JPS59198581A - Tape residual amount display device - Google Patents

Abstract

PURPOSE:To display suitably tape residual amount even at the rewinding and quick traversing mode as well as the normal recording/reproducing mode by arranging a roller for detecting tape speed so as to detect the tape real speed. CONSTITUTION:The roller 11 for detecting tape speed is arranged to a part of a tape running system in order to detect the tape real speed (v) and a rotary pulse in response to the tape real speed (v) is led out of the rotation of the roller 11. In figure, 12 is a tape speed detector including the turning roller 11, the detector 12 receives light by a photo transistor 15 through slits 14, 14- of the rotary disc and 10 pulses are led out at each revolution of the rotary roller 11. Similarly, the detector 16 leds out 10 pulses at each revolution of a supply reel 9. Each detecting pulse led out of the tape speed detector 12 and the supply reel turning speed detector 16 is inputted to a microcomputer 21 and a display device 23 displays digitally in the unit of time the tape residual amount.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a tape remaining amount display device for displaying the remaining amount of tape in a video tape recorder (VTR) or the like.

<Background Art> In general, VTRs have a plurality of recording and reproducing modes for the purpose of making effective use of magnetic tape, and may perform recording and reproducing operations in a long-time mode in addition to the standard mode.

Furthermore, in addition to such constant-speed recording and playback modes, there are variable-speed modes in which the tape running speed gradually changes, such as fast-forward or rewind modes. It was very difficult to display accurately.

<Disclosure of the Invention> The present invention has been made in view of the above points, and provides a tape remaining amount that can accurately display the remaining amount of tape not only in normal recording and playback modes but also in fast forward and rewind modes. The present invention provides a quantity display device.

Basic Principles of the Invention Next, an embodiment according to the present invention will be described, but prior to that description, a general consideration will be made regarding the remaining tape time T of a VTR. FIG. 1 shows a schematic diagram of the tape running state of a conventional general VTR, where 1 is a rotating drum, 2,
3.4 is a guide roller, 5 is a capstan, 6 is a pinch roller, 7 is a magnetic tape, 8 is a cassette, 9 is a supply reel, and IO is a take-up reel. During normal recording and playback mode, the magnetic tape 7 pulled out from the supply reel 9 in the cassette 8 is moved by guide rollers 2 and 3 as shown in the figure.
．． 4 and is attached to the circumferential surface of the rotating drum 1, and is sandwiched between a capstan 5 and a pinch roller 6, driven to run at a constant speed, and wound onto a take-up reel 10.

In this case, the total length of the magnetic tape 7 wound around the supply reel 9, that is, the remaining amount of tape, is MR2-'Lr2 L=□ ・・・・・・・・・・・・ ・−・・・・+1
) However, R is the tape winding radius on the supply reel side, r is the pub radius a of the supply reel, and is expressed as the thickness of the magnetic tape.

Therefore, by dividing this remaining amount of tape by the tape running speed (2) during steady recording and playback, the remaining amount of time T of the tape can be obtained. That is, the remaining amount time T is expressed as. However, although the tape running speed (2) differs between the standard mode and the long-time mode, it is determined by which mode is used during recording and is a constant value.

Therefore, in the above equation (2), all values except the tape winding radius R are constants, and this value R can also be obtained from the following equation. That is, R----v ・・・・・・・・・・・・・・・
- +31ω 271 However, ■ is the actual tape running speed (hereinafter referred to as the actual speed), and t is the rotation period of the supply reel. Here, the actual tape speed V matches the tape running speed V in the steady recording and playback modes, but gradually changes in the fast forward or playback modes.

Therefore, by substituting the above equation (3) into equation (2) and rewriting the remaining amount time T, the following is obtained. If we replace the ratio between the actual tape speed V and the steady recording/playback speed V with the variable X, then equation (4) becomes -αL2X2
−β ・・・・・・・・・ It can be rewritten as (5).

That is, as can be seen from the above equation (5), the remaining amount time T can be determined by detecting the rotation period of the supply reel 9 and the ratio X between the actual tape speed V and the steady recording/playback speed V.
It can be calculated based on the formula.

<Example> Fig. 2 is a schematic diagram of a tape running state of a VTR which is an embodiment of the present invention that is implemented to realize the above-mentioned remaining time display method, and Fig. 3 is a circuit diagram of the same embodiment. The configuration diagram and FIG. 4 are flowcharts for explaining the operation of the microcomputer used in the same embodiment.

In particular, in the embodiment shown in FIG. 2, a rotating roller 11 for tape speed detection is disposed in a part of the tape running system in order to detect the actual tape speed (2), and the rotating roller 11 is rotated when the magnetic tape 11 is running. A rotation pulse corresponding to the actual tape speed V is derived from the timer 11.

Further, in FIG. 3, reference numeral 12 is a tape speed detector including the rotating roller 11, and the detector I2 has a lamp I3.
The light is received by the phototransistor 15 through the rotating disk (Surin) 14, 14..., and ten pulses are derived every time the rotating roller 11 rotates once. Similarly, 16 is a supply reel rotation speed detector that includes a reel shaft 9' that rotates integrally with the supply reel 9, and the detector 16 transmits the light from the lamp to the slits 18, 18, and 18 of the rotating disk. * through the phototransistor 19, and 10 pulses are derived every time the supply reel 9 rotates once. 20
is a tape speed changeover switch that is switched in conjunction with a mode changeover switch (not shown) that changes between standard mode and long-time mode, and the value of recording/playback speed (■ 1 or V2) is input to a microcomputer (hereinafter abbreviated as microcomputer) 21. At the same time, since the hub diameter r and tape thickness a of the supply reel 9 are fixed values known in advance, these values are input to the microcomputer 21 and processed according to the flowchart shown in FIG. 4, (6) From formula and formula (7), α
and find the value of β.

On the other hand, each detection pulse derived from the tape speed detector 12 and the supply reel rotation speed detector 16 is transmitted to the microcomputer 2.
1 is input. The microcomputer 21 operates using a crystal oscillator 22 as a reference clock, and calculates the values of X and t by counting the number of pulses present within a predetermined time based on the reference clock within the microcomputer 21 Next (5
) Find the value of the remaining amount time T based on the formula.

As a result, the remaining amount time information outputted from the microcomputer 21 is supplied to a liquid crystal display (LCD) 2B, and the remaining amount of tape is digitally displayed in time on the display device 23.

<Effects> According to the tape remaining amount display device of the present invention, as described above, a tape speed detection roller is arranged in the tape running system to detect the actual tape speed and calculate and display the remaining tape amount time. Therefore, even if the steady recording and playback speeds are switched to multiple modes, such as VTRs, fast forwarding,
Even in rewind mode, the remaining tape time can be displayed almost accurately.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the tape running system of a conventional general VTR, Fig. 2 is a schematic diagram of the tape running system of a VTR embodying the present invention, Fig. 3 is a circuit configuration diagram of the same embodiment, and Fig. 4 is a schematic diagram of the tape running system of a conventional VTR. It is a flowchart for explaining the operation of the microcomputer used in the same embodiment. 7...Magnetic tape, 9...Supply reel, 10.Take-up reel, 1-tap speed detection rotating roller, 12...
- Tape speed detector, 16... Supply reel rotation speed detector, 20 - Tape speed changeover switch, 21 - Microcomputer, 23 - Display device. Agent Patent attorney Aihiko Fukushi (and 2 others) Figure 1

Claims (1)

[Claims] 1. A tape speed detection roller is disposed in a part of the tape running system to detect the actual tape speed V and the rotation period t of the supply reel, and to calculate the detected values and the known tape steady state. A tape remaining amount display device characterized in that a tape remaining amount time T is calculated by inputting speed V1 tape thickness a, (IIJ-ru hub diameter r) into a microcomputer, and this is displayed on a display device. 2. The remaining tape time T is calculated by the following formula, where X =
A tape remaining amount display device according to claim 1, characterized in that the remaining amount of tape is calculated by V /V.