JPH0591445A - Power supply control circuit - Google Patents

Abstract

PURPOSE:To really cut off a power supply after a prescribed time by keeping a waiting state within the prescribed time and without stopping immediately the operation of a main equipment even if the power supply is operated by mistake in regard of the processing of a power circuit, etc., which is carried out immediately after the cut-off of the power supply of a color TV receiver, etc. CONSTITUTION:A control microcomputer 9 detects a fact that a power supply is cut off by a power switch 1, etc., and then switches a video signal switch circuit 6. Then the microcomputer 9 switches the received video signal to the video signal outputted from a ROM 3. The ROM 3 stores the video signal with which the power supply is apparently cut off and then outputs this signal. synchronously with the received video signal through an H counter 4 and a V counter 5 and also microcomputer 9. The microcomputer 9 counts the time and switches again the video signal outputted from the ROM 3 to the received video signal to reset a normal operation when the power supply is applied again in a prescribed time. The microcomputer 9 outputs a power supply cut-off signal to a power supply switch circuit 8 after a prescribed time. Thus a real power cut-off state is secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the processing of video, audio and power immediately after a power-off operation of a color television receiver or the like.

[0002]

2. Description of the Related Art When a power source is cut off by a conventional color television receiver or the like, the video circuit, the high voltage circuit, the audio circuit, etc. are immediately cut off to stop the operation except for some preheating of a microcomputer.

[0003]

When the power is cut off, an operation may be performed by mistake, and in this case, the power may be turned on again immediately after the power is cut off. When the power supply is cut off, the heater power supply for the cathode ray tube is also cut off. Therefore, even if the power supply is immediately turned on again, it takes a certain amount of time for the heater to rise, so that it takes a certain amount of time for the image to stabilize. Further, when a high voltage is applied to or cut off from the cathode-ray tube in conjunction with power-off and power-on, abnormal noise is generated due to an electrostatic phenomenon, which causes discomfort. The present invention considers the power supply operation due to the above error, does not immediately stop the operation of the device even if the power-off operation is performed, maintains the standby state for the predetermined time, and the predetermined time elapses. Later, the power is cut off. Then, after the power-off operation, a transitional image is switched and displayed so that it looks as if the power was cut off, and then the cathode ray tube is cut off and kept in this state for a predetermined time. Also, the sound is muted. When the power is turned on again within the predetermined time in the standby state, the received image is switched to the normal operation. An object of the present invention is to provide a power supply control circuit that realizes such a function.

[0004]

SUMMARY OF THE INVENTION The present invention provides a means for detecting a power-off operation and a power-on operation, a storage of a specific video signal output after detection of the power-off operation, and the specific video signal. Means for outputting after the power-off operation, and switching the received video signal to the specific video signal when the power-off operation is performed, and again when the power is turned on again within a predetermined time after the power-off operation A means for switching the specific video signal to the received signal, and a means for muting the sound when the power is turned off, and a means for canceling the sound when the power is turned on again within a predetermined time after the turning off. A power supply control circuit comprising means for stopping the power supply output from the power supply circuit after the lapse of the predetermined time.

The following is a more specific version of the above. (1) In the means for detecting the power-off operation and the power-on operation, the control microcomputer is caused to detect from the signal from the power switch or the signal from the remote control light receiving unit. (2) In the means for storing the specific video signal and outputting the specific video signal after the power-off operation, the RO
M, a horizontal counter, and a vertical counter are provided, and the RO
M stores the specific video signal as video data,
The video data is sequentially read from the ROM so as to be synchronized with the video being received by each counter and the control microcomputer.
More red, blue, and green signals should be output. (3) A plurality of video data stored in the ROM are
It should consist of an arbitrary video signal and a black level that can make it look like the power is cut off. (4) In the means for switching between the video signal and the specific signal, a video signal switching circuit for switching between red, blue and green and interlockingly is provided and switched by the control of the control microcomputer. (5) In the means for muting the sound and canceling the muting, the control microcomputer outputs the sound mute signal to the sound circuit and stops the output. (6) In the means for stopping the power supply output, the power supply switching circuit provided in the power supply circuit is controlled after the control microcomputer counts a predetermined time.

[0006]

[Function] The control microcomputer, which detects that the power supply is cut off by the power switch or the remote control light receiving unit, outputs a switching signal to the video signal switching circuit and outputs the received video signal from the ROM to the video signal. Audio is muted at the same time as switching. The ROM stores a video signal and a black level signal that appear as if the power was cut off, and outputs them in synchronization with the received video signal by a horizontal counter, a vertical counter, and the control microcomputer.
The control microcomputer counts time, and when the power is turned on again within a predetermined time, the video switching circuit is switched to the receiving video side again, the audio mute is released, and the normal operation is restored. When the predetermined time has elapsed, a power cutoff signal is output from the control microcomputer to the power supply circuit to bring about a true power cutoff state.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply control circuit according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of essential parts showing an embodiment of a power supply control circuit according to the present invention. In the figure, 1 is a power switch, 2 is a remote control light receiving section, 3 is ROM, 4 is a horizontal (H) counter, 5 is a vertical (V) counter, 6 is a video signal switching circuit, 7 is a power circuit, and 8 is a power circuit. A power supply switching circuit provided in 7 and 9 is a control microcomputer. As existing blocks, 20 is an input MUSE signal, 21 is a low pass filter (LPF), 22 is a PLL circuit that generates a clock signal based on the signal from the LPF 21, and 23 is a MU.
An A / D conversion circuit for converting the SE signal from analog to digital, 24 decodes the MUSE digital signal from the A / D conversion circuit 23 with the clock signal from the PLL circuit 22, and red (R), blue (B), MUSE decoder for outputting as green (G) three primary color signals, 25 to 27 D / A conversion circuits for each color for converting each of the three primary color signals switched by the video signal switching circuit 6 from digital to analog, 28 to 30 are signals Low pass filter (LPF) for each color mainly for smoothing, 31 to 33 are image processing circuits for each color that perform predetermined signal processing such as amplification, and 34 to 36 are image outputs for driving cathodes of cathode ray tubes. circuit,
37 is a cathode-ray tube (C
RT) and 38 are voice circuits.

Next, the operation of the present invention will be described with reference to FIG. FIG. 2 is a flowchart of the control microcomputer 9. The ST number in the following description represents each step in FIG. The power switch 1 determines whether or not the viewer turns off the power.
The control microcomputer 9 detects the signal 41 or the signal 42 from the remote control light receiving unit 2 (ST1). The power switch 1 is the power-off operation itself, and the remote control light receiving unit 2
Can be detected because it receives the signal from the remote control. On the other hand, the ROM 3 stores in advance a signal that looks as if the power was cut off. Normally, when the power of the television receiver is cut off, the image (raster) portion rapidly contracts and disappears and becomes dark. Also, the sound disappears. The above-mentioned "signal that looks as if the power was cut off" refers to such a signal. Such a signal is composed of a transient signal in the process of rapidly contracting and a black level signal for keeping the raster disappeared. When the power is cut off, these signals are output from the ROM 3 in a state of being in horizontal and vertical synchronization with the video signals received by the horizontal counter 4, the vertical counter 5 and the control microcomputer 9 (ST2). The timing of the synchronization is synchronized by switching the video from the next frame based on the frame synchronization signal being received. Further, a switching signal 43 is output from the control microcomputer 9 to switch the video signal switching circuit 6 at this timing (ST3).
Further, an audio mute signal 44 is output to apply audio mute to the audio circuit 38 (ST4).

When the video signal switching circuit 6 is switched to the ROM output, the signal is projected on the CRT through the D / A conversion circuit 25, the video output circuit 34, etc., and then the black level is maintained and the sound is muted. It seems that the device has been turned off at first glance because it disappears. However, the device is actually in operation. Then, this state is maintained for a predetermined time. The predetermined time is predetermined in the design stage and is a problem of software processing of the control microcomputer 9.
Then, the predetermined time is measured by counting the frame synchronization signal with the detection of the power-off operation (ST5). The control microcomputer 9 determines whether it is within a predetermined time (ST6). If the power is turned on again within the predetermined time (ST6-NO) and the operation is detected in the same manner as the power-off operation (ST7-YES), the control microcomputer 9 performs the reverse process to the above. After that, it returns to the receiving state. That is, the black level signal is output from the ROM 3 so as to be the above-mentioned transitional video signal (ST8), and this is displayed. After that, the switching signal 43 is output (ST9) to output the video signal switching circuit 6
To display the received signal. In addition, the voice also releases the voice mute signal 44 (ST10) and returns to the normal operation.
When the predetermined time has elapsed without the power being turned on again, the control microcomputer 9 outputs a power cutoff signal 45 (ST11) to the power supply switching circuit 8 provided in the power supply circuit 7 to stop the power supply output 46. As a result, each circuit is in the normal power-off state. Incidentally, when the power is turned on after a sufficient time has passed after the power was turned off, there is no difference from a normal receiver.

[0010]

As described above, according to the present invention, even if a power-off operation is performed in a color television receiver or the like, the standby state is maintained as a grace period for a predetermined time, and when the predetermined time elapses. Since the power is shut down truly, the power is shut down by mistake, and even if the power is turned on again immediately after that, the rise of the image is not impaired and an unpleasant sound is generated due to the fluctuation of the high voltage applied to the cathode ray tube. Without doing so, the effect of returning to the reception state before power-off is achieved, which contributes to the improvement of the functions of the color television receiver and the like.

[Brief description of drawings]

FIG. 1 is a principal block diagram showing an embodiment of a power supply control circuit according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the control microcomputer 9.

[Explanation of symbols]

 1 power switch 2 remote control light receiving unit 3 ROM 4 horizontal counter 5 vertical counter 6 video signal switching circuit 7 power circuit 8 power switching circuit 9 control microcomputer 43 video switching signal 44 audio mute signal 45 power cutoff signal 46 power output

Claims (7)

[Claims] 1. A means for detecting a power-off operation and a power-on operation in the processing of video, audio and power during a power-off operation of a color television receiver, and a specification for outputting after the power-off operation is detected. Means for storing the video signal and outputting the specific video signal after the power-off operation, and switching the received video signal to the specific video signal when the power-off operation is performed and A means for switching the specific video signal to the received signal again when the power is turned on again within a predetermined time, and muting the sound when the power is turned off, and again within a predetermined time after the shutoff operation. A power supply control circuit comprising means for canceling the mute when the power is turned on, and means for stopping the power supply output from the power supply circuit after the lapse of the predetermined time. .. 2. The control microcomputer detects the signal from the power switch or the signal from the remote control light-receiving unit in the means for detecting the power-off operation and the power-on operation. The power supply control circuit described. 3. A ROM, a horizontal counter, and a vertical counter are provided in the means for storing the specific video signal and outputting the specific video signal after the power-off operation, and the specific video is stored in the ROM. The signals are stored as video data, and the video data are sequentially output from the ROM as red, blue, and green signals so as to be synchronized with the video being received by each counter and the control microcomputer. The power supply control circuit according to claim 1. 4. The plurality of video data stored in the ROM is composed of an arbitrary video signal that can make the power supply look like it is cut off and a black level. 1. The power supply control circuit according to 1. 5. The means for switching between the video signal and the specific signal is provided with a video signal switching circuit for switching between red, blue and green and interlockingly, and switching is performed by the control of the control microcomputer. The power supply control circuit according to claim 1. 6. The sound muffling and means for canceling the muffling are performed by outputting a sound mute signal from the control microcomputer to a sound circuit and stopping the output. The power supply control circuit according to item 1. 7. The means for stopping the power supply output,
After counting a predetermined time with the control microcomputer,
The power supply control circuit according to claim 1, wherein a power supply switching circuit provided in the power supply circuit is controlled.