JP2009147662A - Television - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a television for appropriately detecting a synchronization signal even though a macro vision signal is superposed on a television broadcast signal. <P>SOLUTION: The television detects a synchronization signal of a television broadcast signal and displays a video image based on a television broadcast signal in synchronization with the synchronization signal. The television is equipped with a synchronization signal detection part M1 for obtaining the synchronization signal detected by a synchronization separation circuit 12f at a predetermined slice level; a synchronization width determination part M2 for determining the synchronization signal as a false signal when the width thereof is the predetermined width or less, and a slice level setting part M3 for searching for a slice level with the fewest false signals while changing the slice level of the synchronization detection part, and setting the slice level as the predetermined slice level of the synchronization separation circuit 12f. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a television, and more particularly, to a television that detects a synchronization signal of a television broadcast signal and extracts a video signal by synchronous detection based on the synchronization signal.

  In a television, it is common to detect a synchronization signal of a television broadcast signal with a fixed slice level. However, depending on the output of the broadcast station and the reception status, the strength of the synchronization signal varies (for example, a zag of a television broadcast signal), or the S / N ratio decreases due to a decrease in electric field strength.

  As a technique for dealing with such a problem, a plurality of threshold values are prepared, and for example, a threshold value at which an appropriate number of synchronization signals can be detected from a television broadcast signal in which a zag is generated is set as a slice level, thereby realizing optimization of the slice level. There is a technology (see, for example, Patent Document 1). Also, the electric field strength is determined by the automatic gain control signal of the AGC circuit. When the electric field strength is weak, the slice level for detecting the synchronization signal is changed to the top side, and when the electric field strength is strong, the slice level of the synchronizing signal is changed to the pedestal. There is also a technique of changing to the side (see, for example, Patent Document 3). When the edge of the synchronization signal cannot be detected, synchronization detection is performed while changing the slice level to the pedestal side. On the other hand, when the edge of the synchronization signal is detected, the slice value is changed to the top side and the leading value is reached. It is disclosed that the synchronization detection is performed until the optimum slice level is set in the detected synchronization (see, for example, Patent Document 2).

  Also, in order to optimize the extraction timing of the teletext signal, the difference between the extraction timing (basically the sync signal portion) assumed in advance and the slice level is taken, a parity check is performed, and a parity error is detected by the parity check. If detected, a technique for determining that phase distortion has occurred and changing the extraction timing (see, for example, Patent Document 4), or a technique for appropriately setting the threshold level of the synchronization signal according to the nature of the video signal (For example, see Patent Document 6) is also known.

In addition, in order to prevent the optical reception signal waveform deterioration on the optical communication transmission path, in order to control the size of the eye opening to be the widest, the optical reception signal is identified by three identification levels, and the upper and lower A technique for controlling the identification level so that the data output error due to the identification level is minimized is also known (see, for example, Patent Document 5).
JP-A-9-186910 JP-A-7-115564 Utility Model Registration No. 3086330 JP 2003-274373 A JP 2003-78575 A JP-A-3-23775

  By the way, in recent years, the presence of a macrovision signal has emerged as a factor that hinders detection of a synchronization signal. The macrovision signal is a signal that is superimposed on H10 to H17 and H273 to H280, and is recorded as white brighter than the standard (a signal brighter than 100% white) or dark black below the standard. White that is brighter than the standard does not affect the detection of a sync signal below the pedestal level because it is a signal that protrudes above the pedestal level. However, a black signal darker than the standard is a signal that protrudes below the pedestal level, which affects detection of the synchronization signal.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a television capable of appropriately executing synchronization signal detection even for a television broadcast signal on which a macrovision signal is superimposed.

  In order to solve the above problems, a television of the present invention detects a synchronization signal of a television broadcast signal, and performs a video display process based on the television broadcast signal in synchronization with the synchronization signal. Synchronization signal detection means for detecting a synchronization signal at a level, synchronization width determination means for determining a false signal when the width of the synchronization signal is equal to or less than a predetermined width, and changing the slice level of the synchronization detection means And a slice level setting unit that searches for a slice level with the least signal and sets the slice level as a predetermined slice level of the synchronization signal detection unit.

As described above, according to the present invention, it is possible to provide a television capable of appropriately executing synchronization signal detection even for a television broadcast signal on which a macrovision signal is superimposed.
According to the invention of claim 2, the optimum slice level is preset for each broadcasting station.
According to the third aspect of the invention, it is possible to reliably cope with a sudden change in signal intensity and the presence of a channel or the like on which a macrovision signal is not superimposed.
Further, according to the invention according to claim 4, when the non-use of the macrovision signal is different for each broadcasting station, or when the non-use of the macrovision signal is different for each program even in the same broadcasting station, etc. It becomes possible to respond.
According to the invention of claim 5, it is possible to search for a suitable slice level at the time of high power input.
According to the invention of claim 6, it is possible to search for a suitable slice level at the time of weak power input.
Furthermore, it is needless to say that in a more specific configuration as in claim 7, the same effects as those of the inventions of claims 1 to 6 described above can be achieved.

At least the following matters will become clear from the description of the present specification and the accompanying drawings.
According to the configuration of the main invention, the synchronization signal detecting means detects the synchronization signal at a predetermined slice level. Here, the predetermined slice level is, for example, the slice level set at the time of shipment from the factory, and when the slice level is set by the slice level setting means, the set slice level is set as the predetermined slice level. To do. The synchronization width determination means determines that the signal is a false signal when the width of the synchronization signal is equal to or less than a predetermined width. Furthermore, in addition to the determination of whether or not the predetermined width is H1 or less when the predetermined width is H1, it may be determined whether or not the predetermined width is H2 (H1 <H2) or more. That is, a signal that is greater than or equal to H1 and less than or equal to H2 is determined as a synchronization signal, and a signal having a width smaller than H1 or a signal having a width greater than H2 is determined as a false signal. The slice level setting means searches for the slice level with the least false signal while changing the slice level of the synchronization detection means, and sets it as a predetermined slice level of the synchronization signal detection means.

  Further, as a selective aspect of the present invention relating to the timing at which the slice level search is performed, the synchronization width determination unit and the slice level setting unit perform slice level during auto search in which a broadcast frequency is automatically searched from a television broadcast signal. The adjustment is executed, and the adjusted slice level and the found broadcast frequency are stored in association with each other. According to this configuration, even a broadcast station that has failed to perform an auto search due to a macrovision signal or weak power input even though it is a receivable broadcast station can be searched. In addition, since an optimal slice level is set for each broadcasting station during auto search, auto search processing and subsequent reception processing are efficient, which is preferable.

  Further, as a selective aspect of the present invention, the synchronization width determination unit and the slice level setting unit are configured to constantly adjust the slice level at predetermined time intervals. Even when the presence / absence of superimposition of the macrovision signal changes between channels, between programs, the passage of time, etc., it is possible to reliably receive the broadcast signal by setting the optimum slice level. Therefore, it is possible to reliably cope with a sudden change in the signal intensity and the presence of a channel or the like on which the macrovision signal is not superimposed.

  Further, as a selective aspect of the present invention relating to the timing at which the slice level search is executed, the synchronization width determination means and the slice level setting means are configured to be executed when a tuning signal is input. In other words, it is easy to use when the use / non-use of the macrovision signal is different for each broadcast station, when the use / nonuse of the macrovision signal is different for each program even when the same broadcast station is used, and when the output is different. It becomes possible to cope with.

  Further, as a selective aspect of the present invention relating to the slice level search, the slice level setting means searches for the slice level while changing the slice level in the direction of lowering at the time of strong power input. Therefore, it is possible to search for a suitable slice level at the time of high power input.

  In addition, as a selective aspect of the present invention relating to the slice level search, the slice level setting means searches the slice level while changing the slice level in the direction of increasing the slice level at the time of weak power input. Therefore, it is possible to search for a suitable slice level at the time of weak power input.

Hereinafter, embodiments of the present invention will be described in the following order.
(1) Television configuration:
(2) Slice level adjustment processing:
(3) Summary:

(1) Television configuration:
Hereinafter, the television of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating a configuration of a television according to an embodiment of the present invention. In this embodiment, a liquid crystal television having a liquid crystal panel as an example will be described. However, a cathode ray tube television or a plasma television may of course be used. For example, the present invention can be applied to a recording / playback device such as an HDD recorder or a DVD recorder. In the figure, only the video signal processing system is shown for simplification of the figure.

  In FIG. 1, a television 100 includes a tuner 10, an intermediate frequency amplifier circuit 11, a one-chip IC 12, an AFT circuit 13, a liquid crystal driver 14, a liquid crystal module 16, a sub microcomputer 18, and a nonvolatile memory 20. It is equipped with. The above configuration is connected to be communicable with each other via a bus such as IIC. In this configuration, a TV broadcast signal is input to the tuner 10 via an antenna, and the tuner 10 selects a frequency of a channel selected from the input TV broadcast signal, and receives a signal of the selected frequency. Amplified and output as an intermediate frequency signal.

  The tuner 10 can employ, for example, a PLL synthesizer tuning method, and can control a receivable frequency by controlling the local oscillation frequency. This frequency control is performed according to the control of the microcomputer 12g. More specifically, the tuner 10 selects the carrier frequency corresponding to the channel according to the AFT signal output from the microcomputer 12g, amplifies the received frequency signal, and converts it to an intermediate frequency signal by heterodyne detection. The intermediate frequency signal generated by the tuner 10 is output to the one-chip IC 12.

  The intermediate frequency amplifier circuit 11 amplifies the intermediate frequency signal to a required magnitude. In this intermediate frequency amplification, an amplification factor is determined corresponding to an IF-AGC voltage output from an AGC circuit 12B described later.

  Here, the AFT circuit 13 will be described. The frequency of the intermediate frequency signal generated by the tuner 10 is preferably 58.75 MHz, but an error occurs depending on the reception state of the television radio wave. Therefore, an AFT circuit 13 is provided, and the AFT circuit 13 creates an AFT voltage based on the frequency of the intermediate frequency signal in the intermediate frequency amplifier circuit 11. Specifically, a video carrier is extracted from the intermediate frequency signal of the intermediate frequency amplifier circuit 11, and a voltage corresponding to the difference between the video carrier and the reference frequency (58.75 MHz) is generated by the FM detection circuit. AFT voltage is generated by DC amplification. In the tuner 10 to which the AFT voltage is input, the frequency of the intermediate frequency signal is converged to 58.75 MHz by applying the AFT voltage to the local transmission circuit. When the frequency of the intermediate frequency signal is shifted to the low frequency side, a high AFT voltage is output, and the transmission frequency in the local transmission circuit increases. On the other hand, when the frequency of the intermediate frequency signal is shifted to the high frequency side, a low AFT voltage is output, and the transmission frequency in the local transmission circuit is lowered.

  The one-chip IC 12 includes a video detection circuit 12a, an AGC circuit 12b, a Y / C separation circuit 12c, a color demodulation circuit 12d, a matrix circuit 12e, a synchronization separation circuit 12f, and a microcomputer 12g. The microcomputer 12g has a program execution environment including a CPU, a RAM, and a ROM. The microcomputer 12g communicates with the sub-microcomputer 18, and the CPU executes the program stored in the ROM while using the RMA as a work area. Control of the chip IC 12 and control of the entire television 100 are performed. In addition, in this embodiment, although each part 12a-12g is described as what is integrated in 1-chip IC12, of course, each circuit may be formed separately.

  In the one-chip IC 12, the video detection circuit 12a extracts the carrier signal from the modulated signal (carrier signal + carrier signal). In other words, a decoded video signal (luminance signal + carrier wave-suppressed quadrature two-phase modulated carrier color signal + synchronization signal) is extracted from the intermediate frequency signal. The extracted decoded video signal is output to the AGC circuit 12b, the Y / C separation circuit 12c, and the synchronization separation circuit 12f.

  The AGC circuit 12b acquires the composite video signal (video detection output) output from the video detection circuit 12a, and generates an RF-AGC voltage and an IF-AGC voltage corresponding to the magnitude of the synchronization signal of the video detection output. The RF-AGC voltage is input to the tuner 10, and the tuner 10 performs automatic gain adjustment that decreases the amplification factor as the RF-AGC voltage is higher. Similarly, the IF-AGC voltage is input to the intermediate frequency amplifier circuit 11, and the intermediate frequency amplifier circuit 11 also performs automatic gain adjustment that decreases the amplification factor as the IF-AGC voltage increases. Thus, the amplification performed by the tuner 10 and the intermediate frequency amplifier circuit 11 adjusts the video signal intensity input to the one-chip IC 12 to an ideal value standardized by the size of the synchronization signal. . Incidentally, although the tuner 10 and the intermediate frequency amplifier circuit 11 are described as a forward type, it is needless to say that a reverse type may be used.

  Next, the Y / C separation circuit 12c performs Y / C separation of the decoded video signal, and outputs the luminance signal (Y) to the matrix circuit 12e and the carrier color signal (C) to the color demodulation circuit 12d. Further, the synchronization separation circuit 12e performs synchronization separation of the decoded video signal at a predetermined slice level and outputs the obtained synchronization signal to the microcomputer 12g. The predetermined slice level can be changed according to the control of the microcomputer 12g. That is, the synchronization separation circuit 12f that detects the synchronization signal and outputs it to the microcomputer 12g and the microcomputer 12g that receives the synchronization signal from the synchronization separation circuit 12f constitute the synchronization signal detection means. In the case of synchronous separation, the pedestal level may be clamped using a pedestal level clamp circuit or the like. The synchronization signal is not limited to the microcomputer 12g, and other configurations of the television 100 such as the tuner 10, the liquid crystal driver 14, the liquid crystal module 16, and the sub microcomputer 18 are also connected via the bus. Supplied.

  The separated carrier color signal is demodulated into RY and BY color difference signals in the color demodulation circuit 12d, and then output to the matrix circuit 12e. The matrix circuit 12e performs matrix conversion processing based on the input luminance signal and color difference signal, and generates an RGB signal as image data.

  Here, the auto search function and auto memory function executed by the microcomputer 12g will be described. The auto search function is a function for automatically searching for a broadcast frequency from a television broadcast signal, and the auto memory function is a function for automatically storing the frequencies found by the auto search function as a broadcast frequency list. That is, the microcomputer 12g controls the reception frequency by controlling the local oscillation frequency of the tuner 10 based on the reception signal level output from the AGC circuit 12B, generates a control signal to the intermediate frequency amplification circuit 11, and creates it. The received reception frequency list is stored in the nonvolatile memory 20. When the auto search function is executed, the microcomputer 12g sweeps the local oscillation frequency of the tuner at a constant frequency step over a predetermined frequency range. That is, the reception frequency of the television 100 is swept. In each frequency step, the output level of the one-chip IC 12 is monitored, and if a television broadcast signal can be received, the reception frequency is stored in the nonvolatile memory 20 by the auto memory function.

  The liquid crystal driver 14 includes a pixel number conversion circuit, an image quality adjustment circuit, an output processing circuit, and a frame memory. The pixel number conversion circuit performs a scaling process on the RGB signal input from the matrix circuit 12e to generate an RGB signal for one screen displayed on the liquid crystal panel 16a. Then, RGB signals for one screen are stored in the frame memory as pixel information. The image quality adjustment circuit adjusts brightness, contrast, black balance, and white balance for the RGB signals stored in the frame memory by the pixel number conversion circuit. The output processing circuit performs gamma correction, dither processing, and the like on the RGB signal whose image quality has been adjusted by the image quality adjustment circuit, and adds a background signal, an OSD signal, a blanking signal, etc., and outputs it to the liquid crystal panel 15a. And display an image.

  The liquid crystal module 16 includes a liquid crystal panel 16a, a backlight 16b that irradiates the liquid crystal panel 16a from the back, and an inverter 16c that supplies a predetermined voltage generated from the input power supply voltage to the backlight 16b to light it. When the backlight 16b is composed of a discharge lamp, the inverter 16c converts the input power supply voltage into an AC voltage and then supplies it to the backlight 16b. The backlight 16b uses a DC-driven light source such as a diode. When it does, it converts into an appropriate voltage value and supplies it to the backlight 16b.

  The sub-microcomputer 18 includes a CPU 18a, a RAM 18b, a ROM 18c, and a remote control receiver 18d. The sub-microcomputer 18 is electrically connected to each part of the television 100, and operates as a television by organically controlling each part. For example, when the user performs a predetermined channel selection operation on the remote controller 30, a remote control signal corresponding to the operation is received by the remote control receiver 18 d, and a channel selection command of a frequency corresponding to the selected channel is transmitted to the one-chip IC or the like. It outputs to a tuner and controls so that a user's desired channel may be selected.

(2) Slice level adjustment processing:
When the television 100 configured as described above receives a television broadcast signal on which a macrovision signal having a signal strength close to the strength level of the synchronization signal is received, the detection of the synchronization signal fails and an image flow or the like occurs. There is drowning. Therefore, in the present invention, even when a television broadcast signal on which a macrovision signal is superimposed is input, the microcomputer 12g can appropriately detect synchronization by adjusting the slice level of the synchronization separation circuit 12f. Perform slice level adjustment processing.

  The slice level adjustment program executed by the microcomputer 12g realizes a synchronization signal detection unit M1, a synchronization width determination unit M2, and a slice level setting unit M3 as shown in FIG. According to this configuration, the synchronization signal detection unit M1 acquires the synchronization signal detected by the synchronization separation circuit 12f. The synchronization width determination unit M2 determines that a synchronization signal acquired by the synchronization signal detection unit M1 whose synchronization signal width is equal to or smaller than a predetermined width is a false signal. The slice level setting unit M3 searches for the slice level with the least false signal while changing the slice level of the synchronization separation circuit 12f based on the determination result of the synchronization width determination unit M2, and determines a predetermined slice level of the synchronization separation circuit 12f. Set as.

  The slice level adjustment process is executed, for example, during the above-described auto search, is always executed at a predetermined time interval, or is performed when channel switching is performed. When the slice level is adjusted during auto search, an optimal slice level is set for each channel, and processing other than during auto search can be reduced. Further, if the slice level adjustment is performed at the time of channel switching, it is possible to easily cope with the case where the supervision of the macrovision signal is performed at a specific broadcasting station. In addition, if this process is executed at predetermined intervals, not only when switching channels, it is ensured even when programs with macrovision signals superimposed and programs not superimposed are mixed on the same channel. It becomes possible to respond.

  Hereinafter, the slice level adjustment processing executed by the microcomputer 12g will be described in detail with reference to the flowchart of FIG. When the process is started, in S10, the microcomputer 12g instructs the synchronization separation circuit 12f to perform synchronization detection at the standard slice level. FIG. 3 is a diagram for explaining the pedestal level and the leading value. As shown in FIG. 3, the standard slice level is, for example, a voltage value between 100% of the pedestal level voltage and 0% of the leading value voltage, such as a voltage value of 50%. . Of course, any value from 0 to 100% may be used as a standard, and a slice level that is most easily detected in synchronization in a television broadcast signal without superimposing a macrovision signal may be used as a standard. The head value is a lower end value when the synchronization signal is received at the maximum level.

  In S12, it is determined whether or not the synchronization detection in S10 is successful. This determination is made based on whether or not the synchronization signal has a width equal to or greater than a predetermined value. 4 and 5 are diagrams for explaining synchronization detection. As shown in FIG. 4, in synchronization detection, a signal having a width wider than a predetermined value is determined as a synchronization signal, while a signal having a width smaller than a predetermined value is determined as a false signal such as noise or a macrovision signal (error determination). . More specifically, the synchronization detection succeeds only when the rising edge of the synchronization signal is detected after a predetermined time has elapsed since the falling edge of the synchronization signal was detected. In addition, when the signal is continuously input, a false signal wider than the synchronization signal may be generated. Therefore, as shown in FIG. 5, a signal whose width falls within a predetermined range is determined as the synchronization signal. May be. That is, the condition is that the rising edge is not detected until the first predetermined time elapses after the falling edge of the synchronization signal is detected, and the rising edge is detected before the second predetermined time elapses. When synchronization is detected, the fact that synchronization has been detected and the number of detected false signals (number of errors) are stored in a memory such as a RAM. In S12, if the synchronization detection is successful, the process proceeds to S22, and if the synchronization detection fails, the process proceeds to S14.

  In S14, synchronization detection is executed by increasing the slice level by a predetermined amount. That is, it is determined that the signal intensity is small, and the slice level is changed to the pedestal level side. In this way, by gradually changing the slice level to the pedestal side and performing re-detection, it is possible to reliably detect a frequency at which a receivable broadcast signal is present even during weak power input.

  In S16, it is determined whether or not the synchronization detection is successful in S14. When the synchronization detection is successful, the fact that the synchronization detection was successful at the slice level of S14 and the number of errors at the slice level are stored in a memory such as a RAM, and the process proceeds to S18. On the other hand, if the synchronization detection fails, the process proceeds to S18 without storing in the memory.

  In S18, it is determined whether or not synchronization detection has been attempted up to the maximum slice level. That is, it is determined whether or not the slice level has reached the pedestal level. If the slice level has not reached the pedestal level, the process returns to step S14 to increase the slice level and further attempt to detect synchronization. On the other hand, if the slice level reaches the pedestal level, or if the slice level is increased again if the slice level is increased again, it is determined that the slice level has reached the maximum value and the process proceeds to S20.

  In S20, the optimum slice level is selected from the slice levels that have been successfully detected for synchronization, and the synchronization separation circuit is instructed to detect the synchronization signal based on the slice level. FIG. 6 is a diagram for explaining optimum slice level selection. In the selection, the slice level with the least false signal is set as the optimum slice level. That is, the slice level with the smallest number of errors is selected as the optimum slice level among the slice levels that have been successfully detected in synchronization stored in the memory. If this processing is being executed in the auto memory, the optimum slice level is stored in the nonvolatile memory in association with the channel in the auto memory, and the auto memory processing is continued. When this process is executed at predetermined time intervals or when the channel is changed, the optimum slice level is instructed to the synchronization separation circuit 12f, and the process ends.

  In S22, since the synchronization detection has already been successful in S10, the slice level is lowered by a predetermined amount in order to execute a search for the optimum slice level. That is, the slice level is changed to the head value side and a search is made as to whether or not a more suitable slice level exists. In general, macrovision signals and noise rise from the pedestal level. The closer to the pedestal level, the more false signals exist, and the false signal count may decrease as it approaches the top value side. This is because it is expensive. Therefore, a more suitable slice level can be selected at the time of strong power input.

  In S24, it is determined whether or not synchronization detection has failed. If the synchronization detection fails in S24, it means that the slice level set in S10 is already near the top value, so the process returns to step S14 and the search for the optimum slice level is continued while increasing the slice level. . On the other hand, if the synchronization detection is successful, the fact that the synchronization detection was successful and the number of errors are stored in the memory, and the process returns to step S22. If the synchronization detection fails, the process does not return to S14, but instructs the synchronization separation circuit 12f to set the slice level detected in S10 as the optimum slice level, and this process may be terminated.

  As described above, in S12, 16, and 24, if the width of the signal detected at a predetermined slice level is equal to or greater than a predetermined value, the signal is detected as a synchronization signal. A determination unit is configured. In S10 to S24, the microcomputer 12g searches for the slice level with the smallest number of errors while changing the slice level of the synchronization separation circuit, and sets the slice level with the smallest number of errors as the slice level of the synchronization signal detecting means. Slice level setting means is configured.

(3) Summary:
As described above, in the above-described embodiment, in the television that detects the synchronization signal of the television broadcast signal and executes the video display process based on the television broadcast signal in synchronization with the synchronization signal, the synchronization separation circuit 12f has a predetermined value. The synchronization signal detection unit M1 that acquires the synchronization signal detected at the slice level, the synchronization width determination unit M2 that determines a false signal when the width of the synchronization signal is equal to or less than a predetermined width, and the slice level of the synchronization detection unit are changed However, a slice level setting unit M3 that searches for the slice level with the least false signal and sets it as a predetermined slice level of the synchronization separation circuit 12f is provided. With this configuration, it is possible to provide a television that can appropriately perform synchronization signal detection even for a television broadcast signal on which a macrovision signal is superimposed.

Needless to say, the present invention is not limited to the above embodiments. It goes without saying for those skilled in the art,
・ Applying mutually interchangeable members and configurations disclosed in the above embodiments by appropriately changing the combination thereof.− Although not disclosed in the above embodiments, it is a publicly known technique and the above embodiments. The members and configurations that can be mutually replaced with the members and configurations disclosed in the above are appropriately replaced, and the combination is changed and applied. It is an embodiment of the present invention that a person skilled in the art can appropriately replace the members and configurations that can be assumed as substitutes for the members and configurations disclosed in the above-described embodiments, and change the combinations and apply them. It is disclosed as.

It is a block block diagram of a television. It is a flowchart of a slice level adjustment process. It is explanatory drawing of a synchronizing signal and a slice level. It is a figure explaining the width | variety of a synchronizing signal and a false signal. It is a figure explaining the width | variety of a synchronizing signal and a false signal. It is a figure explaining the relationship between a slice level change and the number of errors.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Tuner, 11 ... Intermediate frequency amplifier circuit, 12 ... 1-chip IC, 12a ... Video detection circuit, 12b ... AGC circuit, 12c ... Y / C separation circuit, 12d ... Color demodulation circuit, 12e ... Matrix circuit, 12f ... Synchronization Separation circuit, 12g ... microcomputer, 13 ... AFT circuit, 14 ... liquid crystal driver, 16 ... liquid crystal module, 16a ... liquid crystal panel, 16b ... backlight, 16c ... inverter, 18 ... sub-microcomputer, 18a ... CPU, 18b ... RAM, 18c ... ROM, 18d ... remote control receiver, 20 ... nonvolatile memory, 30 ... remote control, 100 ... television

Claims (7)

In a television that detects a synchronization signal of a television broadcast signal and executes video display processing based on the television broadcast signal while synchronizing with the synchronization signal,
Synchronization signal detecting means for detecting a synchronization signal at a predetermined slice level;
A synchronization width determining means for determining that the width of the synchronization signal is equal to or less than a predetermined width as a false signal;
Slice level setting means for searching for the lowest slice level of the false signal while setting the slice level of the synchronization signal detection means and setting the predetermined slice level of the synchronization signal detection means,
A television, comprising:   The synchronization width determining means and the slice level setting means adjust the slice level during auto search for automatically searching for a broadcast frequency from a television broadcast signal, and associate the adjusted slice level with the found broadcast frequency. The television of claim 1 for storage.   3. The television according to claim 1, wherein the synchronization width determination unit and the slice level setting unit constantly adjust the slice level at predetermined time intervals.   The television according to any one of claims 1 to 3, wherein the synchronization width determination unit and the slice level setting unit are executed when a tuning signal is input.   5. The television according to claim 1, wherein, at the time of a high power input, the slice level setting unit searches for a slice level while changing the slice level in a lowering direction.   The television set according to any one of claims 1 to 5, wherein the slice level setting means searches for the slice level while changing the slice level in the direction of increasing the slice level at the time of weak power input. In a television that detects a synchronization signal of a television broadcast signal and executes video display processing based on the television broadcast signal while synchronizing with the synchronization signal,
The synchronization signal detecting means is realized by the processing of a microcomputer that acquires the synchronization signal separated by the synchronization separation circuit,
The synchronization width determining means and the slice level setting means are realized by the processing of the microcomputer,
The synchronization width determining means and the slice level setting means associate the adjusted slice level with the found broadcast frequency while performing the adjustment of the slice level during an auto search for automatically searching for a broadcast frequency from a television broadcast signal. It is also executed when a tuning signal is input while constantly adjusting the slice level at a predetermined time interval.
At the time of strong power input, the slice level setting means searches for the slice level while changing the slice level in the lowering direction,
2. The television according to claim 1, wherein the slice level setting means searches for the slice level while changing the slice level in the direction of increasing the slice level at the time of weak power input.

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