JP3286421B2 - Tracking adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking adjustment device such as a video tape recorder (VTR).

[0002]

2. Description of the Related Art Conventionally, tracking servo in a VTR is performed based on a reproduction control signal. However, when a video tape recorded by another VTR is reproduced, tracking adjustment may be shifted. For this reason, the delay time of the reproduction control signal or the reference signal corresponding to the rotation of the rotary head is changed by operating the tracking adjustment button provided on the operation panel, thereby performing the tracking adjustment.

Conventionally, as a tracking adjustment button, a rotary adjustment button for directly rotating a variable resistor or a slide adjustment button has been used. When a good reproduced image is obtained, the variable resistor is used. Center click point (default value)
The compatibility between the video tape and the VTR can be determined by reading how much the video tape deviates from the video tape. Also, when playing back a video tape recorded with its own VTR, the tracking value can be quickly set to the optimum value by returning the tracking adjustment button to the center click point.

In recent years, rotary or slide type adjustment buttons have poor operability, and in order to improve the operability, those having a tracking adjustment button constituted by a count-up button and a count-down button are often used. JP 6
3-52139). As shown in FIG. 5, the apparatus includes a count-up button 11 and a count-down button 12, and a counter 2 for storing a delay time set value, and a delay time set value output from the counter 2 is connected as an input signal. Microcomputer 4 that has been
It comprises a character generation circuit 7 controlled by the microcomputer 4, and a mixer 8 to which an output signal of the character generation circuit 7 and an input video signal from a video circuit system are connected, and which is output from the counter 2. The delay time setting value is sent to a mono multivibrator 5 for delaying a reference signal by a predetermined time via a D / R conversion circuit 3 for converting a digital value into a resistance value.

By operating the count-up button 11 or the count-down button 12, the delay time of the reference signal is adjusted, and the delay time set value stored in the counter 2 is output to the microcomputer 4 for processing. A display control signal corresponding to the value is created.

[0006] The horizontal synchronizing signal HS and the vertical synchronizing signal VS separated from the input video signal by the synchronizing separation circuit 6 are connected to a character generating circuit 7.
Based on the display control signal, a character information video signal to be displayed on a television screen is created and output to the mixer 8. The mixer 8 mixes the input video signal and the character information video signal, creates an output video signal in which a character signal representing a tracking value is multiplexed, and supplies the output video signal to the television receiver.

In the above apparatus, as shown in FIG. 6, the user can easily and quickly perform the tracking adjustment by operating the count-up button 11 and the count-down button 12 while looking at the display mark on the screen 21. it can.
The tracking value can be adjusted by referring to the display mark 22.

The portion indicated by 1 is constituted by a microcomputer.

[0009]

However, when the tracking adjustment is performed in the above device, the delay time set value is changed by operating the count-up button 11, for example.
If tracking adjustment could not be performed before reaching the upper limit of the adjustment range, the user had to operate the countdown button to change the delay time set value in the reverse direction to perform tracking adjustment. Therefore, there is a disadvantage that it takes time to find the best delay time setting value. Further, both the count-up button and the count-down button must be operated, which is very complicated and has poor operability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a tracking adjustment device capable of quickly performing tracking adjustment by only operating one of a count-up button and a count-down button. .

[0011]

According to the present invention, tracking control is performed by comparing the phase of a reproduction control signal from a video tape with a reference signal, and the delay time of the reproduction control signal or the reference signal is reduced by operating a button. A device that performs tracking adjustment by changing, based on the button operation, a delay time setting unit that changes a delay time set value in a direction to increase or decrease the delay amount, and when the button operation is started, A delay time storing means for storing the delay time set value at the time; and a means for detecting that the delay time set value has reached a predetermined adjustment range, wherein the delay time set value has reached a predetermined adjustment range. When the delay time is detected, the delay time is returned to the delay time set value stored in the delay time storage means and the delay time is decreased or increased. It is further provided a configuration control means for varying the value.

[0012]

According to the above configuration, the delay time set value is changed in one direction based on the operation of one of the count up button and the count down button, and the delay time set value at the time when the button operation is started is changed. Remember.

When it is detected that the delay time set value has reached the upper limit or the lower limit of the predetermined adjustment range, the stored delay time set value at the start of the button operation is returned to the stored delay time set value in the other direction. Since it can be changed, tracking adjustment can be performed in a short time and operability is improved.

[0014]

FIG. 1 shows an embodiment of the present invention, and the same parts as those in FIG.

FIG. 1 differs from FIG. 5 in that a storage circuit 15 for storing a delay time set value (hereinafter referred to as a count value) at the start of operation of a count-up button or a count-down button, and that the count value is adjusted to a predetermined value. The difference is that a control circuit 16 that detects the reaching of the range and controls the storage circuit 15 and the counter 2 is added. The portion indicated by 1 is constituted by a microcomputer.

Referring to FIG. 1, the count-up button 11 and the count-down button 12 are connected to the up / down counter 2 via a limiter 13 for defining an upper limit and a lower limit of the count. Here, the limiter 13 prohibits the up-count or down-count input when the output of the counter 2 matches the preset value “0” or “31”, which will be described later.

When the control circuit 16 detects the start of the operation of the count-up button or the count-down button from the output of the limiter, the current count value is stored in the storage circuit 15, and the control circuit 16 sets the count value in advance. Upon detecting that the upper or lower limit of the set adjustment range has been reached,
The count value stored in the storage circuit 15 is set in the counter 2 and the counting operation of the counter 2 is changed in the reverse direction.

An initial setting circuit 14 is connected to the counter 2, and by the operation of the circuit 14, the counter 2 is preset to an initial value serving as a center click point. The initial setting circuit 14 operates when power is supplied to the VTR, when a cassette tape is inserted and removed, and when a reset circuit (not shown) operates.

The count value output from the counter 2 is sent to the microcomputer 4 and
It is sent to the D / R conversion circuit 3. The D / R conversion circuit 3
For example, as shown in FIG. 4, analog switches S1 to S5 whose opening and closing are controlled by binary signals b1 to b5 output from the up / down counter 2, and resistors R1 to R5 divided and connected to both ends of each analog switch. R5, and each analog switch opens and closes according to the output signal of the counter 2. The counter 2 is preset to "15" by the initial setting circuit 14. Each resistance value based on R1 is R2 = 2 · R1, R3 = 4 · R1, R
4 = 8 · R1 and R5 = 16 · R1, and in the example, R was selected to be about 100 ohms.

Generally, it is sufficient for the tracking delay time to be ± 10 milliseconds from the center value. The change width may be about 1 millisecond. Further, the intermediate value of the counter 2 is set to “1”.
5 ", a variable width of ± 15 steps can be obtained. Therefore 1
It was designed to have a variation width of about 0.7 ms per step. When the counter 2 is "15", the delay time of the mono multi 5 is set to 33.3 milliseconds. 33.
Three milliseconds correspond to one cycle of the reproduction control signal.

By opening and closing the analog switch, a voltage signal corresponding to the magnitude of the delay time set value is output to the mono-multi 5. As a result, the reference signal connected to the mono-multi 5 is set in the counter 2. Delayed by time and supplied to a phase comparator (not shown) equipped in the speed servo,
Tracking adjustment is performed.

On the other hand, the delay time set value output to the microcomputer 4 is temporarily stored in the RAM. A data display program as shown in FIG. 6 is set in the RAM of the microcomputer 4.

Next, the operation of the present invention will be described with reference to the flowcharts of FIGS. This flowchart shows the operation when the count-up button is operated. That is, it is detected whether or not the count-up button 11 has been operated (step S1). When the operation has been detected, the current count value of the counter 2 is stored in the storage circuit 15 (step S2). And count up button 1
When 1 is continuously operated (step S3), the count value of the counter 2 is increased by one step (step S4) at a predetermined cycle (for example, 0.3 seconds), and the count value is converted into the D / R conversion circuit 3 (Step S5). D /
As described above, the R conversion circuit 3 outputs a voltage signal corresponding to the magnitude of the count value to the mono multi 5, and performs desired tracking adjustment. This operation is sequentially performed until the count value of the counter 2 becomes “31”. If a good reproduction is obtained until the count value becomes “31” or less, the operation of the count-up button 11 is terminated. By performing (Step S25), a good reproduced image can be seen.

When the count value of the counter 2 has reached "31", a timer circuit (not shown) operates (step S7), and the time during which the count-up button is operated is calculated as follows.
For example, when one second is counted (steps S8 and S9), the count value stored in the storage circuit 15 is set in the counter 2 (step S10). Here, the predetermined time is measured by the timer circuit so that the tracking adjustment operation is stably performed by the upper limit “31” of the count value.

When the count value stored in the storage circuit 15 is set in the counter 2, the timer circuit operates as described above (step S11), and the time during which the count-up button is operated is counted (step S11). S12, S1
3) Yes. Also in this case, the predetermined time is similarly set by the timer circuit so that when the count value of the counter 2 is returned to the value at the start of the count-up button operation as described above, the tracking adjustment is stably performed at that value. To do that.

Next, it is checked whether or not the count-up button 11 is continued (step S14), the count value of the counter 2 is reduced by one step at a predetermined cycle (step S15), and the count value is set to D / D. It is supplied to the R conversion circuit 3 (step S16). As described above, the D / R conversion circuit 3 performs desired tracking adjustment based on the count value. This operation is sequentially performed until the count value of the counter 2 becomes “0”, and if a satisfactory reproduction is obtained until the count value becomes “0”, the operation of the count-up button 11 is terminated ( By performing step S25), a good reproduced image can be viewed.

When the count value of the counter 2 reaches "0", the timer circuit operates (step S18), and when the time during which the count-up button is operated measures, for example, 1 second (step S19, S20), storage circuit 1
The count value stored in 5 is set in the counter 2 again (step S21).

The above operation can be repeated. However, when a good reproduced image cannot be obtained, the operation of the count-up button 11 is terminated when an appropriate reproduced image is obtained.

In the flowchart of this embodiment, the case where the count-up button 11 is operated has been described. However, when the count-down button 12 is operated, steps S1, S3,
The count-up button in S12, S14, S19, and S23 is changed to a count-down button.
Change the description of 5 one step down to one step up. Further, the upper limit value “31” in step S6 is set to the lower limit value “0”, and the lower limit value “0” in step S17 is set to the upper limit value “3”.
1 ".

In this embodiment, the count-up button 11
Although the countdown button 12 and the countdown button 12 are provided, the control may be performed by one countup button or one countdown button.

[0031]

According to the present invention, the delay time set value can be adjusted only by operating one of the count-up button and the count-down button, so that tracking adjustment can be performed quickly and operability is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of a tracking adjustment device embodying the present invention.

FIG. 2 is a flowchart of the operation of the present invention when the count-up button is operated.

FIG. 3 is a flowchart of the operation of the present invention when the count-up button is operated.

FIG. 4 is a diagram illustrating a D / R conversion circuit.

FIG. 5 is a main block diagram of a conventional tracking adjustment device.

FIG. 6 is a diagram showing a display screen of a tracking value of a conventional device.

[Explanation of symbols]

 Reference Signs List 11 count-up button 12 count-down button 15 storage circuit (delay time storage means) 16 control circuit 2 counter (delay time setting means) 3 D / R conversion circuit 5 mono-multi

Claims (1)

(57) [Claims] An apparatus for performing tracking servo by comparing the phase of a reproduction control signal from a video tape with a reference signal and performing tracking adjustment by changing a delay time of the reproduction control signal or the reference signal by operating a button. A delay time setting means for changing a delay time set value in a direction of increasing or decreasing a delay amount based on the button operation, and when the button operation is started, the delay time set value at that time is Delay time storage means for storing, and a means for detecting that the delay time set value has reached a predetermined adjustment range, when it is detected that the delay time set value has reached a predetermined adjustment range, A system for returning to the delay time set value stored in the delay time storage means and changing the delay time set value in a direction to decrease or increase the delay amount. Tracking adjustment apparatus characterized by further comprising means.