JPS60117440A - Capstan motor controller of video tape recorder - Google Patents

Abstract

PURPOSE:To stop a video tape accurately and quickly in an ideal position for still picture reproducing by setting preliminarily motor control signals corresponding to positional relations between a video head and the video tape and controlling a capstan motor driving part with these motor control signals. CONSTITUTION:When the still picture reproducing operation is performed, a pause signal is transmitted from a system controlling computer in a video tape recorder to a normal/variable speed reproducing switching circuit (n). Then, the normal/variable speed reproducing switching circuit (n) transmits a servo switching signal to a capstan motor driving circuit (j) a certain time behind the fall of the first pulse of the control signal after input of this pause signal. When receiving this servo switching signal, a brake pulse generating circuit (o) transmits a brake pulse to the capstan motor driving circuit (j) and causes the capstan motor driving circuit (j) to stop a motor M. The generation timing and the pulse width of this brake signal J are so set and adjusted that the video tape is stopped a little before a position most suitable for still picture reproducing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a new capstan motor control device for a video tape recorder, and in particular to a video tape recorder that controls a capstan motor to perform variable speed playback without producing noise. The present invention aims to provide a new capstan motor control device for a video tape recorder that requires few adjustment points to obtain optimum variable speed playback conditions, has a small number of parts, and is inexpensive. be.

Background Art and Problems When playing back stills using a home video tape recorder, the running of the video tape is stopped and the drum provided with the video head is normally rotated for playback. In that case, the track on which one field's worth of image information is recorded and the trajectory of the video head will inevitably not be parallel to each other as shown in FIG. 1, but the trajectory of the video head (indicated by the broken line in the figure).

) is inclined at an angle closer to the tape running direction than the track Tra. In a three-head type video tape recorder equipped with an auxiliary head for variable speed playback, one main head vHa and the other main head VHb have a predetermined minute gap (electrically One track is alternately scanned by a variable speed playback auxiliary head (the head azimuth angle is the same as the head azimuth angle of the one main head VHa) which are arranged close to each other with an interval of .25H (for example, 556 pm). However, in this case, it is inevitable that the head scans adjacent tracks with different azimuths. Then, the portion where tracks with different azimuths are scanned becomes noise on the screen. Therefore, it is necessary to make sure that the noise appears during the blanking period, and never to appear at least near the center of the screen in the vertical direction. must be scanned by the video head.

Therefore, the positional relationship between the video tape track and the video head is a factor that determines whether or not variable speed playback can be performed well. It must be stopped so that the above-mentioned positional relationship is achieved.

A capstan motor control device that controls the capstan motor to enable noise-free steel playback has generally been constructed of a special discrete circuit. FIG. 3 shows an example of such a capstan motor control device, and FIG. 4 is a time chart thereof.

In FIG. 1, a and a are preamplifiers that amplify the reproduced signal from the video head, and b are two preamplifiers a and RF switching that receives the reproduced signal from a and is controlled by an RF switching signal to be described later. This is a switcher that outputs the reproduction signal specified by the signal. C is a pulse generator provided in the drum motor (not shown), which generates one pulse signal every time the drum motor rotates once. The frequency of that signal is 30Hz. d is an RF switching signal generation circuit that outputs an RF switching signal based on the signal output from the pulse generator C, and the RF switching signal is inputted as a switching signal to the switcher b, as described above. e is switcher
b is a dropout compensation circuit for compensating for dropouts in the reproduced signal outputted from b, f is a limiter for removing level fluctuations in the reproduced signal, and g is an FM demodulator for FM demodulating the reproduced signal.

h is a step pulse circuit that receives an RF switching signal and generates a step pulse having a frequency that is one-fourth of the frequency of the RF switching signal, and the step pulse outputted from the step pulse circuit is passed through a normally closed switching circuit i. It is input to the capstan motor drive circuit j. k is a waveform shaping circuit that receives an RF switching signal and generates a noise position signal having a certain phase difference from it; 1 is a phase comparator that compares the phase of the noise position signal with a noise pulse, which will be described later; The output signal of device 1 is
The signal is input to the normally closed switching circuit i as a switching signal and is used as a signal for head switching from head VHb to head VHc. The noise pulse whose phase is compared with the noise position signal in the phase comparator l is obtained by shaping the noise detection signal detected by the dropout detection circuit of the dropout compensation circuit e by a waveform shaping circuit m. That is, the dropout compensation circuit e reproduces a signal one horizontal period before when a dropout occurs in the reproduced signal, and includes a dropout detection circuit that detects noise occurring during horizontal scanning. ing. Therefore, noise can be detected by this dropout detection circuit, and the position on the screen where a noise band occurs (in the vertical direction position) can be detected. Therefore, the waveform of the noise pulse outputted from the dropout detection circuit in the dropout compensation circuit e is shaped, and the phase of the waveform-shaped noise pulse and the noise position signal is compared.

The phase comparator 1 outputs a "high" output signal when both the noise position signal and the noise pulse are "high" to open the normally-closed switching circuit I, and the step pulse outputs a "high" output signal to open the normally closed switching circuit I. Prevent it from being input to j. Also, head HVb and head V
As described above, head switching between the head and the Hc is also performed.

n is a normal/variable speed playback switching circuit that switches between normal playback and variable speed playback; When a playback operation is performed, a pause signal is received from the system control computer. When the pause signal is received, a servo switching signal is sent to the capstan motor drive circuit j after a predetermined time delay from the control signal. This servo switching signal is a signal for performing servo switching between normal playback and variable speed playback. O is a brake pulse generation circuit which receives the servo switching signal and sends a brake pulse signal to the capstan motor drive circuit j. Mt±capstan motor.

The operation of this capstan motor drive device will be briefly explained as follows.

During normal reproduction, the normally closed switching circuit i maintains a closed state and sends the step pulse output from the step pulse circuit to the capstan motor drive circuit j. Therefore, during normal reproduction, the capstan motor drive circuit j continues to drive the motor M under the control of the step pulse. Therefore, the videotape is running at normal running speed.

When a still playback operation is performed, normal/
A pause signal is transmitted to the variable speed reproduction switching circuit n. Then, the normal/variable speed reproduction switching circuit n sends a servo switching signal to the capstan motor drive circuit j with a certain time delay from the fall of the first pulse of the control signal after inputting the pause signal. When the brake pulse generation circuit 0 receives the servo switching signal, it sends a brake pulse to the capstan motor drive circuit j, causing the capstan motor drive circuit j to stop the motor M. The generation timing and pulse width of this brake signal J are set and adjusted so that the video tape can be brought to a near stop in front of the other party at the optimum position for still playback. Therefore, by the functions of the normal/variable speed playback switching circuit n and the brake pulse generation circuit 0, the videotape is decelerated to a substantially stopped state near the optimal position for still playback.

When the videotape is decelerated in this manner, the phase of the noise pulse output from the dropout compensation circuit e and waveform-shaped by the waveform shaping circuit m gradually changes to match the phase of the noise position signal. This is because the phase of the noise position signal is set and adjusted so that it occurs at the same timing as the noise pulse when the optimal conditions for still playback are established, and the videotape is slowed down to play stills. As the optimum position approaches, the phase of the nozzle pulse naturally approaches the phase of the noise position signal. When the phases match, a switching signal is sent from the phase comparator 1 to the switching circuit i, and the switching circuit I becomes open as shown by the two-dot chain line in FIG. Then, the transmission of the step pulse to the capstan motor drive circuit j is blocked by the switching circuit i, and the videotape is stopped at approximately the optimum position for still playback. At the same time, Video Head VHa
and VHb, the video head VH
The state is switched to a state where playback is performed using a and VHc, that is, the video head is switched, and still playback is performed.

As described above, the capstan motor is controlled using a discrete circuit, but this requires a large number of parts, increases the board area of the circuit, and increases cost. Moreover, there are many objects to be adjusted with great accuracy, such as the phase difference between the control signal and the servo switching signal when a pause signal is input, the pulse width of the servo switching signal, etc., and the time required for adjustment is long. Furthermore, if the characteristics of the motor or other component parts change over time, this will lead to the same result as poor adjustment, making it impossible to regenerate the steel properly.

Purpose of the Invention The present invention has been made to solve the above-mentioned problems, and it is possible to stop the videotape at the optimal still playback position without producing noise, regardless of variations in motor characteristics during variable speed playback, and to adjust the adjustment points. The object of the present invention is to provide a new capstan motor control device for a video tape recorder which has a small number of parts, a small number of parts, and a low manufacturing cost.

SUMMARY OF THE INVENTION A capstan motor control device for a video tape recorder according to the present invention that achieves the above objects includes a head position detection means for detecting the position of a video head, a noise detection means for detecting noise generated on a screen, and a microprocessor. , and a capstan motor drive unit that drives the capstan motor according to the contents of the received motor control signal, and when a variable speed regeneration command is issued, the microprocessor detects the noise detection means based on the detection results of the whine detection means and the noise detection means. A preset motor control signal corresponding to the obtained positional relationship between the video head and the video tape is received, and the motor control signal is sent to the capstan motor drive circuit. It is something.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Below, a capstan motor control device for a video tape recorder according to the present invention will be explained in detail according to embodiments shown in the accompanying drawings.

FIG. 5 shows an example of the implementation of the capstan motor control device for a video cheap recorder according to the present invention. Switcher 13 is a pulse generator provided in a drum motor (not shown); 4 is an R, F switching signal generation circuit that generates an RF switching signal in response to a signal output from the pulse generator 3; -2 is input as a switching signal. Reference numeral 5 denotes a dropout compensation circuit for compensating for dropouts of the reproduced signal that has passed through the switcher 2, 6 a limiter for removing level fluctuations in the reproduced signal, and 7 an FM demodulator for FM demodulating the reproduced signal.

Reference numeral 8 denotes a waveform shaping circuit that shapes the waveform of a noise pulse output from a dropout detection circuit (not shown) inside the dropout compensation circuit 5.

Reference numeral 9 denotes a system control microcomputer provided inside the video tape recorder, which performs various controls for the video tape recorder including control of the capstan motor M. 10 is CPU, 11 is ROM, CPU
A table is stored in a partial area 12 in which programs executed by l0 and basic data are stored. This table shows the phase difference between the noise pulse waveform-shaped by the waveform shaping circuit 8 and the RF switching signal output from the RF switching signal generation circuit 4, whose phases are compared in the phase comparator described later. It stores data that specifies the pulse width of the corresponding drive output and running direction output, which will be described later.When an address signal corresponding to the above phase difference is received, the pulse width of the drive output and running direction output corresponding to that phase difference is stored. Output the specified data.

13 is a RAM; 14 is an input circuit into which signals from the power switch, other various sensors, remote controllers, etc. are input; 15 is a key decoder that decodes key signals from the key matrix 16; 17 is a partial area of the RAM 13; 18 is a timer located in another area of the same RAM 13, and 19 is an output circuit that outputs various signals including drive output, running direction output, normal steel switching signal, and head switching signal.

20 and 21 are switching circuits for normal steel switching, both of which receive the normal steel switching signal from the microcomputer 9 as a switching signal. The switching circuit 20 receives the drive output from the microcomputer 9 at the normal oven switching terminal, and the normal capstan servo unit 2 at the normal close switching terminal.
It receives the drive output from the capstan motor drive circuit 23 and sends out the drive output from the common terminal to the capstan motor drive circuit 23. On the other hand, the switching circuit 21 receives a running direction output at a normally open switching terminal, receives a voltage E at a normally closed switching terminal, and sends a running direction output to the campstan motor drive circuit 23 from a common terminal.

The normal capstan servo unit 22 is for running the videotape in a normal direction at a normal speed.
The capstan receives the control signal reproduced by the control head 24, the signal from the pulse generator 3, and the signal from the frequency generator 25 of the motor M, and runs the videotape at normal speed in synchronization with the reproduced control signal. The motor drive circuit 23 can be controlled. Further, the capstan motor drive circuit 23 receives the drive output and the running direction output, and when the drive output is "low J", it rotates the capstan motor M in the direction according to the content of the running direction output, and the drive output is "low J". It works to stop the motor M when it is "high". still,
When the running direction output is "High J", the videotape is run in the normal playback direction, and when it is "Low J", the video tape is run in the opposite direction.

The operation of the capstan motor control device for a video tape recorder will be described below with reference to the flowcharts shown in FIGS. 6 to 8 and the time chart shown in FIG. 9.

(B) "Has it been input?" When the video tape recorder's AC cord plug is inserted into the outlet, the program starts as shown in Figure 6, and a message "Has it been input?" appears to indicate whether or not the operation command has been input. Make a judgment.

If the judgment result is "no", this judgment is repeated5 until a judgment result of "yes" is obtained.

(B) "Is it switching from playback to steel?" If the judgment result of "Is there an input?" in step (a) is "Yes", the content of the operation command input is changed from normal playback mode to still playback mode. A determination is made as to whether or not the command is to switch from playback to steel.

(c) "Steal processing" If the result of the determination in step (b) "switching from playback to steal?" is ``yes'', the steal processing shown in detail in FIG. 7 is performed. When this steal processing is completed, the process returns to step (a).

(d) “Switching from still to playback?” Playback mode (
B) If the result of the judgment "Is it switching from playback to steel play?" is "No", it is determined whether the content of the operation command input is a command to switch from still playback to normal playback. A determination is made as to whether there is a switch from steal to playback.

6 (e) "Switching process from steal to playback" If the result of the determination in step (d) is "yes", the "switching process from steal to playback" shown in detail in FIG. 8 is performed. When this process is completed, the process returns to step (a).

(v) "General control" If the result of the judgment in step (d) "Is it switching from steal to playback?" is "No", step (
Performs general control over the video tape recorder except for the "still processing" in step (c) and the "switching process from still to playback" in step (e). When this ``general control'' is completed, the process returns to step (a) to determine ``is there an input?''.

Next, the steal processing will be explained in more detail according to FIG.

(g) "Switching various signals from normal to steal" If the result of the judgment of "Switching from playback to steal?" in step (b) of Figure 6 is "Yes", steal from the normal playback state. Processing of various signal switching required in advance when switching to the playback state, that is, "switching of various signals from normal to steel" is performed. Through this process, the normal steel switching signal is switched from "low" to "high" as shown in FIG. Then, the switching circuits 20 and 21 switch from a state in which their common terminals are connected to the normally closed terminal to a state in which they are connected to the normal oven terminal, and as a result, the capstan motor M is controlled by the normal capstan servo section 22. The state is changed from the state to the state controlled by the drive output and traveling direction output output by the microcomputer 9.

(H) "Reverse brake on capstan" In order to abruptly stop the capstan motor M, which is rotating at the normal speed and direction, the running direction output is switched from "high" to "low" and the capstan motor M is reverse reversed. The capstan motor M is abruptly stopped by generating torque in the direction. When the capstan motor M has completely stopped, the running direction output is switched from "low" to "high" to keep the capstan motor M in a stopped state. Tbra
k is the time during which the capstan motor M is braked.

(S) "Wait for a while after braking" Wait for a while after the capstan motor M has stopped.

(NU) "Drive output pulse counter set" Counter 17 to count the number of drive output pulses.
Initialize. This count of the number of pulses of the drive output is a count of the number of pulses of the drive output that are generated until a noise pulse occurs. The reason why the number of pulses of the drive output is counted in this way is to proceed with the program without waiting for the arrival of a noise pulse if a noise pulse does not occur even after the drive output has reached a preset number of pulses. . That is, in the process of transitioning from normal playback mode to still playback, a noise pulse is normally generated, and the phase relationship between the noise pulse and the RF switching signal is detected and the phase relationship is set to a predetermined relationship. It is used to adjust the tape stop position.
There is a possibility that a noise pulse is not generated from the dropout compensation circuit 5 due to a temporary failure or the like, or that even if a noise pulse is generated, it cannot be detected. If such a situation occurs, the progress of the program will stop at the step of waiting for the generation of a noise pulse, and as a result, there is a risk that the microcomputer's control function for the video cheap record will stop. Therefore, even if the number of drive output pulses reaches a certain number, for example 10 pulses, after inputting the steal command (normally, a noise pulse occurs after about 2 to 5 pulses), if no noise pulse occurs, wait for the generation of a noise pulse. This allows forcible head changes and other processing necessary for still playback to be performed without any effort.

Incidentally, in this step (N), the counter 17 is simply initialized, and the count-up is performed in a step a little later.

(Le) Is rRFSW falling? ” Determine whether the RF switching signal has fallen. If the result of the determination is "no", this determination is repeated until a "yes" determination result is obtained.

(wo) "Timer clear and start" Clear the timer 18 and start measuring time.

(Wa) “Is the noise pulse rising?” Determine whether a noise pulse has risen.

(Power) "Timer stop" When the result of the determination in step (W) "Is the noise pulse rising?" is "Yes", the time measurement by the timer 18 is stopped.

(Y) "Read timer value (T)" Read out the time T measured by the timer 18. This time T indicates the phase difference between the RF switching signal and the noise pulse.

(ri)rT=Tst i L? J It is determined whether the time T measured by the timer 18 has become equal to the time difference Tst1t between the falling edge of the RF switching signal and the noise pulse in the case optimal for still playback.

(shi) [Head change and other steel regeneration processing] Step (ri) rT=Ts i t L? If the result of the J judgment is "Yes", it can be said that the video tape is at the appropriate position for still playback, so the video head VH
Performs switching from b to VHc (head change) and other processes necessary for still playback.

(n) "Read out the pulse width according to the timer value T from the table" If the result of the judgment in step (ri) is [NO], that is,
If the phase relationship between the RF switching signal and the noise pulse is not optimal for steel playback, use Table 12 of ROMII to specify the pulse width of the drive output and running output corresponding to that phase relationship. read out.

3 (TS) Is rRFSW falling? ” If the result of the determination “Is the noise pulse rising?” in step (wa) is “NO”, it is determined whether the RF swifting signal has fallen. If the result of the determination is "no", the process returns to step (wa).

(n) "Read the minimum pulse width from the table." If the result of the judgment in step (t) is "yes" (this is not corrected, but the minimum pulse width is read from the falling edge of the RF switching signal detected in step (l)). (This is a case where the noise pulse that was supposed to be output does not appear before one cycle of the RF switching signal has elapsed.), it is assumed that the noise pulse has risen, and the pulse width of the drive output and the pulse width of the traveling direction output are Among the data specifying the minimum pulse width, the data specifying the minimum pulse width is read from the table 12 of the ROMII.

(S) “Drive output pulse counter +l” step (
When step (N) or step (N) is completed, the counter 18 for live output pulse count is set to rlJ.
Count up. The reason for this counting is as described in the explanation of step (nu).

(U) [Is it over the limit? ” It is determined whether the count value of the counter 18 has reached a preset count value, for example “10”. If the determination result is "yes", the processing in step (b) is performed and still playback begins.

(M) "Drive output" ROMII also sends out a drive output with a pulse width corresponding to the phase relationship between the RF switching signal and the noise pulse according to the data read from Table 12, and furthermore, sends out a running direction output with a pulse width corresponding to it. . The rising timing from "low" to "high" of this running direction output is made to match the rising timing from "low" to "high" of the drive output, and by applying feed and then reversing, a certain amount Intermittent feeding is possible. By the way, R
The shorter the time T between the rise of the F switching signal and the rise of the noise pulse is than Tsil, the pulse width of the drive output (however, the pulse width of the drive output is
This refers to the amount of time that a "low" state continues. ) is wide, and the pulse width Tbrak of the running direction output (the pulse width of this running direction output also refers to the time during which it remains "low") is wide. The closer the time T is to TstiL, the narrower the pulse widths of the drive output and traveling direction output become. This means that the more the videotape position deviates from the optimal position for still playback, the larger the feed amount per step will be to quickly and roughly determine the position, so that the videotape position is optimal for still playback. This is to ensure highly accurate positioning by reducing the amount of travel in one run as the position gets closer.

Next, the "switching process from steal to playback" in step (e) of FIG. 6 will be explained with reference to FIG. 8.

(T) Is rRFSW falling? ” When the steal release command is input, it is determined whether the RF switching signal has fallen. If the result of the judgment is "No", the judgment is repeated until the judgment result of "Yes" is obtained. (1) "Timer Start" Is the rRFS data W falling of step (two)? If the result of the determination is "yes", the timer 18 measures the time. Measurement of this time allows switching from the still playback state to the normal playback state to be performed in synchronization with the RF switch signal so that no noise occurs when switching from the still playback state to the normal playback state. do it for the sake of

()) "Is it time over?" The time T measured by the timer 18 is the preset T
Determine whether c1ela has been exceeded. The time Tdata is selected as the time required to reach the most favorable state for switching from still playback to normal playback after the fall of the RF switching signal.

7 (e) "Switching various signals of the drying basin from steel to normal" If a "yes" judgment result is obtained in step ()), the steel state is switched. This switching includes the normal steel switching signal and switching the drive output from "high" to "low", and also includes the switching of the normal steel switching signal and the drive output from "high" to "low".
This also includes switching the head switching signal from "high" to "low" for switching from Hc to VHb. However, this head switching is performed in synchronization with the next falling edge of the RF switching signal detected in step (2).

As mentioned above, in the capstan motor control device of this videotape recorder, the feed amount of the step feed of the videotape is changed by changing the pulse width of the drive output and accordingly changing the pulse width of the running direction output. is changed according to the phase relationship between the RF switching signal and the noise pulse, and if the phase relationship deviates from the optimum phase relationship for steel playback, increase the amount of step feed to reduce the deviation. Accordingly, the amount of feed can be reduced. In other words, the videotape can be stepped in accordance with the phase relationship between the RF switching signal and the noise pulse. Incidentally, if there is a deviation that causes the optimum steel regeneration position to go too far, it can be returned to the optimum steel regeneration position by rotating the capstan motor M in the reverse direction.

Therefore, it is essential to wait until a point in time with a specific time relationship with the phase of the control signal to start the stopping operation, instead of starting the operation to stop the running of the videotape immediately upon receiving a steal command as in the conventional method. It is not necessary at all in the invention. Therefore, the videotape can be stopped at the ideal stopping position very quickly.

Furthermore, as long as the data specifying the pulse width of the drive output with respect to the phase relationship between the RF switching signal and the noise pulse is appropriate, good still playback can be expected, and no adjustment is required.

That is, in the capstan motor control device of a conventional video tape recorder, the timing and pulse width of the brake signal are set so that the video tape, which is running at a constant speed, can be stopped in front of the opponent at the ideal position for still playback. However, it is very troublesome to make good steel regeneration, and there is also the problem that the characteristics of the motor etc. become distorted over time. The capstan motor control device for a video tape recorder as shown avoids such problems.

Since the motor drive signal given to the capstan drive circuit is formed using a microcomputer,
The signals for controlling the motor can be formed using a system control microcomputer that controls the entire video tape recorder. In addition, the head position is detected by detecting the phase of the RF switching signal, and noise is detected by the drop-out detection circuit built into the drop-out compensation circuit. There is no need to provide a circuit.

It should be noted that so-called stop-motion playback can be performed by continuing this still playback, and slow-motion playback can be realized by alternately performing still playback and normal playback.

Modification Example In the above embodiment, the pulse width of the drive output and running direction output corresponding to the phase relationship between the RF switching signal and the noise pulse was read from the table 12 of ROMI 1. It is also possible to calculate the pulse width of the drive output, etc. corresponding to the phase relationship by calculating the phase relationship according to a predetermined calculation formula, instead of reading it from the .

Effects of the Invention As described above, the capstan motor control device for a video tape recorder of the present invention includes a head position detection means for detecting the position of the video head, a noise detection means for detecting noise generated on the screen, and a microcontroller. It consists of a processor and a capstan motor drive unit that drives a capstan motor according to the contents of a received motor control signal, and when a variable speed reproduction command is issued, the microprocessor detects the detection results of the position detection means and noise detection means. A preset motor control signal corresponding to the positional relationship between the video head and the video tape obtained from the above is received, and the motor control signal is sent to the capstan motor drive section. It is something to do.

Therefore, according to the present invention, the motor control signal corresponding to the positional relationship between the video head and the video tape is set in advance, and the capstan motor drive unit is controlled by the motor control signal corresponding to the positional relationship. There is no need to make any special adjustments, and the stopping operation can be started immediately without waiting for the stop operation to start until a point in time that has a special time relationship with the phase of the control signal. It is possible to accurately and quickly realize a state in which the videotape is stopped at an ideal stop position.

According to the present invention, since the capstan motor is controlled using a microprocessor, a microprocessor for controlling a video tape recorder can be used for controlling the capstan motor, and a capstan motor for still playback can be used for controlling the capstan motor. There is no need to provide a special circuit for control.

Therefore, it is possible to provide a capstan motor control device that has a small number of parts and is inexpensive.

[Brief explanation of drawings]

Figures 1 to 4 are for explaining the background technology.
FIG. 1 is a diagram showing the tracks of the video tape and the locus of the video head, and FIG. 2 is a diagram showing the arrangement of heads in a three-head system.
FIG. 3 is a block diagram showing an example of a conventional capstan motor control device for a video tape recorder, FIG. 4 is a time chart, and FIGS. 5 to 9 show a capstan motor control device for a video tape recorder according to the present invention. 2 shows an example of implementation, and FIG. 5 is a block diagram showing the circuit configuration of the device.
FIG. 6 is a flowchart showing an overview of the microprocessor, FIG. 7 is a flowchart showing a specific program for steal processing, FIG. 8 is a flowchart showing a specific program for switching from still to playback, and FIG. 9 is a flowchart showing various programs. It is a time chart showing signals. Explanation of symbols 3.4...Head position detection means, 5@.phi. noise detection means, 9...Microprocessor, 23...Capstan motor drive section, VH...Video head, M.
・・Cab stan motor JP-A-Sho GO-117440 (11)

Claims (1)

[Claims] (1) Head position detection means for detecting the position of the video head, noise detection means for detecting noise generated on the screen, a microprocessor, and a capstan that drives the capstan motor according to the contents of the received motor control signal. When a variable speed playback command is issued, the microprocessor sets a preset value corresponding to the positional relationship between the video head and the video tape obtained from the detection results of the position detection means and the noise detection means. A capstan motor control device for a video tape recorder, characterized in that the capstan motor control device for a video tape recorder is configured to receive a motor control signal generated by the user and send the motor control signal to the capstan motor drive section.