JP2545816B2 - Television receiver - Google Patents

Description

The present invention relates to a television receiver having an abnormal high voltage protection circuit.

[Outline of Invention]

According to the present invention, in a television receiver having an abnormal high voltage protection circuit, when the power is cut off by the operation key of the main body, the protection circuit operates by opening the main power switch without waiting for the vertical blanking period. Even when the vertical blanking period cannot be detected, the power supply can be cut off, and the protection circuit can be released and returned to the normal operation state.

[Conventional technology]

2. Description of the Related Art Conventionally, in a television receiver equipped with a microcomputer for system control, in order to prevent the viewer from feeling uncomfortable when the power is turned off, as shown in FIG. The signal is eg 30
After being gently shut off (step) at the fall time of mS (step), wait until the vertical blanking period of the video signal (step), and then perform video blanking after the image of a certain field has been displayed. (Step), after that, the main power switch (relay) was opened (Step). The vertical blanking period is detected by extracting the vertical blanking pulse (V pulse) from the vertical deflection circuit.

[Problems to be solved by the invention]

By the way, in a television receiver, an abnormal high voltage protection circuit is generally used that shuts off the operation of the horizontal oscillator when the high voltage DC supplied to the picture tube is abnormally increased. There is.

However, when the protection circuit operates and the horizontal oscillation is stopped, the supply of the low voltage DC for the vertical deflection circuit based on the horizontal oscillation is cut off as well as the high voltage for the picture tube.
Therefore, depending on the operation timing of the protection circuit, V
It becomes impossible to detect the vertical blanking period by the pulse, and as described above, it becomes impossible to operate the relay to cut off the main power supply. Further, since the protection circuit is released by shutting off the main power source, there is a serious drawback that the receiver cannot be returned to the normal operating state as it is.

Of course, the above-mentioned problem can be solved by combining a normal timer and V pulse, but the control program by the microcomputer becomes complicated, resulting in problems of reduced efficiency and increased cost.

In view of such a point, an object of the present invention is to provide a television capable of returning to a normal operating state by shutting off the main power supply and releasing the protection circuit regardless of the timing of the operation when the abnormal high voltage protection circuit operates. It is in the area of providing a receiver.

[Means for solving problems]

The television receiver of the present invention is provided with a horizontal oscillator (1) when an abnormal rise of high-voltage DC supplied to the picture tube (10) occurs.
A detection circuit (22) for detecting a vertical blanking period in a television receiver having an abnormal high voltage protection circuit (16) configured to stop the operation of 4) and cut off the supply of high voltage DC.
It has a main power switch (33) controlled by the system control circuit (20), a remote operation key (24) for supplying a command signal to the system control circuit (20) and a main body operation key (23). When a command signal for shutting off the power source was sent to the system control circuit (20) by the remote operation key (24), the image blanking was performed after the detection of the vertical blanking period of the detection circuit (22). After that, the main power switch (33) is operated, and a command signal for shutting off the power source by the main body operation key (23) is sent to the system control circuit (20).
When the signal is sent to, the image is blanked immediately and the main power switch (33) is operated without waiting for the detection of the vertical blanking period.

[Action]

According to the present invention, when an abnormally high voltage is generated, the power is cut off regardless of the operation timing of the protection circuit, the protection circuit is released, and the normal operation of the receiver can be restored.

〔Example〕

An embodiment of the television receiver according to the present invention will be described below with reference to FIGS. 1 and 2.

 FIG. 1 shows the configuration of an embodiment of the present invention.

In FIG. 1, a high frequency signal induced in a receiving antenna (1) is appropriately selected by a tuner (2), converted into an intermediate frequency signal, and supplied to a video intermediate frequency circuit (3). The video signal from the detection circuit (4) is supplied to the video signal circuit (5), and the audio intermediate frequency signal of 4.5 MHz is supplied from the video intermediate frequency circuit (3) to the audio intermediate frequency circuit (6). The audio signal from the detection circuit (7) is supplied to the speaker (9) via the audio amplifier (8).

The output of the video signal circuit (5) is supplied to the picture tube (10) and is also branched and supplied to the sync separation circuit (11). From this sync separation circuit (11), the vertical sync signal and the horizontal sync signal are supplied to the vertical deflection circuit. (12) and the horizontal deflection circuit (13). The horizontal deflection circuit (13) includes a horizontal oscillation circuit (1
4) is included. The outputs of both deflection circuits (12) and (13) are supplied to the deflection coil DY, and the horizontal deflection circuit (13)
Is supplied to the high voltage circuit (15). The high-voltage circuit (15) has a flyback transformer (FBT) (not shown), and as is well known, a high-voltage direct current obtained by rectifying the output of the secondary winding is supplied to the image receiving winding (10). , The low-voltage direct current obtained by rectifying the output of the third winding of the FBT is supplied as the power source of the vertical deflection circuit (12). Furthermore, when the DC voltage obtained by rectifying the output of another winding of the FBT is supplied to the abnormal high voltage detection circuit (16) and the abnormal high voltage is detected, the detection output of this detection circuit (16) is the horizontal deflection circuit (13). ), The operation of the horizontal oscillator (14) is stopped.

The system control circuit (20) has a microcomputer and controls each part of the receiver such as tuning of the tuner (2), blanking of the video signal circuit (5) and muting of the audio amplifier (8). This control state is stored in the memory (21), and when the power is turned on again, the state of each part of the receiver when the power is turned off is reproduced.

As described above, these controls are partly performed on the basis of the V pulse. Therefore, the vertical blanking period detection circuit (22) detects the V pulse of the vertical deflection circuit (12), and the detection circuit (22). Is output to the system control circuit (20).

(23) is an operation key attached to the main body of the receiver, which is directly connected to the system control circuit (20). (2
4) is a remote controller, which has operation keys (25) and an infrared transmitter (26), and is connected to the system control circuit (20) via a receiver (27). The main body operation key (23) has the minimum necessary control functions such as opening and closing of the power supply, sequential tuning, and volume. The remote operation key (25) has a more convenient control function such as direct tuning in addition to the basic control function described above.

Although not shown, the main power supply circuit (31) supplies various predetermined power supply voltages to the respective parts of the receiver such as the tuner (2) to the horizontal deflection circuit (13) and the sub power supply circuit (32). A predetermined power supply voltage is supplied to the system control circuit (20), the memory (21) and the receiver (27). The main power supply circuit (31) is directly connected to the commercial power supply AC via the main power supply switch (relay) (33). Opening and closing the relay (33) is based on the operation of the main unit key (23) or remote key (25), and the system control circuit (2
Controlled by 0).

Next, referring to FIG. 2 as well, the power shutoff operation of the embodiment of FIG. 1 will be described. In this FIG.
The same reference numerals are attached to the steps corresponding to FIG.

When the main body power key (23) or the remote power key (25) is operated and the audio signal is muted (step,), it is determined whether or not the operated power key is the main body key (23). (Step).

In this embodiment, when the main body power key (23) is operated, the microcomputer is reset and the output of an appropriate port becomes "Hi", and this "Hi" output serves as a blanking signal for the video signal circuit ( 5), and video blanking is performed without waiting for the detection of the vertical blanking period of the step (step). As a result, even if an abnormally high voltage is generated and the horizontal oscillator (14) stops oscillating due to the detection output of the detection circuit (16), the V pulse from the vertical deflection circuit (12) cannot be detected. (33)
Is released (step), the protection circuit is released, and the receiver can be returned to the normal operating state.

When the remote power key (25) is operated, the vertical blanking period is detected by the V pulse (step), and then the video blanking and the relay (33) are opened (step).

〔The invention's effect〕

As described above in detail, according to the present invention, when the power is turned off by the operation key of the main body, the image blanking is performed without waiting for the vertical blanking period and the relay is opened. Even when the vertical retrace period cannot be detected due to the operation of, the power supply can be cut off, the protection circuit can be released, and the television receiver can be returned to the normal operation state.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a television receiver according to the present invention, FIG. 2 is a flow chart for explaining the operation of the embodiment of FIG. 1, and FIG. 3 is a conventional television. It is a flow chart for explaining operation of a receiver. (5) is a video signal circuit, (8) is an audio amplifier, (12) is a vertical deflection circuit, (13) is a horizontal deflection circuit, (14) is a horizontal oscillation circuit, (15) is a high voltage circuit, and (16) is Abnormal high voltage detection circuit, (20) system control circuit (microcomputer), (23) main unit operation key, (25) remote operation key, (31) main power circuit, (33) main power switch (relay) ).

Claims (1)

(57) [Claims] 1. A television receiver having an abnormal high voltage protection circuit for stopping the operation of a horizontal oscillator to shut off the supply of high voltage direct current when an abnormal rise of high voltage direct current supplied to a picture tube occurs. It has a detection circuit for detecting a blanking period, a main power switch controlled by the system control circuit, a remote operation key for supplying a command signal to the system control circuit, and a main body operation key. When a command signal for shutting off is sent to the system control circuit, after waiting for the vertical blanking period of the detection circuit to be detected, image blanking is performed, and then the main power switch is operated to operate the main body operation key. When a command signal to cut off the power is sent to the system control circuit by the video blanking immediately without waiting for the detection of the vertical blanking period. A television receiver characterized in that the main power switch is operated by performing a switching operation.