JPH08163592A - H-list discontinuous point image quality correction pulse generation circuit for magnetic reproducing device - Google Patents

Abstract

PURPOSE: To improve the reliability of corrections such as the distortion of image quality and color vanishing, etc., by integrating a correction pulse generation means into one-chip provided with a changeover control means generating the correction pulses corresponding to various kinds of special reproductions. CONSTITUTION: The skew distortion detection pulse signal from a skew detection circuit 16 is inputted in a correction pulse generation circuit 100 which is made into a one-chip integrated circuit. A skew distortion detection pulse that the signal delayed by one-frame in a one-frame ready circuit 17 and the signal which is not delayed are 0Red is supplied to a switch 48. The circuit 100 switches switches 48 and 49, corresponding to various kinds of special reproductions by two heads or four heads by the control of a CPU 99. The skew distortion signals selected by the switches 48 and 49 are frequency-divided by 1/2 frequency divider circuits 21 and 22, switches 55 to 57 are controlled, and skew correction pulses and color correction pulses are generated. Thus, the correction corresponding to various kinds of special reproduction systems can be performed.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention, when recording on a magnetic tape, the recording positions of horizontal synchronizing signals between adjacent video tracks are deviated from each other, that is, the data is recorded on video tracks in which "H alignment" is not maintained. The present invention relates to an H-sequence discontinuity image quality correction pulse generation circuit of a magnetic recording / reproducing apparatus, which improves the reliability of correction of image quality distortion, color skipping, etc., which occurs when special reproduction such as still information or search is performed. This invention is not limited to magnetic recording and reproducing devices,
It can also be applied to a magnetic reproducing device having no recording means.

[0002]

2. Description of the Related Art Conventionally, in an LP mode (double long time mode, tape speed 1/2) of a magnetic recording / reproducing apparatus of NTSC system or PAL system, since "H side-by-side" cannot be maintained, still (still) reproduction is performed. When performing special playback such as search or search (fast forward) playback, the head crosses several tracks, and skew distortion (image distortion) and color skipping (color disappears) due to the fact that the "H alignment" is not maintained. This is a phenomenon (in the case of the PAL method), and it becomes necessary to perform skew correction and color correction.

Next, the occurrence of the skew distortion will be described in detail with reference to FIG. FIG. 11A shows “H arrangement”.
Is maintained, and FIG. 6B shows a case where "H alignment" is not maintained. Video head is 1
The rotary cylinders are arranged at angular intervals of 80 °, and the recording / reproducing signal switches every 180 °. CH1 and CH respectively
2, if, for example, in the NTSC system, CH1 is the horizontal scanning line NO. 1 to NO. Recording / reproduction is performed up to the first half of H.263, and CH2 is the scan line NO. From the latter half of H.263, NO. 5
Recording / playback is performed up to 25.

The vertical line between the scanning lines in the track traveling direction in the figure indicates the horizontal sync signal recording position. Here, in FIG. 11B in which the "H alignment" is not maintained, special reproduction of search reproduction is performed with two heads on the recording track as follows. Scan line NO. 2 for video head C
If H1 is tracing (indicated by A in the figure)
Due to the fast-forwarding, the video head CH1 gradually scans the scanning line NO. It moves to 2 (indicated by A'in the figure). At this time, since the signal passes through the horizontal synchronizing signal position, skew distortion of 0.5H occurs on the screen (H: horizontal synchronizing signal cycle time).

FIG. 10 is a block diagram showing the configuration of an H-sequence discontinuity image quality correction pulse generation circuit of a conventional magnetic reproducing apparatus for performing skew correction and color correction when performing search reproduction with two heads as described above. Is. In the figure,
Reference numeral 1 is a video head arranged in a rotary cylinder with an angular interval of 180 °, 2 is a head amplifier for amplifying a video signal read by the video head 1, 3 is a brightness / color signal processing circuit, and 4 is a brightness / color signal processing circuit. With respect to the video signal output from the color signal processing circuit 3, 0.5 H (H: horizontal sync signal cycle time, between the adjacent horizontal sync signal recording positions on the same track on the magnetic tape as shown in FIG. 11). Is a multiple of H) and a delay time of 0.5 H is added. Reference numeral 5 denotes a correction circuit, which has a video signal 0.5H discontinuity point detection function and a chroma signal phase shift detection / correction function, and a commercially available IC circuit is usually used. 6 is a correction IC
The switch is switch-controlled by the skew correction pulse signal output from the circuit 5.

The H-sequence discontinuity image quality correction pulse generation circuit of the conventional magnetic reproducing apparatus using the correction IC circuit 5 operates as follows. That is, the horizontal sync signal is separated from the video signal output from the luminance / color signal processing circuit (hereinafter referred to as Y / C processing circuit) 3 by the sync separation circuit and the V killer circuit 5a. The output of the PLL (Phase Locked Loop) circuit 5b, which compares and compares the phase of the separated synchronization signal and the phase of the oscillation output signal of the voltage controlled oscillator (VCO), is input to the skew detection circuit 5c, and the phase of "H arrangement" is set. Skew distortion due to not being maintained is detected, and its output is output to the switch 6 as a skew correction pulse. That is, when skew is detected, the switch 6 switches to a video signal that has passed through a 0.5H delay circuit.

Next, in the chroma signal phase shift detection circuit 5d, the APC (automatic phase control) from the Y / C processing circuit 3 is performed.
Of the error signal, the chroma signal phase shift is detected from the periodic signal of the video signal and the skew detection signal. The detection signal is sent to the color correction circuit 5e and the chroma signal from the Y / C processing circuit 3 is corrected and sent back. As a result,
Skew correction and color correction can be performed even when reproducing a track in which “H arrangement” shown in FIG. 11B is not maintained.

The above is the conventional example of the special reproduction with the 2H head, but the special reproduction may be performed with the 4 head. FIG. 12 shows the arrangement of the heads of the 4-head video head 41. As shown in FIG. 12, a head for LP mode (double long time mode) and SP mode (standard mode)
Heads for use in pairs form CH1 and CH2, respectively, and they are at an angular interval of 180 °, and the pair of LPs
The head for SP and the head for SP are video heads 41 having four heads arranged in a rotary cylinder with a predetermined close distance, for example, a 2H gap distance. Next, the H of the conventional magnetic reproducing apparatus when performing special reproduction with the 4H head
The configuration of the array discontinuous point image quality correction pulse generation circuit will be described. This configuration example is disclosed in Japanese Examined Patent Publication No. 1-13271,
A block diagram thereof is shown in FIG. 7 of Japanese Examined Patent Publication No. 1-13271. According to this configuration example, the color correction pulse and the skew correction pulse are generated as follows based on the envelope pulse (output pulse of the comparator 47 of Japanese Patent Publication No. 1-13271 FIG. 7) from the video head of 4 heads. To do. When reproduced by the four heads shown in FIG. 12, this envelope pulse is output from the head amplifier as follows. That is, first, the CH1 (a pair of SP-L and LP-R) head traces the magnetic tape. At this time, since the SP-L and LP-R heads close to each other in the figure both output the envelope output, it is detected whether the SP-L head or the LP-R head of the CH1 head has a large envelope output. it can. The output signals of the SP-L head and the LP-R head change in size each time they cross recording tracks of different azimuths. Now, assuming that the output signal of the SP-L head is L and the output signal of the LP-R head is H, the envelope pulse (ENV-D pulse) of FIG. 13 is output from the comparator. However, in reality, there is noise that cannot be excluded contained in the envelope pulse. This noise is caused by the instability of the sliding state between the deep head and the head, and this noise causes erroneous detection of the reproduction signal level. Therefore, in order to eliminate the noise, a phase locked loop (PLL) circuit 50 is used as shown in FIG. Phase locked loop circuit 5
By setting the time constant of this loop low by passing through 0, the noise is excluded so as not to follow the erroneous detection pulse, and the Japanese Patent Publication No. 1-13271 is based on the removed envelope pulse. No. 11 by the delay control signal generating circuit 59 of FIG.
2 and skew correction signals 110 and 111 are generated. However, as shown in FIG. 7 of JP-B-1-13271, the voltage-controlled oscillator VCO 52 of the phase-locked loop circuit 50 has its center frequency set to the fast-forward reproduction during special reproduction. It is necessary to match each according to the speed. For example, the center frequency differs depending on whether the speed is double speed, N speed, or fast forward (FF) or rewind (RW), and it is necessary to set the center frequencies respectively.

[0009]

The H-sequential discontinuity image quality correction pulse generation circuit of the above-described conventional magnetic reproducing apparatus is constructed as described above, and is used for manufacturing a special reproducing type magnetic reproducing apparatus with two heads. In this case, for example, a commercially available electronic circuit in which the correction circuit 5 is integrated is used. on the other hand,
In the case of manufacturing a special reproducing type magnetic reproducing device with four heads, for example, a noise eliminating circuit of a phase locked loop circuit 50 as shown in FIG. An electronic circuit having a complicated structure for generating a center frequency according to the N times speed is used.
In the case of these electronic circuits, there was a problem in that when the channel was selected by the phase-locked loop circuit, the color was fixed at 50% duty and the color was lost. That is 0.25 when corrected
This is because H skew will occur. 2 each
Since the head and 4 heads are completely different electronic circuits,
Mounting on the printed circuit board is also completely separate, and assembly, manufacturing,
There was a problem in that adjustments were made in separate systems, and extra work was required.

The present invention has been made in order to solve the above-mentioned problems, and recording is performed on a video track in which "H alignment" is not maintained by the H alignment discontinuity point image quality correction pulse generation circuit of the magnetic reproducing apparatus. Regardless of whether it is a magnetic reproduction apparatus of a special reproduction system with 2 heads or a magnetic reproduction apparatus of a special reproduction system with 4 heads, when correcting the distortion of image quality and the color jump that occur when reproducing the stored information, The same electronic circuit having the correction pulse generation means is mounted on a printed circuit board, and its switching control means is adapted to the special reproduction system of 2 heads or 4 heads.
The objective is to simplify the assembly, manufacturing, and adjustment processes to improve the reliability of products and to reduce costs.

[0011]

In the H-sequence discontinuity image quality correction pulse generating circuit of the magnetic reproducing apparatus according to the present invention, the recording positions of the horizontal synchronizing signals between the adjacent video signal recording tracks are deviated. Equipped with skew distortion and color correction pulse generation means for correcting distortion and color distortion of image quality that occurs when various kinds of special reproduction such as search or stealing of information recorded on the track in which "H alignment" is not maintained An H-order discontinuous point image quality correction pulse generation circuit of the magnetic reproducing apparatus, wherein the correction pulse generation means is 2
It is characterized in that it is integrated in one chip by including a switching control means for generating a correction pulse corresponding to each of the various special reproductions by the head or the four heads. Further, in the H-sequence discontinuity point image quality correction pulse generating circuit of the magnetic reproducing apparatus according to claim 1, the correction pulse generating means outputs a burst output from the luminance / color signal processing circuit when performing special reproduction by two heads. Generate a correction pulse by inputting the skew distortion detection signal from which the noise pulse has been eliminated by the skew distortion detection means from the gate pulse or the composite sync signal pulse,
On the other hand, when performing special reproduction with 4 heads, a pulse signal from which noise has been removed by noise pulse removal means from envelope pulses output from the head amplifier for the standard mode head and the head for long time mode is input to generate a correction pulse. It is characterized by doing. Further, in the H-sequence discontinuity point image quality correction pulse generating circuit of the magnetic reproducing apparatus according to claim 2, when the correction pulse generating means performs special reproduction by two heads, the skew distortion detection signal corresponds to one frame of the pulse. It is characterized by further comprising skew distortion detection / correction means for correcting to a new skew distortion detection signal pulse obtained by performing a logical product operation or a logical sum operation with the delayed pulse.

[0012]

The H-sequence discontinuity point image quality correction pulse generating circuit of the magnetic reproducing apparatus according to the present invention includes correction pulses corresponding to various special reproducing systems with 2 heads and various special reproducing systems with 4 heads in the correction pulse generating means. Since the integrated circuit is provided on one chip by providing the switching control means capable of switching to the same circuit, the same electronic circuit having the correction pulse generating means is used for the printed circuit board in any of the two-head and four-head magnetic reproducing devices. It is mounted on top of it, thus simplifying the assembly, manufacturing and adjustment processes and improving the reliability of the product. Also, during special playback with 2 heads, a skew pulse detection signal that excludes noise pulses from the burst gate pulse or composite sync signal pulse is input to generate a correction pulse. Head (SP head)
And a pulse signal from which noise has been removed from the envelope pulse output from the head amplifier of the long time mode head (LP head) is input to generate a correction pulse, and in either case, highly reliable image quality correction is performed. Further, in the special reproduction by the two heads, the delayed image quality correction pulse signal obtained by delaying the image quality correction pulse signal by the skew distortion detection signal by one frame is further ANDed and the image quality correction pulse signal is ANDed. The resulting image quality correction pulse signal is used as a correction signal at the time of still special reproduction, correction is performed by removing the noise of the generated image quality correction pulse signal, and a logical sum operation is performed instead of the logical product operation to obtain the result. The generated image quality correction pulse signal is used as a correction signal during search special reproduction to correct the missing pulse of the generated image quality correction pulse signal, and the information recorded on the video track in which "H alignment" is not maintained is reproduced. To improve the reliability of the correction function performed on the basis of the image quality correction pulse signal with respect to the image quality distortion, color skipping, etc.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the arrangement of an H-sequence discontinuous point image quality correction pulse generation circuit of the magnetic reproducing apparatus of the present embodiment. However, this is a case of special reproduction with two heads. In the figure, 11 is a CH1 video head, 12 is a CH2 video head, and the video head 11 and the video head 12 are arranged in a rotary cylinder at an angular interval of 180 °. Reference numeral 13 is a switch for switching between the CH1 video head 11 and the CH2 video head 12, 14 is a head amplifier for amplifying the video signals read from the video heads 11 and 12, and 15 is luminance / color (Y / C) signal processing. A circuit, 15a is an FM detection unit mounted on the luminance / color signal processing circuit 15, and 15b is a luminance signal processing unit, which outputs a luminance signal and outputs a burst gate pulse (hereinafter referred to as B
It outputs a GP pulse) or a composite sync signal. Reference numeral 15c is a color signal processing unit, 15d is a 1H delay processing unit that delays the output of the color signal processing unit 15c for a period of 1H, and 15e is an output of the color signal processing unit 15c delayed for a period of 1H or not delayed for a period of 1H. A switch circuit that selects one of the outputs of the color signal processing unit 15c based on a color correction pulse (C) described later.
An adder 5f synthesizes the output of the luminance signal processor 15b and the output of the color signal processor 15c.

Reference numeral 16 is a skew detecting circuit (skew distortion detecting means), which is a circuit for detecting skew and eliminating noise pulses. The inverter circuits 16d and 16e are diodes 16a, 16b and 16c. R1 and C1 form a first integrating circuit having a predetermined time constant, and R1
2 and C2 form a second integration circuit having a predetermined time constant. Reference numeral 100 denotes a correction pulse generation circuit (correction pulse generation means having a switching control means) integrated into one chip. The correction pulse generation circuit 100 includes a control unit 99.
(A microcomputer having a switching control means). As will be described below, the switch switching control is performed in correspondence with various special reproductions by two heads and various special reproductions by four heads. The correction pulse generation circuit 100 will be described below. Here, 48 is a switch circuit that is switched under a predetermined condition by the control circuit 99 (switch control means of the microcomputer), and 49 is a switch circuit that is similarly switched under a predetermined condition.

Reference numeral 50 is a 4-head switch signal circuit to which a skew detection pulse signal delayed by one frame is supplied,
Reference numeral 51 is a data selector for selecting and outputting the input 8-bit data D0 to D7, and 52 and 53 are 1/2 frequency dividing circuits. Reference numeral 54 is a switch circuit which is switched by the control circuit 99 under a predetermined condition, and 55, 56 and 57 are switch circuits which are similarly switched under a predetermined condition.
The skew correction pulses (A) and (B) and the color correction pulse (C) are generated respectively. Switch circuits 48, 4
9, 54, 55, 56, 57 are identification codes g, h,
d, a, b, c are attached.

FIG. 6 shows 200 bits and a clock frequency of 5.
FIG. 2 is a block diagram showing a configuration of a 1-frame delay circuit 17 operating at KHz, in which 61 is a delay circuit delaying 141 bits of a skew detection pulse, 62 is a delay circuit delaying 34 bits of a skew detection pulse,
Reference numeral 63 is a switch for switching in accordance with the PAL system or NTSC system, 64 to 67 are delay circuits for delaying 5 bits of the skew detection pulse, 68 and 73 are switch circuits which are switched by the control circuit 99 under a predetermined condition,
Reference numeral 69 is a delay circuit that delays the skew detection pulse by 2 bits, and reference numerals 70 to 72 are delay circuits that delay the skew detection pulse by 1 bit. The switch circuits 68 and 73 are provided with identification codes e and f, respectively.

FIG. 9 shows 160 bits and clock frequency 4K.
FIG. 8 is a block diagram showing a configuration of a 1-frame delay circuit 17 operating at Hz, in which 81 is a delay circuit that delays 113 bits of the skew detection pulse, 82 is a delay circuit that delays 27 bits of the skew detection pulse, and 8
Reference numeral 3 is a switch for switching in accordance with the PAL system or NTSC system, 84 to 87 are delay circuits for delaying 4 bits of the skew detection pulse, 88 and 93 are switch circuits which are switched by the control circuit 99 under a predetermined condition, 8
Reference numerals 9 to 92 are delay circuits that delay one bit of the skew detection pulse. The switch circuits 88 and 93 are provided with identification signals e and f, respectively.

FIG. 7 is a circuit diagram of the switch circuits 55, 56, 57, 54, 68 (88), 73, and 73 shown in FIGS.
(93), 48, and 49 when the control circuit 99 switches the switching contents of each switch circuit.
It is a switching operation explanatory view shown by the switching terminals from to h.
Further, FIG. 8 shows the data selector 51 shown in FIG. 5 during the FF search operation, the REW search operation, and the steel reproduction operation (when the gap between the SP head and the LP head is 2H gap).
6 is a data content explanatory diagram showing data content supplied to data input terminals D0 to D7 of FIG. Reference numeral 18 is an OR circuit for performing a logical sum operation of the output of the 1-frame delay circuit 17 and the output of the skew detection circuit 16, and 19 is an AND circuit for performing a logical product operation of the output of the 1-frame delay circuit 17 and the output of the skew detection circuit 16. Circuit. 21 and 22 are 1 /
It is a divide-by-2 circuit. 23 is a 0.5H delay circuit, 24
Is a switch circuit that is switched by the skew correction pulse (B).

FIG. 2 is a timing chart showing the operation waveforms of the respective parts of the skew detection circuit 16. The operation waveforms (a), (b), (c) ... Shown in FIG. 2 are shown in FIG. It corresponds to the operation waveforms of the respective parts to which the same reference numerals are attached in the skew detection circuit 16 and the like.

The operation is as follows. Normally, the brightness of the BGP pulse as shown in FIG.
When the pulse is output from the color signal processing circuit 15 and the skew point is included in the pulse, the cycle is 1.5H.
And become longer. This BGP pulse is a skew detection circuit 16
2 and is inverted by the inverter circuit 16a to have a pulse waveform as shown in FIG. The output of the inverter circuit 16a shown in (b) of FIG. 2 is input to the inverter circuit 16b as it is during the'L 'level period by the diode 16d, whereas the diode 16d becomes non-conductive during the'H' level period. Therefore, the potential on the input side of the inverter circuit 16b when the level of the BGP pulse changes from "L" level to "H" level rises with the time constant of C1.R1 as shown in (b) of FIG. This C1 ・ R
Since the time constant of 1 is set to a value capable of discriminating the 1H cycle and the 1.5H cycle of the BGP pulse with respect to the threshold value (Vcc / 2), when the BGP pulse reaches the 1.5H cycle, the input of the inverter circuit 16b is input. When the potential on the side exceeds the threshold value TH, an'L 'level pulse signal appears at the output of the inverter circuit 16b as shown in FIG.

This pulse signal is applied to the inverter circuit 16b, the diodes 16e and C which operate in the same manner as described above.
The second integrator circuit having a time constant of 2 · R2 removes and shapes noise pulses and the like generated subsequently to the pulse signal of FIG. 2C, and the inverter circuit 16c
Is output as a skew distortion detection pulse as shown in FIG.

This skew distortion detection pulse signal is a correction pulse generation pulse generation circuit 10 integrated into one chip.
0, and is first supplied to the 1-frame delay circuit 17 to which a delay time of 1 frame is added.
Is supplied to one input terminal of the AND circuit 19. A skew distortion detection pulse signal that does not pass through the 1-frame delay circuit 17 is supplied to the other input terminals of the OR circuit 18 and the AND circuit 19. A new skew detection pulse obtained at the terminal 1 of the switch 48 by the logical sum operation of the skew detection pulse signal with a delay time of one frame and the skew detection pulse signal without a delay time of one frame The signal is supplied, and the terminal 2 of the switch 48 is obtained by the logical product operation of the skew detection pulse signal to which the delay time of 1 frame is added and the skew detection pulse signal to which the delay time of 1 frame is not added. A new skew detection pulse signal is supplied. On the other hand, the correction pulse generating circuit 100 is controlled by its control circuit 99, and in the case of the two-head system (here, described as an FF search by two heads), a =
1, b = 3, c = 2, d = 2, e = 1, f = 1, g =
1, h = 3. This state is shown in FIG. Further, in the case of steel by two heads, g = 2 and h = 2, and the others are the same as the FF search.

Here, correction of an erroneous detection pulse due to scratches on the tape or instability of head sliding which may occur in the skew detection pulse signal during the steel reproducing operation will be described. FIG. 3 is a timing chart for explaining the correcting action of the generated false detection pulse,
Reference numeral 31 indicates an erroneous detection pulse generated in the skew detection pulse signal. Further, (e) in the figure shows the skew detection pulse signal delayed by one frame, and (f) in the figure shows the result of the AND operation of both the skew detection pulse signals shown in (d) and (e) in the figure. This new skew detection pulse signal is switched to the steal side which is the terminal 2 of the switch 48 circuit. As a result, the AND operation is performed to eliminate the erroneous detection pulse 31 and correct it to the original skew detection pulse signal. .

Further, FIG. 4 is a timing chart for explaining the correction operation of the pulse dropout which may occur during the search reproduction operation. In this case, it is switched to the search side which is the terminal 1 of the switch circuit 48. result,
The logical sum operation processing is performed, and the missing pulse is interpolated and corrected to the original skew detection pulse signal as shown in FIG.

The skew distortion detection pulse signal thus corrected is divided by the 1/2 divider circuits 21 and 22 and the output of the 1/2 divider circuit 21 is supplied to the switch circuit 56 as a skew correction pulse. Then, the skew correction signal (B) controls the switch circuit 24 to perform skew correction. The output of the 1/2 frequency dividing circuit 22 is supplied to the switch circuit 15e as a color correction pulse (C) via the switch circuit 57 and controls the switch circuit 15e to perform color correction.

Next, the second embodiment will be described. Figure 5
FIG. 4 is a block diagram showing the configuration of an H-sequence discontinuous point image quality correction pulse generation circuit of the magnetic reproducing apparatus of the present embodiment. This example shows a configuration for special reproduction by four heads. 5, parts that are the same as or correspond to those in FIG. 1 are assigned the same reference numerals and explanations thereof are omitted.

In the figure, reference numeral 41 indicates a pair of an LP mode (double time long time mode) head and an SP mode (standard mode) head, each pair having an angular interval of 180 ° and each pair of LPs. The SP head and the SP head are video heads having four heads arranged in a cylinder with a predetermined close angular distance. Reference numeral 42 is a head changeover switch, and 43 is a head amplifier for amplifying the read video signal. 44 is a 0.75H delay unit that delays the output of the addition unit 15f by 0.75H, 45 is a 0.5H delay unit that delays the output of the addition unit 15f by 0.5H, and 46 is the addition unit 1
This is a 0.25H delay unit that delays the output of 5f by 0.25H. Reference numeral 47 is an analog switch circuit that can be switched based on the skew correction pulses (A) and (B). Reference numeral 100 denotes a correction pulse generation circuit, which is a circuit integrated into one chip, which is exactly the same as the correction pulse generation circuit described in the first embodiment. Switch circuits 54, 55, 56, 5 in this
7 is switched by the control circuit 99 under predetermined conditions. The switch circuits 48 and 49 are irrelevant. Reference numeral 28 denotes a noise pulse removing circuit (noise pulse removing means), which is a circuit for removing noise pulses contained in the envelope pulse output from the head amplifier of the 4-head system. First comparator 28a, second comparator 28b, third comparator
The comparator 28c, a filter circuit including a resistor R and a capacitor C, and a Schmitt circuit 28d. In this Schmitt circuit 28d, the higher threshold value is set to a and the lower threshold value is set to b.

The operation is as follows. First, as shown in the timing chart of FIG. 14, the envelope pulse output from the 4-head amplifier includes an unnecessary pulse due to scratches on the tape or instability of head sliding, and the inverted input of the first comparator 28a. Is supplied to the terminals,
The output of the first comparator 28a has a signal waveform having unnecessary pulses 28e, 28f, 28g having different polarities as shown in FIG. The output waveform of the first comparator 28a is filtered by the filter circuit of the resistor R and the capacitor C to remove noise and the narrow pulse portion 28e of the'L 'level, and is inverted by the second comparator 28b. The signal waveform is as shown in. At the same time, the output waveform of the first comparator 28a is removed by noise due to the filter circuit of the resistor R and the capacitor C and the narrow pulse portion 28f of the'H 'level, and further inverted by the third comparator 28c. And the signal waveform shown in FIG.

The signal waveforms shown in and of FIG. 14 are supplied to the Schmitt circuit 28d (in the same figure), processed by the threshold value a and the threshold value b, and inverted to generate the noise shown in the same figure. It becomes the removed signal waveform. This signal is supplied to the 1-frame delay circuit 17 in FIG. 5, and its output is passed through the switch circuit 54, the skew correction pulse (A), and the skew correction pulse (B) via the 1/2 frequency dividing circuit 52. Is output. Further, it is supplied to the data selector 51. On the other hand, the data selector 51 to which the respective signals have been input via the 1-frame delay circuit 17 and the 1/2 frequency dividing circuits 52, 53 generates a color correction pulse from these 3 signals and outputs the color correction pulse to the switching circuit 15e via the switch circuit 57. A correction pulse (C) is sent to perform correction.

[0030]

As described above, according to the present invention, the following effects can be obtained. (1) 1 for any magnetic reproducing device of various special reproduction by 2 heads and various special reproduction by 4 heads
The same H sequence discontinuous point image quality correction pulse generation circuit integrated in a chip may be used, and since correction pulses corresponding to various special reproduction systems of 2 heads and 4 heads can be generated by the switching control means, assembly and manufacturing are performed. ， Adjustment can be simplified and a high quality product with high reliability can be obtained, and the manufacturing cost can be reduced. (2) In the case of special reproduction by two heads, the skew distortion detection signal from which the noise pulse is removed from the burst gate pulse or the composite sync signal pulse from the luminance / color signal processing circuit is input to generate the correction pulse, so that the reliability is high. High quality image can be corrected. (3) In the case of special reproduction with 4 heads, noise is removed from the envelope pulse output from the head amplifiers of the SP head and LP head, and the signal is input to generate a correction pulse. High image quality can be corrected. (4) In the case of special reproduction with two heads, the skew distortion detection signal is delayed by one frame, and a logical product is obtained in the case of steal special reproduction, and a logical sum is obtained in the case of search special reproduction. Since the correction pulse is generated from the signal, it is effective for correcting noise and omission of the signal and correcting the image quality with higher reliability.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an H-sequence discontinuous point image quality correction pulse generation circuit of a magnetic reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing a skew point detection operation in the H-sequence discontinuous point image quality correction pulse generation circuit of the magnetic reproducing apparatus according to the first embodiment of the present invention.

FIG. 3 is a timing chart showing a correction operation of a skew point detection pulse signal in the H-sequence discontinuous point image quality correction pulse generation circuit of the magnetic reproducing apparatus according to the first embodiment of the present invention.

FIG. 4 is a timing chart showing a correction operation of a skew point detection pulse signal in the H-sequence discontinuous point image quality correction pulse generation circuit of the magnetic reproducing apparatus according to the first embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of an H-sequence discontinuous point image quality correction pulse generation circuit of a magnetic reproducing apparatus according to a second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a 1-frame delay circuit of an H-sequence discontinuous point image quality correction pulse generation circuit of a magnetic reproducing apparatus according to a second embodiment of the present invention.

FIG. 7 is a switching operation explanatory diagram showing the switching contents of each switch circuit when the control circuit switches the switch circuits in FIGS. 5, 6, and 9 by the switching terminals of the respective switch circuits a to h.

8 is a data content explanatory diagram showing the data content supplied to the data input terminals D0 to D7 of the data selector shown in FIG. 5 during the FF search operation, the REW search operation, and the steal reproduction operation (during the 2H gap). .

FIG. 9 is a block diagram showing the configuration of another embodiment of the 1-frame delay circuit 17 used.

FIG. 10 is a circuit diagram showing a configuration of a conventional H-sequence discontinuous point image quality correction pulse generation circuit.

FIG. 11 is an explanatory diagram showing tracks in which “H order” is maintained and tracks in which “H order” is not maintained.

FIG. 12 is an explanatory diagram of a 4-head system.

FIG. 13 is an explanatory diagram of envelope pulses.

FIG. 14 is an explanatory diagram of noise pulse removing means.

[Explanation of symbols]

11, 12, 41 Video head 14, 43 Head amplifier 15 Luminance / color signal processing circuit 16 Skew detection circuit (skew distortion detection means) 17 1 frame delay circuit 18 OR circuit (correction means) 19 AND circuit (correction means) 28 Noise Pulse removal circuit (noise pulse removal means) 48, 49, 54, 55, 56, 57, 68, 73, 8
8, 93 switch circuit 99 control circuit (switch control means) 100 correction pulse generation circuit (correction pulse generation means)

Claims (3)

[Claims] 1. A recording position of a horizontal synchronizing signal between adjacent video signal recording tracks is deviated, and various special information such as searching or stealing information recorded on the tracks where the "H alignment" is not maintained. An H sequence discontinuity image quality correction pulse generating circuit of a magnetic reproducing apparatus provided with a skew distortion and color correction pulse generating means for correcting the distortion of image quality and the color skip that occur when reproducing, the correction pulse generating means A magnetic reproducing apparatus characterized by being provided with a switching control means for generating a correction pulse corresponding to each of the various special reproductions by two heads or four heads and being integrated in one chip. H-arranged discontinuous point image quality correction pulse generation circuit. 2. The H-sequence discontinuity point image quality correction pulse generation circuit of the magnetic reproduction apparatus according to claim 1, wherein the correction pulse generation means outputs from the luminance / color signal processing circuit when performing special reproduction by two heads. A skew distortion detection signal from which a noise pulse has been removed by a skew distortion detection means is input from a burst gate pulse or composite sync signal pulse to be generated to generate a correction pulse, while a special mode head is used when performing special reproduction by four heads. And a H-sequence discontinuity point of a magnetic reproducing apparatus characterized in that a correction pulse is generated by inputting a pulse signal from which noise has been removed by noise pulse removal means from an envelope pulse output from a head amplifier for a long time mode head. Image quality correction pulse generation circuit. 3. The H-sequence discontinuity point image quality correction pulse generation circuit of the magnetic reproduction apparatus according to claim 2, wherein the correction pulse generation means performs special reproduction by two heads,
The skew distortion detection signal is provided with a skew distortion detection correction means for correcting the skew distortion detection signal pulse to a new skew distortion detection signal pulse obtained by performing a logical product operation or a logical sum operation with the pulse delayed by one frame. An H-sequence discontinuous point image quality correction pulse generation circuit of the characteristic magnetic reproducing apparatus.