JPS58164073A - Device for outputting remaining time of tape - Google Patents

Abstract

PURPOSE:To correctly find remaining time of a tape under all modes, by detecting and operating signals proportional to the rotating cycle of the reel at the feeding side when tapes are run at a fixed speed, and detecting and calculating the number of revolution of the reel at the feeding side when the tape runs at an unfixed speed. CONSTITUTION:The output of a rotating cycle detecting section 1 of the feeding side reel is given to an operating section 2 for calculating the remaining time of a tape. Discrimination of the diameter of a reel hub is performed at an operating section 3 for discriminating the hub diameter and the output of the operating section 3 is also given to the operating section 2. The input information required for discriminating the hub diameter is obtained from the detecting section 1 and a separately installed rotating cycle detecting section 4 of the winding side reel. The remaining time of the tape thus calculated is outputted from the operating section 2 and displayed in an output section 5. When the remaining time of a tape is known at the begining by running the tape at a fixed speed, the remaining time of the tape can be outputted and displayed thereafter even when the tape is run under vaious operations modes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape remaining time output device that is particularly useful for tape recording and reproducing equipment such as video tape recorders (hereinafter abbreviated as VTR).

When recording on and playing back a cassette tape using a VTR, it would be convenient to be able to know how far the tape has progressed and how much tape remains, even when the cassette tape is loaded into the VTR body.

Conventionally used mechanical counters that are linked to the reel rotation axis can identify the movement of the tape, but because they do not have a linear relationship with time, they have not been able to accurately determine the elapsed time or remaining time.

One way to accurately know the remaining time (amount) of this waste tape is to detect the rotation period of the tape supply reel while the tape is running at a constant speed, and to obtain the remaining tape time through arithmetic processing. The principle is as follows.

The length of the tape wound on the supply reel is e.

If the thickness of the tape is S, the diameter of the tape wound on the supply reel is Do, and the diameter of the reel hub is d, then 7? =-□(D2-d2) ・・・・・・・・・
... (1) Represented by S O .

Here, the relationship between the rotational angular velocity ω and the constant tape running speed V is v D□−1 (
3)ω Still, the relationship between the rotation period Tω and the rotational angular velocity ω is T, -1-
−−−−−−−・(4) (Since ω, Do−Q−−・・・・・・・・・・ (5) π 5be.Converting the above equation (5) to (1) By substituting into the equation, we obtain: Since the constant tape running speed V during recording and playback is constant, the remaining time t of the tape is, and if the tape thickness S is constant, the nop diameter d By knowing , it is possible to calculate the remaining tape time from the rotation period.

However, the above calculation is based on the assumption that the tape speed is constant, and accurate calculations cannot be performed at other undefined speeds.

In addition to recording and playback, VTRs and other devices have tape fast-forward mode, rewind mode, etc. In this case, the tape running speed is often not constant, but even in these modes, the remaining tape time If changes in the tape can be calculated continuously, the user will be able to continuously check the remaining time on the tape in any operating mode, which is extremely convenient.

It is an object of the present invention to provide a device that calculates changes in the remaining amount of tape when the tape is running at an irregular speed, and can accurately determine the remaining time in any operating mode. Hereinafter, the present invention will be explained based on illustrated embodiments.

In the drawing, reference numeral 1 denotes a supply side reel rotation period detection section, and its output is given to a calculation section 2 for calculating the remaining time.

Identification of the reel hub diameter is performed by the calculation unit 3 which is used to identify the hub diameter.
The output is given to the arithmetic unit 2. The input information for identifying the hub diameter is obtained from the supply side reel rotation period detection section 1 and the winding side reel rotation period detection section 4 provided separately. The remaining time on the tape is output from the calculation section 2 and displayed on the output section 6. Note that this output section 5 may have a function of displaying the remaining tape time in numbers on a part of the picture tube of a television receiver, for example. The operation mode and tape running speed (standard mode, 3x mode, etc.) are set using the mode operation section 6, and accordingly, in the case of recording 2 normal playback mode, calculation is performed according to the calculation formula (7) explained in section 7 above. Ru.

The gist of the present invention relates to calculation processing of changes in tape amount during times other than constant speed running, and is intended to be calculated based on the rotational speed of the reel rotating shaft.

Now, considering the time of tape fast forwarding, the total amount of tape fed from the tape wound on the supply reel to the take-up reel is 1, 2, 3, etc. of the supply reel. ...for n rotations,
The tape delivery length is πD, π(D-2S), yr (
D-43) , --------yr (D-2nS)
Then, the tape feed amount after n rotations of the supply reel is nπ(D - (n-1) S) -------
--・-(8) Regarding the change in remaining time, n is the number of revolutions of the supply reel, an integer greater than or equal to 1, and V
is the constant running speed of the tape, D is the diameter of the tape wound on the supply reel before delivery, and S is the thickness of the tape.

When these are known in advance, the change Δt in the remaining tape time can be calculated by simply knowing the rotation speed n of the supply reel in fast-forward mode, and by subtracting this from the remaining time before fast-forwarding, the fast-forwarding It becomes possible to display the remaining time. Of course, even in the middle of fast-forward mode, if you perform calculations sequentially according to the rotation speed n,
It is also possible to continuously display the remaining time in output 2.

We have separately explained the fast forward mode as a mode in which the tape running speed is not constant, but in the rewind mode the remaining time changes as follows, and by adding this to the remaining time before rewinding, the change in the remaining time during rewinding is The remaining amount of time can be displayed.

Of course, these methods can also be implemented in variable speed playback modes such as slow playback and reverse playback.

As is clear from the above explanation, if you first run the tape at a constant speed and know the remaining time of the tape (in this case, of course, if you know the diameter of the tape on the supply side from equation (6) above) After that, the remaining time can be continuously displayed in output 2 even after passing through all operation modes.

These can be realized by calculation by obtaining only the rotation information of the supply reel, and can be outputted only by the calculation processing of the calculation unit 2 without requiring an additional detection unit or the like.

As described above, according to the present invention, with a simple configuration, it is possible to accurately know the remaining tape time in any operation mode, and the effect is very large.

[Brief explanation of drawings]

The drawing is a block diagram of main parts of an embodiment of the present invention. 1... Supply side reel rotation period detection section, 2, 3.
...Calculating section, 4... Winding side reel rotation period detection section, 5... Output section, 6... Mode operation section.

Claims (3)

[Claims] (1) detection means for detecting rotation information of the supply reel;
It is equipped with a calculation section that calculates the remaining time of the tape from the output signal of the detection means, and an output section that outputs the calculation result. A signal proportional to the rotation period is detected to calculate the remaining tape time, and in an operation mode in which the tape does not run at a constant speed, the reel rotation speed is detected and integrated as rotation information of the supply reel. 1. A tape remaining time output device characterized in that the tape remaining time output device is configured to obtain the tape remaining time by calculating changes in the tape remaining time. (2) The remaining tape time output device according to claim (1), wherein the remaining tape time t during constant speed running is processed by the following. (3) In the operation mode in which the tape runs in the forward direction,
Calculate the change Δt in the remaining time of the tape (where n is an integer greater than or equal to 1, D is the diameter of the tape wound on the supply reel before sending out, and S is the thickness of the tape.) The tape remaining time output device according to claim 1 or 2, wherein the remaining tape time output device is configured to perform arithmetic processing so as to decrease the time from the remaining time and output the result. G4) In the operation mode in which the tape runs in the opposite direction, the change in the remaining tape time Δt (where n is an integer greater than or equal to 1, D is the diameter of the tape wound on the supply reel before sending out, and S is the tape (thickness.) According to claim (1) or (2), the calculation is performed on three pages, and the calculation process is performed and output in such a way as to be added to the remaining time before the operation. tape remaining time output device.