JPWO2010116468A1 - Signal waveform correction apparatus and signal waveform correction method - Google Patents

Abstract

A signal waveform correction device corrects a waveform of a signal input via a signal cable based on a correction parameter, and outputs a correction waveform, a frequency correction unit (100) and a gain correction unit (101), and the correction waveform Window comparator (105), high range counter (106), middle range counter (107), low range counter (108), window comparator (105), and high range counter for detecting a high output level period in which the high output level indicates (106), a control unit (104) for setting the correction parameter so that the high output level period detected by the middle range counter (107) and the low range counter (108) becomes the longest.

Description

  The present invention relates to a signal waveform correction apparatus and a signal waveform correction method for correcting a signal waveform transmitted by a signal cable.

  A conventional signal waveform correction device corrects a transmitted signal waveform on the premise that a transmission loss generated when a signal is transmitted through a signal cable is proportional to the length of the signal cable (for example, Patent Document 1). reference).

In addition, a conventional signal waveform correction device corrects a signal waveform by inserting a key signal, which is a special signal, into a signal on the transmission side in advance and restoring the signal based on the key signal on the reception side (for example, , See Patent Document 2).
Japanese Patent Laid-Open No. 7-38886 JP 2003-259149 A

  However, for example, the device disclosed in Patent Document 1 corrects the signal waveform without measuring the signal waveform on the assumption that the transmission loss generated when the signal is transmitted through the signal cable is proportional to the length of the signal cable. ing. For this reason, when the transmission loss is not proportional to the length of the signal cable due to manufacturing variation of the signal cable, the signal waveform correction device does not always correct the signal waveform optimally. Further, for example, in the device disclosed in Patent Document 2, there is a problem that the reception side must restore the signal using a key signal that is a special signal inserted into the signal on the transmission side.

  The present invention has been made based on the above problem recognition, and has an object to provide a signal waveform correction device that reliably corrects a signal waveform transmitted through a signal cable without using a special signal. To do.

  The present invention has been made to solve the above-described problem, and corrects a waveform of a signal input via a signal cable based on a correction parameter and outputs a corrected waveform, and the correction A detection unit that detects a high output level period in which a waveform indicates a high output level; and a control unit that sets the correction parameter so that the high output level period detected by the detection unit is longest. Is a signal waveform correction device.

  Further, the present invention is the signal waveform correction device, wherein the signal input via the signal cable is a video signal.

  Further, the present invention is the signal waveform correction device, wherein the comparator outputs a counting signal when the correction waveform is equal to or higher than a lower limit value of the predetermined output level range.

  The present invention is also a processing method in the signal waveform correction apparatus, wherein the correction unit corrects the waveform of the signal input via the signal cable based on the correction parameter, and outputs a correction waveform. A step of detecting a high output level period in which the correction waveform indicates a high output level, and a step of setting the correction parameter so that the high output level period detected by the detection unit is the longest. And a signal waveform correction method characterized by comprising:

  According to the present invention, the signal waveform correction device detects a period in which the signal after AD conversion falls within a predetermined output level range, so that the signal waveform transmitted through the signal cable is reliably corrected without using a special signal. be able to.

1 is a block diagram of a signal waveform correction apparatus according to an embodiment. It is a figure which shows the procedure which detects the high output level of the signal after AD conversion. It is a figure which shows the procedure which detects the period when the signal after AD conversion is settled in the predetermined output level range. It is an operation | movement flowchart of the signal waveform correction apparatus by this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Frequency correction part 101 Gain correction part 102 AD conversion part 104 Control part 105 Window comparator 106 High range counter 107 Middle range counter 108 Low range counter 109 Synchronization signal processing part

  Hereinafter, an embodiment for carrying out the present invention will be described. FIG. 1 is a block diagram of a signal waveform correction apparatus according to this embodiment. In FIG. 1, the signal waveform correction apparatus includes a frequency correction unit 100, a gain correction unit 101, an AD conversion unit 102, a control unit 104, a window comparator 105, a high range counter 106, a middle range counter 107, A low range counter 108 and a synchronization signal processing unit 109 are provided.

  The frequency correction unit 100 includes a high-pass filter (hereinafter referred to as HPF). The frequency correction unit 100 corrects the frequency of the input signal transmitted by the signal cable by changing the HPF gain and the cutoff frequency according to the correction parameter instruction from the control unit 104, and the frequency-corrected input signal is gained. The data is output to the correction unit 101. Here, the input signal is, for example, a video signal typified by an RGB (Red Green Blue) signal input to the display device, and there may be a plurality of input systems (Red signal, Green signal, Blue signal).

  The gain correction unit 101 corrects the gain of the signal input from the frequency correction unit 100 according to the correction parameter instructed from the control unit 104, and outputs the gain-corrected input signal to the AD conversion unit 102. For example, when the input synchronization signal is a synchronization signal in which a horizontal synchronization signal and a vertical synchronization signal are mixed (HV mixing), the synchronization signal processing unit 109 converts the synchronization signal into a horizontal synchronization signal and a vertical synchronization signal. To separate. The synchronization signal processing unit 109 shapes the waveform of the input synchronization signal so as to have a predetermined output level and polarity. The synchronization signal processing unit 109 outputs the synchronization signal subjected to these necessary processes to the AD conversion unit 102.

  The AD conversion unit 102 AD-converts the signal input from the gain correction unit 101 in synchronization with the synchronization signal, and outputs the AD-converted signal, the sampling clock used for AD conversion, and the synchronization signal to the window comparator 105. Output to a signal processing unit (not shown).

  The window comparator 105 takes a timing using the input synchronization signal and the sampling clock, and reads the AD-converted signal input from the AD converter 102. The window comparator 105 is set with an output level range setting for classifying the output level of the signal after AD conversion into a predetermined range from the control unit 104.

  The window comparator 105 outputs the counting signal only during a period in which the output level of the signal after AD conversion is within the set output level range. When the output level of the signal after AD conversion input from the AD converter 102 is “high range”, the window comparator 105 outputs a counting signal to the high range counter 106, and the output level of the signal after AD conversion is “ When it is “middle range”, the count signal is output to the middle range counter 107, and when the output level of the signal after AD conversion is “low range”, the count signal is output to the low range counter 108. Note that the window comparator 105 may start outputting the counting signal when the signal after AD conversion becomes equal to or higher than the lower limit value of the output level range.

  The control unit 104 sets the output level range in the window comparator 105 based on the count values input from the high range counter 106, the middle range counter 107, and the low range counter 108. In addition, the control unit 104 includes a frequency correction unit 100 and a gain according to the high output level period of the signal after AD conversion measured using any of the high range counter 106, the middle range counter 107, and the low range counter 108. Correction parameters are set in the correction unit 101.

  The high range counter 106 counts the period during which the count signal is input from the window comparator 105 and outputs the count value to the control unit 104. The same applies to the middle range counter 107 and the low range counter 108.

  A specific operation of the window comparator 105 will be described with reference to FIGS. FIG. 2 is a diagram illustrating a procedure for detecting a high output level of a signal after AD conversion. In order to simplify the explanation, in FIG. 2 and FIG. 3, the signal after AD conversion is expressed as a waveform. Here, the horizontal axis indicates time.

  For example, it is assumed that the output level ranges “high range”, “medium range”, and “low range” are set as shown in FIG. In this case, since the count signal is never input from the window comparator 105 to the high range counter 106, the high range counter 106 outputs a count value “0” to the control unit 104.

  Further, since the counting signal is input from the window comparator 105 to the middle range counter 107 during the period “TM” within the “middle range”, the middle range counter 107 has a count value indicating the period “TM”. Is output to the control unit 104. The low range counter 108 receives a counting signal from the window comparator 105 during the period “TL1 + TL2” within the “low range”. Is output to the control unit 104.

  The control unit 104 compares the count values “0”, “TM”, and “TL1 + TL2” from each counter, and selects the maximum count value. As can be seen from FIG. 2A, the high output level of the AD-converted signal exists in the range (“medium range”) indicated by the selected maximum count value “TM”.

  In order to further narrow down the value of the high output level, the control unit 104 further classifies the selected range into “high range”, “medium range”, and “low range” as shown in FIG. Set to. Then, the count values input from the high range counter 106, the middle range counter 107, and the low range counter 108 are compared again to select the maximum count value. The control unit 104 repeats these procedures to detect the high output level of the signal after AD conversion.

  The control unit 104 sets a predetermined range around the high output level value “E” in the window comparator 105. This setting may be set as any one of “high range”, “medium range”, and “low range”, but here the upper limit value “E + F” and the lower limit value “EF” of the output level range are set as “high range”. Set. However, “F” is a predetermined positive value.

  FIG. 3 is a diagram illustrating a procedure for detecting a high output level period of a signal after AD conversion. Here, the high output level period is a period during which the output level of the signal after AD conversion falls within the range from “E + F” to “EF”. 3A is the original signal, FIG. 3B is the case where the waveform of the signal after AD conversion is uncorrected, FIG. 3C is the case where the waveform of the signal after AD conversion is appropriately corrected, and FIG. ) Shows the case where the waveform of the signal after AD conversion is overcorrected. Here, the horizontal axis indicates time. In this case, the window comparator 105 continues to output a signal to the high range counter 106 during the high output level period.

  As shown in FIG. 3B, when the waveform of the signal after AD conversion is not yet corrected, the high range counter 106 counts the high output level period in which the signal after AD conversion indicates the “high range” of the output level range. Thus, the count value of the high output level period “T1” is output to the control unit 104. The control unit 104 stores a count value “T1” indicating the high output level period.

  Thereafter, the control unit 104 instructs the frequency correction unit 100 to use different correction parameters (gain and cut-off frequency). Further, the control unit 104 instructs the gain correction unit 101 to use a correction parameter (gain) different from the current one. As a result, the frequency correction unit 100 and the gain correction unit 101 correct the waveform of the signal after AD conversion. The control unit 104 stores the instructed correction parameter.

  Assume that the waveform of the signal after AD conversion becomes as shown in FIG. In this case, the high range counter 106 outputs a count value “T2” indicating the high output level period to the control unit 104. The control unit 104 stores a count value “T2” indicating the high output level period.

  Similarly, it is assumed that the waveform of the signal after AD conversion becomes as shown in FIG. For example, in the case shown in FIG. 3D, the control unit 104 stores the count value “T3” indicating the high output level period. Note that the control unit 104 may further set the output level range a predetermined number of times, and store more count values by changing the gain and the cutoff frequency.

  Here, as shown in FIGS. 3B to 3D, the count values have a relationship of “T2> T1” and “T2> T3”. That is, when the count value indicating the high output level period is maximum, the waveform of the signal after AD conversion is appropriately corrected so as to be the same waveform as the original signal. Therefore, the control unit 104 resets the gain and cut-off frequency set when the high output level period indicates the longest “T2” in the frequency correction unit 100 and the gain correction unit 101, thereby performing AD conversion. The waveform of the subsequent signal, that is, the input signal waveform after transmission loss is corrected appropriately.

  The high output level value “E” of the signal after AD conversion may be known in advance as a design matter. In this case, since it is not necessary to narrow the output level range to the above-mentioned “high range”, “medium range”, and “low range”, it is not necessary to provide a plurality of counters.

  FIG. 4 is an operation flowchart of the signal waveform correction apparatus according to the present embodiment. A signal is input to the frequency correction unit 100 via the signal cable (step S1). The frequency correction unit 100 corrects the frequency of the input signal and outputs it to the gain correction unit 101 (step S2). The gain correction unit 101 corrects the gain of the signal input from the frequency correction unit 100 and outputs the signal to the AD conversion unit 102 (step S3).

  The AD conversion unit 102 AD-converts the signal input from the gain correction unit 101 in synchronization with the synchronization signal, and outputs the AD-converted signal, the sampling clock used for AD conversion, and the synchronization signal to the window comparator 105. It outputs to a signal processing part (not shown) (step S4). The control unit 104 sets the output level range in the window comparator 105 (step S5). The window comparator 105 outputs a signal to each counter according to the output level range (step S6).

  Each counter outputs a count value to the control unit 104 (step S7). Note that step S5 to step S6 may be repeated a predetermined number of times as the control unit 104 resets the output level range further narrowly. The control unit 104 detects the high level of the signal after AD conversion (step S8). The control unit 104 sets the output level range setting “E + F” and “EF” as the “high range”, for example, in the window comparator 105 (step S9). The window comparator 105 continues to output a signal to the high range counter 106 for the high output level period (step S10).

  The high range counter 106 outputs the high output level period of the signal after AD conversion to the control unit 104 (step S11). The control unit 104 stores the high output level period (step S12). The control unit 104 instructs the frequency correction unit 100 on the gain and the cutoff frequency (step S13). The frequency correction unit 100 performs frequency correction of the input signal (step S14).

  The control unit 104 instructs a gain to the gain correction unit 101 (step S15). The gain correction unit 101 performs gain correction (step S16). The control unit 104 stores the set gain and cut-off frequency, respectively (step S17). It is determined whether or not the number of times of setting the output level range has reached a predetermined number. If the predetermined number of times has been reached, the process proceeds to step S19 (step S18).

  The control unit 104 resets the gain and cut-off frequency indicating the longest high output level period in the frequency correction unit 100 and the gain correction unit 101 (step S19). In this way, the input signal waveform after transmission loss is corrected appropriately.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  The correction unit described in the present invention corresponds to the frequency correction unit 100 and the gain correction unit 101, and the detection unit includes the window comparator 105, the high range counter 106, the middle range counter 107, and the low range. The control unit corresponds to the control unit 104.

  Further, by recording a program for realizing each step shown in FIG. 4 of the control unit 104 in a computer-readable recording medium, causing the computer system to read and execute the program recorded in the recording medium, You may perform the execution process of a communication terminal. Here, the “computer system” may include hardware such as an OS (Operating System) and peripheral devices.

  Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used. The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a CD-ROM, a hard disk built in a computer system, etc. This is a storage device.

Further, the “computer-readable recording medium” refers to a volatile memory (for example, DRAM (Dynamic) in a computer system serving as a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. Random Access Memory)) that holds a program for a certain period of time is also included.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
The program may be for realizing a part of the functions described above.
Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  According to the above-described embodiment, the signal waveform correction device detects a period during which the signal after AD conversion falls within a predetermined output level range, so that the signal waveform transmitted through the signal cable can be reliably transmitted without using a special signal. It can be corrected. The signal waveform correction apparatus described in this embodiment is suitable for correcting RGB signal waveforms input to the display apparatus.

Claims (4)

A correction unit that corrects a waveform of a signal input via a signal cable based on a correction parameter, and outputs a correction waveform;
A detection unit for detecting a high output level period in which the correction waveform indicates a high output level;
A control unit that sets the correction parameter such that the high output level period detected by the detection unit is the longest;
A signal waveform correction apparatus comprising:   The signal waveform correction apparatus according to claim 1, wherein the signal input via the signal cable is a video signal.   2. The signal waveform correction apparatus according to claim 1, wherein the comparator outputs a counting signal when the correction waveform is equal to or more than a lower limit value of the predetermined output level range. A processing method in a signal waveform correction apparatus,
A correction unit that corrects a waveform of a signal input via a signal cable based on a correction parameter, and outputs a correction waveform;
A detecting unit detecting a high output level period in which the correction waveform indicates a high output level; and
A control unit setting the correction parameter such that a high output level period detected by the detection unit is longest;
A signal waveform correction method comprising:

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