JPH05161093A - Power supply control circuit - Google Patents

Abstract

PURPOSE:To cut off the power after the on-state is kept for a prescribed time with respect to processing of a video signal, an audio signal and a power supply just after switch off operation of the power for a color television receiver or the like, CONSTITUTION:A microcomputer 3 detecting the operation of power switch off by using a power ON/OFF operation key 2 or the like shifts the output data of each of selector sections (4-6) for red, blue, green to the LSB side, decreases the shift quantity timewise to be zero finally. Furthermore, audio muting is applied. When the output data reaches zero, a cathode ray tube 28 is cut off. Thus, the device reaches power cut-off tentatively. In the case of this state, the microcomputer 3 counts time and shifts each of the selector sections to the MSB side when power is applied within a prescribed time to restore the state to the normal operation. Moreover, the voice muting is released. When no power is applied and the prescribed time elapses, the microcomputer 3 outputs a power cut-off signal 49 to a power supply changeover circuit 9 to set the state to the true power OFF state.

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 turned off by a conventional color television receiver or the like, the video circuit, the high voltage circuit, the audio circuit, etc. are immediately shut off and the operation is stopped except for some preheating of a microcomputer or the like.

[0003]

When the power is turned off, an operation may be performed by mistake, and in this case, the power may be turned on again immediately after the power is turned off. When the power source is turned off, the heater power source for the cathode ray tube is also shut off. Therefore, even if the power source 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 CRT in conjunction with the power being turned on and off, an abnormal noise is generated due to an electrostatic phenomenon, which gives a discomfort to the user.
The present invention considers the power supply operation due to the above error, does not immediately stop the operation of the device even when the power-off operation is performed, maintains the standby state for a predetermined time, and the predetermined time elapses. After that, make a true power cut. When a power-off operation is performed, a transitional image is displayed so that it looks as if the power was turned off. After that, the cathode ray tube is cut off and the apparatus stands by 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 returned 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 According to the present invention, a power-off operation and a power-on operation are respectively performed in the processing of video, audio and power during a power-on / off operation of a color television receiver provided with a digital video signal processing circuit. A means for detecting, a means for shifting the data of the digital video signal to the LSB side or the MSB side, and a means for shifting the data of the digital video signal to the LSB side with the passage of time when the power off operation is detected, and muting the sound, Further, when the power-on operation is detected again within a fixed time after the power-off operation, the control means for shifting the data of the digital video signal to the MSB side with the passage of time and canceling the muting of the voice, and the fixed time. A power supply control circuit consisting of a means for truly turning off the power supply output when It is intended to.

A concrete example of the method of each of the above means is as follows. (1) In the means for detecting the power-off operation and the power-on operation respectively, the control microcomputer detects the signal from the power-on / off operation key or the signal from the remote control signal light receiving unit. (2) In the means for shifting the data of the digital video signal, the selector section or barrel shifter is provided for each circuit of red, blue and green. (3) The control means is controlled by the control microcomputer. (4) In the means for turning off the power supply output, the control microcomputer controls the power supply switching circuit after the control microcomputer counts a fixed time.

[0006]

[Function] The control microcomputer that detects that the power-on / off operation key or the remote control light-receiving unit has turned off the power reduces the output data value of each selector section or each barrel shifter of red, blue, and green with time to zero. To control. This "reduction" means that the image level is reduced, and specifically, the data of each selector section or each barrel shifter is shifted to the LSB side. When the output data value becomes zero, the cathode ray tube is cut off. On the other hand, the control microcomputer turns on the audio mute together with the above control. As a result, the device is turned off at first glance. The control microcomputer counts the time in the above state, and shifts the selector unit or the barrel shifter to the MSB side when the power is turned on within a certain time, and returns to the normal operation. Also, the audio mute is canceled. When the power-on operation is not performed and the predetermined time has elapsed, a power-off signal is output from the control microcomputer to the power circuit, and the power is turned off.

[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. 1 is a block diagram of essential parts of an embodiment of a power supply control circuit according to the present invention, FIG. 2 is an explanatory view of a selector section and its data shift example, and a barrel shifter, and FIG. 3 is a flow chart for explaining the operation of a control microcomputer 3. Is. In FIG. 1, 1 is a remote control signal light receiving unit (hereinafter, light receiving unit), 2 is a power on / off operation key (hereinafter, power key), 3 is a control microcomputer (hereinafter, microcomputer), 4 is a red (R) signal Selector section or barrel shifter, 5 is a selector section or barrel shifter for green (G) signal, 6 is a selector section or barrel shifter for blue (B) signal, 7 is an audio circuit, 8 is a power supply circuit, 9 is the power supply circuit 8. It is a power supply switching circuit included. As another block, 21 is
MUSE decoder that decodes MUSE signal and outputs as three primary color (RGB) signals, 22 to 24 are D / A conversion circuits that convert the digital output from each selector section or each barrel shifter into an analog signal, and 25 to 27 are each D A video circuit for each color that processes a signal from the A / A conversion circuit into a signal required to drive each cathode of the cathode ray tube, and 28 is a cathode ray tube (hereinafter, CRT).

Next, the operation of the present invention will be described.
The ST numbers in parentheses in the following description represent each step in FIG. The presence or absence of the power-off operation by the viewer is detected by the microcomputer 3 by the power-on / off operation signal 41 from the light receiving unit 1 or the power key 2 (ST1). On the other hand, each selector unit or each barrel shifter (4 to 6) [hereinafter, referred to as "each selector unit or the like"] directly receives the input data (42 to 44) for each color from the MUSE decoder 21 as it is for each D.
Since it is outputting to the A / A conversion circuit (22 to 24), CRT28
Is normally driven by each video circuit (25 to 27),
A color image is displayed.

Now, the device which has been in the power-on state is powered off, and the microcomputer 3 which has detected the power-off outputs the current input data (42 to 44) to each selector section (4 to 6).
Signals (45 to 47) that shift to the (least significant bit) side,
A signal for muting audio to the audio circuit 7 is output (ST2) (ST3). The data shift of each selector section and the like is such that the output data value becomes smaller with the lapse of time, and finally the data is set to zero data. This state is shown in FIG. 2 [2-2] (A). (A) shows the data before the shift is started, which is sequentially shifted and finally becomes the zero data of (e) (selector section etc. will be described later).
The fact that the output data value decreases with time is C
Since the amplitude of the video signal voltage that drives the cathode of the RT28 becomes smaller, the video gradually becomes darker on the screen with time, and finally the cutoff state (all black) occurs. Also, the sound disappears due to the audio mute, so it looks as if the power was turned off. However, the device body is in operation. If the time from the power-off operation to the video cut-off is too long, it feels uncomfortable, so the time is set to a state close to the process when the power is turned off in a normal television receiver.

The above state is maintained for a fixed time. The fixed time is a waiting time for turning on the power again and is predetermined in the design stage. The microcomputer 3 counts this time (ST4) and determines whether it is within a certain time (ST
5). When the power is turned on again within a fixed time (ST5-NO) and it is detected (ST6-YES), the microcomputer 3 shifts to the MSB (most significant bit) side opposite to the above (45). To 47) are output to each selector unit (ST
At the same time as 7), the audio mute is canceled (ST8). M
Shifting to the SB side means returning the current cutoff state to normal operation. Specifically, as shown in [2-2] (B) of FIG. 2, the current zero data (e) is shifted to the normal output state (a). Again,
[2-2] As with (A), return with time. By this operation, an image appears, and it seems that the power is turned on at first glance together with the cancellation of the audio mute. On the other hand, if the power is not turned on within the above fixed time (ST5-
In YES), the microcomputer 3 outputs the power supply cutoff signal 49 to the power supply switching circuit 9 (ST9) and stops the power supply output 50. As a result, each circuit is in a true power-off state. And L
The shift state to the SB side and the audio mute are also canceled (ST10) to prepare for the next new power-on. The above is the description of the overall operation of the present invention.

Next, the selector section and barrel shifter (4
To 6) each will be described with reference to FIG. The selector section is provided for each color (red, blue, green), but they are the same. One of them is shown in [2 of FIG.
-1], and this figure constitutes reference numeral 4 and the like. For facilitating understanding of the explanation, a signal consisting of 4 bits is taken as an example, and therefore, the first to fourth selectors are provided, and the input of each selector is as shown. Furthermore, each selector has a microcomputer 3
Further, selection signals (S1 to S4) are input to select the output of each selector. Where (S1 to S4)
The signal consisting of the "shifting signal" (symbol
45 or 46 or 47). The output of each selector is Y1 to Y4. 2 is a diagram [2-1]
Shows the state of shift of. The outputs (Y1 to Y4) before the shift are the inputs (MSB to LSB) themselves [(A) B]. The 1-bit shift to the LSB side is as follows. The first selector is S1 and Y1 is 0, the second selector is S2 and Y2 is MSB, the third selector is S3 and Y3 (MSB −1), and the fourth selector is S4 and Y4 ( MSB −2
) Are selected respectively (above is (A) b). In the 2-bit shift, data is similarly selected by each selector as shown in [(A) C]. Such selection signals (S1 to S4) are output. In this way [(A)
As shown in [e], all are shifted to zero. MSB
The shift to the side is the reverse of the above. Such selection signals (S1 to S4) are input from the microcomputer 3 to each selector.

Next, the barrel shifter will be described. There is a barrel shifter as one of other specific methods for performing the same operation as the selector described above. Figure [2-3]
(1) shows a barrel shifter when 4-bit input is used as an example. Generally, the numerical value is MSB (or
When shifting to the LSB side by 1 bit, a shift register is used. In the shift register, each numerical value is shifted based on "clock". In the case of the barrel shifter, no sequential circuit element intervenes. The shift amount is not a "clock" but a "control signal" that gives how many bits are desired. FIG. [2-3] (2) is a diagram showing the input / output relationship with respect to the control signal in (1), and the same results as in FIG. [2-2] can be obtained.

[0013]

As described above, according to the present invention, the standby state is maintained as a grace period within a predetermined time even when the power supply is cut off in a color television receiver or the like, and when the predetermined time elapses. Since the power is truly shut down, the power is shut down by mistake, and even if the power is turned on again immediately after that, the rising of the image is not impaired, and the high voltage is still applied to the CRT, so high voltage is applied. The effect of returning to the reception state before the power is cut off without any unpleasant sound at the time is provided, which contributes to the improvement of the functions of the color television receiver and the like.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a selector unit (4 to 6) and data shift.

FIG. 3 is a flowchart for explaining the operation of the control microcomputer 3.

[Explanation of symbols]

 1 remote control signal light receiving section 2 power on / off operation key 3 control microcomputer 4 red (R) signal selector section 5 green (G) signal selector section 6 blue (B) signal selector section 7 audio circuit 9 power supply Power supply switching circuit included in circuit 21 21 MUSE decoder 28 cathode ray tube (CRT)

Claims (4)

[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 on / off operation of a color television receiver provided with a digital video signal processing circuit, and a digital video signal. Means for shifting the data to the LSB side or the MSB side, and when the power-off operation is detected, the data of the digital video signal is shifted to the LSB side with the passage of time and the sound is muted, and after the power-off operation is made constant. When the power-on operation is detected again within the time, control means for shifting the data of the digital video signal to the MSB side with the passage of time and canceling the muting of the voice, and when the predetermined time has elapsed, the power source is truly output. And a means for turning off the power supply. 2. A means for detecting each of the power-off operation and the power-on operation is such that the control microcomputer detects from a signal from a power-on / off operation key or a signal from a remote control signal light receiving section. The power supply control circuit according to claim 1. 3. The power supply control circuit according to claim 1, wherein the means for shifting the data of the digital video signal is provided with a selector section or a barrel shifter for each circuit of red, blue and green. 4. The power supply control according to claim 1, wherein the means for turning off the power supply output controls the power supply switching circuit after the control means counts a fixed time. circuit.