JPH06168505A - Video recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce the mode discriminating time and to rapidly set an optimum reproduction speed. CONSTITUTION:When the recording mode is changed over, e.g. from a threefold mode to a standard mode, the tape speed is forced to be the standard mode by a microcomputer 12 at the point of time when a capstan FG read out by a head 20 of capstan FG exceeds '24'. After that, when the number of capstan FG becomes '72' twice continuously, the mode discrimination result becomes the standard mode by the microcomputer 12, then the standard mode is maintained. Thus, the mode discriminating time is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video recording / reproducing apparatus, and more particularly to a video recording / reproducing apparatus having an automatic discriminating function for reproducing speed.
The present invention relates to a video recording / reproducing device such as a CR or VTR.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional video tape recorder.
As in (A) and (B), the rising of the control signal CTL is used as a trigger to count the number of capstans FG in one cycle of the control signal CTL every cycle. Then, when the recording mode is switched from the triple mode to the standard mode as shown in FIG. 7C, the number of capstans FG is the same twice consecutively, as can be seen from FIG. 7D. The tape speed was being switched when the value was reached.

[0003]

In such a conventional video tape recorder, the tape speed is not changed until the determination of the recording mode is decided. Therefore, FIG. 7 (E)
As can be seen from the above, it takes 200 ms from when the recording mode is switched from the triple mode to the standard mode until the tape speed is switched from the triple mode to the standard mode, during which the image and sound are disturbed. In addition, when the recording mode is changed from the double mode to the standard mode, the mode determination time is 133 ms.
Mode change time is 100ms when changing to double mode
Is.

Therefore, a main object of the present invention is to provide a video recording / reproducing apparatus capable of controlling the reproduction speed faster and more appropriately.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the number of reference signals is increased in a video recording / reproducing apparatus for discriminating a recording mode according to the number of reference signals included in a predetermined period during reproduction and switching the tape speed. The video recording / reproducing apparatus is provided with a speed forcing unit for forcing the tape speed to a predetermined tape speed at the time.

[0006]

When the recording mode is switched from the triple mode to the standard mode, for example, when the capstan FG exceeds "24", the tape speed is held in the standard mode by the speed forcing means. After that, if the number of capstans FG becomes “72” twice in succession, for example, the mode determination result becomes the standard mode, and the standard mode is maintained. This shortens the mode determination time.

[0007]

According to the present invention, since the mode discrimination time is shortened, the optimum reproduction speed can be set quickly.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a video tape recorder 10 of this embodiment includes a microcomputer 12. This microcomputer 12
The video tape 1 by the control head 14
The control signal CTL detected from 6 is the amplifier 18
Be entered via. Also, the capstan FG head 2
The FG signal of the capstan motor 22 is detected by 0, and is input to the microcomputer 12 via the amplifier 24. Then, a PWM signal is output from the microcomputer 12 according to the determination result, and the driver 26 drives the capstan motor 22 at a predetermined speed in response to this.

Referring to FIGS. 2 and 3, the microcomputer 12
The processing operation will be described. First, in step S1 of FIG. 2, it is determined whether or not the recording mode has changed within 3 seconds. If there is a speed change, the speed change flag 28 is set in step S3, but if there is no speed change, the speed change flag 28 is reset in step S5. Next, in step S7, it is determined whether the value of the capstan FG counted this time is larger than the previous count value. Here, if it is larger than the previous count value, it is determined in step S9 whether the speed change flag 28 is set. If not set, the tape speed is set to the standard mode in step S11, and then the count value is stored in the memory 30 in step S13. On the other hand, if it is determined in step S7 that the current count value is not greater than the previous count value and if the speed change flag 28 is set in step S9, the process directly proceeds to step S13 and the count value is stored in the memory 30. Remember.

Subsequently, in step S15 of FIG. 3, it is determined whether the count value stored in the memory 30 is smaller than "36". If it is smaller than "36", it is determined in step S17 whether the speed flag 32 is EP. If the speed flag 32 is EP, the recording mode is determined to be EP in step S19.
Otherwise, the speed flag 32 is set to E in step S21.
Write P. On the other hand, in step S15, the memory 3
If the count value stored in 0 is not smaller than “36”, it is determined in step S23 whether 36 ≦ count value <60. Where 36 ≦ count value <60
If so, the speed flag 32 is set to L in step S25.
If it is P, and if it is LP, the recording mode is determined to be LP in step S27. On the other hand, step S
If the speed flag 32 is not LP in 25, LP is written in the speed flag 32 in step S29. If 36 ≦ count value <60 in step S23, it is determined in step S31 whether the speed flag 32 is SP. If SP, the recording mode is determined to be SP in step S33. However, step S3
If the speed flag 32 is not SP in step 1, SP is written in the speed flag 32 in step S35. Steps S19, S21, S27, S29, S33 and S
After the processing in 35 is performed, the processing from step S1 is repeated again.

In operation, when the recording mode is changed from the triple mode to the standard mode as shown in FIG. 4C, the tape speed remains the triple mode as shown in FIG. 4D after the change. Therefore, the capstan FG is counted as “24” during 33.33 ms from point W to point X in FIG. 4 (E), and when it exceeds “24”, the tape speed is changed as shown in FIG. 4 (D). Is changed to the standard mode and is retained. As can be seen from FIG. 4B, since the capstan FG is continuously counted “72” twice from the W point to the Z point, the mode determination result is Z as shown in FIG. 4D. At this point, the standard mode is set, and the standard mode tape speed is maintained. From this, the period from point X to point Y is 22.
22 ms, and the period from the Y point to the Z point is 33.33.
Since it is ms, the mode discrimination time is 88.88 ms, which is less than half that of the conventional 200 ms. Moreover, since the tape speed becomes the standard mode at the point X as shown in FIG. 4D, when the recording mode is changed to the standard mode as shown in FIG.
It takes only 3.33 ms and can be reproduced with extremely short disturbance of video and audio.

Even when the recording mode is changed from the double mode to the standard mode as shown in FIG. 5C, the tape speed is changed to the standard mode at the point X as shown in FIG. 5D.
As shown in (E), the mode determination result becomes the standard mode at the Z point. Therefore, as can be seen from FIG. 5 (F), the mode discrimination time is 83.33 ms and the tape speed switching time is 33.33 ns. From this, the conventional 133 ms
Compared with, the video and audio distortion is significantly improved.

On the other hand, as shown in FIG. 6C, the recording mode is 3
When changing from the double mode to the double mode, the tape speed first becomes the standard mode at the point X as shown in FIG.
After that, at the point Z, the mode becomes the double mode according to the mode determination result of FIG. Therefore, both the mode determination time and the tape speed switching time until the double mode is 61.11n.
s, which takes almost twice as long as in the cases of FIGS. 4 and 5. However, since the time is still shortened as compared with the conventional 100 ns, video and audio are reproduced better than before.

When the count value changes a plurality of times within a fixed period, the tape speed is not changed to the standard mode. In this way, the count value changes many times within a certain period, for example, when the control signal is lost due to the quality of the tape or other causes.In such a case, the tape is switched to the standard mode. Since the speed is not forced, the reproduction speed can be stably controlled even if the control signal is lost.

[Brief description of drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention.

FIG. 2 is a flowchart showing a part of the operation of the embodiment in FIG.

FIG. 3 is a flowchart showing a part of the operation of FIG. 1 embodiment.

FIG. 4 is a timing chart when the recording mode changes from the triple mode to the standard mode.

FIG. 5 is a timing chart when the recording mode changes from the double mode to the standard mode.

FIG. 6 is a timing chart when the recording mode changes from the triple mode to the double mode.

FIG. 7 is a timing diagram showing a conventional technique.

[Explanation of symbols]

 10 ... Video tape recorder 12 ... Microcomputer 14 ... Control head 20 ... Capstan FG head 22 ... Capstan motor

Claims (2)

[Claims] 1. A video recording / reproducing apparatus for discriminating a recording mode and switching a tape speed according to the number of reference signals included in a predetermined period during reproduction, wherein the tape speed is changed when the number of the reference signals increases. An image recording / reproducing apparatus comprising a speed forcing unit for forcing a predetermined tape speed. 2. The video recording / reproducing apparatus according to claim 1, wherein the speed forcing means is not operated when the number of the reference signals changes a plurality of times within a fixed period.