KR100195616B1 - Method for detecting tape-end in vcr - Google Patents

Abstract

The present invention relates to a method of detecting the beginning and the end of a video tape, and to detect the beginning and the end of a video tape to accurately detect the beginning and the end of a video tape by using a thickness difference of the video tape. A method comprising: a first step of detecting a rotation change amount of a reel from a video tape currently running; A second step of sequentially detecting the number of pulses output from the capstan motor frequency generator while the reel is rotated once; And a third step of stopping the video tape when the amount of change in the number of output pulses detected in the second step is greater than the reference amount of change.

Description

How to detect start and end of videotape

The present invention relates to a method of detecting the beginning and the end of a video tape, and more particularly, to a video tape recorder having a start and an end sensor removed, wherein a video tape is started using a neural network algorithm and a thickness difference of a tape. And a method for detecting the beginning and the end of a video tape to detect the end.

In general, a video tape recorder is provided with sensing means for detecting the beginning and the end of a video tape. This is due to the inertia force of the video tape being conveyed because when the user selects the function to transfer the video tape at high speed, the high speed transfer function is not stopped even though the video tape which has been transferred at high speed has reached the beginning or the end. This is to prevent a problem that may cause damage to the video tape, such as the tape is broken or stretched.

As shown in FIG. 1, the sensing means has a light emitting element 2 protrudingly mounted at a predetermined position of the deck 1, and can receive an optical signal (light) emitted from the light emitting element 2. It consists of a pair of light-receiving elements (commonly referred to as "start and end sensors") 3 and 4 on the left and right sides of the deck 1.

In addition, as shown in FIG. 2, a typical home video system (VHS) standard video tape includes an opaque magnetized area coated with a magnetization material to record various types of information, and a start of the video tape. And a transparent lead area having a predetermined length (about 2 meters) at the end.

In a typical video tape recorder having such a configuration, the process of detecting the beginning and the end of the video tape is as follows.

When the video tape travels, the pair of light receiving elements 3 and 4 detect different signals depending on the magnetization region and the lead region of the video tape, respectively. In other words. When the video tape is located in the magnetization region, the optical signal output from the light emitting element 2 is blocked by the video tape and cannot be transmitted to the light receiving elements 3 and 4. As a result, the light receiving elements 3 and 4 are turned off to output the running control signal of the video tape to the control means for controlling the running state of the video tape. Thus, the video tape runs normally.

On the other hand, when the video tape is positioned in the lead region, the optical signal output from the light emitting element 2 passes through the transparent lead region of the video tape and is transmitted to the light receiving elements 3 and 4. As a result, the light receiving elements 3 and 4 are turned on to output the stop control signal of the video tape to the control means. Thus, the video tape is stopped.

However, the conventional method of detecting the beginning and the end of the video tape as described above has to have one light emitting device and at least two light receiving devices, and thus, there is a problem that the production cost of the product increases.

In addition, the above-described light emitting device is mounted to the center of the deck protruding, and the light receiving device is mounted on the side of the deck using a separate printed circuit board, so the mounting process of the deck by the mounting position of the light emitting device and the light receiving device This complexity is difficult, there is a problem that the work efficiency is lowered.

In addition, in order to prevent the light receiving element from malfunctioning due to external light, it must be housed in a separate case. Therefore, a separate free space is required to mount such a separate case in the deck, thereby miniaturizing the video tape recorder. There was a problem that it is difficult.

As a result, in order to solve the above problems, it is necessary to remove the light emitting device and the light receiving device, and it is very important to accurately detect the beginning and the end of the video tape in a state where the light emitting device and the light receiving device are removed.

A method using a neural network among the methods for detecting the beginning and the end of a video tape recorder from which light emitting elements and light receiving elements have been removed is described in detail in the following application filed by the present applicant.

(1) Patent application No. 92-26344 (92.12.28), title of the invention: Method of detecting the beginning and end of tape

(2) Patent Application No. 94-20803 (94.08.23), title of the invention: Apparatus and method for running control of tape

(3) Patent Application No. 94-20806 (94.08.23), title of the invention: Method of controlling the running of tape

(4) Patent application No. 95-5141 (95.03.13), title of the invention: Method of determining the end of tape of a video tape recorder and a device suitable therefor

As described above, the method of detecting the beginning and the end of a conventional video tape using a neural network is as follows.

The number of rotations of the capstan motor in terms of frequency (PS, PT) is squared during one rotation of the supply reel and take-up reel mounted on a conventional VHS standard video tape recorder. Summation is always the same (PS ² + PT ² = PC ² ). Therefore, each PS ² and PT ² are detected and trained by the neural network algorithm. Accordingly, the size of the hub is determined. The details are described in detail in patent application No. 96-15477 (96.05.10) filed by the present applicant (name of the invention: a method for determining the hub size of a video tape).

On the other hand, as the video tape is conveyed, the rotational speed of the reel varies. For example, in forward driving, the rotational speed of the supply reel gradually increases with the running of the video tape. Therefore, by detecting the rotational speed of the reel, it is possible to detect the beginning and the end of the tape.

In general, although the feed reel rotation speed increases gradually with the progress of the video tape, in detail, the rotation speed of the reel is changed to pulse operation at each moment. Therefore, by periodically sampling the instantaneous value of the reel rotation speed and inputting a plurality of sampling values to the neural network algorithm, it is possible to more accurately detect the beginning and the end of the video tape according to the hub size determined in the above-described process. do.

However, as described above, according to the conventional video tape start and end detection method using the neural network algorithm, by detecting the start and end of the video tape according to a plurality of sampling values, it is detected by the neural network algorithm In the beginning and the end of the cycle and the actual beginning and the end, the error of approximately 10 turns occurs. Thus, there is a problem that the effect on the original purpose of detecting the beginning and end of the videotape is insufficient.

Accordingly, an object of the present invention is to solve the above-described problems, and an object of the present invention is to start and end a video tape using a neural network algorithm and a video tape thickness difference to accurately detect the beginning and end of a video tape. An end detection method is provided.

1 is a schematic structural diagram of a conventional video tape recorder.

2 is a schematic structural diagram of a conventional VHS standard video tape.

3 is a schematic block diagram of a video tape recorder for carrying out the method of detecting the beginning and the end of a video tape according to the present invention.

4 is a flowchart of the operation of the microcomputer shown in FIG.

* Explanation of symbols for main parts of the drawings

5: capstan motor 6: capstan motor frequency generator (CFG)

7: Servo system 8: Reel detection unit

9: microcomputer

A feature of the present invention for achieving the above object is a method for detecting the beginning and the end of a video tape, comprising: a first step of detecting a rotational change amount of a reel from a video tape currently running; A second step of sequentially detecting the number of pulses output from the capstan motor frequency generator while the reel is rotated once; And a method of detecting the beginning and the end of a video tape to perform a third process of stopping the video tape when the amount of change in the number of output pulses detected in the second step is greater than a reference change amount.

In the above-described feature of the present invention, after performing the aforementioned second process, a fourth process of determining whether the number of output pulses detected in the second process represents a value equal to or less than the reference pulse number is added to the fourth process. Therefore, it is preferable to perform the third process only when the number of output pulses indicates a value equal to or less than the reference pulse number.

Best Mode for Carrying Out the Invention Preferred embodiments of the start and end detection methods of a videotape according to the present invention will now be described in detail with reference to the accompanying drawings.

3 shows a schematic block diagram of a video tape recorder according to the present invention.

Referring to FIG. 3, a capstan motor 5 driving a video tape at a constant speed in a predetermined direction, and a capstan motor frequency generator for generating a pulse signal according to a rotation state of the capstan motor 5, hereinafter, ' 6), the capstan motor 5, the servo system 7 for controlling the driving state of various components in the deck (not shown) such as the supply reel and the winding reel, and the supply reel and the winding. The reel sensing unit 8 which detects the amount of rotation change of the reel is comprised, and the microcomputer 9 which controls each component mentioned above.

The operation of the present invention having the configuration as described above will be described with reference to FIG.

The microcomputer 9 checks via the reel detecting unit 8 whether the video tape is currently set to the running state (playback mode, fast-forward, rewind, forward and reverse fast search) (S1). If it is determined in this step S1 that the video tape is not in the running state, the microcomputer 9 returns to the above-described step S1 and continues checking until the video tape is set in the running state.

If the user inputs a predetermined command for running the video tape, the microcomputer determines that the video tape is in the running state in the above-described step S1 to drive the servo system 7. Accordingly, the capstan motor 5 and the reel are rotated at a predetermined speed. Here, the microcomputer 9 controls the reel detection unit 8 to detect the amount of change in rotation of the reel (S2). Here, the rotational change amount of the supply reel is detected when the video tape travels forward, and the rotational change amount of the winding reel is detected when the video tape travels in the reverse direction.

Thereafter, the microcomputer 9 checks whether the reel has rotated by one revolution using the rotation change amount of the reel detected in the above-described step S2 (S3). Return to) to repeat the entire process after step (S2).

If it is determined that the reel is rotated once in step S3, the microcomputer 9 detects the number of output pulses per revolution of the reel generated from the CFG 6 (S4), and then detects the output pulses. Whether the number is equal to or less than the preset reference pulse number is compared (S5). If it is determined in this step S5 that the number of output pulses detected from the CFG 6 is not less than or equal to the reference pulse number, this indicates that the remaining amount of video tape is equal to or larger than the set value, and therefore the microcomputer 9 goes to step S1 described above. Returning to repeat the whole process after step S1.

If the number of output pulses detected from the CFG 6 in step S5 described above is equal to or less than the reference pulse number, this indicates that the remaining amount of video tape is almost exhausted, and therefore the microcomputer 9 rapidly reduces the number of output pulses. It is checked whether or not (S6).

Here, in the case of a typical video tape, the thickness of the magnetized area is approximately 20 mu m, and the thickness of the lead area is approximately 40 mu m. Therefore, the reduction ratio of the number of output pulses of the CFG 6 when the video tape is the lead area has a very large value with respect to the reduction ratio of the number of output pulses of the CFG 6 when the video tape is the magnetization area. That is, in the magnetization region, the output pulse number of the CFG 6 per revolution of the reel decreases at a small rate, while in the lead region, the output pulse number of the CFG 6 per revolution of the reel is due to the thickness of the video tape. It decreases at an abrupt rate. As a result, if it is judged that the number of output pulses detected from the CFG 6 in step S6 described above does not decrease drastically, this indicates that the magnetization region of the video tape remains on the reel, and therefore the microcomputer 9 is not equipped with the video tape. It is judged that the start and end of? Have not been reached, and it is returned to the above-described step S6 to check whether the number of output pulses of the CFG 6 is drastically decreased.

If it is determined in step S6 that the number of output pulses of the CFG 6 is drastically reduced, this indicates that the magnetization area of the video tape is exhausted and only the reed area is present on the reel. ) Controls the servo system 7 to stop the video tape (S7), and then ends all the proceedings. Thus, the beginning and end of the video tape can be detected more accurately.

Finally, according to the method of detecting the beginning and the end of the video tape according to the present invention, the video tape is rapidly reduced at the point where the number of output pulses of CFG per one revolution of the reel is drastically reduced by using the thickness difference between the magnetization region and the lead region of the video tape. By stopping the running state of, there is an advantage that the start and end of the video tape can be detected more accurately.

Claims (2)

A method of detecting the beginning and the end of a video tape, the method comprising: a first step of detecting a rotation change amount of a reel from a currently running video tape; A second step of sequentially detecting the number of pulses output from the capstan motor frequency generator while the reel is rotated once; And a third step of stopping the video tape when the amount of change in the number of output pulses detected in the second step is greater than a reference change amount. The method of claim 1, wherein after performing the second process, a fourth process of determining whether the output pulse number detected in the second process represents a value less than or equal to a reference pulse number is added to the output pulse number by the fourth process. And the third process is performed only when the value is equal to or less than the reference pulse number.