b is used to generate display discharge. That is, by keeping the discharge current low, the glow discharge of each discharge dot 6 becomes a so-called normal glow discharge and is limited to the area of the space 6a, and by increasing the discharge current, it becomes an abnormal glow discharge. It spreads to the area of the moving space 6b. When the pilot flame is discharged in the space 6a, the anode wire 4 is made of a thick film of opaque metal in the form of a band, so the discharge light from the pilot flame is shielded and light leaks from the front of the discharge dot 6. is almost invisible. On the other hand, when the discharge spreads into the space 6b, display light emission is obtained from the front surface of the discharge dot 6. In other words, by increasing or decreasing the discharge current within the space of the same discharge dot 6, the binary state (on-off state) of display discharge and pilot discharge is determined for each discharge dot 6. can be displayed. As described above, in the display device previously proposed by the present inventors, the pilot discharge in the space 6a has a function equivalent to a Burrows-type scanning electrode. Therefore, a display device having this structure has a simpler display surface configuration, is easier to manufacture, and is less expensive to manufacture than a Burrows type device. Moreover, there is no crosstalk between adjacent discharge dots 6, and a stable and highly recognizable display can be realized. Furthermore, the present inventors proposed a method for driving the display device shown in FIG. 1 in Japanese Patent Application No. 52-139335. The basic operation of the above driving method will be explained based on FIGS. 3 and 4. FIG. 3 schematically shows an arbitrary anode 4, reset cathode 3', and subsequent cathode 3 of the display device in FIG. 1~8-
9. Resistor 9 for limiting display discharge current, power supply E _S
(V _S =250V) and the capacitance added to the anode 10
It represents. Since the reset cathode 3' is the first cathode at which scanning begins, in order to ensure the start of discharge, the potential applied to the reset cathode 3' must be lower than that applied to the other cathodes, and the cathode selection time must be longer than that of the other cathodes. method is used. Figure 3 shows the former case, i.e.
This shows that a lower potential is applied to the cathode by E' (50V) compared to the other cathodes. FIG. 4 shows a timing relationship of part of the driving operation of the display device shown in FIG. 3. In FIG. TK ₃ , TK ₄ , TK ₅ ………
... represents the cathode selection time when the cathodes 8-3, 8-4, 8-5... are turned on. _TCHG3 ,
TCHG ₄ , TCHG ₅ . . . represents the time during which the anode switch 7 is turned on and the capacitor 10 is charged from the power source E _S to the discharge start voltage when all the cathodes are off. Next, explanation will be given according to this timing diagram.
First, at charging time TCHG ₃ , the anode switch 7 is turned on and the capacitor 10 is charged through the resistor 9, so that the potential V _A of the anode 4 rises to the discharge starting voltage. Turn off the anode switch 7 and turn off the cathode switch 8.
-3 is turned on, the charge stored in the capacitor C instantly flows, a minute pilot discharge current i _D flows, and the discharge stops. At this time, the anode potential V _A drops rapidly, and when the discharge stops, it gradually rises because it is charged by the leakage current of the anode switch 7 (for example, the base-collector current of the transistor is disconnected). When the charging time TCHG ₄ is reached, all the cathode switches are turned off, the anode switch 7 is turned on, and the capacitor 10 is charged again. Cathode selection time
At TK ₄ and TK ₅ , if the anode switch 7 is male in both cases, a pilot discharge is performed as in TK ₃ . When the anode switch 7 is kept on during the cathode selection time TK ₆ after the charging time TCHG ₆ , a constant display discharge current flows from the power source E _S through the resistor 9 after a momentary pilot discharge flows. At this time, the anode potential V _A maintains a discharge sustaining voltage with respect to the ground potential of the cathode. As explained above, the capacitance 10 added to the anode is charged every time the cathode is scanned, and the pilot discharge is performed even at this charging voltage, so the brightness of the pilot discharge does not increase, and the pilot discharge does not increase. No leakage or flickering of fire discharge. Therefore, it is possible to realize a display device that performs display discharge and pilot discharge within one discharge space and obtains stable scanning discharge. By the way, in this driving method, the maximum value of the charging voltage of the anode potential is the voltage V _S of the power source E _S . Also, in this case, the anode switch 7 has a withstand voltage value of V _S
is required. Generally, the operating voltage of a gas discharge type display device is as high as about 200 to 300 V, and a low voltage is desired from the viewpoints of withstand voltage, reliability, manufacturing cost, etc. of the drive power source and drive circuit elements. An object of the present invention is to provide a display device and a driving method that can reduce the voltage of a driving power source and a driving circuit. The present invention will be described below based on examples together with drawings. FIGS. 5 and 6 show an embodiment of a display device drive circuit and its basic operation timing diagram according to the present invention. FIG. 5 shows the main parts of the display device having the configuration shown in the following table, namely the reset cathode 3', the cathode 3-
1, 3-2, anodes 4-1, 4-2, 4-3, and each display discharge dot 6. Reset cathode 3'
The upper discharge dot has a black coating applied to the glass surface to prevent discharge light from leaking outside. These electrodes are provided with cathode switches 8', 8-1, 8-2 and anode switches 7-1, 7-1, 8-2, as in FIG.
7-2, 7-3, and resistors 9-1, 9-2, 9
-3 is connected. Note that the voltage V _S of the drive power source E _S is 180 V, which is 70 V lower than that of the power source E _S in Fig. 3.
It is.

[Table] Now, each anode in Figure 5 has a stray capacitance of 10-
In addition to 1, 10-2, 10-3, starting auxiliary capacity 1
1-1, 11-2, and 11-3 are connected at one end, and the other end is connected to a starting assist switch 12 which performs the basic operation of the present invention. This switch 12 is connected to either the ground side or the starting auxiliary power supply E _C side. Next, the anode 4-1 shown in FIG. 5 and the drive circuit added thereto will be explained based on the timing diagram shown in FIG. 6. First, during the selection time T _K ' of the reset cathode 3',
The anode switch 7-1 and cathode switch 8' are turned on to cause a reliable reset discharge. Next, during charging time TCHG ₁ , all cathode switches 8-
1 and 8-2 off, and start assist switch 12.
Connect it to the ground side and charge the stray capacitance 10-1 and starting auxiliary capacitance 11-1 from the power supply E _S. The anode potential V _A charged during this time reaches the maximum V _S (180V). Even if this voltage V _S is applied to the discharge dot, reliable starting with quick response cannot be expected. Therefore, in the driving method of the present invention, a time is provided between the charging time and the cathode selection time to raise the anode potential V _A higher than the power supply voltage V _S to assist in starting. This time will hereinafter be referred to as pull-up time. Now, during the pull-up time T _P1 , all the cathode switches are kept off, and the anode switch 7-1 is turned off.
Turn off the power, and switch the starting auxiliary switch 12 to the power source E _C side. At this time, as shown in FIG. 6, the potential V _B of the starting auxiliary switch 12 rises to the voltage V _C of the starting auxiliary power supply E _C with the time constant of the resistor 13 and the stray capacitance of the switch 12, so the starting auxiliary power supply capacitance During this period, the anode potential increases from V _S to V _P . This potential difference (V _P -V _S ) is determined by the following equation. V _P -V _S =C/C+C _O・V _C …………(1) Here, C _O is the stray capacitance 10-1, 10-2, 1
0-3 capacity value, C is starting auxiliary capacity 11-1,1
The capacitance values of 1-2 and 11-3 are shown. The stray capacitance C _O of the anode of the display panel shown in the previous table is approximately 30PF (including the stray capacitance of each anode drive circuit), and if the starting auxiliary capacity is set to 20PF, for example, to obtain V _P of 250V, V _C must be increased. Just set it to 175V. After the anode potential reaches V _P at pull-up time T _P1 and enters cathode selection time T _K1 , the cathode switch 8-
When the anode switch 7-1 is turned on and the anode switch 7-1 is kept off, the discharge dot 6-1 has a stray capacitance 10-1.
1 and the starting auxiliary capacity 11-1, a discharge current i _D flows instantaneously as shown in FIG. 6, and a pilot discharge is performed. At this time, all starting auxiliary capacity 11-
Since a discharge current flows from 1, 11-2, 11-3... through the resistor 13, the potential V _B of the switch 12 drops instantaneously, and the discharge stops and returns to the potential V _C. When the pilot discharge stops, the anode potential V _A gradually increases as explained in FIG. 4. Next, when the charging time TCHG ₂ begins, the stray capacitance 10-1 and the starting assist amount 11-1 are charged from the current E _S in the same way as in TCHG ₁ . At the pull-up time T _P2 , the anode switch 7-1 is turned off in the same way as T _P1 , and the anode potential V _A rises from V _S to V _P by the operation of the starting assist switch 12. The cathode selection time T _K2
When the anode switch 7-1 is turned on, a pilot discharge current flows from the capacity at T _K1 , and at the same time,
A display discharge current (0.6 mA) constantly flows from the power source E _S through the resistor 9-1 during the cathode selection time T _K2 to perform display discharge. During this time, the anode potential V
_A holds the discharge sustaining voltage V _D. As explained above, by providing a pull-up time between the charging time and the cathode selection time according to the present invention,
If the starting assist operation as described above is performed, the voltage of the drive power source E _S can be lowered, and the withstand voltage of the anode switch circuit can be lowered. A specific example of the present invention for the anode drive circuit shown in FIG. 5 is shown in FIG. Reference numerals 14 and 15 indicate low voltage circuits that control the anode switches 7-1, 7-2, 7-3... and the starting assist switch 12, respectively. Anode switch 7-1, 7-2, 7-3...
...... used gas discharge display drivers DI-500, DI-505, and DI-510 from Dionics (USA). The internal circuit of this driver is shown in FIG. This driver is a high-voltage monolithic integrated circuit using dielectric isolation. Since the anode potential of the diodes 16-1, 16-2, 16-3, etc. in FIG. 7 becomes higher than the voltage V _S during the pull-up time, they function to prevent the reverse breakdown voltage of the anode switch. The diode also simplifies anode control by eliminating the need to keep the anode switch off during pull-up time. Now, starting auxiliary capacity 1 shown in Figures 5 and 7
If capacitive elements such as ceramic capacitors are attached to the drive circuit of the display device as 1-1, 11-2, 11-3..., the external size of the drive device becomes larger. FIGS. 9 and 10 show an embodiment of the present invention in which a display device is provided with a starting auxiliary capacitor by taking advantage of the fact that one end of this starting auxiliary capacitor can be constructed from a common electrode. FIG. 9 is a developed view of a display device in which the capacitive elements are formed by thick film capacitors formed by screen printing. First, the common electrode 16 of the capacitive element connected to the starting assist switch 12 shown in FIG.
Take one end out of the display device. Next, a dielectric material 17 is printed on the common electrode 16 so that the common electrode 16 is not exposed to the discharge space. After that, dielectric 1
If the anode 4 is formed on the upper layer of 7 by printing a conductive paste, the starting auxiliary capacitors 11-1, 11-2, 11-3, etc. shown in FIG. 5 or FIG. 7 can be formed.
...... can be added to each anode. Generally, the capacitance value of a planar capacitive element is inversely proportional to the thickness of the dielectric and proportional to its area. Therefore, when forming a dielectric with a thick film, the capacitance value will be low if the area is small, so if the entire area of the anode is used effectively as shown in Figure 9, a sufficient capacitance value can be obtained. . For example, with the display device shown in the previous table,
The line width of anode 4 and the corresponding common electrode is 200μ.
m, the capacitance value between each electrode 4 and the common electrode 16 was approximately 20PF. Thick film capacitive elements have a high withstand voltage and therefore have high reliability, and are very preferable because they do not cause manufacturing troubles. On the other hand, FIG. 10 shows a portion of the surface glass of a display device in which the capacitive elements are formed by thin film capacitors formed by vacuum evaporation. Although a thin film capacitor has a lower withstand voltage than a thick film capacitor, a sufficient capacitance value can be obtained even with a small area, so it can be formed in a part of a display device. FIG. 10 shows a case where the starting auxiliary capacitor is provided at one end of the surface glass that is not exposed to the discharge space. First, an anode 4 is applied to the surface glass 1 using a conductive paste. A portion of the anode 4 serving as the electrode of the starting auxiliary capacitor is made slightly thicker than 200 μm in anode line width in order to obtain a capacitance value. Next, a dielectric material 17 is vacuum-deposited on the upper layer, and a common electrode 16 is further vacuum-deposited on the upper layer, and one end of the common electrode 16 is taken out to the outside of the display device. This common electrode 1
6 is made into a discharge space, as explained in FIG. 6, it must be maintained at the ground potential during the charging time, and at this time, the common electrode 16 and each anode may cause a discharge phenomenon. As shown in FIG. 9, the common electrode 16 is first provided by printing or vapor deposition, then the dielectric 17 is vapor deposited, and finally the anode 4
If formed by vapor deposition, a starting auxiliary capacitance element can be provided even in the electrode space. However, when the anode 4 is formed by printing the upper layer of the dielectric thin film, the quality of the thin film inevitably deteriorates, especially depending on the firing temperature of the conductive paste. By the way, anode 4
If it is formed by vapor deposition, the manufacturing cost will increase, especially for large-sized display devices, which is undesirable. As described above, according to the driving method of the present invention, it is possible to reduce the driving voltage, thereby reducing the withstand voltage and reliability of the driving circuit elements, and simplifying the driving circuit and reducing the manufacturing cost.

[Brief explanation of the drawing]

1 and 2 are a cutaway perspective view and a cross-sectional view of the main parts of a gas discharge type display device proposed by the present applicant, and FIGS. 3 and 4 are a principle configuration diagram of the main parts of the display device and 5 and 6 are enlarged configuration diagrams and timing diagrams of the main parts showing one embodiment of the present invention, and FIGS. 7 and 8 are specific circuit diagrams of the main parts of the device according to the embodiment. , FIG. 9, and FIG. 10 are perspective views showing main parts of other embodiments of the present invention. 3', 3-1, 3-2... cathode, 4-1, 4-
2, 4-3...Anode, 6...Discharge dot, 7-
1, 7-2, 7-3...Anode switch, 8', 8
-1,8-2...Cathode switch, 9-1,9-
2,9-3...Resistance, 10-1,10-2,10
-3... Stray capacitance, 11-1, 11-2, 11-
3... Starting auxiliary capacity, 12... Starting auxiliary switch.

Claims (1)

[Claims] 1. Sequentially scanning each of the plurality of first electrodes,
During a period when any of the first electrodes is being scanned,
A method for driving a gas discharge type display device in which display discharge is performed by applying a display discharge voltage to a predetermined one of a plurality of second electrodes intersecting with the first electrode, wherein the first electrode is charging a capacitance added to the second electrode each time before being scanned, further increasing the charging voltage of the capacitance to a starting voltage by means of a starting aid means, and applying the starting voltage of the capacitance to the second electrode; A method for driving a gas discharge type display device, characterized in that a scanning discharge is performed by applying an electric current. 2. The method of driving a gas discharge type display device according to claim 1, wherein the capacitance added to the second electrode consists of a stray capacitance and a capacitive element. 3. The method for driving a gas discharge display device according to claim 1, wherein the capacitive element added to the second electrode is a thin film capacitor or a thick film capacitor formed on a substrate. .