JPH0993804A - Power supply protective circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a system device that connects a power supply and a plasma display through a junction cable so that, if the junction cable is disconnected, high-voltage power supply will be interrupted to eliminate the danger of electric shock. SOLUTION: Of the power supply input connectors 31 of a plasma display 3, the pin #1 is connected with the ground of the plasma display 3, and the corresponding pin #1 of the power supply output connectors 11 of a power supply 1 is connected with a detecting terminal for the judgment of whether a junction cable 2 is connected. The wires in the junction cable 2 is made to correspond to that so that it will be judged according to whether the detecting terminal is connected with ground whether to turn on power. Further, low- voltage power is first supplied to the plasma display 3, and, if current is passed through, then high-voltage power supply is actuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver having a constitution in which a power supply means for supplying electric power such as a driving voltage and an image display means for displaying an image are separated, and both are connected by a relay cable, or The present invention relates to a power supply protection circuit used in a video display device such as a display.

[0002]

2. Description of the Related Art In recent years, color CR has been used as an image display device.
T is widely used, but instead of this, for example, a liquid crystal panel or a plasma display for color display having a memory function is demanded as a device that can be significantly thinned. As the thickness of the display unit has been reduced, a two-body image display device of this type has been developed in which an image display means for displaying an image and a power supply means for supplying a drive voltage to the image display means are separated. As an example, a DC type plasma display will be described below.

As shown in FIG. 4, a DC type plasma display generally has two types of display: a scanning electrode group 101 composed of cathodes K1, K2,... And a display electrode group 102 composed of anodes A1, A2, A3,. Having a matrix electrode group,
Each intersection constitutes an individual display discharge cell. A discharge gas is sealed between the display electrode group 102 and the scan electrode group 101, and discharge / emission occurs at a discharge cell at the intersection of the display electrode and the scan electrode to which a voltage is applied in accordance with display information. Recognized as information. In the case of performing color display, a phosphor is provided in each discharge cell, and a discharge gas such as helium-xenon, which emits ultraviolet light at the time of discharge, is sealed. A method of driving the thus configured plasma display by a pulse memory method will be described with reference to FIG.

[0004] As shown in FIG.
The write pulse VA is applied to the electrodes 1, A2, A3,.
Is applied according to the display information, and the scanning electrode group 101
, A negative voltage scanning pulse VK is sequentially applied to each of the cathodes K1, K2 ,. In such an applied voltage waveform, for example, a method of writing display information into the discharge cell 103 corresponding to the intersection of the anode A2 and the cathode K2 and maintaining the discharge will be described.

As shown in FIG. 5, when the write pulse VA is applied to the anode A2 while the scan pulse VK1 is applied to the cathode K2, a pulse discharge is generated in the discharge cell 103 at the intersection of the anode A2 and the cathode K2. And lower the firing voltage of the cell. The discharge cell 103 once written in this way discharges and emits light every time the sustain pulse VK2 is applied until the erase pulse VE is applied to the cathode. Since the voltage of the erase pulse VE is set so that the voltage between the cathode and the display anode is equal to or lower than the discharge start voltage, the subsequent discharge stops. When no write pulse is applied, or after the erase pulse is applied and the discharge is once stopped, the discharge start voltage of the display discharge cell 103 is kept at a high state, so that the discharge light emission by the sustain pulse does not occur. As described above, in the memory driving method represented by the pulse memory method, high luminance can be obtained because pulse emission repeated during a period from a writing pulse to an erasing pulse can be used for display.

[0006]

In a system using the above-described plasma display device, if an example of each applied pulse voltage is given, the display electrode pulse voltage is about 65.
V, scanning cathode pulse voltage is about -150V to -250V
Voltage is required. Therefore, the power supply voltage is 65V,
Requires relatively high voltages such as -150V, -250V.

In a conventional plasma display device, an integrated device including a power supply as shown in FIG. 3A or a power supply device 1 having a built-in power supply circuit as shown in FIG. There is a method of forming a two-body type with the plasma display device 3. Here, in the integrated type shown in FIG. 3A, even if a high voltage is used, it is in the same cabinet and no particular problem occurs. However, in order to take advantage of the thin features of the plasma display, it is better to separate the power supply device to take advantage of the features. In this case, it is necessary to connect the power supply device and the plasma display device with the relay cable 2 and supply the high voltage through the relay cable 2. At this time, if the relay cable 2 is detachable, a high voltage is applied to the output connector terminal 29 of the power supply device 1 or the connector terminal 21 of the relay cable 2 when the relay cable 2 is removed while the power supply device 1 is powered on. There was a problem of exposure and risk of electric shock.

In view of the above problems, it is an object of the present invention to avoid the above-mentioned risk of electric shock even if the relay cable 2 is removed while the power supply 1 is still powered.

[0009]

In order to solve the above-mentioned problems, in the power supply protection circuit of the present invention, at least one of the power supply input connector pins of the plasma display device is dropped to the ground of the plasma display device, and it corresponds thereto. At least one pin of the power supply output connector of the power supply device is connected to a detection terminal for determining whether a relay cable is connected, and at least one electric wire in the relay cable is made to correspond to the connector pin, and the power supply device and the plasma are connected. When connecting to the display device with a relay cable,
The power supply operates by dropping the detection terminal of the relay cable to the ground of the plasma display device, and the power supply does not operate when the detection terminal is not at the ground potential when the power supply device and the plasma display device are not connected by the relay cable. It was made to become.

As a second means, first, a low-voltage system is supplied to the plasma display device, a high-voltage system voltage is supplied when a low-voltage system current flows, and a low-voltage system is supplied when a relay cable is not connected. Since no current flows, the high voltage power supply is not turned on.

[0011]

With the above-described structure, the present invention can provide a power supply protection device which does not turn on even if the power supply device is turned on when the relay cable is not connected and does not cause an electric shock.

[0012]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a basic circuit of a power supply protection circuit according to the first embodiment of the present invention. A description will be given using a plasma display as an example of a two-body image display means.

In FIG. 1, 1 is a power supply device, 2 is a relay cable, 3 is a plasma display device, 11 is a power supply output connector, 11a to 11g are terminals of the power supply output connector 11, 12 is a power supply circuit, 13 is a detection circuit, Reference numeral 14 is a base resistance for connecting the base of the transistor 15 and 5V of the power supply circuit 12, 15 is a transistor, and 16 is a power supply circuit 1.
2 connected to 5V is a collector resistor. The collector of the transistor 15 is for turning on and off each power supply of the power supply circuit 12.
It is connected to the F terminals 12a to 12c. Reference numeral 17 is a ground of the power supply device, 18 is an input terminal of the detection circuit 13, 21 is an input side connector of the relay cable, 21a to 21g are respective terminals of the input connector 21, 22 to 28 are respective connection lines in the relay cable, and 29 is Output side connector of relay cable, 29
a to 29g are terminals of the output connector 29, 31 is a power input connector of the plasma display device 3, and 31a to 3a.
1 g is each terminal of the power supply input connector 31, 32 to 36 are each drive circuit of the plasma display, 37 is the ground of the plasma display device 3, and 38 is a detection line grounded to the ground. The power supply protection circuit configured as above will be described.

Each output voltage of the power supply circuit 12 including a high voltage such as −250 V in the power supply device 1, the ground 17 and the input terminal 18 of the detection circuit 13 are the output connector 11 of the power supply device 1.
Is output to each of the terminals 11a to 11g. Output connector 1
1 is added to each terminal 21 a to 21 g of the relay cable 2, and each terminal 29 of the output side connector 29 of the relay cable 2
Through a to 29g, the respective terminals 31a to 31g of the power input connector 31 of the plasma display device 3 are connected to the respective drive circuits 32 to 36 and the grounds 37 and 38 of the plasma display device 3. Further, the detection circuit 13 in the power supply device 1 turns on the high-voltage power supply circuit of the power supply circuit 12,
It is connected to the OFF terminals 12a to 12c.

In this way, when the relay cable 2 connects the power supply device 1 and the plasma display device 3,
The input terminal 18 of the detection circuit 13 is dropped to the detection ground 38 of the plasma display device 3, and the base of the transistor 15 is 0V. At this time, the collector of the transistor 15 is 5V. If the high-voltage power supply of the power supply circuit 12 is turned on by this 5V, each output of the power supply circuit 12 is supplied to each drive circuit 32-36 of the plasma display device 3. With the above configuration, when the relay cable 2 is connected, a voltage is output from the power supply device to the image display device and the device operates normally.

Next, when the relay cable 2 is not connected, the input terminal 18 of the detection circuit 13 is open, so that the base of the transistor 15 becomes high and is turned on. The collector of the transistor 15 becomes 0V. This allows the power supply circuit 1
The high voltage system power supply circuit 2 is turned off, and the high voltage system power supply voltage is not output to the power supply output connector 11 of the power supply device 1.
In this way, the input side connector 21 of the relay cable 2,
Alternatively, when the output connector 29 or both of them are removed, the power does not turn on, and even if each connector of the power supply device 1 is touched, there is no danger of electric shock.

(Second Embodiment) Next, a second embodiment will be described with reference to the drawings. FIG. 2 is a basic circuit of a power supply protection circuit according to the second embodiment of the present invention.

Only points in FIG. 2 different from those in FIG. 1 will be described. Reference numeral 39 is a resistor inserted in the 5V output line of the power supply circuit 12, 40 is a resistor connecting the base of the transistor 42 and the 5V output connector terminal 11e side, 41 is a smoothing capacitor, 42 is a transistor, and 43 and 44 are ground. Collector resistance of connected transistor 42, resistance 4
The middle points of 3, 44 are ON and O of the high voltage system circuit of the power supply circuit 12.
It is connected to the FF terminals 12a, 12b, 12c. The power supply protection circuit configured as above will be described.

Each output voltage of the power supply circuit 12 including a high voltage such as −250 V in the power supply device and the ground 17 are output to each terminal 11a to 11f of the output connector 11 of the power supply device 1. The output connector 11 is each terminal 21 of the relay cable 2.
a to 21f, and the terminals 31a to 29f of the power input connector 31 of the plasma display device 3 through the terminals 29a to 29f of the output side connector 29 of the relay cable 2.
The drive circuits 32 to 36 and the ground 37 of the plasma display device 3 are connected through 31f. Further, the resistor 39 of the detection circuit 13 is connected in series to the 5V line of the power supply circuit 12 of the power supply device 1 and is connected to the power supply output connector 11e. One of the outputs of the detection circuit 13 is the ON / OFF terminals 12a to 12 of the high-voltage power supply circuit of the power supply circuit 12.
It is connected to C.

When the relay cable 2 connects the power supply device 1 and the plasma display device 3 in this way,
First, the low-voltage system voltage of the power supply circuit 12, 5V, 12V is supplied to the plasma display device 3, where a current of 5V flows to cause a voltage drop in the resistor 39 and the transistor 42.
Turns on, and the collector resistance 43 of the transistor 42,
An electric current flows through 44. The voltage generated between the resistor 44 and the ground causes a high voltage system such as −250 V of the power supply circuit 12 to start working, and the high voltage system voltage of the power supply circuit 12 passes through the relay cable 2 and the drive circuits 32 to 36 of the plasma display device 3.
Is supplied to. In this way, if the relay cable 2 is connected, it will operate normally.

Next, when the relay cable 2 is not connected, the 5V current of the power supply circuit 12 does not flow, and there is no voltage drop across the resistor 39 of the detection circuit 13, so the transistor 42 remains OFF. Yes, transistor 42
No voltage is generated at the collector of. Therefore, the power supply circuit 12
No high voltage system such as -250V is generated. In this way, when the input side connector 21 and / or the output side connector 29 of the relay cable 2 are removed, the high voltage system power does not turn on, and even if each connector is touched, there is no risk of electric shock.

[0022]

As described above, according to the present invention, even in the case of the two-body type video display means in which the power supply means and the image display means are separated, the required high voltage is supplied through the relay cable as in the plasma display device. Therefore, there is no danger of electric shock, and it is possible to supply safely.

[Brief description of drawings]

FIG. 1 is a configuration diagram in a first embodiment of the present invention.

FIG. 2 is a configuration diagram according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a plasma display system.

FIG. 4 is a diagram for explaining electrodes forming a main part of the plasma display device.

FIG. 5 is a diagram illustrating a driving method of a plasma display device of a pulse memory system.

[Explanation of symbols]

 1 Power Storage 2 Relay Cable 3 Plasma Display Device 11 Power Output Connector 12 Power Supply Circuit 13 Detection Circuit 21 Relay Cable Input Side Connector 29 Relay Cable Output Side Connector 31 Power Supply Input Connector 201 Scanning Electrode Group 202 Display Electrode Group 203 Discharge Cell

Claims (3)

[Claims] 1. An image display device that displays an image, a power supply device that supplies power to the image display device, and a relay cable that connects the image display device and the power supply device. A power supply protection circuit, wherein the power supply circuit does not operate when a current is not applied to the image display device. 2. A power supply device including an image display device for displaying an image, and a power supply circuit and a detection circuit for checking a connection state,
It comprises a relay cable connecting the image display device and the power supply device, at least one pin of the power input connector pins of the image display device is connected to the ground, and the pin is the power supply via the relay cable. A signal from the detection circuit is connected to the input terminal of the detection circuit of the device, and when the power supply device and the image display device are connected by the relay cable, the input terminal of the detection circuit is grounded. A power supply protection circuit, which is output to the power supply circuit and operates. 3. A power supply device including an image display device for displaying an image, a power supply circuit for supplying power to the image display device, and a detection circuit for checking a connection state, and the image display device and the power supply device are connected to each other. When the output connector in which a resistor is inserted in the low voltage output line of the detection circuit is connected to the image display device by a relay cable, a current flows across both ends of the resistor to cause a voltage drop. When the detection circuit operates and outputs a signal to the power supply circuit, the high voltage system voltage is supplied to the image display device, and the relay cable is not connected, the voltage across the resistor inserted in the low voltage system output line of the power supply device. A power supply protection circuit characterized in that no drop occurs, the output of the detection circuit is turned off, and a high voltage system voltage is not supplied from the power supply circuit to the image display device.