JPH0127517B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape position detecting device in a tape position detecting device in a magnetic recording/reproducing device using a magnetic tape as a recording medium. The purpose of this invention is to accurately detect with a simple configuration that the magnetic tape has been positioned again.

When automatically changing the mode at a certain tape position in a VTR, etc., for example, when inserting and editing a new image into a part of a tape that has already been recorded, set the insertion recording end point and set the end point. It is necessary to finish the insertion recording with high accuracy.

Conventionally, electronic counters used in VTRs and the like to display the tape position have two rotating counters that generate square wave pulses with different phases on the tape take-up reel or supply reel in accordance with the rotation of the reel. A detection device is provided, and the reel pulses output from these two rotation detection devices are used to count up and count down, and the counter value is displayed on a fluorescent display tube or the like. A schematic diagram is shown in FIG. In FIG. 1, two rotation detecting devices 3 and 4 are installed near a take-up reel stand 1 at positions with different phases. This rotation detection device 3, 4
For example, as shown in Fig. 1, four reflective surfaces 1a are provided at equal intervals around the outer circumference of the reel stand, and the rotation pulses of the reel are detected using optical element rotation detection devices 3 and 4, which are a combination of light emitting diodes and phototransistors. It happens. In the case of FIG. 1, the rotation detection device is provided on the take-up reel 1, but it may also be provided on the supply reel 2. The output waveforms of these two rotation detection devices 3 and 4 are reel pulses A and B in FIG. The counter circuit 5 uses the two reel pulses A and B to set the counter to 1 if, for example, the reel pulse B is at a low level at the rising edge of the reel pulse A.
If reel pulse B is low level at the fall of reel pulse A, the counter is counted down by 1.The rotation direction of the reel is also detected by two reel pulses with different phases, and the rotation speed of reel 1 is determined. , and the counter value is displayed on the display 6.
A video signal is recorded or reproduced on the tape discharged from the supply reel 2 by a video head attached to a rotating drum 7, and the tape is wound onto the take-up reel 1. Therefore, the counter value displayed on the display 6 makes it possible to roughly know the tape position currently being recorded or played back.

The present invention provides a device equipped with such an electronic reel counter that uses two reel pulses with different phases from the electronic reel counter to perform more accurate tape position detection control. It is something to do.

When using a VTR, there are many cases where it is desired to insert and record a title or the like into a portion of a tape that has already been recorded. In this case, the starting point for insertion recording is to play back the recorded tape and, while looking at the screen,
If the tape is moved by trick playback such as reverse slow playback, still playback is performed at the point where insertion recording is desired to be started, and insertion recording is started from there, insertion recording can be started with great precision. However, the conventional method for ending insertion recording is that the user either measures the insertion recording time from the tape position where the user wants to start insertion recording to the tape position where he or she wants to end it, and manually ends the insertion recording, or the user manually ends the insertion recording at the end point as described above. Memorize the value of the electronic reel counter consisting of the configuration,
Either the electronic reel counter automatically ends when it reaches the set value. The method of timing and ending the recording is to first play the recorded tape, measure how long the insertion recording will take from the start point of the insertion recording, return the tape to the start point of the insertion recording again, and then finish the insertion. It takes a lot of time and effort to start recording, measure the time, and finish it. Alternatively, if you start insert recording suddenly and end it at an appropriate time without measuring the time from the start point to the end point of insert recording, the part you do not want to erase may be erased by the inserted recorded video signal. , things like inserting and recording for a little longer may happen. Next, a method for automatically terminating the insertion recording by storing the counter value at the end point in memory will be described. For example, as shown in FIG. 1, an electronic reel counter that counts 4 in one rotation of the take-up reel is provided.
On a VTR, when using a 120-minute VHS tape, the tape speed at the maximum diameter of the take-up reel is 11.12 mm/
When inserting and recording in seconds, it takes about 6 seconds for the electronic reel counter to increment by one count. This means that with the method of automatically ending insertion recording by setting a counter value at the end point, the worst case scenario is that it may be recorded 6 seconds shorter than the end point, or it may be recorded 6 seconds longer than the end point, erasing important parts that you do not want to erase. This method cannot be said to be very accurate.

The present invention improves the above-mentioned problems and improves the tape performance by setting the end point of insertion recording not only by the counter value of the electronic reel counter but by setting the counter value and the state of the reel pulse. It performs position control.

FIG. 3 is a block diagram showing the configuration of the present invention. Reel pulses are generated by the rotation detection devices 3 and 4 provided at positions with different phases near the take-up reel 1, and these two reel pulses cause the up-down counter 5 to detect the rotation of the reel in the same manner as described above. The number is counted and the value is displayed on the display 6. SW1 is a switch for setting the end point of insertion recording. When the switch SW1 is pressed, the counter memory 12 stores the value of the up-down counter 5 at that time, and the reel pulse memory 13 stores the output state of the rotation detection devices 3 and 4 at that time. That is, it stores whether the outputs of the rotation detection devices 3 and 4 shown in FIGS. 2A and 2B are at high level or low level. Control circuit 14
When the mechanism control circuit 15 is in the insertion recording mode, if the values of the up-down counter 5 and the counter memory 12 match, and the state stored in the reel pulse memory 13 and the output state of the rotation detection devices 3 and 4 match, This circuit outputs a signal indicating the end of insertion recording to the mechanism control circuit 15. SW2 is a switch for switching the control circuit 14 to a set/reset state, and the control circuit 14 is
In the set state, as described above, an insertion recording end signal is output to the mechanism control circuit 15 at the memorized insertion recording end point, and in the reset state, no signal is sent to the mechanism control circuit 15 at the memorized insertion recording end point. It is configured not to be sent. switch SW1, switch
It may be configured so that SW1 and SW2 are used in combination so that when pressed once, the control circuit 14 is placed in the set state, and when pressed once more, the control circuit 14 is placed in the reset state.

A method for performing insertion recording in this configuration will be described in detail. First, a recorded tape on which insertion recording is to be performed is played back, and at a point where insertion recording is desired to end, still playback is performed, and movement of the tape is stopped. At this time, set the end point while watching the playback screen on the monitor TV receiver.
By using trick playback such as reverse slow playback, you can select the point at which you want to end the insertion recording with great precision. Now press switch SW1,
The value of up-down counter 5 is transferred to counter memory 1.
2, and the output states of the rotation detection devices 3 and 4 are stored in the reel pulse memory 13. Next, operate the switch SW2 to bring the control circuit 14 into the set state. In FIG. 2, A is the output waveform of the rotation detection device 3, B is the output waveform of the rotation detection device 4, C is the magnetic tape at the recording point, D is the magnetic tape inserted and recorded by the conventional method, and E is the invention of the present invention. The figure shows a magnetic tape inserted and recorded using a . Now, in FIG. 2, assume that switch SW1 is pressed at a point. Then, the counter value N is stored in the counter memory 12, and the reel pulse memory 13
It is stored that the outputs A and B of the rotation detection devices 3 and 4 are both at low level. Thereafter, the magnetic tape is played back in reverse, moved to the insertion recording start point E while watching the television screen, and insertion recording is started from there. When the tape moves and reaches the point where the counter value is N and the outputs A and B of the rotation detection devices 3 and 4 are both low level, that is, point N', the insertion recording automatically ends. The state of the magnetic tape at this time is E in FIG. 2, and the video signal has been inserted with the portion marked "T'". In the conventional method of storing only the counter value and ending the insertion recording, even if the switch SW1 is pressed at the point A', the insertion recording ends at the point A'. The state of the magnetic tape at this time is shown in FIG. 2D, where the video signal has been inserted with the part marked "G", and is much shorter than the set point. In this way, when ending insertion recording using the present invention, even if the counter value is the same, SW1 is used in section A.
If is pressed, it will be at point A', if SW1 is pressed in section B, it will be at point B', if SW1 is pressed in section C, it will be at point C', and if SW1 is pressed in section D, it will be at point C'. The insertion recording is completed at , and the tape position accuracy is 2×2 times that of the conventional method.

In this embodiment, a case has been described in which two rotation detection devices with different phases are used, but n rotation detection devices with different phases (n is an integer of 2 or more) are used, and the reel pulse memory 13 is also used with n number of rotation detection devices. By using an n-bit system that stores the state of each pulse, it is possible to achieve accuracy 2×n times higher than that of the conventional method.

Furthermore, in this embodiment, an electronic reel counter in which the counter value increases or decreases by 1 in one period of reel pulses is explained, but an electronic reel counter in which the counter value increases or decreases by 1 in m periods of reel pulses is used. , SW
When 1 is pressed, the counter memory also stores the counter value at that time and the number of cycles of the reel pulse of the counter value, and compares the number of cycles at the time of insertion recording and calculates the counter value, number of cycles, The insertion recording may be terminated when the reel pulse state matches those in the memory.

Also, a normal electronic reel counter has a counter clear switch that clears the counter value, so use that counter clear switch instead of switch SW1 and press the counter clear switch at the point where you want to end the insertion recording. If configured, the configuration can be made cheaper.

In addition, in the above explanation, the case where the present invention is used to set the end point of insertion recording has been described, but the present invention can also be used to set the start point of insertion recording, and when the end point is set, it automatically returns to the starting point. , it is also possible to configure the system to start insertion recording.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of an electronic reel counter, FIG. 2 is a diagram showing the relationship between reel pulse waveform and tape position, and FIG. 3 is a block diagram of a tape position detection device according to an embodiment of the present invention. It is a diagram. 1... Take-up reel, 2... Supply reel, 3, 4...
Rotation detection device, 5... Up-down counter, 6...
Display device, 7... Rotating drum, 8... Take-up reel,
12... Counter memory, 13... Reel pulse memory, 14... Control circuit, 15... Mechanism control circuit.

Claims (1)

[Claims] 1. A plurality of rotation detection devices that correspond to the rotation of a tape reel stand and generate a plurality of rectangular reel pulses at equal intervals in one rotation with mutual phase differences, and each reel of the plurality of rotation detection devices. an up-down counter that counts sequentially when the pulse reaches a predetermined state; and a first memory that stores the counted value of the up-down counter in conjunction with the operation of the switch. , a second memory that stores the state of each reel pulse at the time of the operation in conjunction with the operation of the switch; and
The stored count value of the memory matches the count value of the up-down counter, and the state of each reel pulse stored in the second memory matches the state of each reel pulse of each rotation detection device. 1. A tape position detecting device comprising: a detecting means for detecting this, and detecting the tape position at the time of the switch operation as an output of the detecting means.