JPH082871Y2 - Real time counter - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention counts the running amount of the tape from an arbitrary position as a time amount by using the FG pulse generated with the rotation of the capstan, and the running time It relates to a real-time counter of a video tape recorder (VTR) which forms and derives information.

(B) Conventional Technology In recent years, a so-called real-time counter, which displays a tape running amount from an arbitrary position as a time amount, has been favored as a VTR tape counter. This real-time counter is, for example, as shown in Japanese Utility Model Publication No. 54-3692 (G11B27 / 14), counts after appropriately dividing the FG pulse, which is a rotation detection pulse of a capstan for tape running,
It is a counter that adds the tape running amount as a time amount.

(C) Problem to be solved by the invention Although the conventional real-time counter has no problem during normal reproduction in which tape feeding is continuously performed at a constant speed,
After performing still playback for n (n: integer) frame periods, normal playback is performed while feeding the tape for only one frame, and intermittent playback in which the still playback and normal playback are alternately repeated, or while feeding the tape for only one frame The normal playback is performed, the still playback is executed after that, and the same operation is repeated when a new frame advance command is issued. The frame is advanced (frame advance). (In the mode in which the capstan motor is repeatedly moved and stopped in units of one frame, and the intermittent slow playback and the frame advance playback described above are part of this intermittent running mode.) The actual tape feed amount is increased by FG by increasing the slip generated between the tape and the capstan.
Since the number of pulses cannot be accurately indicated, the error between the two becomes large, and the more the intermittent feeding is repeated, the larger the error becomes, and finally the real-time counter is obtained by counting the FG pulses. There is a risk that the tape running amount obtained in step 1 will be significantly different from the actual value.

(D) Means for Solving the Problems The present invention is directed to a capstan motor that is controlled by a drive control circuit to drive a capstan, an FC detector that outputs an FG pulse according to the rotation of the capstan motor, and a still. The frame advance pulse obtained by dividing the RF switching pulse is used as a command to cause the capstan motor to execute the tape feed for one frame in the intermittent feed mode in which the playback and the normal playback for one frame are alternately repeated. And the frame advance pulse generating means to output to, the tape running time is calculated by counting the number of FG pulses in the normal playback mode, and when the mode is changed from the playback mode to the intermittent feed mode, the counting of the number of FG pulses is stopped. However, each time the frame advance pulse is output, the time corresponding to one frame Characterized in that it comprises a counting means for adding to the tape running time of the preceding mode migrate.

(E) Operation Since the present invention is configured as described above, it is possible to minimize the deviation of the count value of the real-time counter even in the mode in which the capstan alternately repeats rotation and stop.

(F) Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of the present embodiment, in which a capstan (2) driven by a capstan motor (1) runs a tape by interposing a tape between it and a pinch roller (not shown). The rotation state is magnetically detected by the FG detector (3) and supplied as an FG pulse to the microcomputer (4) that functions as a real-time counter.

In the normal reproduction mode, the capstan motor (1) is controlled by the drive control circuit (5) so that the capstan (2) rotates at a standard speed at a low speed. The FG pulse obtained at this time is counted by an FG counter (not shown) built in the microcomputer (4), and this count value is the recording speed (long-time recording (EP) mode or standard recording (SP) of the tape being reproduced. ) Mode) and is replaced with a time amount by a frequency division ratio according to (1) mode), and running time information from an arbitrary tape position is formed and derived and displayed on the display (7).

In the intermittent feed mode in which normal reproduction and still are alternately repeated to perform slow or frame advance, the drive control circuit (5) controls the drive of the capstan motor (1) intermittently. That is, when this intermittent feed mode is selected by the user, every time a frame advance (F / ADV) pulse generated based on the RF switching pulse is issued from the syscon (8), the motor ( Start 1) and accelerate until you reach standard speed,
When the control speed (CT) pulse is detected from the control head (not shown) after the standard speed is reached, the tape is run for one frame, and the drive control circuit (5) Immediately, a voltage of reverse polarity is applied so as to stop the motor (1). Immediately after this stop operation, the drive control circuit (5) issues only one frame pulse (FP) to the microcomputer (4) to the microcomputer (4), which indicates that the tape running for one frame is completed. Thus, when the motor (1) is stopped and the next F.ADV pulse is generated, the above-mentioned operation is repeated again, and as a result, the normal reproduction operation and the stop operation are alternately repeated. still,
The F / ADV pulse is RF at the frequency division ratio according to the desired slow ratio.
It is obtained by dividing the switching pulse.

When the microcomputer (4) receives a mode command from the system controller (8) that the mode has been switched from the normal reproduction mode to the intermittent feed mode, it stops counting the divided FG pulses,
Instead, it enters the frame pulse (FP) input standby state. In this state, each time one frame pulse (FP) is input, the amount of time for one frame (1/30 sec) is added to the traveling time information immediately before the mode switching to update the traveling time information. Is displayed on the display (7). Therefore,
While the intermittent feed mode is continued, the frame pulse (F
Every time P) is obtained, the above-mentioned travel time information is updated. Further, when the mode is changed to the normal reproduction mode again, the traveling time information immediately before the transition is updated by adding the amount of time based on the FG pulse.

As another method, in the intermittent feed mode,
The input of the FG pulse to the FG counter is cut off, and the number of FG pulses corresponding to one frame prepared in advance according to the recording speed of the tape being played is calculated every time one frame pulse is input. It is also possible to display the running time information on the display unit (7) by adding to, and dividing the count value of the FG counter after the addition.

A flowchart for processing the series of operations described above by software is as shown in FIG.

(G) Effect of the Invention According to the present invention as described above, the number of FG pulses from the capstan motor is directly measured in the intermittent feed mode such as the intermittent slow playback and the frame advance playback as in the normal playback mode. Of course, every time the tape feeding of one frame is commanded, the amount of time corresponding to this one frame is added, so that the tape that is repeatedly moved and stopped is slipped between the capstan and the actual tape. Even if the number of FG pulses cannot be accurately indicated as the feed amount, the deviation between the tape running time calculated by the counting means and the actual value can be suppressed to be small.

[Brief description of drawings]

The drawings are all related to one embodiment of the present invention. FIG. 1 is an overall circuit block diagram and FIG. 2 is a flow chart. (2) …… Capstan, (4) …… Microcomputer (real-time counter)

Claims (1)

[Scope of utility model registration request] 1. A capstan for feeding a tape by interposing a tape between pinch rollers, a capstan motor for driving the capstan under the control of a drive control circuit, and an FG according to the rotation of the capstan motor. In the intermittent feed mode in which the FG detector that outputs a pulse and the still playback and the normal playback for one frame are alternately repeated, the RF switching pulse is divided as a command to cause the capstan motor to feed the tape for one frame. A frame advance pulse generating means for outputting the frame advance pulse obtained by the above to the drive control circuit, and a normal reproduction mode for continuously sending the tape at a constant speed,
The tape running time is calculated by counting the FG pulses, and in the intermittent feed mode, the counting of the FG pulses is stopped, and one frame is added to the immediately preceding tape running time each time the frame advance pulse is output. A real-time counter equipped with counting means for adding a corresponding amount of time to update the tape running time.