KR100195615B1 - Method for detecting tape-end in vcr - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of detecting the beginning and the end of a video tape, wherein the beginning and the end of a video tape using a thickness difference between a magnetization region and a lead region of a video tape, and auxiliary signals such as control signals and video and audio signals. A method of detecting the beginning and the end of a video tape, in order to be able to accurately detect the method, the method comprising: a first step of detecting an amount of rotation change 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; A third step of checking whether an auxiliary signal is detected when the amount of change in the number of output pulses detected in the second step is greater than a reference change amount; And a fourth process of stopping the video tape when the auxiliary signal is detected through the third process.

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 in which a light emitting element and a light receiving element (start and end sensors) are removed, wherein a neural network algorithm and a thickness of a video tape are used. A method of detecting the beginning and the end of a video tape to detect the beginning and the end of a video tape by using an auxiliary signal composed of a difference, a control signal, a video signal, an audio signal, and the like. It is about.

In general, a video tape recorder is provided with sensing means for detecting the beginning and 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 that 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 disconnected or stretched video tape.

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

In addition, a typical home video system (VHS) standard video tape includes an opaque magnetization region coated with a magnetization material to record various types of information, as shown in FIG. 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 runs, the pair of light receiving elements 3 and 4 detect different signals according to the magnetization area and the lead area of the video tape, respectively. That is, 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 traveling control signal of the video tape to the control means for controlling the traveling state of the video tape. Thus, the video tape runs normally.

On the other hand, when the video tape is located 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 above-described method for detecting the beginning and the end of a video tape, as described above, has to have one light emitting device and at least two light receiving devices, thereby increasing the production cost of the product.

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, and thus a separate free space is required to mount such a separate case in the deck, thereby realizing miniaturization of a video tape recorder. There was a problem that it is difficult.

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

As a result, in order to solve the problems described above, it is necessary to remove the light emitting element and the light receiving element, and it is very important to accurately detect the beginning and the end of the video tape in the state where the light emitting element and the light receiving element 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 94-20806 (94.08.23), title of the invention: a running control method of the tape

(4) Patent application No. 95-05141 (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, a 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 the 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. A detailed description thereof is 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 the forward travel, the rotational speed of the feed reel gradually increases with the travel of the video tape. Thus, by detecting the rotational speed of the reel, it is possible to detect the beginning and the end of the video 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, the reel rotation speed periodically samples the instantaneous value and inputs a plurality of sampling values to the neural network algorithm, so that the start and end portions of the video tape can be detected more accurately 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 use a neural network algorithm and a thickness difference between a video tape and an auxiliary signal composed of a control signal recorded on a video tape, a video signal, an audio signal, and the like. A method of detecting the beginning and the end of a video tape to detect the beginning and the end of a video tape is provided.

1 is a schematic block 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: head 10: 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 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; A third step of checking whether an auxiliary signal is detected when the amount of change in the number of output pulses detected in the second step is greater than a reference change amount; And a method of detecting the beginning and the end of the video tape to perform a fourth process of stopping the video tape when the auxiliary signal is detected through the third process.

In the above-mentioned aspect of the present invention, before performing the above-described first process, if the video tape is currently in a high speed driving state, a fifth process of detecting a current position of the video tape using a neural network algorithm; And if it is determined that the current position of the video tape detected through the above-described fifth process reaches the lead region, it is preferable to perform the sixth process of driving the video tape at constant speed.

In addition, after performing the above-described second process, a seventh process of determining whether the number of output pulses detected in the second process indicates a value less than or equal to the reference pulse number is added, and the output pulse number is determined by the seventh process. It is preferable to perform the above-described third process only when the following values are indicated.

In addition, in the above-described third process, it is preferable to determine that an auxiliary signal is detected when at least one of a control signal, a video signal, and an audio signal is detected.

In addition, it is preferable to use the control signal, video signal, and audio signal which have already been recorded as the auxiliary signal.

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 for carrying out the method of detecting the beginning and the end of a video tape 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. A reel detecting unit 8 for detecting the amount of change in the rotation of the reel, and a head for detecting control signals and video and audio signals recorded on a video tape (where 'head' is a control head and video mounted in a conventional video tape recorder). And a microcomputer 10 for controlling each of the above-described components.

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

The microcomputer 10 checks through the reel detecting unit 8 whether the video tape is currently in the high-speed driving state (fast forward, rewind, forward and reverse fast search modes) (S1). If it is determined in this step S1 that the video tape is not in the high speed running state, the microcomputer 10 checks via the reel detecting unit 8 whether the video tape is currently in the constant speed running state (playback mode) (S2). If it is determined in this step S2 that the video tape is not in the constant speed driving state, this indicates that the video tape is currently stopped, and the microcomputer 10 returns to the above-described step S1 so that the video tape is currently running at high speed. Keep checking if it is in the state.

If it is determined in the above step S1 that the video tape is in the high-speed driving state, the microcomputer 10 detects the current position of the video tape by using a neural network algorithm (S3). Thereafter, the microcomputer 10 checks whether the current position of the video tape detected in the above-described step S3 is the beginning or the end (S4), and if it is determined that the current position of the video tape is not the beginning or the end, The process returns to the above-described step S3 to repeat the whole process after the step S3.

If it is determined in step S4 that the current position of the video tape is at the beginning or end, the microcomputer 10 controls the servo system 7 to drive the video tape at constant speed (S5).

On the other hand, after determining that the video tape is in the constant speed driving state in the above-described step (S2), or after performing the above step (S5), the microcomputer 10 detects the amount of rotation change of the reel through the reel detection unit (8) (S6). 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 10 checks whether the reel has rotated once by using the rotation change amount of the reel detected in the above-described step S6 (S7). If it is determined in this step S7 that the reel has not made one revolution, the microcomputer 10 returns to the above-described step S6 to continue checking the rotation change amount of the reel.

If it is determined that the reel is rotated once in the above step S7, the microcomputer 10 detects the output pulse number per revolution of the reel generated from the CFG 6 (S8), and then the CFG 6 Whether the number of output pulses detected from the reference pulse number or less is set in advance (S9). If it is determined in this step S9 that the number of output pulses detected from the CFG 6 is not equal to or less than the reference pulse number, this indicates that the remaining amount of video tape is greater than or equal to the set value, and therefore the microcomputer 10 goes to step S6 described above. Returning to repeat the whole process after step S6.

If the number of output pulses detected from the CFG 6 in step S9 is determined to be less than or equal to the reference pulse number, this indicates that the remaining amount of video tape is almost exhausted. It is checked whether the decrease (S10).

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 is very large (about 2 times) relative to the reduction ratio of the number of output pulses of the CFG 6 when the video tape is the magnetization area. Has 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 S10 described above does not abruptly decrease, this indicates that the magnetization region of the video tape remains on the reel, and therefore the microcomputer 10 determines the video tape. It is judged that the start and end of? Have not been reached, and the flow returns to step S10 described above to continuously check whether the number of output pulses of the CFG 6 decreases drastically.

If it is judged that the number of output pulses of the CFG 6 has sharply decreased in the above step S10, this indicates that the magnetization area of the video tape is almost exhausted, and therefore the microcomputer 10 assists from the head 9. It is checked whether signals (control signals, video and audio signals) are detected (S11). If it is determined in this step S11 that an auxiliary signal is detected from the head 9, this indicates that the magnetized area of the video tape is in contact with the head 9, the microcomputer 10 proceeds to step S11 described above. The feedback is continued to check whether an auxiliary signal is detected from the head 9.

If it is determined in the above step S11 that no auxiliary signal is detected from the head 9, this indicates that the lead area of the video tape is in contact with the head 9, and thus the microcomputer 10 has a servo system ( After controlling 7) to stop the video tape (S12), all the processing ends. Thus, the beginning and end of the video tape can be detected more accurately.

As a result, according to the method of detecting the beginning and the end of the video tape according to the present invention, 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 the video tape at the point where auxiliary signals such as video and audio signals are not detected, there is an advantage that the start and end of the video tape can be detected more accurately.

Claims (5)

A method of detecting the beginning and the end of a video tape, the method comprising: a first step of detecting an amount of rotational change 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; A third step of checking whether an auxiliary signal is detected when the amount of change in the number of output pulses detected in the second step is greater than a reference change amount; And a fourth process of stopping the video tape when the auxiliary signal is detected through the third process. The method of claim 1, further comprising: a fifth process of detecting a current position of the video tape by using a neural network algorithm if the video tape is currently running at high speed before performing the first process; And if it is determined that the current position of the video tape detected through the fifth process reaches the lead region, a sixth process of driving the video tape at a constant speed is further performed. The method of claim 1, further comprising: after performing the second process, adding a seventh process of determining whether the number of output pulses detected in the second process represents a value equal to or less than a reference pulse number, and outputting the same by the seventh process. And the third process is performed only when the number of pulses indicates a value equal to or less than the reference number of pulses. The start and end portions of the video tape according to claim 1, wherein the third process determines that an auxiliary signal is detected when at least one of a control signal, a video signal, and an audio signal is detected. Detection method. The method of claim 1, wherein the auxiliary signal uses a previously recorded control signal, a video signal, and an audio signal.