JPH0225892A - Electrochromic 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 Field of Industrial Application The present invention relates to an electrochromic display device used as a display section of various types of equipment.

BACKGROUND ART In general, electrochromic display devices produce clear colors and are highly visible, and when a -degree voltage is applied to develop a color, the color state is maintained for a long period of time even after the current is turned off. Has many advantages.

It is used for digital presentation boards, etc.

A first conventional example of such an electrochromic display device will be explained based on FIGS. 11 and 12. First, this electrochromic display device 1 has a plurality of approximately rectangular EC pixels (electrochromic display pixels) 2 arranged in a Japanese character shape so as to display a digital number. Furthermore, these EC pixels 2 are provided with flat transparent electrodes 4. below the transparent substrate 3. ECC consisting of WO, etc.
6. Electrolyte layer containing 50Li or the like. It is constructed by stacking counter electrodes 7 and the like. Further, an insulating layer 8 is provided around the EC film 5 to the counter electrode 7 to insulate each EC pixel 2 from each other. - On the other hand, power supplies 9a and 9b whose energizing directions are opposite to each other and a switch 10 for switching these are connected to the transparent electrode 4 and the counter electrode 7.

In such a configuration, by operating the switch 10, 1
For example, by applying a voltage such that the transparent electrode 4 is - and the counter electrode 7 is -, the ECC50 electrolyte layer 6 causes the following chemical reaction.

WO, +L th++ a-→LiWO.

Here, WO3 is a colorless substance, but the product L
iWO, exhibits a blue color.Also, even if the electricity is turned off after this reaction is completed, LiWOs is chemically stable and will not disappear in a short time.Furthermore, the above chemical reaction is a reversible reaction, so By applying a voltage in the opposite direction to that described above, Li W Os is again decomposed into Wo3 and Li, and one color is erased. That is, by electrically controlling each EC pixel 2, it is possible to display a desired digital number.

Next, a second conventional example of an electrochromic display device will be explained based on FIGS. 13 to 15.

This electrochromic display device 11 has a large number of square EC pixels 2a arranged in a matrix. Therefore, the electrical configuration of the drive circuit 12 that controls these EC pixels 2a will be explained based on FIG. 15. Each EC pixel 2a has a TFT (thin film transistor) 1
No. 3 drain electrodes 13a are connected. Further, the source electrodes 13b of each of the TPTs 13 are wired in each row and connected to a first pulse power source (not shown). Similarly, the gate electrodes 13o are wired for each column and connected to a second pulse power source (not shown).

In such a configuration, in response to the pulse current generated by each TFT 13i1 and the first and second pulse power sources, for example,
Control is performed sequentially for each column. and.

By synchronizing the pulse currents applied to the source electrode 13b and the gate electrode 13c, a predetermined TFT 13 applies a voltage to the EC pixel 2a, and a coloring operation is performed. That is, a desired image can be obtained by dot matrix display in which the EC pixel 2a is one dot.

Here, the electrochromic display device 11 like the first conventional example is good for displaying a specific image such as the above-mentioned digital number, but cannot display any desired image. Can not.

In addition, a second conventional electrochromic display device 1
In No. 1, it is possible to obtain a desired image by setting the EC pixel 2a as one dot, but in this case, the number of EC pixels 2a becomes enormous, and the response speed of the EC pixel 2a becomes a problem.

That is, the EC pixel 2a takes a considerable amount of time to complete coloring after voltage is applied, and even if the amount of current is increased,
Approximately 0.5 sand diameter is required. Here, the scanning for one image display is 1
This is done for each column, so for example, if the matrix screen is 12
If it is composed of 0 columns, how long does it take to display the screen?

o, 5xizo==so (see) In other words, it would take one minute, which is not practical.

Therefore, as a device that overcomes these disadvantages, there is an electrochromic display device disclosed in Japanese Patent Application Laid-Open No. 56-6594 entitled "Display Device".

Therefore, this electrochromic display device will be described as a third conventional example with reference to FIGS. 16 and 17.

This electrochromic display device 14 has EC pixels 15 arranged in a matrix like the second conventional example. Here, these EC pixels 15 are formed by attaching a frame-shaped sealing member 16 to two transparent support plates 17a, 17.
A counter electrode 182 and a display medium 19.b are sandwiched between the supporting plates 17a and 17b. It is constructed by laminating a power supply electrode 209, a display body 21, etc.

Further, the electrical configuration of the drive circuit 22 will be explained based on FIG. 17. First, the drain electrode 23a of the -th TFT 23 is connected to one end of each EC pixel 15, and the common counter electrode 24a is connected to the other end. Further, the gate electrode 23b of this -th TFT 23 is connected to the drain electrode 25a of the second TFT 25 and one end of the capacitor 26.

Furthermore, the other end of this capacitor 26 is connected to the -th TFT.
It is connected to a grounded common power supply electrode 24b together with the source electrode 23c of No. 23. - side, the second TFT
25 gate electrodes 2t5b are connected to the row electrodes 24c,
Source electrode 25c is connected to column electrode 24d.

In such a configuration, the row electrode 24c and the column electrode 24d
A pulse current corresponding to each image to be displayed is applied. Scanning using this pulsed current.

The process is performed on the capacitor 26 and is completed in a relatively short time. At this time, only the -th TFT 23 that is electrically connected to the capacitor 26 that has stored electricity has its source electrode 23o and drain electrode 23a electrically electrically connected. Therefore, by applying a voltage between the common counter electrode 24a and the common power supply electrode 24b, the voltage is applied to predetermined EC pixels 15 at the same time. Therefore, each EC pixel 15 starts coloring operation almost simultaneously, and image display is quickly completed.

Problems to be Solved by the Invention As described above, even in a dot matrix type electrochromic display device 11 in which a large number of EC pixels 2a are arranged in a matrix, for example, a capacitor 26 and two TP
By configuring the drive circuit 22 with T23.25,
It is possible to create an electrochromic display device 14 that can complete image display in a short time. However, in this case, the conduction state of the -th TFT 23 is set depending on the presence or absence of the charged voltage of each scanned capacitor 26, and the common power supply electrode 24b
An electric path from the EC pixel 15 to the predetermined EC pixel 15 is secured. Therefore, the capacitor 26 needs to continue to maintain its charging voltage until the EC pixel 15 completes coloring. However,
The capacitor 26 has its own leakage current and the second TFT 25
It is difficult to maintain a high voltage for a long period of time due to the off-state current and other factors.

For this reason, there is a possibility that the coloring of the EC pixel 15 may stop midway, which impairs the reliability of the electrochromic display device 14.

Therefore, in order to correct such problems, a method can be considered in which the capacitor 26 is manufactured in a large size to provide a margin for its capacitance. but.

Since the area of the circuit pattern of the drive circuit 22 corresponding to each EC pixel 15 is limited, it is extremely difficult to increase the size of the capacitor 26, and such an electrochromic display device 14 is difficult to manufacture. This is impractical because the yield rate deteriorates and the equipment becomes expensive.

Means for solving the problem A plurality of electrochromic display pixels are provided in a matrix, and a power supply circuit is connected to each of these electrochromic display pixels via a switching transistor.
A flip-flop circuit was connected between each switching transistor and a signal output circuit that outputs an image signal corresponding to an image.

Further, the flip-flop circuit and the signal output circuit were connected through a thin film transistor provided for each electrochromic display pixel.

In addition, an AND circuit formed of two thin film transistors is provided for each electrochromic display pixel, and this AND circuit is provided for each electrochromic display pixel.
The flip-flop circuit and the signal output circuit were connected through the circuit.

By arranging a plurality of electrochromic display pixels in a matrix, it is possible to display a desired image in a dot matrix manner.A power supply circuit is connected to each of these electrochromic display pixels via a switching transistor, and a power supply circuit corresponding to the image can be displayed. By connecting a flip-flop circuit between the signal output circuit that outputs the image signal and each switching transistor, scanning of one image signal is performed on the flip-flop circuit, and this flip-flop circuit turns on the switching transistor. The state is set to ensure an electrical path from the power supply circuit to the predetermined electrochromic display pixel.

All electrochromic display pixels start coloring at the same time, completing image display in a short time, and the flip-flop circuit maintains the conduction state of the switching transistor, which is different from maintenance using the charging voltage of a capacitor. Therefore, the coloring operation of the electrochromic display pixels is reliable and stable.

In addition, the flip-flop circuit and the signal output circuit are connected through a thin film transistor provided for each electrochromic display pixel, or an AND circuit formed of two thin film transistors is provided for each electrochromic display pixel. By connecting the flip-flop circuit and the signal output circuit through an AND circuit, the flip-flop circuit can be operated from the synchronization of main scanning and sub-scanning by two image signals.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 9. Note that the same parts as in the conventional example described above are given the same names and numerals, and explanations thereof will be omitted.

Here, as the electrochromic display device 27,
An example will be explained in which a display board 28 and a drive circuit board 29 which are manufactured separately are joined together. First, on the surface 28a of the display substrate 28, one EC pixel 2b is provided in a matrix of, for example, 4 rows and 7 columns. In addition, EC pixel 2b
The first pad 30, which is an input part, is electrically connected to the counter electrode 7 of
But, for example, by screen printing chrome,
It is provided on the back surface of the display base 28 so as to protrude slightly.

Here, this EC pixel 2b is the same as that of the second conventional example mentioned above.
It has the same configuration as the C pixel 2a.

On the other hand, on the surface 29a of the drive circuit board 29.

A second pad 31 serving as an output portion is provided at a position where it comes into contact with the seventh pad 30 in a slightly protruding manner. Further, inside the drive circuit board 29, an a-dynamic circuit 32 is provided under each of the second pads 31. On the other hand, an electrode bundle 33 is provided on the outer periphery 29b of the drive circuit board 29 and is electrically connected to various electrodes of a drive circuit 32, which will be described later.

Further, these electrode bundles 33 are connected to a signal output circuit (not shown) that transmits image information to the drive circuit 32.

Therefore, the electrical configuration of the drive circuit 32 will be explained below.

This will be explained based on FIGS. 4 and 5. First, for each EC pixel 2b, an FF composed of two TPTs and a resistor is used.
A circuit (flip-flop circuit) 34 is provided.

Therefore, a pair of input electrodes 34a, 3 of the FF circuit 34 with
4b directly and the other through a delay circuit 35 composed of a resistor and a capacitor, respectively, to the power supply electrodes 36 and 37.
is electrically connected. Further, the output electrode 34e of the two-OFF circuit 34 is electrically connected to the ground electrode 38. Furthermore, the trigger electrode 34d of this FF circuit 1834 is electrically connected to the source electrode 39b of the TFT 39, and the gate electrode 39a and drain electrode 39c of this TPT 39 are connected to the fifth row electrode 40.
and the column electrode 41. Further, the switching electrode 34a of the FF circuit 34 is the gate electrode 4 of a switching transistor 42 formed of a thin film transistor.
2a. Further, a display W1 pole 43 to which a power supply circuit (not shown) is connected to the source electrode 42b of the switching transistor 42 is connected to apply a reversed voltage in positive and negative directions to color or decolor the EC pixel 2b. The second pad 31 is connected to the drain electrode 42c.
is conductive. Due to this.

Each EC pixel 2b can be electrically connected to the power supply circuit. Further, the FF circuit 34 includes two TFTs 44a, for example.
, 44. b, resistors 45a, 45b, etc. °C
There is.

Next, the practical structure and manufacturing method of the drive circuit board 29 will be explained based on FIGS. 6 to 8. First, the various electrodes 36 to 43 mentioned above.

For example, a thin chromium film is formed on the transparent substrate 3a by sputtering or photoetching.

Further, an insulating layer 46 substantially covering these is formed of SiO, Sj, Nz, etc. by plasma CVD, for example.

Furthermore, through holes are formed in this straddle f546 by etching at the positions of the switching electrodes 34d and 4 column electrodes 41. Also.

On this insulating layer 46, the amorphous silicon layer 39d of the TPT 39 and the like are also formed by plasma CVD, etching, or the like. On the other hand, the power supply electrode 36.
The column electrode 41. The column electrode 41 is connected to the column electrode 41 via the source electrode 39b of the TFT 39, the through hole, the lower electrode 47, etc.
The drain electrode 39c and the like are formed of chromium. A protective layer 48 covering each of these members is, for example,
It is formed from an insulator such as polyimide by screen printing. At this time, the second pad 31 is connected to the protection M48.
It is provided so as to penetrate up to the surface 29a thereof.

Therefore, the display board 28 and the quick-acting circuit board 29 provided as described above are placed, for example, in a state where the first pad 30 and the second pad 31 are in contact with each other, as illustrated in FIG. Either a conductive paste (not shown) is applied to each of them and then they are stacked, or as illustrated in FIG. By stacking, heating and pressurizing and integrating,
The electrochromic display device 27 of this example is manufactured.

In such a configuration, image display of the electrochromic display device 27 of this embodiment will be described. first,
Due to the voltage applied from the power supply electrodes 36 and 37 whose timing is shifted by the delay circuit 35, no voltage flows from the FF circuit 34 to the gate electrode 42a, and the switching l-run raster 42 is normally in an OFF state. Therefore, for example, as shown in the timing chart shown in FIG. 9, the image signals X and Y emitted from the signal output circuit are
Each is input from the row and two column electrodes 40 and 41. At this time,
The TFT 39 is operated by the synchronization of the main scanning and sub-scanning by these image signals x and Y, and a predetermined FF circuit 34 is turned on. Then, within this FF circuit 34, the power supply electrode 3
The voltage that has been applied to the ground electrode 38 from the switch 7 is now applied to the gate electrode 42a of the switching transistor 42. As a result, each switching transistor 42 is turned ON corresponding to the image to be displayed.

Set to OFF state. Therefore, by applying positive and negative voltages as desired from the power supply circuit connected to the display electrode 43, all the EC pixels 2b perform coloring and decoloring operations at the same time, and promptly display an image.

Image deletion is performed.

Although the TFT 39 is connected to the row electrode 40 in this embodiment, the present invention is not limited to this, and it is also possible to connect the TFT 39 to the first column electrode 41, for example.

Next, a second embodiment of the present invention will be described based on FIG. 10. The drive port of this electrochromic display device
At 851, the drain electrode 39c of the TFT 39 is electrically connected to the source electrode 52b of the TFT 52 provided in parallel. and.

The gate electrode 52a of this TFT 52 is electrically connected to the column electrode 41, the drain electrode 52c is electrically connected to the ground electrode 53, and these two TPTs 39 and 52 form an AND circuit 54.

In such a configuration, the TFTs 39 and 5 are synchronized by synchronizing the main scanning and sub-scanning of the image signals
2 operates, a predetermined FF #f34 is turned on, and each switching transistor 42 is set to the ON or OFF state corresponding to the image to be displayed. Therefore, by applying a voltage from the power supply circuit connected to one display electrode 43, all the EC pixels 2b perform a coloring operation, etc. at the same time, and image display, etc. is quickly performed.

Effects of the Invention As described above, the present invention is capable of displaying a desired image in a dot matrix manner by providing a plurality of electrochromic display pixels in a matrix. A power supply circuit is connected to the circuit, and a flip-flop circuit is connected between each switching transistor and a signal output circuit that outputs an image signal corresponding to the image, so that scanning of one image signal is performed to the flip-flop circuit. This flip-flop circuit sets the conduction state of the switching transistor and secures an electrical path from the power supply circuit to a predetermined electrochromic display pixel, so it is possible to start coloring operations of all electrochromic display pixels at the same time. Therefore, image display can be completed in a short time, and since the flip-flop circuit maintains the conduction state of the switching transistor, the coloring operation of the electrochromic display pixels is reliable, unlike maintenance using the charging voltage of a capacitor. It is possible to obtain a stable and highly reliable electrochromic display device, and since the manufacturing conditions of the electrochromic display device do not become strict, the yield does not deteriorate, and the electrochromic display device can be manufactured at a low cost. In addition, the flip-flop circuit and the signal output circuit can be connected through a thin film transistor provided for each electrochromic display pixel, or an AND circuit formed of two thin film transistors is provided for each electrochromic display pixel. By connecting the flip-flop circuit and the signal output circuit through this AND circuit, the flip-flop circuit can be operated from the synchronization of main scanning and sub-scanning by two image signals, so more reliable image information can be obtained. You can expect the settings.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing the first embodiment of the present invention;
Figure (a) is a side view, Figure 2 (b) is a vertical side view, Figure 3 (a) is a vertical side view, Figure 3 (b) is a perspective view of the connector plate, and Figure 3 (c) is a vertical side view. An enlarged perspective view of main parts. Figure 4 is a circuit diagram of the drive circuit, Figure 5 is an explanatory diagram of the configuration, and Figure 6 is a circuit diagram of the drive circuit.
The figure is an explanatory diagram of the structure, Figure 7 is a vertical front view of Figure 6 taken along line A-A, Figure 8 is a side view of Figure 6 taken along line B-B, and Figure 9 is an image signal. FIG. 10 is an explanatory diagram of the configuration of a drive circuit showing the second embodiment of the present invention, FIG. 11 is a perspective view of the first conventional example, and FIG.
13 is a plan view of the second conventional example, FIG. 14 is a vertical side view, FIG. 15 is a circuit diagram, FIG. 16 is a vertical side view of the third conventional example, and FIG. The figure is a circuit diagram. 2b... Electrochromic display pixel, 27...
Electrochromic display device, 34... flip-flop circuit, 39... thin film transistor, 42...
Switching transistor, 52... Thin film transistor, 54... AND circuit, X, Y... Image signal 3.
1 Illustration of Tokyo Electric Co., Ltd.

Claims (1)

[Claims] 1. A signal output device in which a plurality of electrochromic display pixels are provided in a matrix, a power supply circuit is connected to each of these electrochromic display pixels via a switching transistor, and an image signal corresponding to an image is output. An electrochromic display device characterized in that a flip-flop circuit is connected between the circuit and each of the switching transistors. 2. The electrochromic display device according to claim 1, wherein the flip-flop circuit and the signal output circuit are connected through a thin film transistor provided for each electrochromic display pixel. 3. The electrochromic display according to claim 1, wherein an AND circuit formed of two thin film transistors is provided for each electrochromic display pixel, and the flip-flop circuit and the signal output circuit are connected via this AND circuit. Device.