JP2000242238A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation of picture quality caused by the disconnection of a signal connecting means of a liquid crystal display device. SOLUTION: The device is provided with detecting means 284, R17, 258 and 290 which detect the connecting condition of a signal connecting means L11, which is beforehand selected among plural signal connecting means L10 to L11, and a control means 258 which puts the arrangements of changing liquid crystal molecules to an initial condition prior to displaying of a picture on a liquid crystal display means 200 when a detection is made by the detecting means to indicate that the signal connecting means are disconnected and then, stops displaying of the picture. Thus, when the signal connecting means are reconnected, the displaying of the picture, which was being displayed immediately before the disconnection of the signal connecting means, on the liquid crystal display means is avoided and the degradation of the picture quality caused by the disconnection of the signal connecting means is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and is suitably applied to, for example, a plasma addressed liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, large and thin television receivers and rear projection type projectors have become widespread in order to obtain powerful images in consideration of the installation space that can be secured in a home. . These television receivers and rear-projection type projector devices have been considerably thinned as compared with the prior art with the progress of technology. In the case of a television receiver, for example, a cathode ray tube (CRT: Ca
In the case of a rear projection type projector device, there is a limit to the reduction in thickness, depending on the structural conditions such as the angle at which the projection lens is installed.

A liquid crystal display using a thin film transistor (TFT) is considered as a display device that can be made thinner than such a television receiver or a rear projection type projector device. However, this TFT
Liquid crystal display using IC (Integrated Circuit)
It is necessary to increase the size of the TFT by increasing the number of TFTs formed using the it) technique, which requires a more precise manufacturing technique, and lowers the manufacturing yield, resulting in extremely high cost.

Accordingly, a plasma-addressed liquid crystal display element (PALC: Plasma Addressed L) which can form a large screen as large as a television receiver or a rear projection type projector device and realizes a thickness as thin as a liquid crystal display.
A display device using an iquid crystal has been proposed.
This PALC can realize a large screen by the technology of a PDP (Plasma Display Panel) while taking advantage of a liquid crystal display using a TFT such as a high luminance and a high contrast, for example. That is, the PALC is a transmissive display element that generates an image by selectively transmitting a light beam emitted from a backlight disposed on the back surface of the PALC by an active matrix method. Specifically, the PALC sequentially supplies a drive voltage to a drive electrode for driving each pixel of the liquid crystal display element, and sequentially discharges the plasma gas filled in the scanning groove, thereby forming each of the liquid crystal display elements. An image is displayed by sequentially applying image signals to the pixels.

Hereinafter, the configuration of a plasma address type liquid crystal display device using such a PALC will be described by dividing it into a video circuit block and a power supply circuit block. First, FIG. 14 shows the configuration of the video circuit block 1 of the plasma addressed liquid crystal display device. The video system circuit block 1 of the plasma addressed liquid crystal display device inputs an input signal S1 supplied from the outside to the video processing block 3.

The video processing block 3 generates a video signal S 9 by demodulating the input signal S 1 and sends it to the video signal processing circuit 17 of the video display block 15. The video signal processing circuit 17 converts the video signal S9 from analog to digital, and sends the resulting video data S12 to the liquid crystal column driver 23.

The liquid crystal column driver 23 operates based on a power supply voltage S13 supplied from a power supply system circuit block (not shown), and converts the video data S12 for one horizontal period supplied from the video signal processing circuit 17 into one. After the latch, the video data S12 is read out for each horizontal line at the timing when the plasma discharge occurs in the scanning groove (not shown) of the PALC 25, and the read out video data S12 is converted into the analog drive voltage S16 to convert the read data to the analog drive voltage S16. It is sent to a drive electrode (not shown).

On the other hand, LCD (Liquid Crystal Display)
The controller 29 is operated by a power supply voltage S17 supplied from a power supply circuit block (not shown), and operates based on an operation clock supplied from the control unit 9.
A plasma pulse S22 for generating a plasma discharge for each scanning groove (not shown) of the LC 25 is generated, and the plasma pulse S22 is supplied to the plasma via a switch SW1 which is turned on / off based on a switching signal S24 supplied from the control unit 9. It is supplied to the driver 33.

The plasma driver 33 is operated by a power supply voltage S26 supplied from a power supply circuit block (not shown), and scans each scanning groove (not shown) of the PALC 25 based on the supplied plasma pulse S22. A drive signal S28 for sequentially selecting a desired order to generate a plasma discharge is generated,
5

As described above, in synchronization with the video data S12 input to the liquid crystal column driver 23, the scanning grooves (not shown) are sequentially subjected to plasma discharge and the plasma discharge is repeated for each field, so that the video data S12 is generated. A desired image is displayed by driving a liquid crystal display element (not shown) of the PALC 25 according to the supplied timing.

FIG. 15 shows the configuration of a power supply system circuit block 50 of the plasma addressed liquid crystal display device. The power supply system circuit block 50 receives AC (Alternating Cu
rrent) An AC power supply voltage S40 supplied via an outlet (not shown) is supplied to an AC rectifier circuit 52 to rectify the AC power supply voltage S40, thereby generating a DC power supply voltage S42, and switching the power supply voltage S42 to a main power supply system switch. It is input to the unit 58 and the standby power supply voltage generation circuit 60.

The standby power supply voltage generation circuit 60 supplies the power supply voltage S
42 is converted to a power supply voltage S46 of 5 [V], and the power supply voltage S46A is supplied to the control unit 9 (same as the control unit 9 shown in FIG. 14). At the same time, the standby power supply voltage generation circuit 60
Supplies the power supply voltage S46B to the input terminal y of the AND circuit 68 via a first switch SW10 constituting a main power switch 66 provided for performing an on / off operation of the plasma addressed liquid crystal display device by a user operation. To be supplied.

The control unit 9 includes a standby power supply voltage generation circuit 6
From 0, a power supply voltage S46A of 5 [V] is supplied via a resistor R7, and a voltage of 0 [V] is supplied from the ground via a second switch SW12 constituting a main power supply switch 66. The main power switch 6
When 6 is off, the standby power supply voltage generation circuits 60 to 5
[V] power supply voltage S46A is supplied. In this state, when the user turns on the main power switch 66,
The power supply voltage supplied to the control unit 9 is changed from 5 [V] to 0 [V].
The control unit 9 detects that the main power switch 66 has been turned on based on the change in the supplied voltage, and sets the logic level “H” for turning on the main power switch unit 58. The control signal S49 is supplied to the input terminal x of the AND circuit 68.

The AND circuit 68 calculates the logical product of the power supply voltage S46A supplied from the standby power supply voltage generation circuit 60 and the control signal S49 supplied from the control unit 9, and obtains the control signal S51 obtained as a result. To the main power system switch unit 58. Therefore, the AND circuit 68 turns on the main power supply system switch section 58 when the power supply voltage S46A supplied from the standby power supply voltage generation circuit 60 and the control signal S49 supplied from the control section 9 are both at the logic level “H”. Then, the power supply voltage S53 output from the main power supply system switch section 58 is supplied to the main power supply voltage generation circuit 70.

The main power supply voltage generation circuit 70 is provided with a power supply voltage S necessary for operating the plasma addressed liquid crystal display device.
13, S17 and S26, of which the power supply voltage S
17 is supplied to the LCD controller 29 (FIG. 14), and the power supply voltage S13 is supplied to the liquid crystal column driver 23 (FIG. 14) via the switch SW13 that is turned on and off under the control of the control unit 9. Switch S that is turned on and off under the control of the control unit 9
It is supplied to the plasma driver 33 (FIG. 14) via W15.

FIG. 16 shows the relationship between the drive voltage S16 (FIG. 14) applied to the drive electrode of the PALC 25 and the plasma pulse S22 (FIG. 14) applied to the plasma driver 33. FIG. 16A shows a drive voltage S16 for two lines applied to the drive electrode, FIG. 16B shows a plasma pulse S22 of the first line applied to the plasma driver 33, and FIG. ) Shows the power supply voltage S26 of the first line applied to the cathode (not shown) formed in the scanning groove of the PALC 25 via the plasma driver 33, and FIG.
16 (E) shows a plasma pulse S22 on the second line, and FIG. 16 (E) shows a power supply voltage S26 on the second line applied to the cathode (not shown) via the plasma driver 33.

The video circuit block 1 applies the plasma pulse S22 of the first line to the plasma driver 33 at the timing shown in FIG.
At the timing shown in FIG.
26 is applied. In this state, the video circuit block 1 continuously applies the drive voltage S16 of a maximum of 60 [V] sampled and held by each pixel for one line at the timing shown in FIG. 16A to the drive electrodes of the PALC 25. By doing so, one line of video is written on the liquid crystal display element (not shown) of the PALC 25.

Subsequently, the video circuit block 1 is shown in FIG.
A plasma pulse S22 of the second line is applied to the plasma driver 33 at the timing shown in FIG.
The power supply voltage S26 of the second line is applied to the cathode at the timing shown in FIG. In this state, the video system circuit block 1 has a maximum of −60 sampled and held at each pixel of one line at the timing shown in FIG.
By continuously applying the drive voltage S16 of [V] to the drive electrodes of the PALC 25, one line of video is
Writing is performed on a C25 liquid crystal display element (not shown).

As described above, the video system circuit block 1
The drive voltage S16 is input to the PALC 25 while inverting the polarity of the drive voltage S16 for each of the odd line and the even line, and the liquid crystal display element (not shown) is driven by the AC voltage to continuously reduce the DC voltage. This prevents the deterioration of the liquid crystal molecules caused by the application. Hereinafter, similarly, by sequentially writing the drive voltage S16 for 450 lines to the liquid crystal display element, an image for one field can be formed and displayed on the PALC 25.

When the user turns off the power or cuts off the power supply while displaying an image on the PALC 25, the plasma discharge in the scanning groove causes the power supply to stop. It may become unstable at the moment of turning off, and may partially disappear even in the same scanning groove. In this case, in the PALC 25, since the power supply is cut off in a state where the liquid crystal molecules are twisted by the drive voltage applied to the liquid crystal display element, that is, the residual charge, the image written when the power supply is turned off is partially left as it is. Will be retained. If the liquid crystal molecules are left in an irregular arrangement as described above, a phenomenon similar to the burn-in of the CRT (hereinafter referred to as a burn-in phenomenon) occurs in the PALC 25.

In this state, when the power is turned on again, the liquid crystal display element is supplied from the liquid crystal column driver 23 because the liquid crystal molecules are left in a twisted state for a certain time while the power is off. Drive voltage S
A predetermined time is required until the operation according to No. 16 is performed. As described above, in the PALC 25, when the power is turned on again, a so-called burn-in phenomenon in which an image displayed when the power was turned off in the past is displayed as an afterimage for a predetermined time occurs, and an image that gives a feeling of strangeness to the user is displayed. You. In the PALC 25, if the liquid crystal molecules of the liquid crystal display element are left in a twisted state, that is, a state in which a DC voltage is continuously applied to the liquid crystal display element, the liquid crystal molecules are degraded due to ionization and the life of the liquid crystal display element is reduced. Is shortened.

Therefore, in order to avoid the occurrence of such a burn-in phenomenon, when the power is turned off, 0 [V] is applied.
Is applied to the liquid crystal display element (not shown) of the PALC 25 to stop the display of an image after removing the twist of the liquid crystal molecules. Generally, in a normal TFT liquid crystal display element, the burn-in phenomenon can be prevented by turning on all the TFT transistors and applying a drive voltage of 0 [V] to each pixel. However, in the plasma address type liquid crystal display device, in order to stop the display using the method used in the TFT liquid crystal display element, it is necessary to generate a plasma discharge in all the scanning grooves, so that several tens of amperes are required. Therefore, a large-capacity power supply circuit having the above current is required, and there is a disadvantage that the weight of the element increases and the device becomes large. In order to avoid such inconvenience, the plasma-addressed liquid crystal display device uses 0 [V] for the liquid crystal display element of the PALC 25.
The liquid crystal molecules are twisted by sequentially performing plasma discharge for each line while applying the drive voltage S16 of FIG.

FIG. 17 shows the drive voltage S after the power is turned off.
16 (FIG. 14) to the PALC 25 and the plasma pulse S22 (FIG. 14)
3 shows the relationship with the supply timing. FIG. 17 (A)
Is a power supply voltage S26 supplied to the plasma driver 33.
FIG. 17B shows the power supply voltage S13 supplied to the liquid crystal column driver 23, and FIG.
A drive voltage S16 applied to a drive electrode of the LC 25;
FIG. 17D shows a plasma pulse S22 applied to the plasma driver 33, and FIG. 17E shows a plasma pulse S22 applied to the plasma driver 33 after the power is turned off.

When the power is turned off in the middle of the third line as shown in FIG. 17B, the liquid crystal column driver 23 turns off the power after the power is turned off as shown in FIG.
A drive voltage S16 of 0 [V] is applied to the liquid crystal display element of the PALC 25 over one field (450 lines). At the same time, the plasma driver 33
As shown in (A), after the power is turned off, the power supply voltage S26 is supplied from the main power supply voltage generation circuit 70 for at least one field, and the operation state is maintained.

On the other hand, the LCD controller 29
As shown in (E), after the power supply is turned off, the plasma pulse S22 is sequentially applied to the plasma driver 33 via the switch SW1 which is turned on and off under the control of the control unit 9, whereby the plasma discharge for one field is performed. 1
It is generated over a period of 6.9 [msec]. By applying the driving voltage S16 of 0 [V] to the liquid crystal display element while sequentially generating the plasma discharge in this manner, all the pixels of the liquid crystal display element consisting of the scanning lines from the first line to the 450th line are applied. The driving voltage S16 of 0 [V] can be applied, and thus, the electric charge remaining after the power is turned off can be eliminated, and the alignment of the liquid crystal molecules can be returned to the initial state.

Next, a control procedure performed by the control unit 9 when the power is turned off will be described with reference to a timing chart shown in FIG. FIG. 18A shows a switch SW1 for controlling the supply of the power supply voltage S26 to the plasma driver 33.
FIG. 18B shows a power supply voltage S26 supplied to the plasma driver 33, and FIG.
(C) shows the power supply voltage S for the liquid crystal column driver 23.
FIG. 18 (D) shows the on / off operation of the switch SW13 for controlling the supply of the plasma pulse S22 to the plasma driver 33.
FIG. 18E shows the on / off operation of the main power supply system switch unit 58.

As shown in FIG. 18C, the control unit 9
By detecting that the power has been turned off and setting the switch SW13 to the off state, the liquid crystal column driver 23
Then, writing of the driving voltage S16 of 0 [V] to the liquid crystal display element of the PALC 25 is started. At the same time, as shown in FIG. 18D, when the control unit 9 detects that the power is turned off, the control unit 9 sets, for example, one time from the time when the power is turned off to the time when the switch SW1 is turned off.
During 6.9 [msec], the plasma pulse S22 is sequentially supplied from the LCD controller 29 to the plasma driver 33 to generate plasma discharge for one field. Then, the control unit 9 turns off the switch SW15 at the timings shown in FIGS. 18A and 18B to stop the operation of the plasma driver 33, and thereafter, at the timing shown in FIG. Turn off 58. Thus, in a plasma addressed liquid crystal display device,
When the power is turned off, the display of an image is stopped after the twist of the liquid crystal molecules is removed.

Recently, a wall-mounted plasma-addressed liquid crystal display device that uses the above-described plasma-addressed liquid crystal display device on a wall has been developed and introduced. In a wall-mounted plasma address type liquid crystal display device, when used by hanging on a wall, a signal cable such as a cable for inputting a video signal output from an external device such as an antenna line for a UV / BS tuner or a VTR, for example. Are pulled out from the apparatus main body hung on the wall and used, giving an unpleasant impression to the user.

To avoid such inconvenience, as shown in FIG. 19, a wall-mounted plasma addressed liquid crystal display device 100 is provided with an image display unit 102 for displaying an image on a display panel, and a plurality of external devices. And a control unit 104 for connecting a cable input from the video display unit 10.
2 and a control unit 104 connected by one multi-cable 106 are proposed.

FIG. 20, in which parts corresponding to those in FIG. 14 and FIG. 15 are assigned the same reference numerals, shows the circuit configuration of a wall-mounted plasma addressed liquid crystal display device 100. In the plasma addressed liquid crystal display device 100, of the video system circuit block 1 shown in FIG. 14, the video processing block 3 and the operation unit 11 are housed in the control unit 104, and the video display block 15 is housed in the video display unit 102. . Further, the plasma addressed liquid crystal display device 100
Stores the main power switch 66 of the power supply system circuit block 50 shown in FIG. 15 in the control unit 104 and stores the circuits other than the main power switch 66 in the video display unit 102.

Further, the plasma addressed liquid crystal display device 1
Reference numeral 00 stores the control unit 9 shown in FIGS. 14 and 15 separately in a control unit 9A for controlling the video display block 102 and a control unit 9B for controlling the control unit 104. By separating the control unit 9 and storing the control unit 9 in the video display unit 102 and the control unit 104, it is possible to reduce the number of wires of the multi-cable 106, thereby increasing the size of the connector of the multi-cable 106. Avoid the video display unit 102
Can be made thinner.

More specifically, the plasma addressed liquid crystal display device 100 connects the video display unit 102 and the control unit 104 via a multi-cable 106 composed of connection lines L1 to L5. Connection line L1
Is the standby power supply voltage generation circuit 6 of the video display unit 102.
0 to the first switch S of the main power switch 66 of the control unit 104.
It is for supplying to W10.

The connection line L2 is connected to the video display unit 10
This is for exchanging control signals between the control unit 9A of the second control unit and the control unit 9B of the control unit 104. The connection line L3 is connected from the ground of the control unit 104 to the second switch SW of the main power switch 66.
A voltage of 0 [V] is applied to the video display unit
Is supplied to the control unit 9A. The connection line L4 connects the power supply voltage S46B supplied from the first switch SW10 of the main power supply switch 66 of the control unit 104 to the AND circuit 68 of the video display unit 102.
To the input terminal y. The connection line L5 transmits the video signal S9 supplied from the video processing block 3 of the control unit 104 to the video display unit 1.
02 to be supplied to the video display block 15.

Thus, in the plasma addressed liquid crystal display device 100, the connection lines L1 to L1
When all the L5s come off at the same time, the drive voltage S16 of 0 [V] is applied to the liquid crystal display element of the PALC 25 for each line under the control of the control unit 9A, as in the case where the user turns off the main power switch SW66. , The display of the image is stopped after the twist of the liquid crystal molecules is removed.
5 is prevented from causing a burn-in phenomenon.

[0035]

In the plasma addressed liquid crystal display device 100 having such a configuration, the multi-cable 106 is oblique as in the case where the connection line L1 is disconnected first and then the connection line L3 is subsequently disconnected. In this case, the power supply voltage S46B indicating the logical level "L" is supplied to the input terminal y of the AND circuit 68 due to the disconnection of the connection line L1. The control signal S51 of the logical level “L” is supplied to the main power supply switch unit 58, and the main power supply switch unit 58 is turned off.

As described above, in the plasma addressed liquid crystal display device 100, when the multi-cable 106 is pulled out obliquely, the control unit 9A controls the switches SW1 and SW10.
Before controlling the timing of turning off the SW 15 and causing each part to perform an operation of removing the twist of the liquid crystal molecules,
Because the power of the entire device is turned off, PALC
No. 25 had a problem that a burn-in phenomenon occurred.

FIG. 21 shows the relationship between the timing at which the drive voltage S16 (FIG. 20) is supplied to the PALC 25 and the timing at which the plasma pulse S22 (FIG. 20) is supplied to the plasma driver 33 after the connection line L1 is disconnected. FIG. 22 shows a control procedure performed by the control unit 9A when the connection line L1 is disconnected. That is, in the plasma-addressed liquid crystal display device 100, as shown in FIG. 22E, the main power switch 58 is turned off at the timing when the connection line L1 is disconnected, and as a result, as shown in FIG. Pulse S22 is plasma driver 3
3, the power of the entire device is turned off without removing the twist of the liquid crystal molecules without generating a plasma discharge.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a liquid crystal display device capable of preventing deterioration of image quality caused by disconnection of signal connection means.

[0039]

According to the present invention, there is provided a video selecting means for selecting a desired video signal from a plurality of types of video signals supplied via a plurality of paths. In a liquid crystal display device that transmits and receives a selected video signal and a control signal related to the video signal via a plurality of signal connection units to and from a video display unit that displays a video corresponding to the selected video signal, the video display unit includes: A liquid crystal display for displaying the selected image, and a drive for driving each pixel forming the liquid crystal display to change the arrangement of liquid crystal molecules corresponding to each pixel to display an image on the liquid crystal display. Means, detecting means for detecting the connection state of any one of the plurality of signal connecting means selected in advance, and the detecting means disconnecting the signal connecting means. When detecting that was the arrangement of liquid crystal molecules is changed by controlling the drive means to provide a control means for stopping the display of the image after returning to the initial state before displaying an image on the liquid crystal display unit.

The connection state of any one of the plurality of signal connection means selected in advance is detected. As a result, when the disconnection of the signal connection means is detected, the arrangement of the changed liquid crystal molecules is changed. By stopping the display of the image after returning to the initial state before displaying the image on the liquid crystal display means, when the signal connection means is reconnected, the image displayed immediately before the signal connection means was disconnected is displayed on the liquid crystal display. It is possible to avoid being displayed on the means.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

In FIG. 1, reference numeral 200 denotes a plasma address type liquid crystal display element (PALC: Plasma Address) as a whole.
ed Liquid Crystal). First, on the plasma substrate 202, partition walls 204A to 204E are provided so as to protrude at predetermined intervals along the horizontal direction indicated by the arrow X in the drawing, whereby the scanning grooves partitioned in a hollow shape by the partition walls 204A to 204E are provided. 206A to 206D are formed. An anode 208 is provided in each of the scanning grooves 206A to 206D.
A to 208D and cathodes 210A to 210D are respectively formed as a pair in the horizontal direction. As described above, each of the scanning grooves 206A to 206D forms a horizontal scanning line corresponding to an effective screen of the PALC 200, and is formed by the number of scanning lines (for example, 450).

Further, the scanning grooves 206A to 206D can be sealed by placing a glass substrate 212 on which an insulating layer is formed on each of the partition walls 204A to 204E. For example, the scanning grooves 206A to 206D are sealed in the sealed scanning grooves 206A to 206D. A mixed rare gas such as helium gas is filled as a plasma gas. A power supply voltage of, for example, -300 [V] is applied to each of the cathodes 210A to 210D from a plasma driver circuit (not shown), and the anodes 208A to 208D are supplied based on a plasma pulse supplied at a predetermined timing.
A plasma discharge is generated between 8D and the cathodes 210A to 210D. Each of the scanning grooves 206A to 206D is
After the plasma discharge occurs, an operation such as a switching element can be performed by forming an electric conductor, that is, a plasma channel, until plasma particles formed by ionizing the plasma gas are completely extinguished. .

On the glass substrate 212, a liquid crystal display element 214 for forming pixels in a matrix, a striped filter layer 216 made up of filter portions 216R, 216G and 216B corresponding to each color of RGB, and a liquid crystal display element 21
4 drive electrodes 218R and 218 for driving each pixel
Striped transparent electrodes 218 of G and 218B are sequentially placed in a direction orthogonal to the scanning grooves 206A to 206D. Therefore, each drive electrode 218R, 218G
And 218B are supplied with the video signals for one horizontal line, and the plasma gas in the scanning grooves 206A to 206D is sequentially discharged in the vertical direction (the direction of arrow Y in the drawing), so that the driving electrodes 218R, 218G, and 218B are connected to each other. A driving voltage is sequentially applied to the liquid crystal display elements 214 of pixels intersecting the scanning grooves 206A to 206D, and color display is performed by utilizing the fact that the transmittance of light emitted from a backlight (not shown) differs for each pixel. It is made to be able to do.

That is, the PALC 200 is
The polarization filter 22 is provided on each of the incident side and the reflection side of 200.
0 and 222, the liquid crystal display element 21
The transmission amount of the light polarized in 4 can be controlled using the polarizing filters 220 and 222, and a color image can be obtained by the same principle as that of the TFT liquid crystal display element.

Next, the switching operation by the plasma channel when generating an image for one field is shown in FIGS.
This will be described in detail with reference to FIG. As shown in FIG.
In the LC 200, when a power supply voltage of -300 [V] is applied to the cathode 210A and plasma discharge occurs, a plasma channel is formed in the scanning groove 206A. Since this plasma channel serves as a virtual electrode, a voltage is applied between the transparent electrode layer 218 and the anode 208A, which means that the virtual switch SW20 is connected.

FIG. 3A shows that the cathode 210A has -30
When a power supply voltage of 0 [V] is applied, the cathode 210A
And a state in which plasma discharge has occurred between the anode 208A and the anode 208A. When the plasma channel is formed by the plasma discharge as described above, the scanning groove 206A becomes conductive, and as shown in FIG. 3B, the cathode 210A is set to the gate, the anode 208A is set to the source, and the plasma channel is set to the drain. FET (Field
Effect Transistor) Operates as a switching element.

By such a switching operation of the plasma channel, a virtual electrode is generated on the inner surface of the glass substrate 212. At this time, a driving voltage for driving a pixel, that is, a video signal, is applied to each of the driving electrodes 218R, 218G and 218B. By applying, the scanning groove 206A during the plasma discharge and the driving electrodes 218R, 218G and 218B
A driving voltage is applied to each pixel of one line of the liquid crystal display element 214 existing at the intersection with.

Therefore, the plasma discharge is applied to each scanning groove 206.
(1st line to 450th line) 450 to scan sequentially and generate one field of video
The video signals for this line are applied to the drive electrodes 218R, 218 for each line.
By applying the voltage to G and 218B, an image for one field can be displayed. In this way, an image for one field is formed by sequentially performing plasma discharge from the first line to the 450th line in synchronization with the driving of the pixels for one line.

FIG. 4 shows a PAL as this liquid crystal display means.
Plasma-addressed liquid crystal display device 23 using C200
0, and is configured by connecting a video display unit 232 as video display means and a control unit 234 as video selection means via a multi-cable 236 as signal connection means including connection lines L10 to L12. Have been.

The control unit 234 of the plasma addressed liquid crystal display device 230 is an NTSC (National T
elevision System Committee) broadcast receiving means (not shown) such as U / V tuner or BS tuner, and V
A plurality of input terminals for inputting a video signal reproduced by an external device such as a TR (Video Tape Recorder); a video signal received by a broadcast receiving unit or a video signal input from the input terminal; A plurality of input signals S
100A to 100N are input to the signal selection unit 238 of the video processing block 237. The signal selection unit 238 selects a desired input signal S102 based on the signal selection information S101 input via the operation unit 239, and sends it to the NTSC demodulation unit 240.

The NTSC demodulator 240 receives the input signal S10
2 is demodulated to obtain a video signal S103 including a luminance signal and a color difference signal, and the video signal S103 is transmitted to the double speed conversion unit 241. The double speed conversion unit 241 has a frame memory capable of storing the video signal S103 for one frame inside, and performs motion detection using the frame memory. That is, the double speed converter 241
Indicates that in the still image area of the video signal S103, the field image to be read and the field image
The video signal for one horizontal period with the field image before the field is read twice consecutively at twice the writing speed. In the moving image area of the video signal S103, the double speed conversion unit 241 converts the video signal of one horizontal period of the field image to be read and the video signal of one horizontal period above and below the horizontal period. An interpolation video signal is generated by performing interpolation processing, and the generated interpolation video signal is read at double speed. In this manner, the double speed conversion unit 241 converts the scanning method of the video signal S103 from the interlaced scanning method to the non-interlaced scanning method, and obtains the resulting non-interlaced scanning video signal S104.
To the video signal processing unit 243.

The video signal processing section 243 generates the video signal S10
After performing the color adjustment and the hue adjustment on the image signal S4, the image signal is converted into a video signal S106 of each of the primary colors of R, G, and B by inverse matrix processing, and the video signal S106 is connected to the connection line L12 of the multi cable 236. To the analog-to-digital (A / D) conversion circuit 247 of the video display block 245 of the video display unit 232.

The analog-to-digital conversion circuit 247 performs analog-to-digital conversion on the video signal S106 with 8-bit quantization precision, and sends out the resulting video data S108 to the frame rate conversion circuit 249. The frame rate conversion circuit 249 converts the 8-bit video data S108 into 7-bit video data S11 with an accuracy of about 8 bits.
Then, the video data S110 is transmitted to the white balance adjustment circuit 251. The white balance adjustment circuit 251 performs white balance processing on the video data S110, and sends out the resulting video data S112 to the liquid crystal column driver 253.

Liquid crystal column driver 25 as driving means
3 operates based on the power supply voltage S114 supplied from the power supply circuit block 255. The video data S112 for one horizontal period supplied from the white balance adjustment circuit 251, ie, 768 pixels × 3 channels (RGB) Latches the video data S112 of the pixel of (color),
The video data S112 is held for one horizontal period. In this state, the liquid crystal column driver 2
53 reads out the video data S112 for each horizontal line at the timing when the plasma discharge occurs in the scanning groove 206 of the PALC 200, and reads out the read video data S112.
As drive voltage data S114 to the digital / analog (D / A) conversion circuit 255. The digital-to-analog conversion circuit 255 converts the drive voltage data S114 from digital to analog, and converts the resulting analog drive voltage S116 to the drive electrodes 218R, 21
8G and 218B.

On the other hand, LCD (Liquid Crystal Display)
The controller 257 is operated by the power supply voltage S118 supplied from the power supply circuit block 255, and based on the operation clock signal S119 supplied from the control unit 258 of the power supply circuit block 255, the S-correction waveform generation circuit 259 Is generated, and the count clock signal S120 is generated.
To the S-shaped correction waveform generation circuit 259. The S-shaped correction waveform generation circuit 259 outputs the count clock signal S12
0, generates an S-shaped correction waveform S122 for controlling the driving rates of the driving electrodes 218R, 218G, and 218B according to the transmittance characteristics of the liquid crystal molecules of the PALC 200, and supplies the generated S-shaped correction waveform S122 to the liquid crystal column driver 253, where S11
2 is subjected to S-shaped correction.

At the same time, the LCD controller 257
Operation clock signal S119 supplied from control unit 258
A switch SW1 that generates a plasma pulse S124 for performing a plasma discharge for each scanning groove 206 of the PALC 200 based on the switching signal S126 that is turned on and off based on a switching signal S126 supplied from the control unit 258.
00 to the plasma driver 263.

Plasma driver 263 as driving means
Are operated by a power supply voltage S128 supplied from a power supply circuit block 255, and based on the supplied plasma pulse S124, a horizontal scanning line corresponding to 450 lines forming an effective screen of NTSC, that is, a PALC 200. A drive signal S1 for sequentially selecting each scanning groove 206 in a desired order to generate a plasma discharge
30 is supplied to the PALC 200.

More specifically, as shown in FIG. 5, a power supply voltage S128 of -300 [V] is supplied to the plasma driver 263, and the power supply voltage S128 is connected to the resistors RA to R.
N, the cathodes 210A-2 of each line LA-LN
10N (N indicates the number of effective scanning lines, for example, 450)
Has been applied. Cathodes 210A to 210N are NMOS (N-channel MOS) transistors TrA to Tr arranged as switching elements for plasma discharge.
It is connected to the drain of N.

The sources of the NMOS transistors TrA to TrN are commonly connected and, for example, 100 [m
A), whereby the current at the time of plasma discharge is controlled to be constant so that stable plasma discharge can be performed. The LCD controller 25 is connected to the gates of the NMOS transistors TrA to TrN.
For example, a plasma pulse S124 composed of, for example, a positive pulse of 10 [μsec] supplied from 7 is sequentially applied line by line.

Therefore, the NMOS transistors TrA-T
When the plasma pulse S124 is applied to the gate of rN, for example, a plasma discharge is generated between the anode 208A and the cathode 210A of the first line LA. Hereinafter, similarly, by sequentially applying the plasma pulse S124 to the gates from the second line LB to the Nth line LN, an image for one field can be formed.

Returning to FIG. 4, in synchronization with the image data S112 input to the liquid crystal column driver 253, the scanning grooves 206 are sequentially subjected to plasma discharge, and the plasma discharge is repeated for each field, thereby obtaining image data. PALC2 according to the timing at which S112 is supplied.
00 is driven to display a desired image. The backlight 265 is arranged as a light source for irradiating the PALC 200 from the back side.
An image is formed by transmitting the light flux emitted from the pixel 65 through the pixels of the liquid crystal display element 214, and picture adjustment can be performed by adjusting the brightness of the light source.

On the other hand, the power supply system circuit block 255 of the video display unit 232 externally supplies an AC (Alternating Curr
ent) The AC power supply voltage S140 supplied via an outlet (not shown) is input to the AC filter unit 270. The AC filter unit 270 removes noise from the power supply voltage S140, and converts the resulting power supply voltage S142 to A
The signal is sent to the C rectifier 272. The AC rectifier 272 generates a DC power supply voltage S144 by rectifying the AC power supply voltage S142, and converts the power supply voltage S144 to the main power supply switch 276 and the standby power supply 27 of the main power supply 274.
8 and the voltage obtained by dividing the power supply voltage S144 by the resistors R10 and R11 is input to the comparator 282.

The standby transformer 280 has a power supply voltage S
144 is converted into a power supply voltage S146 having a desired voltage value, and the power supply voltage S146A is converted to the standby rectifier 2
84 and supply the power supply voltage S146B to the resistor R1.
The voltage divided by R2 and R13 is supplied to the comparator 282. The comparator 282 detects the power supply voltage S
144 is divided by resistors R10 and R11 and the voltage obtained by dividing the power supply voltage S146B by resistors R12 and R13 to detect that the outlet has been removed, and the detection result signal S14
7 is notified to the control unit 258.

The standby rectifier 284 is connected to the power supply voltage S1
The power supply voltage S14 of 5 [V] is obtained by rectifying 46A.
8 and supplies the power supply voltage S148 to the control unit 258, and connects the connection line L1 of the multi-cable 236.
0 through the control unit 286 of the control unit 234.
To supply. By the way, this standby rectifier 284
It is connected to ground via a charging capacitor C10 that stores a power supply voltage to be supplied to the control unit 258 for a predetermined time even when the power is turned off.

The control unit 234 includes first and second switches SW102 and SW104.
A main power switch 288 is provided as switching means, and operates in conjunction with a user's operation to perform a power on / off operation.

Control unit 28 of control unit 234
6, the power supply voltage S148 of 5 [V] is supplied from the standby rectification unit 284 via the connection line L10 and the resistor R15, and 0 [V] from the ground via the first switch SW102 of the main power switch 288. The power supply voltage S150 of 5 V is supplied from the standby rectifier 284 when the power is off.
148 are supplied.

On the other hand, the control unit 2 of the video display unit 232
A power supply voltage S148 of 5 [V] is supplied from a standby rectifier 284 via a resistor R17 to a connection line 58 between the ground of the control unit 234 and the second switch SW104 of the main power switch 288 and the multi-cable 236. A power supply voltage S152 of 0 [V] is supplied via L11. When the main power switch 288 is off, a power supply voltage S148 of 5 [V] is supplied from the standby rectifier 284.

The inversion buffer 290 is provided in the control unit 25 described above.
8, the resistance R from the standby rectifier 284
17, a power supply voltage S148 of 5 [V] is supplied, and 0 is connected from the ground of the control unit 234 through the second switch SW104 of the main power switch 288 and the connection line L11 of the multi-cable 236.
When the power supply voltage S152 of [V] is supplied and the main power supply switch 288 is off, the standby rectifier 284
To 5 [V] of the power supply voltage S148.

In this state, when the user turns on main power switch 288, the power supply voltage supplied to control unit 286 of control unit 234 changes from 5 [V] to 0.
Since the voltage changes to [V], the control unit 286 detects that the main power switch 288 has been turned on based on the change in the supplied voltage, and starts controlling the video processing block 237. At the same time, since the power supply voltage supplied to the control unit 258 of the video display block 232 changes from 5 [V] to 0 [V], the control unit 258 determines the main power switch based on the change in the supplied voltage. It is detected that the switch 288 has been turned on, and a control signal S154 of a logic level “H” for turning on the main power supply switch 276 is generated and supplied to the input terminal x of the AND circuit 292.

Similarly, when the user turns on the main power switch 288, the inversion buffer 290 is supplied with a power supply voltage S152 of 0 [V] from the control unit 234 via the connection line L11, and reduces the power supply voltage to 0 [V]. ]
The logic level "H"
Is input to the input terminal y of the AND circuit 292.
To supply.

AND circuit 292 takes the logical product of the logical level indicated by control signal S154 supplied from control section 258 and inverted data S156 supplied from inverting buffer 290, and outputs the resulting control signal S158 to the main power supply. It is sent to the system switch unit 276. Therefore, the AND circuit 292
Turns on the main power supply system switch unit 276 when the control signal S154 supplied from the control unit 258 and the inverted data S156 supplied from the inversion buffer 290 are both at the logic level "H".

As a result, the plasma addressed liquid crystal display device 230 turns on the main power switch 288 and controls the control signal S of logic level "L" from the control unit 258.
If 154 is set to be supplied to the AND circuit 292, a standby state in which a power-on signal for turning on the power from a remote controller (not shown) is waited can be set. In this state, the control unit 258 receives a power-on signal from the remote controller,
The control signal S154 of the logic level “H” is supplied to the AND circuit 29.
The main power supply switch 276 is turned on by supplying the power to the input terminal x of the second power supply. Incidentally, the input terminal y of the AND circuit 292 is connected to the ground via a charging capacitor C11 for storing a power supply voltage to be supplied to the AND circuit 292 for a predetermined time even if the AC code is disconnected.

The main power supply switch 276 supplies the power supply voltage S 160 to the boost chopper 294 at a timing based on the control signal S 158 supplied from the AND circuit 292. The boost chopper 294 converts the power supply voltage S160 into a high-voltage power supply voltage S162,
6 Converter unit 296 is connected to power supply voltage S16
2 to generate power supply voltages S164A to S164C necessary for operating the plasma addressed liquid crystal display device,
These are supplied to the rectification unit 298.

The rectifying unit 298 controls each of the power supply voltages S164A to S164A.
By rectifying S164C, the power supply voltage S118,
S114 and S128 are generated, of which the power supply voltage S1
18 is supplied to the LCD controller 257, the power supply voltage S114 is supplied to the liquid crystal column driver 253 via the switch SW106 which is turned on and off under the control of the control unit 258, and the power supply voltage S128 is supplied under the control of the control unit 258. SW that turns on and off
The signal is supplied to the plasma driver 263 via the. Incidentally, the output line for outputting the power supply voltage S118 from the rectifying unit 298 is connected to the LC line for a predetermined time even if the AC cord is disconnected.
The output line which is connected to the ground via a charging capacitor C13 for storing the power supply voltage to be supplied to the D controller 257 and outputs the power supply voltage S128 from the rectifying unit 298 has a predetermined voltage even if the AC cord is disconnected. Is connected to the ground via a charging capacitor C15 for storing the power supply voltage supplied to the plasma driver 263 only for the time.

The control unit 258 of the video display block 232 is for controlling the operation of the video display block 232, and is supplied from the operation unit 239 of the control unit 234 via the connection line L10. While controlling the operation of each unit based on the information, the control unit 286 of the control unit 234 is for controlling the operation of the control unit 234, and based on operation information input via the operation unit 239. The operation of each unit is controlled.

FIG. 6 shows the relationship between the driving voltage S116 (FIG. 4) applied to the driving electrodes of the PALC 200 and the plasma pulse S124 (FIG. 4) applied to the plasma driver 263. FIG. 6A shows a driving voltage S116 for two lines applied to the driving electrode, and FIG. 6B shows a plasma pulse S124 of the first line applied to the plasma driver 263, and FIG. ) Indicates PALC200
6D shows the power supply voltage S128 of the first line applied to the cathode 210 formed in the scanning groove 206 through the plasma driver 263, and FIG. Pulse S1
FIG. 6E shows the power supply voltage S128 on the second line applied to the cathode 210.

The video display block 245 applies the plasma pulse S124 of the first line to the plasma driver 263 at the timing shown in FIG.
The power supply voltage S128 of the first line is applied to the cathode 210 at the timing shown in FIG. In this state, the video display block 245 holds a maximum of 6 pixels sampled and held by each pixel for one line at the timing shown in FIG.
0 [V] drive voltage S116 is continuously applied to the PALC 200
Is applied to the drive electrodes 218R, 218G, and 218B, so that an image for one line is written to the liquid crystal display element 214 of the PALC 200.

Subsequently, the image display block 245 is
At the timing shown in FIG.
While applying the plasma pulse S124 of the line,
The power supply voltage S128 on the second line is applied to the cathode 210 at the timing shown in FIG. In this state, the video display block 245 continuously applies the drive voltage S116 of a maximum of −60 [V] sampled and held at each pixel for one line at the timing shown in FIG.
By applying to the drive electrodes 218R, 218G and 218B of the C200, one line of video is
0 is written to the liquid crystal display element 214.

Thus, the image display block 245
Changes the drive voltage S116 by PALC while inverting the polarity of the drive voltage S116 for each odd line and even line.
The liquid crystal display element 214 is driven by an AC voltage by inputting the signal to the AC voltage 200, thereby preventing the deterioration of the liquid crystal molecules caused by the continuous application of the DC voltage.
Hereinafter, similarly, the drive voltage S116 for 450 lines
Are sequentially written to the liquid crystal display element 214, an image for one field can be formed and displayed on the PALC 200.

When the connection line L11 of the multi-cable 236 is disconnected from the image display unit 232 or the control unit 234 while displaying an image on the PALC 200, the control unit 258 of the image display unit 232 is connected to the connection line L11. Power supply voltage supplied to the
Since the voltage changes from [V] to 5 [V], the control unit 258
Is based on the change of the supplied voltage.
Is detected, the main power switch 288 is regarded as being turned off when the multi-cable 236 is disconnected, and the switches SW100, SW106, SW108, and the main power system switch unit 276 are shifted from the on state to the off state. By controlling the timing, each part performs an operation to remove the twist of the liquid crystal molecules, and then the power of the entire device is turned off.

Hereinafter, the operation timing of each unit performed when the connection line L11 of the multi-cable 236 is disconnected will be described with reference to timing charts shown in FIGS. FIG. 7 shows the relationship between the timing at which the drive voltage S116 (FIG. 4) is supplied to the PALC 200 after the connection line L11 is disconnected and the timing at which the plasma pulse S124 (FIG. 4) is supplied to the plasma driver 263. FIG. 7A shows a power supply voltage S128 supplied to the plasma driver 263, and FIG. 7B shows a power supply voltage S114 supplied to the liquid crystal column driver 253.
(C) shows the drive electrodes 218R and 218 of the PALC 200.
G and driving voltage S116 applied to 218B, FIG. 7D shows a plasma pulse S124 applied to the plasma driver 263, and FIG. 7E shows a plasma pulse S124 applied to the plasma driver 263 after the connection line L11 is disconnected. The applied plasma pulse S124 is shown.

As shown in FIG. 7C, when the connection line L11 is disconnected in the middle of the third line, the liquid crystal column driver 253, after the connection line L11 is disconnected, as shown in FIG. The power supply is cut off, and a drive voltage S116 of 0 [V] is applied to the liquid crystal display element 214 of the PALC 200.
Is applied over one field (450 lines). At the same time, the plasma driver 263 operates as shown in FIG.
As shown in FIG. 7, after the connection line L11 is disconnected, the power supply voltage S128 is supplied by at least one field or more by the power supply voltage charged in the capacitor C15,
The operation state is maintained.

On the other hand, the LCD controller 257
As shown in (E), after the connection line L11 is disconnected, the plasma pulse S124 is sequentially applied to the plasma driver 263 via the switch SW100 that is turned on and off under the control of the control unit 258, so that one field worth of plasma driver S263 is applied. A plasma discharge is generated over a period of 16.9 [msec]. As described above, by applying the driving voltage S116 of 0 [V] to the liquid crystal display element 214 while sequentially generating the plasma discharge, the fourth line is applied from the first line to the fourth line.
The driving voltage S116 of 0 [V] can be applied to all the pixels of the liquid crystal display element 214 composed of the scanning lines up to the 50th line, and thus the charge remaining after the connection line L11 is disengaged is eliminated, and the arrangement of the liquid crystal molecules is eliminated. Can be returned to the initial state. After the connection line L11 is disconnected, the backlight 265 is also turned off.
1 is removed, the driving state of the liquid crystal display element 214 becomes PAL.
It is not displayed on C200.

FIG. 8 shows a control procedure by the control unit 258 when the connection line L11 is disconnected. FIG. 8A shows the on / off operation of the switch SW108 for controlling the supply of the power supply voltage S128 to the plasma driver 263.
FIG. 8B shows the power supply voltage S128 supplied to the plasma driver 263, and FIG. 8C shows the on / off operation of the switch SW106 for controlling the supply of the power supply voltage S114 to the liquid crystal column driver 253. (D)
Is the plasma pulse S for the plasma driver 263.
FIG. 8E shows the on / off operation of the switch SW100 for controlling the supply of the power supply 124, and FIG.
Shows the on-off operation of.

As shown in FIG. 8C, the control unit 258
Detects that the connection line L11 has been disconnected and sets the switch SW106 to the off state, so that the liquid crystal display driver 21 of the PALC 200 is connected to the liquid crystal column driver 253.
Writing of a drive voltage S116 of 0 [V] to 4 is started. At the same time, as shown in FIG. 8D, when the control unit 258 detects that the connection line L11 has been disconnected, the control unit 258 performs, for example, 16.2 from the timing when the connection line L11 is released to the time when the switch SW100 is turned off.
During 9 [msec], the plasma pulse S124 is sequentially supplied from the LCD controller 257 to the plasma driver 263 to generate plasma discharge for one field. Then, the control unit 258 turns off the switch SW103 at the timings shown in FIGS. 8A and 8B to stop the operation of the plasma driver 263.
The main power system switch unit 276 is turned off at the timing shown in FIG.

In the above configuration, the control unit 234 for selecting a desired one of the video signals S100A to S100N supplied from the outside and the video signal S106 supplied from the control unit 234 are transmitted to the PA.
In the plasma address type liquid crystal display device 230 constructed by connecting the video display unit 232 for displaying on the LC 200 via the multi-cable 236 including a plurality of connection lines L10 to L12, each connection forming the multi-cable 236 Based on a voltage supplied only through a desired connection line L11 among the lines L10 to L12,
The disconnection of the multi-cable 236 from the video display unit 232 or the control unit 234 is detected by a detection unit including the standby rectifier 284, the resistor R17, the controller 258, and the inversion buffer 290, and the detachment of the multi-cable 236 is detected. In this case, a plasma discharge is sequentially generated for each scanning groove 206 of the PALC 200 while applying a drive voltage S116 of 0 [V] to the liquid crystal display element 219 of the PALC 200 under the control of the control unit 258 as a control means. Thus, the display of the image is stopped after the twist of the liquid crystal molecules is removed, so that when the multi-cable 236 is connected again, a part of the image immediately before the multi-cable 236 comes out is PAL.
The occurrence of the burn-in phenomenon as displayed in C200 is avoided.

According to the above configuration, the multi-cable 23
6, it is detected that the multi-cable 236 has been disconnected from the video display unit 232 or the control unit 234 based on the voltage supplied only through the desired connection line L11 among the connection lines L10 to L12 forming When it is detected that the multi-cable 236 is disconnected, the drive voltage S116 of 0 [V] is applied to the PALC20.
0 to the liquid crystal display element 219
By sequentially generating a plasma discharge in each of the scanning grooves 206 of 200, the display of an image can be stopped after the twist of the liquid crystal molecules is removed, and thus, when the multi-cable 236 is reconnected, the burn-in phenomenon is caused by PAL.
It is possible to avoid occurrence in the C200 and prevent deterioration of image quality caused by insertion and removal of the multi cable 236.

In the above-described embodiment, an operation for turning off the power when detecting that the center connection line L11 of the connection lines L10 to L12 forming the multi-cable 236 has come off is performed. However, the present invention is not limited to this, and the power supply is turned off when it is detected that one of the connection lines at both ends of the plurality of connection lines forming the multi-cable is disconnected. May be performed.

For example, as shown in FIG. 9 in which parts corresponding to those in FIG.
In the multi-cable 310 including L136, a connector 312A provided at an end thereof is connected to the control unit 314, and a connector 312B is connected to the video display unit 315.

The connection lines L101 and L1 connected to the pins PA1 and PA36 at both ends of the connector 312A.
36 are connected to the ground in the control unit 314, respectively. On the other hand, the connection lines L101 and L136 connected to the pins PB1 and PB36 at both ends of the connector 312B are connected to the standby rectifier 284 via the resistors R20 and R22 in the video display unit 315, respectively, and to the OR circuit 317. It is connected. The OR circuit 317 includes a connection line L10
1 and a connection line L
By multiplying the logical level of the logical level indicated by the power supply voltage S172 input via the
A connection state signal S174 indicating a connection state of 0 is generated and sent to the control unit 258.

When the multi-cable 310 is connected to the control unit 314 and the video display unit 315, the video display unit 315 is connected to the logic level “L” from the ground of the control unit 314 via connection lines L101 and L136, respectively. Are input to the OR circuit 317,
The connection state signal S174 of the logic level “L” is input to the control unit 258 via the OR circuit 317.

In this state, for example, the connector 312A of the multi-cable 310 is connected to the control unit 31.
When the pin PA1 is detached by completely or partially deviating from 4, the power supply voltage S170 input to the OR circuit 317 via the connection line L101 changes from 0 [V] to 5 [V]. The OR circuit 317 receives the change of the logic level of the input power supply voltage S170 from “L” to “H”, and receives the connection state signal S of the logic level “H”.
174 is generated and transmitted to the control unit 258 to notify the control unit 258 that the multi-cable 310 has been disconnected. Thus, the standby rectifier 284,
Each of the connection lines L101 to L136 is detected by a connection state detection unit including resistors R20 and R22 and an OR circuit 317.
By detecting that one of the connection lines L101 or L136 at both ends of the multi-cable 310 has been disconnected, it is possible to reliably detect that the multi-cable 310 has been disconnected, and accurately perform an operation for turning off the power. 258.

In the above-described embodiment, the case where the disconnection of the multi-cable 236 is detected by the detecting means including the standby rectifier 284, the resistor R17, the controller 258, and the inverting buffer 290 has been described. However, the present invention is not limited to this. In the plasma addressed liquid crystal display device 320 shown in FIG. 10, the control unit 324 of the video display unit 322 and the control unit 328 of the control unit 326 are exchanged via the multi-cable 330. The connection state of the multi-cable 330 may be detected by examining the control data S176.

The control unit 324 of the video display unit 322 and the control unit 328 of the control unit 326 exchange control data with each other via the connection lines L20 to L23 of the multi-cable 330. Of the control data S176, FIG.
Shows chip select data S176A exchanged via the connection line L20, and FIG. 11B shows clock data S176 exchanged via the connection line L21.
FIG. 11C shows input data S176C input to the control unit 324 via the connection line L22.
FIG. 11D shows output data S176D output from the control unit 324 via the connection line L23.

Returning to FIG. 10, the control unit 3
The control unit 328 of the 26 operates the video processing block 237 based on operation information input by the user via the operation unit 300 (for example, switching of input video signals and image quality adjustment such as color adjustment and hue adjustment). And sends the operation information as input data to the control unit 324 of the video display unit 322 via the connection line L23.

The control unit 324 of the video display unit 322
Is based on input data S176C that is operation information supplied from the control unit 328 of the control unit 326.
An operation clock is generated and the luminance of the backlight 265 is adjusted. The control unit 324 includes the control unit 3
The control state of the control unit 326 is transmitted to the control unit 328 of the control unit 326 via the connection line L20 as output data S176D.

The clock data S176B and the input data S176 transferred via each of the connection lines L20 to L23.
C and the output data S176D are transferred in units of 7 bytes by the SEP select data S176A. The first byte data of each control data S176 is fixed to “01”, and the last byte data is set to the first byte data. And the sixth byte data, and these are used as error correction data to detect communication errors. At this time, in the plasma addressed liquid crystal display device 320, the sep select data S176A, the clock data S176B, and the input data S176
Of the connection lines L20 to L23 for transferring the output data 176C and the output data S176D, desired two connection lines L2
0 and L23 are arranged at both ends of the multi cable 330,
Connection line L20 or L at both ends of multi cable 330
When any one of the connection lines L is disconnected, the operation for turning off the power of the entire apparatus is performed based on the detection result, thereby reliably detecting that the multi-cable 330 has been disconnected. Thus, it is possible to prevent the burning phenomenon from occurring when the multi-cable 330 is reconnected.

In the above-described embodiment, a case has been described in which control unit 258 detects that multi-cable 236 has been disconnected, and performs an operation for turning off the power based on the detection result. However, the present invention is not limited to this. The plasma addressed liquid crystal display device 3 shown in FIG.
At 40, the power supply voltage S180 generated by the power supply voltage generation circuit 344 as the power supply voltage generation means including the AC filter unit 270, the AC rectification unit 272, and the main power supply system 274 of the video display unit 342 is connected to the multi-cable 34.
6, the control unit 350 is supplied to the control unit 348 when the multi-cable 346 is disconnected.
Is a switch SW based on the detection result supplied from the detection unit 352 that detects the connection state of the multi-cable 346.
By turning off the power supply 110 and shutting off the power supply from the video display unit 342 to the control unit 348, the user is prevented from touching a disconnected part such as the multi-cable 346 or the video display unit 342 to prevent an electric shock. be able to.

Further, in the above-described embodiment, a case has been described where the control unit 258 detects that the multi-cable 236 has been disconnected, and performs an operation for turning off the power based on the detection result. However, the present invention is not limited to this. In the plasma address type liquid crystal display device 360 shown in FIG. The power supply voltages S182 to S184 generated by the circuit 344 are connected to the multi-cable 3
When the multi-cable 364 is disconnected when the power is supplied to the control unit 366 via the
8 is a switch S based on the detection result supplied from the detection unit 352 that detects the connection state of the multi-cable 364.
By turning off W112 to SW114 and shutting off the power supply from the control unit 362 to the video display unit 366, the user disconnects the multi-cable 36.
Electric shock can be prevented by touching a connection part such as the image display unit 4 or the video display unit 366.

Further, in the above-described embodiment, the case where the present invention is applied to the plasma addressed liquid crystal display device 230 has been described. However, the present invention is not limited to this, and a plurality of types supplied through a plurality of paths are provided. A plurality of signal connection means between a video selection means for selecting a desired video signal from among the video signals and a video display means for displaying a video corresponding to the selected video signal. The present invention can be widely applied to a liquid crystal display device that transmits and receives a control signal related to the video signal.

[0102]

As described above, according to the present invention, the connection state of any one of a plurality of signal connection means selected in advance is detected, and as a result, the signal connection means is disconnected. When the signal connection unit is reconnected, the display of the image is stopped after returning the changed arrangement of the liquid crystal molecules to the initial state before displaying the image on the liquid crystal display unit. It is possible to prevent the image displayed immediately before the disconnection from being displayed on the liquid crystal display means, thereby preventing the deterioration of the image quality caused by the disconnection of the signal connection means.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a PALC according to the present invention.

FIG. 2 is a schematic diagram for explaining a switching operation by a plasma channel.

FIG. 3 is a schematic diagram for explaining a switching operation by a plasma channel;

FIG. 4 is a block diagram showing a configuration of a wall-mounted plasma addressed liquid crystal display device.

FIG. 5 is a block diagram illustrating a configuration of a plasma driver.

FIG. 6 is a timing chart showing a relationship between a video signal and a plasma pulse.

FIG. 7 is a timing chart showing a relationship between a driving voltage and a plasma pulse.

FIG. 8 is a timing chart showing a control procedure by a control unit.

FIG. 9 is a schematic diagram illustrating a configuration of a multi-cable according to another embodiment.

FIG. 10 is a block diagram showing a configuration of a plasma addressed liquid crystal display device according to another embodiment.

FIG. 11 is a schematic diagram illustrating a format of data transfer.

FIG. 12 is a block diagram showing a configuration of a plasma addressed liquid crystal display device according to another embodiment.

FIG. 13 is a block diagram showing a configuration of a plasma addressed liquid crystal display device according to another embodiment.

FIG. 14 is a block diagram showing a configuration of a video circuit block of a conventional plasma addressed liquid crystal display device.

FIG. 15 is a block diagram showing a configuration of a power supply system circuit block of a conventional plasma addressed liquid crystal display device.

FIG. 16 is a timing chart showing a relationship between a video signal and a plasma pulse.

FIG. 17 is a timing chart showing a relationship between a driving voltage and a plasma pulse.

FIG. 18 is a timing chart showing a control procedure when the power is turned off by the control unit.

FIG. 19 is a schematic diagram illustrating a configuration of a conventional wall-mounted plasma addressed liquid crystal display device.

FIG. 20 is a block diagram illustrating a configuration of a conventional wall-mounted plasma addressed liquid crystal display device.

FIG. 21 is a timing chart showing a relationship between a driving voltage and a plasma pulse.

FIG. 22 is a timing chart showing a control procedure by a control unit.

[Explanation of symbols]

1 ... video circuit block, 9, 258, 286 ... control unit, 11, 239 ... operation unit, 15, 245 ... video display block, 23, 253 ... liquid crystal column driver,
25, 200 PALC, 29, 257 LCD controller, 33, 263 Plasma driver, 50
... Power supply circuit block, 58, 276 Main power supply switch section, 68, 292 AND circuit, 66, 288
... Main power switch, 100, 230... Plasma address type liquid crystal display device, 102, 232... Video display unit, 104, 234.
6, 236: Multi cable, 206: Scan groove, 2
08 Anode, 210 Cathode, 214 Liquid crystal display element, 218 Transparent electrode layer, 238 Signal selection unit, 272 AC rectification unit, 284 Standby rectification unit, 290 Inverting buffer .

Continued from the front page F-term (reference) 2H093 NA20 NA71 NC52 NC62 ND02 ND12 ND60 NF04 5C006 AA01 AA22 AC27 AF42 AF44 AF46 AF52 AF64 AF65 AF68 AF81 AF83 BB18 BF14 BF21 BF26 BF46 EA01 FA34 5C058 AA05 BB01 AB30 AA10 BB05 DD18 DD29 EE17 FF11 GG08 JJ02 JJ03 JJ04 JJ06 5C082 AA02 BA34 BC03 BD02 CB01 CB10 MM03

Claims (6)

[Claims] An image processing apparatus comprising: a video selection unit configured to select a desired video signal from a plurality of types of video signals supplied through a plurality of paths; and a video display unit configured to display a video according to the selected video signal. A liquid crystal display device that transmits and receives the selected video signal and a control signal related to the video signal via a plurality of signal connection units between the plurality of signal connection units, wherein the video display unit includes a liquid crystal display unit that displays the selected video. Driving means for driving the pixels forming the liquid crystal display means to change the arrangement of liquid crystal molecules corresponding to the pixels to display the image on the liquid crystal display means; and the plurality of signal connection means. Detecting means for detecting a connection state of any one of the signal connecting means selected in advance; and detecting that the signal connecting means has been disconnected by the detecting means. Control means for controlling the driving means and returning the arrangement of the changed liquid crystal molecules to an initial state before displaying the image on the liquid crystal display means and then stopping the display of the image. Characteristic liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein said detection means detects a connection state of any one of the plurality of signal connection means located near the center. . 3. The apparatus according to claim 1, wherein said detecting means detects a connection state of both or any one of the signal connecting means located at both ends of said plurality of signal connecting means. The liquid crystal display device as described in the above. 4. The error detection of the control signal transmitted / received to / from the video selection means via one of the plurality of signal connection means selected in advance from among the plurality of signal connection means. The liquid crystal display device according to claim 1, wherein the connection state of the signal connection means is detected by performing the following. 5. A video processing apparatus comprising: a video selection unit for selecting a desired video signal from a plurality of types of video signals supplied via a plurality of paths; and a video display unit for displaying a video corresponding to the selected video signal. A liquid crystal display device that transmits and receives the selected video signal and a control signal related to the video signal via a plurality of signal connection units between the plurality of signal connection units. A power supply voltage generating means for generating a power supply voltage for operating the device; a detecting means for detecting a connection state of any one of the plurality of signal connecting means selected in advance; When detecting that the signal connection means has been disconnected, the supply of the power supply voltage from the power supply voltage generation means to the video selection means via the signal connection means is stopped. A liquid crystal display device comprising: 6. A video selecting means for selecting a desired video signal from a plurality of types of video signals supplied via a plurality of paths, and a video display means for displaying a video corresponding to the selected video signal. A liquid crystal display device that transmits and receives the selected video signal and a control signal related to the video signal via a plurality of signal connection units between the plurality of signal connection units. A power supply voltage generating means for generating a power supply voltage for operating the device; a detecting means for detecting a connection state of any one of the plurality of signal connecting means selected in advance; When detecting that the signal connection means has been disconnected, the supply of the power supply voltage from the power supply voltage generation means to the video display means via the signal connection means is stopped. A liquid crystal display device comprising: