JP3091454U - Television receiver - Google Patents

Abstract

(57) [Problem] To provide a means for notifying a viewer when a power-on state is equivalent to a power-off state by using an existing configuration, thereby providing a power-on state. Provided is a television receiver which can reduce the number of dedicated display devices. A video processing unit that demodulates a video signal from a broadcast receiving unit and displays the image on a display after demodulating the video signal, and a video processing unit that displays a dark image equivalent to that at power-off on the display. A dark screen detection means 15 for outputting a dark screen determination signal by determining based on the brightness level of the brightness signal extracted from 8; and a content indicating that the display is powered on when the dark screen determination signal is output. And a control unit 10 that controls the on-screen display to continue until the black screen determination signal is no longer output.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

  The present invention reduces the dedicated display function of the power-on state by turning on the indicator light. Even a TV receiver that allows the viewer to clearly recognize the power-on state It is about machines.

[0002]

[Prior art]

  The television receiver is powered on because of the presence of the high voltage circuit. According to the Japanese Electrical Safety Act, it is necessary to display such a state that the viewer can always recognize it. Is prescribed. Therefore, existing television receivers generally use brown An indicator lamp such as an LED is provided below the display such as a tube or LCD to supply power. The indicator light is turned on when is on. By lighting such an indicator light The power-on state display function is used in most electric devices.

[0003]

[Problems to be Solved by the Invention]

  However, unlike other types of electrical equipment, television receivers are Even if there is no indication that the power is on due to the indicator light illuminating, an image is displayed on the display. , And the audio output from the speaker means that the viewer is in the power-on state. Can be clearly recognized, but nevertheless the provisions of the Electrical Safety Act Based on this, the power-on status is displayed. This display device in the power-on state, Using an indicator light such as an LED dedicated to displaying the power-on state, load resistance and wiring Since a lighting circuit configured is required, the cost is increased accordingly. Also tv An installation space for the above display device is required in the John receiver main body. Furthermore, the table LEDs generally used as indicator lights consume less power than other indicator lights. Although it is small, it is always lit when the power is on, so This is accompanied by corresponding power consumption.

[0004]   As mentioned above, there is a kind of dedicated display device in the power-on state of the television receiver. It seems useless, but a black image is displayed on the display when the power is on If the volume setting volume at this time is set to the minimum level, The state is the same as when it is off, and the viewer can clearly recognize that the power is on. It will be lost and the above-mentioned provisions of the Electrical Safety Law cannot be met. Above If the display screen of the display is completely dark and there is no audio output, If you operate the Mocon transmitter by mischief, a television receiver is installed near the window. As the display contrast decreases, the video If you switch to receiving a television broadcast program after viewing the playback image , If snow noise is displayed as an image after the program has finished broadcasting, or if the external input Therefore, if a completely dark screen is displayed, the image contrast is set low. There is a possibility that it may occur when a dark image is displayed at night, etc. is there.

[0005]   Therefore, for some reason when the power is turned on, the state is the same as when the power is turned off. If there is, a means is provided to let the viewer recognize that the power is on only at that time. If it is possible to reduce the number of dedicated display devices that are in the power-on state, The existing configuration can be used to provide a means for the listener to recognize the power-on state. For example, downsizing and power consumption by cost reduction and installation space reduction Should be achieved.

[0006]   In the past, when the power was turned on and no operation continued for a certain period of time, In this case, after displaying the warning message for a certain time such as 10 seconds, it will automatically Recording / reproducing apparatus for turning off power to enter power saving mode (Japanese Patent Laid-Open No. 2000-036143) No.), and no one is looking at the displayed image even though the image is being displayed. If there is no image, the image is reduced or displayed in a part of the display area of the display. Measures such as reducing the image brightness or stopping the image display and outputting only audio By adopting the image display device, power consumption is reduced (Japanese Patent Application Laid-Open No. 2000-2 No. 42255) are known. However, the technologies disclosed in these Power consumption by eliminating the display and warning for turning off the power, or the unnecessary image display state. The purpose is to reduce the force efficiently, and the above-mentioned power supply is in the ON state. However, it is detected that the viewer is in the same state as when the power is turned off. Nothing can be used to construct a means of making the person clearly aware.

[0007]   Therefore, the present invention has been made in view of the above problems of the related art. If there is a situation similar to when the power is off, the existing means to notify the viewer Deletion of the dedicated display device in the power-on state by using the configuration It is an object of the present invention to provide a television receiver capable of operating.

[0008]

[Means for Solving the Problems]

  In order to achieve the above-mentioned object, the television receiver of the invention according to claim 1 is a receiver. The broadcast reception unit that detects the frequency of the received television broadcast radio waves after frequency conversion, After demodulating the audio signal from the broadcast receiver, low-frequency amplification and output from the speaker Audio processing section and the video signal from the broadcast receiving section are demodulated and then displayed. A video processing unit for displaying an image on the screen and the brightness level of the brightness signal extracted from the video processing unit. Brightness lower than the reference brightness level by comparing the bell with a preset reference brightness level The total output time of the level luminance signal in one vertical period is a preset time A black screen detection means for outputting a black screen discrimination signal when the black screen is shorter than When the dark screen discrimination signal is continuously output within the set time, the on-screen Indicates that the display is powered on via a display circuit. Content is displayed on-screen and the on-screen display is Equipped with a control unit that performs control to continue until the dark screen discrimination signal is no longer output It is characterized by

[0009]   In this television receiver, the display screen on the display is When a dark state occurs, change the state to the reference brightness level within one vertical period. When the power is off, the detection is performed reliably based on the total output time of the brightness signal of the lower brightness level. On screen of the display that the power is on The viewer can clearly recognize it and Operate the display screen image so that the contrast of the image is higher than the set level. The above on-screen display continues until it is created or the power is turned off. Therefore, even if it does not have a power-on display function such as turning on the indicator lamp, It will be able to fully satisfy the national electrical safety standards.

[0010]   Moreover, the detection function of the occurrence of the state where the display screen of the display is pitch black is generally The existing hardware configuration is used for a conventional television (B) Only changing the software such as the control program of the control unit consisting of a computer Since it can be configured with, the above function is added with almost no increase in cost. be able to. Therefore, this television receiver has an existing power-on The cost can be reduced by eliminating the need for a display device, and the installation space for the display device can be reduced. This eliminates the need for a switch and reduces the power consumption associated with the power-on lighting display.

[0011]   A television receiver according to a second aspect of the present invention restores a video signal from a broadcast receiving section. The video processing unit that displays the image on the display after adjusting the Extracted from the video processing unit the state where a dark image equivalent to that when the power was turned off was displayed. Outputs a screen discrimination signal based on the luminance level of the luminance signal. The screen detection means and the display when the pitch-dark screen discrimination signal is output. In addition to displaying on-screen the contents indicating that the power is on, The on-screen display is continued until the pitch-dark screen discrimination signal is no longer output. It is characterized in that it is provided with a control section for performing control.

[0012]   According to this television receiver, the display screen of the display is If the same state as when the power is turned off occurs in the darkness, the state is changed to the luminance signal. Based on the brightness level of, the state is the same as when the power is turned off, but the power is on. The on-screen display of the display clearly to the viewer In addition to the recognition, the image brightness of the display screen of the display can be changed by the viewer's operation. Do not operate to turn the contrast above the set level or turn off the power. The on-screen display will continue until it is performed. Satisfies Japan's Electrical Safety Act standards even without a power-on display function It is possible, and in addition, the occurrence of the state where the display screen of the display is pitch black The detection function uses the existing hardware configuration for a general television receiver. , Software such as the control program of the control unit mainly consisting of a microcomputer The existing power-on display device cannot be configured because it can be configured only by changing the hardware. The cost can be reduced by the amount required, and the installation space for the display device is unnecessary. As a result, it is possible to reduce the power consumption associated with the power-on lighting display.

[0013]   The television receiver according to the invention of claim 3 is the true receiver according to the invention of claim 2. The dark screen detection means detects the brightness level of the brightness signal extracted from the video processing unit as The reference brightness level set in advance to a brightness level at which the screen of the display does not turn black. Detected every time a brightness level lower than this reference brightness level is detected compared to the bell The brightness level detection circuit that outputs a signal and the sync separation circuit of the video processing unit The luminance level is set in one vertical period set based on the vertical synchronizing signal separated from the signal. The total input time of the detection signals input from the When the interval is shorter than a preset predetermined time, a pitch-dark screen discrimination signal is sent to the control unit. It is composed of an image light / dark contrast discrimination circuit which outputs the image. This configuration According to the report, even though the power is on, it is in the same state as when the power is off. Can be accurately detected with a simple configuration.

[0014]   A television receiver according to the invention of claim 4 is the television receiver according to claim 2 or 3. The control unit turns on the content indicating that the display is powered on. Instead of performing the display control, the contrast control circuit of the video processing unit Command, and the contrast of the display screen is higher than the set level. The automatic control is performed so that According to this configuration, Confirm that the viewer who sees the screen display performs the operation to cancel the same state as when the power was turned off It is no longer necessary to confirm that the power is on by the image displayed on the display. It is possible for the viewer to recognize the and.

[0015]   The television receiver of the invention according to claim 5 is the television receiver according to claim 2 or 4. The controller displays the contents indicating that the power is on on the display. Informs that the power is on instead of controlling the display. The control for outputting the sound from the speaker is performed. With this configuration, It was detected that the power supply was turned on, but the power supply was turned off. For example, the existing sin wave generation function in the microcomputer that is the control unit By utilizing the above-mentioned sin wave through the audio signal superimposing circuit to transmit the television broadcast radio wave. With a simple configuration that superimposes on the audio signal and outputs it An alarm sound can be output to clearly inform the viewer that the power is on. it can.

[0016]

[Embodiment of device]

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.   FIG. 1 is a block diagram showing a television receiver according to an embodiment of the present invention. Is. This figure is inevitably provided in practical application for ease of understanding. The known configuration is omitted and illustrated as a simplified configuration.

[0017]   That is, the television receiver main body 1 has a well-known tuner and IF (intermediate frequency). Number) A television equipped with an amplification section, a detection section, etc. and received through the receiving antenna 2. Broadcast reception unit 3 that detects the frequency of John's broadcast radio waves and then detects them. An audio processing section 4 including a control section, an audio amplification section, an audio output section, and the like; The speaker 7 that outputs the audio signal of the broadcast wave, the well-known video amplifier, color demodulator, A video processing unit 8 including an image output unit and a CRT or L for displaying a video signal as an image. A display 9 such as a CD, a CPU that controls each unit, and a CPU The main body of the television receiver equipped with a ROM that stores control programs 1. A control unit 10 including a microcomputer that executes control of each unit of the whole Under the control of the control unit 10, the ounce of the receiving channel is displayed on the screen of the display 9. OSD (on-screen display) for inserting and displaying clean data via the character signal superimposing circuit 12 (Lean display) Circuit 11 and remote control signal from remote control transmitter 14 are received. The remote control signal receiving section 13 which receives the signal and outputs it to the control section 10 is provided. Note that The video processing unit 8 has a sync separation circuit 8a and a contrast control circuit 8b. There is. The above configuration is the existing one provided in the conventional television receiver. .

[0018]   Further, the television receiver main body 1 has a luminance signal ( (Y signal) luminance level is compared with a preset reference luminance level, and the reference luminance level is compared. Brightness level detection circuit that outputs a detection signal each time a brightness level lower than the 17 and the vertical sync signal separated by the sync separation circuit 8a from the video signal. Total input of detection signals input from the brightness level detection circuit 17 in one vertical period After calculating the time, if the total input time is shorter than the preset time Image bright / dark contrast discrimination circuit for outputting a pitch dark screen discrimination signal to the control unit 10. 18 is provided.

[0019]   The reference brightness level set in the brightness level detection circuit 17 is the contrast. Brightness before the display screen goes black when the control circuit 8b is set to the minimum value It is set to level. In other words, the image brightness contrast determination circuit 18 During one vertical period, that is, one image period that can be displayed on the entire display 9, the reference luminance is High brightness level above the level When the brightness signal is not input for a certain period of time, it becomes pitch dark Outputs a screen discrimination signal. That is, the brightness level detection circuit 17 and the image brightness control The last discrimination circuit 18 indicates that the display 9 is turned on even if the power is on. A blackout screen discrimination signal that determines the state in which a blackout image equivalent to when the power is off is displayed The pitch-black screen detecting means 15 for outputting

[0020]   The control unit 10 determines that the detection signal input from the brightness level detection circuit 17 is predetermined. When it is determined that the set number has been reached within the time, the image brightness contrast determination circuit 18 On the other hand, a start command signal is output, and the image brightness / darkness contrast determination circuit 18 controls the control unit 10 Is driven only when the above start command signal is input from the brightness level detection circuit 17 An arithmetic operation for calculating the total input time of the detection signals input from the device is performed.

[0021]   Furthermore, in the television receiver body 1, an audio signal is extracted from the audio processing unit 4. And the volume level detection circuit 19 for detecting the volume level of the audio signal, The detected volume level of the level detection circuit 19 is compared with a preset volume level. , Output the inaudible discrimination signal when the detected volume level is lower than the set volume level. A volume level discriminating circuit 20 is provided. The above set volume level is The lowest level that can be clearly heard as the audio output from the speaker 7. Is set to. Therefore, the volume level detection circuit 19 and the volume level determination circuit 20 is the inaudible judgment when it is determined that the voice output has dropped to an unaudible low level. The inaudible volume level detecting means 16 for outputting another signal is configured.

[0022]   The television receiver described above is used when an image is displayed on the display 9 Based on these, when the audio signal is being output from the camera 7, the viewer can turn on the power. Since the status can be clearly recognized, the power is on by turning on the indicator light such as LED. Does not have a dedicated display device. So, in the above television receiver, Due to the cause, the display screen of the display 9 goes black and the speaker 7 This is detected when there is no audio output, which is the same as when the power is turned off. Function that allows the viewer to clearly recognize that the power is on. It has. Next, make sure that the power to the television receiver is on. Refer to the flowchart of FIG. 2 for the control processing for displaying the content indicating Explain.

[0023]   In FIG. 2, the control unit 10 is a television receiver main body operated by a viewer. When it is determined that the power is turned on (step S1), the brightness level detection circuit Based on whether the detection signal input from 17 has reached the set number within a predetermined time It is determined whether or not the brightness level of the signal has dropped below the set level (step S2). ). In addition, after the power is turned on, the broadcast receiving unit 3 uses the receiving antenna 2 to perform the television broadcast. When the radio wave is received, the television 9 is displayed on the display 9 by well-known signal processing. The video signal of the broadcast radio wave is displayed as an image and the audio signal is output from the speaker 7. However, since this signal processing is extremely well known, its explanation is Omit the light.

[0024]   The control unit 10 controls the image based on the detection signal input from the brightness level detection circuit 17. When it is determined that the brightness level of the signal is below the set level (step S2) , A start command signal is output to the image brightness contrast determination circuit 18 to start driving. (Step S3), and at the same time, the timer circuit part built in itself measures the predetermined time. The time operation is started (step S4). By this, the image contrast The circuit 18 has one vertical period set based on the vertical sync signal from the sync separation circuit 8a. Find the total input time of the detection signals input from the brightness level detection circuit 17 in Then, based on the comparison between the total input time and the preset time, the display is It is judged whether the image contrast of image 9 is lower than the set level. , When the image brightness contrast is lower than the set level, The discrimination signal is output to the control unit 10.

[0025]   The control unit 10 receives the pitch-dark screen discrimination signal from the image brightness contrast discrimination circuit 18. When input, the image contrast of the display 9 is below the set level. Therefore, it is determined that the state is the same as when the power is turned off (step S5), and this state is Whether to continue until the set time elapses due to the time-up of the imager circuit Monitoring is performed (step S6). Now, for example, the image displayed on the display 9 is In a dark scene, when a pitch-black screen discrimination signal is temporarily output, , The black-and-white image from the image brightness contrast determination circuit 18 before the set time elapses. Since the output of the surface discrimination signal is stopped, the control unit 10 sets the image brightness contrast. When it is determined that the level has become equal to or higher than the level (step S5), the timing operation of the timer circuit unit is started. The work is reset (step S7), and at the same time, the image brightness contrast discrimination circuit 1 After stopping the driving of No. 8 (step S8), return to step S2, and The same control process as described above is repeated.

[0026]   As described above, the display screen of the display 9 is caused by the image displayed by the video signal. If the image becomes black for a moment, the image contrast is set to the set level. When it is determined that the above has been reached, the driving of the image brightness / contrast contrast determination circuit 18 is stopped. As a result, it is possible to reliably prevent erroneous detection that the state is the same as when the power was turned off. Be done.

[0027]   On the other hand, for example, a child mischievously operates the remote control transmitter 14 to display an image on the display 9. If the image contrast has dropped below the set level, Even if the fixed time has elapsed, the display screen of the display 9 is in the same dark state as when the power is off. Continue to. At this time, the control unit 10 controls the image brightness contrast determination circuit 18 The state that the pitch-dark screen discrimination signal is input is due to the time-up of the timer circuit section. When it is determined that the timer has continued for the set time (step S6), the timer circuit counts the time. After the operation is reset (step S9), the volume level discrimination circuit 20 recognizes the sound. The volume level of the output sound from the speaker 7 is changed based on the presence / absence of the input of the failure determination signal. Determine whether or not it has fallen below a set level that is difficult to reliably hear. (Step S10).

[0028]   If the volume level is set above the set level, Even if the display screen of B is completely dark, the output sound from the speaker 7 causes the viewer Since it can be clearly confirmed that the power is on, the control unit 10 controls the volume level. When it is determined that is above the set level (step S10), the image brightness control After stopping the drive of the last determination circuit 18 (step S8), the process proceeds to step S2. After returning, the same control process as described above is repeated.

[0029]   On the other hand, when the display screen of the display 9 is completely dark, for example, the above-mentioned child When the volume level has been set below the set level due to mischief of the attendant Is a character indicating "power on" by the control unit 10 instructing the OSD circuit 11 to drive. Alternatively, the graphic or symbol is displayed on the screen 9 on the screen (step S11). As a result, the display screen of the display 9 is completely dark and the output sound is Even if the power is on, it is the same as when the power is off. Even if it is in the state, the on-screen display of the display 9 Then, it can be clearly recognized that the power is on.

[0030]   Then, the control unit 10 is in the power-on state by the on-screen display. When the viewer recognizes, the operation to increase the contrast of the image brightness or the operation to turn off the power Keep watching to do any of the work. That is, the control unit 10 controls the image brightness control. If the last is above the set level, the image brightness contrast determination circuit 18 outputs It is determined whether the dark screen determination signal is no longer input (step S12), and the viewer And whether or not the operation of turning off the power supply has been performed (step S13). To continue. When the power is turned off by the viewer, a series of control processing is ended However, if it is determined that the image contrast is above the set level, That the person wants to continue watching the television broadcast program, The SD circuit 11 was instructed to erase the on-screen display (step S14). Then, the driving of the image brightness contrast determination circuit 18 is stopped (step S8). Then, the process returns to step S2 and the same control process as described above is repeated.

[0031]   As mentioned above, in this television receiver, the display is When the display screen of 9 is completely dark and the output voice cannot be heard, Output the brightness signal of the brightness level below the reference brightness level within one vertical period Reliable detection based on the total time, and the power is on even though it is in the same state as when the power was turned off. The on-screen display of the display 9 makes it clear to the viewer In addition to ensuring accurate recognition, the brightness of the display screen on the display can be adjusted by the viewer's operation. Do not operate to turn the contrast above the set level or turn off the power. The on-screen display is continued until it is performed. Therefore, this TV Although the receiver does not have a power-on display function such as the Always display an image on the display 9 and / or output sound from the speaker 7. Can the voice clearly recognize that the viewer is powered on? Can fully meet the standards of Japan's Electrical Safety Act. Also, the display 9 If a dark image is displayed and the display screen becomes temporarily dark, Determines whether the light-dark contrast remains below the set level for the set time Therefore, even though the power is on, it is the same as when the power is off. There is no false detection.

[0032]   Moreover, in the above television receiver, the display screen of the display 9 is completely dark. There is a function to detect the occurrence of a state in which the output sound is not audible by a general television receiver. Using the existing hardware configuration for the image machine, mainly from a microcomputer Consist of only changing software such as control program of control unit 10 Therefore, the above function can be added with almost no increase in cost. Therefore, the television receiver described above does not require the existing power-on display device. The cost can be reduced and the installation space for the display device is unnecessary. , It is possible to reduce the power consumption associated with the power-on lighting display.

[0033]   Further, in the above-described embodiment, the contrast of the display screen of the display 9 is The state below the set level continues for the set time, and the volume level of the speaker 7 is set. When the two conditions that the level is below a certain level are met, the power is turned on. The lean display is used, but the contrast of the display screen of the display 9 is When the state below the set level continues for the set time, the power is turned on. It may be configured to display the code. As a result, the output sound from the speaker 7 is radiated. If the sound source is from another audio device such as a receiver and the If it is turned off, the viewer is prevented from misidentifying.

[0034]   In another embodiment of the present invention, "power on" is displayed on screen. Instead of the function, it is in the same state as when the power was turned off, even though the power was on. When it is detected, the control unit 10 controls the contrast control circuit 8 of the image processing unit 8. a command to a to set the image brightness contrast on the display screen of the display 9. It is also possible to adopt a configuration in which automatic control is performed so that the level is equal to or higher than the bell. When configured in this way In this case, the viewer who sees the on-screen display cancels the same state as when the power was turned off. There is no need to confirm the operation, and the image displayed on the display 9 The viewer can clearly recognize that the source is on.

[0035]   In addition, as a further embodiment of the present invention, "power on" is turned on. The same function as when the power is turned off despite the power being on When it is detected that the state has been reached, the microcomputer that is the control unit 10 has already been detected. Using the existing sin wave generation function, the sin wave is transmitted through the audio signal superimposing circuit 21. Then, by superimposing it on the audio signal of the television broadcast radio wave, Outputs a beeping sound to make it clear to the viewer that the power is on. It may be configured to notify.

[0036]

[Effect of device]

  As described above, according to the television receiver of the present invention, the When a state in which the display screen of play becomes completely black occurs, the state is changed to 1 vertical period. Reliable based on the total output time of the luminance signal of the luminance level below the reference luminance level within Is detected and it is in the same state as when the power was turned off, but the power is turned on. The on-screen display of the spray allows the viewer to clearly recognize , The image brightness contrast of the display screen of the display is set by the viewer's operation Until the level is exceeded or the power is turned off, the above Since the on-screen display is continued, the display device is turned on by turning on the indicator light. Even if it does not have the function, it will be able to fully satisfy the standards of Japan's Electrical Safety Law.

[0037]   Moreover, the detection function of the occurrence of the state where the display screen of the display is pitch black is generally The existing hardware configuration is used for a conventional television (B) Only changing the software such as the control program of the control unit consisting of a computer Since it can be configured with, the above function is added with almost no increase in cost. be able to. Therefore, this television receiver has an existing power-on The cost can be reduced by eliminating the need for a display device, and the installation space for the display device can be reduced. This eliminates the need for a switch and reduces the power consumption associated with the power-on lighting display.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a schematic configuration of a television receiver according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control process in the above television receiver.

[Explanation of symbols]

3 Broadcast receiver 4 Voice processing unit 7 speakers 8 Video processing section 9 display 10 Control unit 11 OSD (on-screen display) circuit 15 Black screen detection means 17 Luminance level detection circuit 18 Image brightness contrast circuit

Claims (5)

[Scope of utility model registration request] 1. A broadcast receiving unit for detecting a received television broadcast radio wave after frequency conversion, and a voice processing unit for demodulating an audio signal from the broadcast receiving unit and then low-frequency amplifying and outputting from a speaker. A video processing unit that demodulates a video signal from the broadcast receiving unit and then displays an image on a display; and a brightness level of a brightness signal extracted from the video processing unit is compared with a preset reference brightness level to obtain a reference brightness. A pitch-dark screen detection unit that outputs a pitch-black screen discrimination signal when a total output time of a luminance signal having a luminance level lower than the level within one vertical period is shorter than a predetermined time set in advance; Indicating that the display is powered on via the on-screen display circuit when continuously output in Causes on-screen display the content, the television receiver characterized by comprising a control unit that performs control to continue until the dark screen discrimination signal of the on-screen display is not output. 2. A video processing unit for displaying an image on a display after demodulating a video signal from a broadcast receiving unit, and a state in which the display unit displays a pitch-dark image equivalent to that when the power is off. A pitch-dark screen detection unit that outputs a pitch-dark screen discrimination signal by discriminating on the basis of the luminance level of the luminance signal extracted from, and contents indicating that the display is in a power-on state when the pitch-dark screen discrimination signal is output And a control unit that controls the on-screen display to be continued until the pitch-black screen determination signal is no longer output. 3. The black screen detection means according to claim 2, wherein the brightness level of the brightness signal extracted from the video processing unit is:
A brightness level detection circuit that outputs a detection signal each time a brightness level lower than this reference brightness level is detected by comparing with a reference brightness level that is preset to a brightness level at which the screen of the display does not become dark, and the video processing After the total input time of the detection signals input from the brightness level detection circuit in one vertical period set based on the vertical sync signal separated by the sync separation circuit from the video signal is calculated, the total input time is preset to a predetermined value. A television receiver comprising an image bright / dark contrast discrimination circuit that outputs a pitch-dark screen discrimination signal to the control section when the time is shorter than the time. 4. The contrast control circuit according to claim 2, wherein the control unit controls the display to display on-screen a content indicating that the display is in a power-on state. A television receiver for automatically controlling so that the contrast of image brightness on the display screen becomes higher than a set level. 5. The control unit according to claim 2, wherein instead of performing control to display on-screen the content indicating that the power is on, the control unit notifies that the power is on. A television receiver that controls to output a notification sound from a speaker.