JPH06180972A - Tape position code recording method - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a tape position code recording method that guarantees accurate recording of a tape position code having a plurality of different detection systems and is effective in search, residual amount detection, and the like. [Structure] During recording of first and second position codes of a plurality of types of position codes recorded on a tape, a change point of the second position code becomes a plurality of predetermined values of the first position code. Since a plurality of position codes can be accurately recorded on the tape by providing a means for recording the first and second position codes so as to be synchronized, a single position code was incomplete. Since the position on the tape can be uniquely represented by the position code, the efficiency of search is dramatically increased, and the value of the remaining amount up to the end of the tape can be easily obtained. Therefore, use the tape as the medium. This greatly contributes to the improvement of the operability of the recording / reproducing apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape position code recording method, and particularly when a user searches for a desired position on a tape which is a recording medium such as a recording / reproducing apparatus.
It is also very effective in efficiently recording the position code on the tape for the recording / reproducing apparatus to automatically search a certain position on the tape.

[0002]

2. Description of the Related Art In recent years, one of the strong demands of users in recording / reproducing apparatuses is the speed of retrieval. In particular, when a tape is used as a recording medium, its search speed and search accuracy are inferior to those of a disk or the like due to its structure. Therefore, it is necessary to devise a particularly efficient search.

Therefore, in a tape recording / reproducing apparatus such as a video tape recorder, a time code, which is an absolute position on the tape, is recorded on the tape so that the position on the tape and the numerical value of the time code are unique. The efficiency and accuracy of the search were improved by supporting the.

A search using a time code in a conventional tape recording / reproducing apparatus will be described below by using an example of a video tape recorder (hereinafter referred to as VTR).

The VTR records the time elapsed from the tape start end and the number of frames for each frame in the time code dedicated track on the tape or in the vertical synchronization period, etc., and uniquely sets the time code value at the position of each frame on the tape. It corresponds to each other.

At the time of search, therefore, it is easy for the user to give the time code to the VTR, or to find the position of the time code obtained by reading the time code stored in the storage device by the VTR itself. Is.

In order to continuously record this time code from the beginning of the tape, in the case of recording from the middle of the tape, the time code immediately before the start position is read and the time code is recorded so as to be continuous with the read time code. I have to do it. If the time code cannot be continued at the start of recording, the absolute position on the tape and the uniqueness of the time code cannot be maintained, and the accuracy of the search cannot be guaranteed.

On the other hand, one of the functions of the VTR in terms of effective use of the tape is to detect the remaining tape amount. Remaining amount information indicating how much time can be recorded after the final recording end point, that is, time information from the current position to the end of the tape is very effective information for the VTR user.

Conventionally, the detection by the reel cycle is the most general method for detecting the remaining amount. The VTR measures the rotation period and the tape speed of both reels of the tape, and calculates the length of the tape and the time from the current position to the end of the tape by using the data of the tape thickness and the hub diameter of the reel given in advance.

Therefore, in order to maintain the continuity of the time code, the detection of the tape position based on the reel cycle is used to record the detected value as the time code at the point where the time code discontinuity occurs, and the value is sequentially increased. There is a method of letting you record.

However, when the tape recording / reproducing apparatus has a plurality of reproducing modes (standard / three times both recording / reproducing modes in the VHS (registered trademark) system), the time code is recorded according to each mode. Therefore, even if recorded on the same length of tape, the time code increment may differ, and even if the absolute position on the tape is detected by the reel cycle detection, multiple playback modes are mixed. It is not possible to make the time code continuous on tapes recorded as.

Therefore, in addition to the first time code which is normally recorded and is reset to 0 when a discontinuity occurs, the absolute position from the tape start end is similarly set in any of a plurality of recording modes in which the tape running speed is different. The second time code for recording is recorded, and when the discontinuity of the time code occurs, the reel cycle detection value is recorded in the second time code.

However, when the reel cycle is detected, the tape must be running at a constant speed, and when the remaining amount is detected from the stopped state, the time until the tape is running at a constant speed. Then, it takes several seconds to measure the reel cycle thereafter, and the detection accuracy does not reach the unit of 1 second.

Therefore, the accuracy of the second time code may be generally coarse, while the first time code is generally in frame units, while the unit of several seconds to tens of seconds is sufficient, and the tape is The time code recording area above is also limited, and the data amount of the second time code must be reduced, so that the unit is often 10 seconds or more.

However, by recording the above-mentioned second time code, the absolute position on the tape is judged from the second time code even if the accuracy is a little rough, and the precise position is determined by the fine first time code. In addition to being able to search, the monotonicity of the second time code is less likely to be lost even if the reel cycle detection value is recorded due to the coarseness of accuracy of the second time code. is there.

[0016]

However, in the above configuration, the second time code is a rough time code due to a problem such as the recording area, and the time from the change point of the time code to the next change point. (Hereinafter referred to as unit time) is often relatively long.

Generally, the time code is recorded in parallel at the time of recording a video signal, an audio signal, etc., and the time code in frame units like the first time code is 1 for each frame.
The change point of the second time code is counted in the device for a unit time from the start point of the recording or the change point of the second time code to determine the next change point.

However, although the second time code has passed a certain time shorter than the unit time from the previous change point at the start of normal recording, the next change point has passed a unit time from the start of recording. Because it becomes a point,
The interval between the change points before and after the start of recording becomes longer than the unit time, resulting in an error. The average value of the above error is 1/2 of the unit time per start of recording.

Further, when the recording time of one time is shorter than the unit time of the second time code, the recording of the second time code ends without changing, and such a short time is required. When recording is repeated, there is a disadvantage that the second time code will not change forever.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a tape position code recording method which is very effective in recording the position code on the tape required for functions such as search.

[0021]

In order to achieve the above object, a tape position code recording method of the present invention comprises a first position code of a plurality of kinds of position codes recorded on a tape, and a first position code. There is a second position code that has a detection accuracy lower than that of the position code, and the first and second positions are set so that the changing point of the second position code is synchronized with the predetermined value of the first position code during recording. And means for recording the code.

[0022]

According to the tape position code recording method of the present invention having the above-described structure, the change point of the second position code following the recording start point is recorded with a higher detection accuracy than the second position code. Since it is determined depending on the value of the position code, the interval between the change points before and after the recording start point depends on the first position code, and the accuracy of the change point of the second position code is The position code detection system of (1) is approached, and more accurate position code recording becomes possible.

[0023]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the operation of a video tape recorder (hereinafter referred to as VTR) having a tape position code recording method according to an embodiment of the present invention.

The operation of the VTR of this embodiment during recording will be described below. In FIG. 1, video and audio signals are recorded on the tape 2 in the tape cassette 1 by a recording head (not shown) attached to the side surface of the cylinder 3. Normally, at the same time, a command is issued by the microcomputer 4. The time code processing unit 5 receives the first time code and the second time code, which are recorded on the tape 2
The head attached to the cylinder 3 records on the time code dedicated track above.

The first and second time codes will be described below with reference to FIGS. 2, 3 and 4.

FIG. 2 is a graph showing the relationship between the first and second time code values and the tape position, where the vertical axis represents the time code value and the horizontal axis represents the absolute position from the start end on the tape. It represents. The polygonal line 21 represents the first time code. In the section 23, recording is performed in a mode recorded at a normal tape traveling speed (hereinafter referred to as SP), and in a section 24, a mode recorded at a normal tape traveling speed of 1/3 (hereinafter referred to as LP). The slope of the polygonal line 21 is three times as large as that of the section 23. Section 25
Was recorded again in SP in the
After that, recording starts again from 0.

The discontinuous section will be described with reference to FIG. The time code is a numerical value that indicates the position on the tape and is used for searching programs, etc. Therefore, it is required that the time code is always continuous from the beginning of the tape. Therefore, in the VTR of this embodiment, at the start of recording, the microcomputer 4 issues a command to the tape drive circuit 6 and a length corresponding to several seconds to the position where the last time code recorded immediately before the tape may be recorded. Just rewind and perform the playback operation to read the previous time code.
Then, the time code processing unit 5 newly generates a time code so as to be continuous from the read time code.

However, when the time code immediately before cannot be read only by rewinding for several seconds at the start of recording, the time code processing section 5 runs out of time codes to be generated, and the time codes are continued at the recording start point. You will not be able to. That is, discontinuity of the time code will occur.

Since the first time code is reset to 0 at the time of discontinuity and recording is started again, recording is started from 0 after the discontinuous section 26. The polygonal line 22 represents the second time code.

Recording is performed in the same manner as in the SP mode from the section 23 to the section 25 regardless of SP and LP. After the discontinuous section 26, a new time code 27 is generated by detecting the reel cycle.

The reel cycle detection will be described below with reference to FIG. The microcomputer 4 includes a supply side reel 9 (hereinafter referred to as an S reel) in the tape cassette 1.
The rotation cycle of the take-up reel 10 (hereinafter referred to as the T reel) is obtained from the S reel cycle detection device 7 and the T reel cycle detection device 8, and S is obtained from the data of the reel hub diameter and the running speed of the tape 2. The cross-sectional area of the tape 2 wound around the reel 9 and the T reel 10 is obtained, and the length of the tape 2 in the tape cassette 1 is obtained from the data of the thickness of the tape 2. Then, the time from the tape starting end at the current position is calculated from the area ratio of the tapes wound around the S reel 9 and the T reel 10.

The time code processing unit 5 generates a new time code 27 based on the calculated value and records the second time code after the discontinuous section 26.

As is apparent from the above, it can be said that the first time code indicates the recording or reproducing time, and the second time code indicates the absolute position in the tape.

FIG. 3 is a format diagram of the time code recording area on the tape recorded by the VTR of this embodiment.

In the present embodiment, the time code recording area has 5 bytes, and the first and second time codes are recorded separately therein. Hereinafter, the first time code is TC1, the second time code is TC2, and the hours, minutes, seconds, and frames are H, M, S, and F, respectively. All the data are recorded in BCD (binary coded decimal).

TC1H (at the time of the first time code) 31
Consists of 6 bits, TC1M32 is 7 bits, T
C1S33 is 7 bits, TC1F34 is 6 bits, TC
2H35 is 4 bits, TC2M36 is 7 bits, TC2
S37 consists of 3 bits.

[0038] TC1 can be represented by a normal BCD from 0:00:00 to 0: 23: 59: 59: 29, but for TC2, it can be increased from 00:00:00 to every 10 seconds. It can be expressed up to 9:59:50.

TC2 can represent only 10 hours with respect to 24 hours of TC1, but there is no problem because 8 hours of SP corresponds to 24 hours of LP. Although TC2 is set in units of 10 seconds, the operation at the time of search is to determine the direction of the target point from the current position by TC2, determine the accurate position by TC1, and detect the reel cycle at the time of discontinuity. From the above two points, it seems that there is no problem with the relationship with accuracy.

FIG. 4 is a timing chart showing the recording timing relationship between TC1 and TC2.
Is the relationship between TC1 and TC2 at the start of recording from the beginning of the tape, 41 is TC1 for SP, 42 is TC1 for LP, and 43 is TC2. Reference numerals 44 to 46 represent the relationship between TC1 and TC2 at the start of recording from an arbitrary position on the tape, 44 represents TC1 in the case of SP, 45 represents TC1 in the case of LP, and 46 represents TC2. 47 to 49 are TC1 and TC for short-time recording from an arbitrary position on the tape
2, 47 is TC1 in the case of SP, 48 is TC1 in the case of LP, and 49 is TC2.

When recording is started from the beginning of the tape, TC1,
Since both TC2 start from 0:00:00, in SP, TC1 and TC2 increase similarly as in 41 to 43, and in LP, TC2 is increased every time TC1 is counted for 30 seconds.
Will be increased by 10 seconds (unit time).

At the start of normal recording, it cannot be said that the values of TC1 and TC2 are the same in both cases of SP and LP, so the timing of increasing TC2 becomes a problem. TC2 increases every 10 seconds in SP and every 30 seconds in LP. At 44 to 46, TC2 is 10 seconds after the recording start point 440, or 30 seconds after TC2 is reached.
In the case of the first method of increasing the value, the change point of TC2 becomes the point 441, which is the original change point 44.
It is far from 2 and causes a large error.

Therefore, a second method is adopted in which the change point of TC2 is determined by using the value of TC1. In SP, 0, 10, 20, 30, 40, 50 seconds of TC1 and in LP, 0 and 30 seconds of TC2 are points of change of TC2, and TC2 is not changed in other points.

Then, the changing point of TC2 becomes the point 442 regardless of SP and LP, which coincides with the original changing point.

In the case of short-time recording, the value of TC2 may not change unless the change point of TC2 is determined as described above. In 47-49, the record is point 4
70 to 471, 471 to 472, 472 to 473, and any recording ends within 10 seconds for SP and within 30 seconds for LP, so TC2 cannot be changed by the first method. However, in the second method, point 47
4, TC2 can be changed at point 475.

In any case, by determining the change point of TC2 by the second method, it becomes possible to accurately count TC2, and by combining TC1 and TC2, it is possible to It is possible to associate an arbitrary position with the time code one-on-one.

By doing so, when searching an arbitrary position on the tape, the direction from the current tape position to the target position is determined by TC2, and the accurate position is determined by TC1. Search efficiency can be increased.

Further, since TC2 accurately represents the absolute position on the tape, if the total recordable time of the tape is known, it becomes easy to calculate the recordable time from the current position of the tape to the end. The total recordable time is possible by using the reel cycle detection.

[0049]

As is apparent from the above description, by using the tape position code recording method of the present invention, it is possible to make any position on the tape correspond to the time code on a one-to-one basis.

As a result, since the position on the tape required by the user can be uniquely held in the form of a time code inside the tape recording / reproducing apparatus, the efficiency of the search is dramatically increased, and further, up to the end of the tape. Since an accurate value of the remaining amount can be easily obtained, it is considered to greatly contribute to the increase in the usage efficiency of the tape.

It is considered that the above-mentioned two effects of the increase of the search efficiency and the increase of the use efficiency have great significance as a supplement to the conventional defects of the medium called the tape as one of the recording media.

[Brief description of drawings]

FIG. 1 is a block diagram showing an operation of a video tape recorder using a tape position code recording method according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the values of TC1 and TC2 and the tape position in the example.

FIG. 3 is a format diagram of a time code recording area on a tape recorded by the tape position code recording method of the embodiment.

FIG. 4 is a timing chart showing the relationship between the timings when TC1 and TC2 are recorded in the embodiment.

[Explanation of symbols]

 1 Tape Cassette 2 Tape 3 Cylinder 4 Microcomputer 5 Time Code Processor 6 Tape Drive Circuit 7 S Reel Rotation Cycle Measuring Device 8 T Reel Rotation Cycle Measuring Device 9 S Reel 10 T Reel

Front Page Continuation (72) Inventor Shobun Ide 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A first position code of the plurality of position codes in a tape recording / reproducing apparatus or the like having means for recording a plurality of types of continuous position codes on a tape which is a recording medium. There is a second position code whose detection accuracy is lower than that of the first position code, and the change point of the second position code is synchronized with a plurality of predetermined values of the first position code during recording. And a means for recording the first and second position codes, the tape position code recording method.