JP4771839B2 - Power supply control device, power supply control method, and video display device - Google Patents

Description

  The present invention relates to a power supply control apparatus, a power supply control method, and a video display apparatus provided with the power supply control apparatus for automatically turning on / off a power supply of a video display apparatus such as a television receiver according to ambient brightness. Is.

In a conventional television receiver, the power (on / off) or switching of the standby state is performed by the user (viewer) pressing the power button disposed on the remote control or the main body of the television receiver. It had to be done manually.
Therefore, before turning off at the time of going to bed, it is necessary to turn off the power of the television receiver by pressing the power button on the remote control or the television receiver body.
Conversely, when the television receiver is forgotten to be turned off, useless power is consumed.

As an improvement measure against this forgetting to turn off the power, there is a television receiver that automatically turns off its own power if the television receiver is not operated for a certain time or longer.
In addition, some devices automatically turn off their own power if no moving object is detected for a certain period of time in front of the television receiver. (For example, see Patent Document 1)
Furthermore, some information processing devices and mobile phones detect ambient brightness, and automatically turn off their own power immediately or after a predetermined time has elapsed when the brightness becomes darker than a predetermined reference value. (For example, refer to Patent Document 2 or Patent Document 3).
JP 2000-295543 A (FIG. 1, paragraph 0007) Japanese Patent Laid-Open No. 5-119874 (FIG. 1, paragraph 0009) JP 11-98226 A (FIG. 1, paragraph 0008)

However, in a conventional television receiver configured to automatically turn off its own power if the television receiver is not operated for a certain period of time or longer, the power is turned on while the user is watching the television. In order to avoid running out, it is necessary to detect a no-operation state for a sufficiently long time such as several hours.
Therefore, useless power is consumed during that time, and in order to avoid it, the user must turn off the power of the television receiver.
Moreover, in the television receiver power supply control device disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2000-295543), a detection sensor for detecting the movement of an object is required, which causes an increase in cost.

Further, in a television receiver to which the technique of Patent Document 2 (Japanese Patent Laid-Open No. 5-111987) or Patent Document 3 (Japanese Patent Laid-Open No. 11-98226) is applied, the brightness of the room is determined by only one threshold value. Will do.
Therefore, if you watch a television receiver without turning on the room lights when it becomes dark gradually after sunset, even if the viewer intends to keep watching the television receiver, There was a problem that John's receiver would turn off.

  The present invention has been made to solve such a problem, and is a power source for a video display device such as a television receiver that is viewed when the brightness of a room gradually becomes dark at sunset. An object of the present invention is to provide a power supply control device and a power supply control method capable of automatically turning off the power of the video display device when the room lighting is turned off at night.

A power supply control device according to the present invention comprises an image receiving circuit for displaying an image received, a drive power supply for driving the image receiving circuit, and a switch for turning on / off the output of the drive power to the image receiving circuit. And a power supply control device for controlling the drive of the image receiving circuit by turning on / off the switch according to the level fluctuation of ambient brightness detected by the light detecting means,
Illumination on detection means for detecting that the brightness of the place where the image receiving circuit is installed is not less than the first brightness, and the brightness is not less than the first brightness by the illumination on detection means. Brightness transition detecting means for detecting a transition to a second brightness lower than the first brightness within a predetermined first time after detection, and the second brightness or less And a power supply control means comprising an illumination off detection means for detecting that the second brightness continues for a predetermined second time after transition to
The power control means turns off the switch based on the detection result of the illumination off detection means and stops driving the image receiving circuit.

A power supply control method according to the present invention is a power supply control method for controlling on / off of a drive power supply of a video display device,
The illumination in the room where the video display device is installed is turned on, and an illumination on detection step for detecting that the brightness of the room is equal to or higher than the first brightness, and in the illumination on detection step, Brightness that detects a transition to a second brightness lower than the first brightness within a predetermined first time after it is detected that the brightness is greater than or equal to the first brightness. An illumination that determines that the illumination is off when it is detected that the state below the second brightness has continued for a predetermined second time after transitioning to the second brightness or less. An off detection step,
Based on the detection result in the illumination-off detection step, the drive power supply of the video display device is turned off.

  According to the power control device or the power control method of the present invention, the power of the video display device such as a television receiver is not turned off unintentionally when the brightness of the room gradually becomes dark at night, In addition, when the room is turned off at night, the video display device can be automatically turned off.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the drawings, the same reference sign indicates the same or equivalent.
Embodiment 1 FIG.
FIG. 1 is a block diagram conceptually showing the structure of a power supply control apparatus according to the present invention.
As shown in the figure, the power supply control device according to the present invention detects ambient brightness, outputs a detection signal corresponding to the brightness, inputs a detection signal from the light detection means 1, Power supply control means 2 that determines whether the power is turned on / off based on the input detection signal, a switch 3 that is turned on / off by the power supply control means 2, a drive power supply 4 that drives the image receiving circuit, and an image receiving circuit 5 that displays an image It consists of

The image receiving circuit 5 displays, for example, a video signal received by a television receiver, and the drive power supply 4 receives a video signal received by the television receiver and displays it. This will be described as an example.
That is, the power supply control device according to the present embodiment will be described on the assumption that the power supply of a television receiver which is an example of a video display device is turned on / off.

FIG. 2 is a block diagram showing a schematic configuration of the power supply control apparatus according to Embodiment 1 of the present invention, and shows a specific example of the light detection means 1 and the power supply control means 1 of FIG.
In the power supply control device according to the present embodiment, the photodetector 11 detects the ambient brightness where the television receiver is installed. For example, the ambient brightness in a range from 0 lx (lx: lux) to 100 lx or more. Outputs a voltage roughly proportional to.
The light detector 11 corresponds to the light detection means 1 in FIG. 1, and is disposed in the main body (housing) of the television receiver.

  Further, the power control means 21 (corresponding to the power control means 2 in FIG. 1) receives a voltage from the photodetector 11, and inputs a voltage equal to or higher than a voltage corresponding to, for example, 30 lx brightness (referred to as the first brightness). Then, the voltage from the first comparator 61 that outputs the control signal “H” and the photodetector 11 is input. For example, when a voltage equal to or lower than 10 lx brightness (referred to as the second brightness) is input. A second comparator 62 that outputs an “H” control signal, and has an internal CPU, timer, memory, etc., and receives control signals from the first comparator 61 and the second comparator 62, and an algorithm described later. It is comprised by the microcomputer 91 which performs power supply control.

The microcomputer 91 of the power supply control means 21 turns on / off the switch 3 based on the control signals from the first comparator 61 and the second comparator 62 and receives the power supply voltage image receiving circuit 5 output from the drive power supply 4. Control application / non-application to.
That is, the microcomputer 91 of the power supply control means 21 controls the switch 3 to be turned on / off based on the control signals from the first comparator 61 and the second comparator 62 so that the image receiving circuit 5 is in an operating state or a non-operating state. To control.

Hereinafter, the operation of the power supply control device according to the present embodiment will be described.
FIG. 3 is a diagram illustrating an example of a change in the operating environment (that is, a change in brightness) in a place (for example, a room) where a video display device such as a television receiver is installed.
First, consider the situation when the room lights are turned off at night.
The case where the room illumination is turned on at night as in the illumination on period in FIG. 3 and the illuminance at the photodetector 11 of the television receiver is 50 lx will be described.
At this time, due to the voltage output from the photodetector 11, the output of the first comparator 61 becomes "H", while the output of the second comparator 62 becomes "L".

Next, in the brightness transition state in which the room illumination is turned off and the amount of light emitted from the luminaire is decreasing as in the brightness transition period in FIG. 3, the illuminance in the photodetector 11 is, for example, 20 lx. When the light detector 11 detects the brightness at the level, the output of the first comparator 61 becomes “L”, and the output of the second comparator 62 remains “L”.
Furthermore, as in the illumination-off period in FIG. 3, when the light emission from the luminaire stops and the illuminance at the photodetector 11 becomes less than or less than 10 lx, which is the second brightness, the first comparator 61. However, the output of the second comparator 62 becomes “H”.

In this process, the microcomputer 91 that receives the control signals of the first comparator 61 and the second comparator 62 (that is, the output signals of the first comparator 61 and the second comparator 62) operates as follows.
The microcomputer 91 determines control signals from the first comparator 61 and the second comparator 62 periodically (here, every 50 ms), and performs power supply control according to an algorithm as shown in FIG.
The control signal determination cycle is preferably set to be within several hundreds of milliseconds in order to detect a brightness transition period when the illumination is turned off and a movement of a person in the room.

Hereinafter, the operation algorithm of the power supply control means in the present embodiment will be described with reference to FIG.
First, an on-counter for measuring the time of the illumination on period, a transition counter for measuring the time of the brightness transition period, and an off counter for measuring the time of the illumination off period are prepared in an initial stage (initial setting step). Then, both are set to “0”. (Step S101)
Next, in the illumination on detection step (step S102), it is detected that the illumination is on for a predetermined time (for example, 2 seconds here).

It is determined whether or not illumination is on, that is, whether or not the control signal from the first comparator 61 is “H”. If “H” (illumination is on), the on-counter is incremented by one and the next 50 ms later (50 ms wait).
Conversely, if the control signal from the first comparator 61 is “L” (illumination is not on), the illumination may have been extinguished, and the on counter is 40 or more, that is, the illumination on state is 2 seconds or more. Only when it has continued, the process proceeds to the next brightness transition detection step (S103).
If the on-counter is less than 40, that is, if the lighting-on state has not continued for 2 seconds, the on-counter is cleared to “0”, and the lighting-on detection step is repeated from the beginning.

In the brightness transition detection step (step S103), the time after the illumination is not turned on (for example, after the first brightness of 30 lx or less or less) is measured.
That is, in this step, the brightness transition counter is incremented by 1 every 50 ms, and if the brightness transition counter reaches “120” (that is, the power-off process described later cannot be reached within 6 seconds). When all the counters are cleared to “0”, the lighting on detection step starts again, and if the brightness transition counter has not yet reached “120”, the process proceeds to the lighting off detection step (step S104).

In the illumination-off detection step (step S104), it is detected that the illumination-off state (that is, the state where the second comparator 62 is “H”) continues for a predetermined period (here, 4 seconds).
In this illumination off detection step, if the illumination is off (ie, the output of the second comparator 62 is “L”), the off counter is incremented by one, and if the off counter is “80” (ie, 4 seconds). If the illumination off state continues continuously), the switch 3 is turned off, and the power supply from the drive power supply 4 to the image receiving circuit 5 is turned off.
On the contrary, if it is not in the illumination off state, it is considered that the brightness transition is still in progress, and the off counter is cleared to 0 and illumination off detection is performed from the beginning.
Here, as described above, “the power is turned off if it is detected that the illumination is off for 4 seconds continuously in the illumination off detection step while measuring 6 seconds in the transition detection step”. Is returned, the power is turned off if the transition period is within 6-4 = 2 seconds.

As described above, since it detects that the illumination on state continues for a predetermined time (here 2 seconds), it does not cause malfunction due to instantaneous noise output from the photodetector, and further, the user can It is possible to detect a state in which lighting is reliably performed.
Here, the detection time of the illumination on state may be any time that can confirm that the television receiver has been watched with noise elimination and illumination, so it is not necessary to stick to 2 seconds. If it is a system that does not become a problem, the main purpose of eliminating the case of gradually darkening at the time of sunset can be achieved simply by detecting the “light on” state for a moment.
In addition, since it can be detected that the lighting has suddenly changed from the lighted state to the lighted state within 2 seconds, the television receiver can be turned on while the room is gradually darkening at nighttime in an unlit room. When watching, the power is never turned off without permission.

Furthermore, by giving a margin of about 2 seconds (Note, it was “likelihood” in your manuscript, but I think it is not an appropriate expression, so I will change it to “margin”.) Even in a luminaire that adjusts the illuminance by a variable volume, the power can be turned off when the volume is turned to turn off the illumination.
Here, as the brightness transition period, it is not necessary to stick to 2 seconds as long as it is a time sufficient to turn off the illumination by the variable volume type illumination switch, and the state where it gradually becomes dark at nightfall can be excluded.
Furthermore, since the illumination off state is detected for 4 seconds, when a person or the like crosses in front of the television receiver, the illuminance of the light detector section becomes dark for a moment and the illumination is detected to be turned off and the power is turned off. There is nothing.
Here, the detection time of the illumination off state is not limited to 4 seconds as long as it is longer than the time for a person or the like to cross in front of the television receiver.

  As described above, the power supply control device according to the present embodiment has the image receiving circuit 5 that displays the received video, the drive power supply 4 for driving the image receiving circuit 5, and the drive power supply 4 for the image receiving circuit 5. A power supply composed of a switch 3 for turning on / off the output and controlling the drive of the image receiving circuit 5 by turning on / off the switch 3 in accordance with the level fluctuation of ambient brightness detected by the light detecting means (light detector 11). In the control device, the brightness of the place where the image receiving circuit 5 is installed is equal to or higher than the first brightness (“larger” means “brighter than the first brightness”). Illumination on detection means for detecting that the brightness is greater than or equal to the first brightness by the illumination on detection means, and the above within a predetermined first time Second light lower than the first brightness Brightness transition detecting means for detecting transition to less than or less than the second brightness, and detecting that the second brightness continues for a predetermined second time after transition to less than or less than the second brightness The power supply control means 21 comprises an illumination off detection means, and the power supply control means 21 turns off the switch 3 based on the detection result of the illumination off detection means and stops driving the image receiving circuit 2.

  The power supply control means 21 includes a first comparator 61 for detecting that the brightness level detected by the light detection means is equal to or higher than the first brightness, and the ambient brightness detected by the light detection means. Based on detection results of the second comparator 62, the first comparator 61, and the second comparator 62 that detect that the level is equal to or lower than the second brightness, illumination on detection, brightness transition detection, illumination The microcomputer 91 is configured to detect off.

  Further, the power control method according to the present embodiment is a power control method for controlling on / off of driving power of the video display device, in which the illumination of the room in which the video display device is installed is turned on. Illumination on detection step (S102) for detecting that the brightness of the room is greater than or equal to the first brightness, and that the brightness of the room is greater than or equal to the first brightness in the illumination on detection step A brightness transition detection step (S103) for detecting a transition to a second brightness lower than or lower than the first brightness within a predetermined first time after detecting Illumination off detection step (S1) for determining that the illumination is off when it is detected that the state of less than or less than the second brightness has continued for a predetermined second time after transitioning to less than or less than brightness. 4) and has, on the basis of the detection result of the illumination-off detection step, turning off the driving power to the image display device.

  Therefore, according to the power supply control device or the power supply control method according to the present embodiment, the power of the video display device such as a television receiver is turned off unintentionally when the brightness of the room gradually becomes dark at night. In addition, when the room lights are turned off at night, the video display device can be automatically turned off.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing a schematic configuration of the power supply control apparatus according to the second embodiment.
In the present embodiment, as shown in FIG. 5, the power supply control means 22 is composed of an A / D converter 70 and a microcomputer 92.
As will be described later, the A / D converter 70 reads the output voltage (analog voltage) of the photodetector 11 and converts it into a digital value, and outputs the converted digital signal.
The microcomputer 92 includes a memory, a timer, a CPU, and the like. The microcomputer 92 turns on / off the switch 3 in accordance with the digital signal from the A / D converter 70, and outputs the output voltage of the drive power supply 4 to the image receiving circuit 5. Control application / non-application.

The operation of the power supply control device according to this embodiment will be described below with reference to FIG.
The ambient brightness is converted into a voltage by the photodetector 11, further converted into a digital signal by the A / D converter 70, and input to the microcomputer 92.
In the microcomputer 92, processing is performed with the algorithm shown in FIG. 4 as in the case of the first embodiment.
However, in FIG. 4, the output value (digital signal) from the A / D converter 70 is used for the illumination on determination in the illumination on detection step (S102) and the illumination off determination in the illumination off detection step (S104). Is different from the case of the first embodiment.
Hereinafter, differences from the first embodiment will be described in more detail.

The output value of the A / D converter 70 (that is, the microcomputer) when the illuminance detected by the photodetector 11 (that is, the brightness of the room in which the television receiver or the like is installed) is 30 lx (first brightness). 92) is “A”, and the output value of the A / D converter 70 when the illuminance is 10 lx (second brightness) is “B” (0 <B <A <256).
In the memory in the microcomputer 92, values “A” and “B” are stored in advance.
The values of “A” and “B” may be variable by the user.
At this time, as an illumination-on determination method in the illumination-on detection step (S102) in FIG. 4, the output value of the A / D converter 70 (that is, the input value of the microcomputer 92) is greater than or equal to “A”. Or not.

Similarly, as an illumination-off determination method in the illumination-off detection step (S104), it is determined that the output value of the A / D converter 70 (that is, the input value of the microcomputer 92) is less than or less than “B”. Good.
Other processes are the same as those described in the first embodiment.
The A / D converter 70 in the present embodiment is described as being separate from the microcomputer 92, but in reality, the A / D converter 70 is often incorporated as a part of the function of the microcomputer 92, so that the cost increases. It is not a factor.

In the above description, it is determined that the illumination is on when the output value of the A / D converter 70 (that is, the input value of the microcomputer 92) is equal to or greater than the threshold “A”. When the output value is larger than the threshold “A”, it may be determined that the illumination is on.
Further, it is determined that the illumination is off when the output value of the A / D converter 70 is equal to or less than the threshold “B”, but the illumination is determined when the output value of the A / D converter 70 is less than the threshold “B”. You may determine that it is off.

As described above, the power supply control device according to the present embodiment has the image receiving circuit 5 that displays the received video, the drive power supply 4 for driving the image receiving circuit 5, and the drive power supply 4 for the image receiving circuit 5. A power supply composed of a switch 3 for turning on / off the output and controlling the drive of the image receiving circuit 5 by turning on / off the switch 3 in accordance with the level fluctuation of ambient brightness detected by the light detecting means (light detector 11). An illumination on detection means for detecting that the brightness of the place where the image receiving circuit 5 is installed is greater than or equal to the first brightness and the illumination on detection means. Brightness that is detected as having transitioned below or below the second brightness lower than the first brightness within a predetermined first time after it is detected that the brightness is greater than or greater than A transition detection means and a second After transition below or below is that, the second brightness is a power supply control unit 22 composed of the illumination-off detection means for detecting to continue the second time set in advance.
Then, the power supply control means 22 converts the A / D converter 70 to which the voltage corresponding to the ambient brightness detected by the light detection means (the photodetector 11) is input, the first brightness and the second brightness. The microcomputer 92 is configured to store the output value of the corresponding A / D converter in advance, and the microcomputer 92 detects illumination on detection, brightness transition detection, illumination off detection based on the output of the A / D converter 70. I do.

In the above-described embodiment, the first comparator 61 that detects that the brightness level detected by the photodetector 11 is equal to or higher than the first brightness, and the ambient brightness level detected by the photodetector 11. The two comparators of the second comparator 62 for detecting that is less than or equal to the second brightness are used.
However, in this embodiment, the function of the two comparators is realized by using one A / D converter, and the circuit configuration can be simplified.

Embodiment 3 FIG.
FIG. 6 is a block diagram showing a schematic configuration of the power supply control apparatus according to the third embodiment.
Embodiments 1 and 2 described above are examples where only one photodetector that detects brightness is used.
In the power supply control devices according to the first and second embodiments, when a person or the like crosses in front of a video display device such as a television receiver, illumination light to only one photodetector is blocked, and the room is There is a risk that the power supply control device will malfunction because it is determined to have become dark.
Therefore, it is conceivable to use a plurality of photodetectors in order to detect more accurately and quickly that a person or the like has crossed in front of a video display device such as a television receiver.
In the following, in order to prevent the illumination light from being blocked to the light detector and the power supply control device from malfunctioning when a person or the like crosses in front of a video display device such as a television receiver, An example when two are used will be described.

As shown in FIG. 6, the light detection means 12 in the present embodiment includes two light detectors, a first light detector 13 and a second light detector 14.
Then, as shown in FIG. 7, the first photodetector 13 and the second photodetector 14 provide a predetermined interval (predetermined distance) to the housing of a video display device such as a television receiver. It is provided and arranged.
Moreover, the power supply control means 23 in this Embodiment is comprised with the 1st A / D converter 71, the 2nd A / D converter 72, and the microcomputer 93, as shown in FIG.
The first A / D converter 71 reads the output voltage of the first photodetector 13 and converts it into a digital value, and outputs the converted digital signal to the microcomputer 93.
Similarly, the second A / D converter 72 reads the output voltage of the second photodetector 14 and converts it into a digital value, and outputs the converted digital signal to the microcomputer 93.

The microcomputer 93 includes a memory and a timer in which output values of the first A / D converter and the second A / D converter corresponding to the first brightness and the second brightness are stored in advance. And a CPU and the like, and the switch 3 is turned on / off in accordance with the digital signals output from the first and second A / D converters, and the output voltage of the drive power supply 4 is applied to / not applied to the image receiving circuit 5 To control.
Also in this embodiment, the first A / D converter 71, the second A / D converter 72, and the microcomputer 93 may be integrally formed.
The characteristic operation of the power supply control device according to the present embodiment will be described in detail below.

FIG. 8 shows that when a video display device is a large-sized television receiver of, for example, 25 inches or more, a person or the like crosses from the right to the left in front of the television receiver in a room illuminated at night. The change of the output value of the 1st A / D converter 71 and the 2nd A / D converter 72 at the time is shown.
In the case of a television receiver of such a size, when a person or the like crosses the front, the light enters the two photodetectors (that is, the first photodetector 13 and the second photodetector 14). Two photodetectors can be arranged at an interval (distance) that does not block the illumination light at the same time.
Before a person crosses the front of the television receiver, both the first photodetector 13 and the second photodetector 14 directly receive the illumination light as in the period before T1 shown in FIG. Therefore, both the first A / D converter 71 and the second A / D converter 12 output a value higher than the threshold value “A” for determining that the illumination is on.

When a person starts to cross the front of the second photodetector 14 arranged on the right side, the output of the second A / D converter 72 suddenly decreases, and it is determined that the illumination is off during the period T2-T4. It falls below the threshold “B”.
However, even during that time, the illumination of the first photodetector 13 arranged on the left side is not blocked, so the output of the first A / D converter 71 is higher than the threshold “B”.
Further, as the person moves to the left, the detection value of the second detector 14 increases, and conversely, the detection value of the first photodetector 13 decreases.
As a result, the output value of the first A / D converter 71 becomes lower than the threshold “B” as shown in the period of T5 to T7. At that time, the output value of the second A / D converter 72 is Is higher than the threshold “B”.

Further, when the person moves to the left and the first photodetector 13 is not blocked, the first A / D converter 71 and the second A / D converter 72 again in the period after T8. Both output values exceed the threshold “A”.
That is, when a person crosses, the outputs of the two A / D converters (that is, the first A / D converter 71 and the second A / D converter 72) do not fall below the threshold “B”. When the illumination is actually turned off, the outputs of the first A / D converter 71 and the second A / D converter 72 are both below the threshold “B”.
Therefore, as a method for determining illumination OFF in the illumination OFF detection step (S104) shown in FIG. 4, the output value of the first A / D converter 71 is lower than “B” and the second A / D converter is used. If it is determined whether the output value of 72 is also lower than “B”, it is possible to instantly distinguish whether the person has crossed or the light is turned off without waiting for 4 seconds. It is.
Therefore, in this system, the illumination-off detection time in the illumination-off detection step (S104) can be made sufficiently shorter than 4 seconds.

On the other hand, as a lighting-on determination method in the lighting-on detection step (S102), it is detected that either the first A / D converter 71 or the second A / D converter 72 is equal to or greater than the threshold “A”. It ’s fine.
Incidentally, in FIG. 8, the time from when the illumination starts to be blocked until it is completely hidden, for example, between T1 and T2, between T3 and T5, is it a single point light source such as a bare light bulb? Alternatively, since it depends on whether the light source is a planar light source such as a chandelier or a fluorescent lamp, the context of T3 and T4 or T5 and T6 in FIG. 8 has little meaning.

On the other hand, FIG. 9 shows the first A / A when a person or the like crosses from the right to the left in front of the television receiver in a room illuminated at night in the case of a small television receiver of 20 inches or less. The change of the output value of D converter 71 and the 2nd A / D converter 72 is illustrated in figure.
In the case of a television receiver of such a size, there is a moment when the two photodetectors are simultaneously shielded from illumination when a person or the like crosses.
First, the second photodetector 14 is shielded from illumination, the output of the second A / D converter 72 falls below the threshold “B” after time T3, and the first photodetector 13 is subsequently shielded from illumination. Thus, the output of the first A / D converter 71 also falls below the threshold “B” after time T4.
Thereafter, at time T5, the second photodetector 14 comes out of the shadow of the illumination, and the output of the second A / D converter 72 is restored to the threshold “B” or more.
Thereafter, at time T6, the first photodetector 13 also comes out of the shadow of the illumination, and the output of the first A / D converter 71 is restored to the threshold “B” or more.

That is, in this case, both the first A / D converter 71 and the second A / D converter 72 are both below the threshold “B” between T4 and T5.
Therefore, it is impossible to distinguish whether the person has crossed or the illumination has actually been turned off only by the illumination-off determination method as in the case of the large television receiver described above.
However, in this case as well, the difference in time when the two A / D converters (ie, the first A / D converter 71 and the second A / D converter 72) are below the threshold “B”, ie, T3−T4. By focusing on the time, it is possible to distinguish between when the person crosses and when the lighting is turned off.

That is, when a person crosses, the time difference | T4−T3 |
| T4-T3 | = L / v Formula (1)
Here, L is the distance between the first photodetector 13 and the second photodetector 14,
v is the speed at which a person crosses, but | T4-T3 | is basically regarded as “0” when the light is turned off.
However, in the actual processing of the microcomputer, the detection value of one A / D converter has a threshold value “B” due to the difference in input timing from the first A / D converter 71 and the second A / D converter 72. Even if the value falls below the threshold value, the detection value of the other A / D converter may not yet fall below the threshold value “B”.
In this case, T3 and T4 may be detected with a shift of one determination period (here, 50 ms).

So if the lights are turned off,
| T4-T3 | ≦ 1 * (judgment cycle) Equation (2)
It can be. Therefore, whenever a person crosses, | T4-T3 |> 1 * (determination period) Equation (3)
In this case, it is possible to distinguish between a case where a person crosses and a case where illumination is turned off.
In the formulas (2) and (3), “*” represents x (product).
Conversely, from Equation (1) and Equation (3),
(Judgment cycle) <L / v equation (4)
Is required.
Specifically, even when a person runs in a house and crosses in front of a small television receiver at 2 m / second, for example, when the distance between the first and second photodetectors is 20 cm. Then, the determination cycle may be less than 100 ms. The determination period of 50 ms in the present embodiment satisfies this condition.

Furthermore, when the expression (4) is satisfied, the illumination off detection step shown in the algorithm of FIG. 10 is provided so that the power is not turned off when a person crosses, and the power can be turned off only when the illumination is turned off. It becomes.
FIG. 10 shows the illumination-off detection step of the power supply control device in the present embodiment, and the illumination-off detection step (S104) of all the detection steps (operation algorithms) in Embodiment 1 shown in FIG. ).
The initial setting step, illumination on detection step, and transition detection step of the power supply control device in the present embodiment are the same as the initial setting step (S101), illumination on detection step (S102), and transition detection step (S103) in FIG. Are the same.

Hereinafter, the illumination off detection step shown in FIG. 10 will be described in detail.
An off counter 1 corresponding to the first A / D converter 71 and an off counter 2 corresponding to the second A / D converter 72 are prepared in advance. In both cases, the initial value of the counter is zero.
First, it is determined whether the output of the first A / D converter 71 is lower than the threshold “B”. If the output is lower, the off-counter 1 is incremented by 1. If not lower, the off-counter 1 is cleared to “0”.
Next, it is determined whether the output of the second A / D converter 72 is lower than the threshold “B”. If the output is lower, the off-counter 2 is incremented by 1. If not lower, the off-counter 2 is cleared to “0”. .
Here, it is determined whether or not the difference between the off-counter 1 and the off-counter 2 is 1 or less. If it is not 1 or less, it is considered that a person has crossed, all the counters are cleared to 0, and the lighting on detection step is started from the beginning. Try again.
If it is 1 or less, it is considered that illumination-off is detected. Further, when the illumination off is detected, the power is turned off when the predetermined counter value (here, 10) is reached, that is, when the illumination off is detected continuously for 0.5 seconds.

In the above description, the case where there are two photodetectors and two A / D converters has been described, but the same processing can be performed if there are two or more.
That is, when there are as many off-counters as the number of photodetectors and the difference between the counter values is not less than 1, that is, when the difference in time when the output of the A / D converter falls below the threshold “B” is not less than the determination cycle. By judging that a person has crossed, even a small television receiver can reliably prevent malfunction when a person crosses. Furthermore, it goes without saying that this processing method can also be applied to medium and large television receivers.
The difference in time that falls below the threshold “B” is ideally 1 time of the determination period, but it is the same even if it is 2 or 3 times of the determination period within the range satisfying Equation (4). An effect is obtained.

  As described above, the power supply control device according to the present embodiment has the image receiving circuit 5 that displays the received video, the drive power supply 4 for driving the image receiving circuit 5, and the drive power supply 4 for the image receiving circuit 5. A power supply control device that includes a switch 3 for turning on / off an output, and controls driving of the image receiving circuit 5 by turning on / off the switch 3 in accordance with a change in ambient brightness level detected by the light detection means 12. Illumination on detection means for detecting that the brightness of the place where the image receiving circuit 5 is installed is greater than or equal to the first brightness, and the brightness is greater than or equal to the first brightness by the illumination on detection means. Brightness transition detecting means for detecting that the transition has been detected to be less than or less than the second brightness lower than the first brightness within a predetermined first time after being detected to be greater, Less than 2 brightness or After transition to the full, second brightness is a power supply control unit 23 constituted by the illumination-off detection means for detecting to continue the second time set in advance.

  The light detection means 12 is composed of a first light detector 13 and a second light detector 14 arranged at a predetermined interval, and the power supply control means 23 includes the first light detector 13. A first A / D converter 71 to which a voltage corresponding to the ambient brightness to be detected is input, and a second A / D converter to which a voltage corresponding to the ambient brightness detected by the second photodetector 14 is input. 72, a first A / D converter 13 corresponding to the first brightness and the second brightness, and a microcomputer 93 in which output values of the second A / D converter 14 are stored in advance. The illumination-off detection means determines that the illumination is off when the detection levels of the first photodetector 13 and the second photodetector 14 are equal to or lower than the level corresponding to the second brightness.

  Further, in the illumination-off detection means of the power supply control device according to the present embodiment, the detection levels of the first photodetector 13 and the second photodetector 14 are less than or less than the reher corresponding to the second brightness. When the difference in time is within or less than a predetermined time, it is determined that the illumination is off.

Further, in the power supply control method according to the present embodiment, the illumination of the room where the video display device is installed is turned on, and the illumination is detected to detect that the brightness of the room is greater than or equal to the first brightness. After it is detected in the on detection step S102 and the lighting on detection step 102 that the brightness of the room is equal to or higher than the first brightness, the first brightness is exceeded within a predetermined first time. A brightness transition detection step S103 for detecting a transition to a lower second brightness or less, and a transition to a second brightness or less and a transition to a second brightness or less after the transition to a second brightness or less. When it is detected that the second time has continued, the illumination off detection step S104 determines that the illumination is off. Based on the detection result in the illumination off detection step, the video display device A power supply control method for on / off driving power,
The brightness of the room is detected by using the first photodetector 13 and the second photodetector 14 arranged with a predetermined interval, and the illumination-off detection step S104 is performed in the first photodetector 13. When the detection level of the second photodetector 14 is equal to or lower than the second brightness, it is determined that the illumination is off.

  Further, according to the power supply control method according to the present embodiment, the brightness of the room is detected using the first photodetector 13 and the second photodetector 14 arranged with a predetermined interval, In the illumination-off detection step S104, the difference in time when the detection levels of the first photodetector 13 and the second photodetector 14 are less than or less than the level corresponding to the second brightness is within a predetermined time. Or, when it is less, it is determined that the illumination is off.

  Therefore, according to the power supply control device or the power supply control method according to the present embodiment, the power supply of the video display device such as a television receiver that is viewed when the brightness of the room gradually becomes dark at sunset is intended. The image display device can be automatically turned off when the room lights are turned off at night, and a person crosses the image display device to the photodetector. Even when the illumination light is blocked, it can be determined that the room has become dark and the power supply control device can be prevented from malfunctioning.

In the above first to third embodiments, examples of the power supply control device that controls on / off of power to an image receiving circuit such as a television receiver according to the brightness of the room have been described. Such a power supply control device may be incorporated into a video display device that includes a display device that displays the image and a drive power supply that drives the display device.
As a result, even when the brightness of the room gradually becomes darker at nightfall, the power of the display device that was being watched does not turn off unintentionally, and it is automatically displayed when the room lights are turned off at night. An image display device that can turn off the power of the device can be obtained.
Further, even when a person crosses in front of the display device, it is possible to obtain a video display device that can prevent a malfunction in which the room is darkened and the power is turned off.
In the first to third embodiments, the power supply control device that controls the power on / off of the video display device such as a television receiver has been described. Such a video display device is a television. It goes without saying that the present invention is not limited to a receiver, and may be a personal computer or a projection display device that displays an image.

  The present invention does not unintentionally turn off the power of the video display device that was being watched at nightfall when the brightness of the room gradually darkens, and automatically displays the video when the room lights are turned off at night. This is useful for realizing a power supply control device that can turn off the power of the device.

It is a block diagram which shows notionally the structure of the power supply control apparatus concerning this invention. It is a block diagram which shows schematic structure of the power supply control apparatus by Embodiment 1 of this invention. It is a figure which shows the example of a change of the change of the operating environment (brightness) of the place where the video display apparatus is installed. It is a flowchart for demonstrating the operation | movement algorithm of the power supply control apparatus by embodiment. It is an algorithm which shows operation | movement of the power supply control means of Example 1 of this invention. FIG. 3 is a block diagram illustrating a schematic configuration of a power supply control device according to a second embodiment. FIG. 6 is a block diagram illustrating a schematic configuration of a power supply control device according to a third embodiment. In Embodiment 3, it is a figure which shows the arrangement | positioning state of two photodetectors. In Embodiment 3, it is a figure for demonstrating operation | movement of the power supply control means when a person crosses in front of a medium size and large sized image display apparatus. In Embodiment 3, it is a figure for demonstrating operation | movement of the power supply control means when a person crosses in front of a small image display apparatus. 10 is a flowchart for explaining an operation algorithm of an illumination off detection step in the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photodetection means 2 Power supply control means 3 Switch 4 Drive power supply 5 Image receiving circuit 11 Photodetector 12 Photodetection means 13 1st photodetector 14 Second photodetector 20, 22, 23 Power supply control means 61 1st Comparator 62 Second comparator 70 A / D converter 71 First A / D converter 72 Second A / D converter 91, 92, 93 Microcomputer

Claims (9)

An image receiving circuit for displaying the received image, a driving power source for driving the image receiving circuit, and a switch for turning on / off the output of the driving power source for the image receiving circuit, and the surroundings detected by the light detecting means A power supply control device for controlling driving of the image receiving circuit by turning on / off the switch in accordance with a change in brightness level;
Illumination on detection means for detecting that the brightness of the place where the image receiving circuit is installed is equal to or higher than the first brightness;
After the illumination on detection means detects that the brightness is greater than or equal to the first brightness, the transition is made to a second brightness lower than the first brightness within a predetermined first time. Brightness transition detecting means for detecting that,
Power supply control means comprising illumination off detection means for detecting that the second brightness continues for a predetermined second time after transition to the second brightness or less,
The power control unit is configured to stop driving of the image receiving circuit by turning off the switch based on a detection result of the illumination off detection unit.   The power control means includes a first comparator that detects that the brightness level detected by the light detection means is equal to or higher than the first brightness, and the ambient brightness level detected by the light detection means is A microcomputer that performs illumination on detection, brightness transition detection, and illumination off detection based on detection results of the second comparator that detects that the brightness is equal to or less than the second brightness, the first comparator, and the second comparator. The power supply control device according to claim 1, comprising:   The power control means includes an A / D converter to which a voltage corresponding to ambient brightness detected by the light detection means is input, and the A / D converter corresponding to the first brightness and the second brightness. Output value is stored in advance, and the microcomputer performs the illumination on detection, brightness transition detection, and illumination off detection based on the output of the A / D converter. The power supply control device according to claim 1. The light detection means includes a first light detector and a second light detector arranged with a predetermined interval,
The power control means corresponds to the first A / D converter to which a voltage corresponding to the ambient brightness detected by the first photodetector is input, and the ambient brightness detected by the second photodetector. Output values of the first A / D converter and the second A / D converter corresponding to the first brightness and the second brightness. Is configured with a pre-stored microcomputer,
The illumination off detection means determines that the illumination is off when the detection levels of the first photodetector and the second photodetector are equal to or lower than a level corresponding to the second brightness. The power supply control device according to claim 3. The light detection means includes a first light detector and a second light detector arranged with a predetermined interval,
The power control means corresponds to the first A / D converter to which a voltage corresponding to the ambient brightness detected by the first photodetector is input, and the ambient brightness detected by the second photodetector. Output values of the first A / D converter and the second A / D converter corresponding to the first brightness and the second brightness. Is configured with a pre-stored microcomputer,
In the illumination off detection means, the difference in time when the detection levels of the first photodetector and the second photodetector are equal to or lower than the level corresponding to the second brightness is within a predetermined time. The power supply control device according to claim 3, wherein it is sometimes determined that the illumination is off.   An image display device comprising the power supply control device according to claim 1. A power control method for controlling on / off of a drive power of a video display device,
Illumination on detection step of detecting that the illumination of the room where the video display device is installed is turned on, and that the brightness of the room is equal to or higher than the first brightness;
After detecting that the brightness of the room is equal to or higher than the first brightness in the lighting-on detection step, the second brightness lower than the first brightness within a predetermined first time is detected. A brightness transition detection step for detecting transition to
An illumination off detection step for determining that the illumination is off when it is detected that the state below the second brightness has continued for a predetermined second time after the transition to the second brightness or less; And
A power control method comprising: turning off the drive power of the video display device based on a detection result in the illumination off detection step. The brightness of the room is detected using a first photodetector and a second photodetector arranged at a predetermined interval,
In the illumination off detection step, it is determined that the illumination is off when detection levels of the first photodetector and the second photodetector are equal to or lower than a level corresponding to the second brightness. The power supply control method according to claim 7. The brightness of the room is detected using a first photodetector and a second photodetector arranged at a predetermined interval,
In the illumination off detection step, the difference in time when the detection level of the first photodetector and the second photodetector becomes equal to or lower than the level corresponding to the second brightness is within a predetermined time. 8. The power supply control method according to claim 7, wherein it is sometimes determined that the illumination is off.

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