JPS58143481A - Measuring device for tape running time - Google Patents

Abstract

PURPOSE:To measure tape running time by generating clock pulses of frequencies corresponding to plural gradients approximated to the characteristic curves of running time which use the turning period of a reel shaft as a parameter, and counting the clock pulses. CONSTITUTION:The oscillation signal of a crystal oscillator 1 is supplied to a timing pulse generating circuit 4 and a pulse generating circuit 5 through a frequency divider 2. The running time of a tape is approximated by straight lines l1 and l2 containing the turning period t1 of the reel shaft as a boundary. The output of a detector 3 which detects the turning of the tape take-up side reel shaft is inhibited from being counted by a counting circuit 7 thrugh a selecting circuit 6 before time t0. In time (t1-t0), the circuit 7 counts clock pulses of frequency corresponding to the gradient of the straight line l1 and in time (t2-t1), the circuit counts clock pulses of frequency corresponding to the gradient of the straight line l2; after the counting is completed, the result is latched by a latch circuit 8 and displayed on a display 10 through a decoder 9. Thus, the tape running time is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape running time meter shelf device.

Some conventional magnetic tape playback/recording devices detect the rotational speed of a tape winding shaft, perform the following calculations using a so-called microcomputer, and display the running time of the tape.

Since the tape is normally fed at a constant speed, the tape running time TFi is expressed by an equation where the rotation period t of the take-up shaft is expressed.

However, M: tape feeding speed, Δr: tape thickness, T
Bow tape reel hub diameter, α: Number of detection poles.

Conventionally, the running time was displayed on a microcomputer by configuring a program to calculate the rotation period and a program to calculate the above equation (1) from the calculation result.
However, there was a drawback that the calculation process took a long time and was expensive.Moreover, the display time unit was coarse, at more than 1 minute, and other functions such as a numerical counter, It was difficult to realize this.

SUMMARY OF THE INVENTION Therefore, the present invention provides a tape running time measuring device which has an extremely simple and inexpensive configuration, can set the running time unit to a very small value, and is capable of high-speed processing, thereby eliminating the drawbacks of the conventional tape running time measuring device. .

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, 1Vi is a crystal oscillator, and 2 is a frequency divider. Reference numeral 3 denotes a detection 1IcfIl for detecting the rotation of a reel shaft (not shown) on the tape winding side, which generates, for example, one detection pulse every rotation. In the 4Fi timing pulse generation circuit, its output terminals a-e are as shown in Figure 2 (1).
Each time a detection pulse arrives, pulses shown in FIGS. 5 is a pulse generation circuit whose output terminal fy
A clock pulse of (')+(w) in FIG. 2 is generated from g. The width of the pulses in FIG. 2 ("L (■), (W) and the period of the clock pulse in FIG. 2 (W) t (%11) will be described in detail later.)
7 is a running time counting circuit, 8 is a latch circuit, 9 is a decoder, and 10Fi display device.

In the above configuration, first, the respective pulse widths and the period of the clock pulse will also be explained. As described above, the tape running time T is expressed by equation (1) using the rotation period t of the take-up reel shaft as a parameter, and this is expressed by the quadratic curve @X· in FIG.

In the figure, the rotation period t@ indicates the minimum rotation period of the take-up reel, that is, the period when the tape travel distance is 0 and the IJ-reel is rotating in an empty state.

Further, the rotation period tl indicates the maximum period of the take-up reel, that is, the rotation period when the tape is wound to the maximum extent.

In this example, the quadratic curve 1 is set to 2 with the rotation period of 1 m as the boundary.
Book Direct @J! By approximating by *, 1-, and counting the clock pulses of the frequency corresponding to the slope of each straight line,
It measures running time.

To be more specific, the width tube time t of the pulse shown in FIG.
@ is set to prohibit counting by the counting circuit 7 while this pulse is being generated. Then, set the width of the pulse shown in Figure 2 (Seal) to the time (ts to), and set the width of the pulse shown in Figure 2 (
The frequency of the clock pulse of w) is made to correspond to the gradient of direct@11, and T 1 /(tl-1o) (T1: rotation period TI
ts to
) During this clock pulse, let the tube count. Furthermore, the width of the pulse in Fig. 2 (W) is calculated as time < ts ts )K
At the same time, the frequency of the clock pulse in FIG. 2 (1) is changed to a straight line 1. (TI − TI )
/(tz tt ) (T snow: the rotation period is the running time when it is snowing), and this clock pulse is counted during the above time (ts-tt).

By performing the above-mentioned counting operation until the next detection pulse arrives, the content of the count is displayed as the running time.

Next, the operation will be explained in detail.

When a detection pulse is generated from the detection device 5, a pulse as shown in FIG. The pulse shown in FIG. 2 (ma) is generated, and the counting circuit 7 is reset. Next, when the pulse shown in Figure 2 (marked) is generated from the terminal, the pulse generating circuit 5
The clock pulses shown in FIG. 2(1) from the terminal f of are selected and passed through, and are counted by the counting circuit 7. When the pulse shown in FIG. 2 (IF) is generated from terminal C, the clock pulse shown in FIG. 2 (III) from terminal g is selected and passed.
It is counted by the counting circuit 7.

For example, as shown by the broken line in Figure 2, if a detection pulse occurs after a time tl from the generation of the detection pulse, this detection pulse will stop the pulse from the terminal, and the counter will stop. .

At the same time, the pulse shown in FIG. 2 (1) is generated from the terminal 2, and the count contents of the counting circuit 70 are latched by the latch circuit 8 and displayed. The count content at this time is the rotation period tsKThf
The running time is T3, and without performing any calculations or conversions, the! All you have to do is display 1.

In the above actual stock example, the unit time can be set smaller by approximating the quadratic curve with two straight lines and the hole with a larger number of straight lines.

The running time can be similarly measured not only by detecting the rotation period of the reel shaft of the take-up paycheck but also by detecting the rotation period of the reel shaft on the supply side. However, in this case, the characteristic curve of the running time is the quadratic curve λ in Fig. 3.
Rewarded with 3.

ζ et al. In the above embodiment, the measurement of the running time is described, but the remaining time of the tape can be measured in the same manner. In other words, the remaining amount time T' is not expressed by the equation formed by the rotation period t' of the supply shaft.

Therefore, in the above embodiment, the remaining amount time can be obtained from the rotation period of the supply shaft in exactly the same way as the running time was obtained from the rotation period of the take-up shaft.

As described above, according to the present invention, the running time of the tape can be measured simply by counting clock pulses, and there is no need for processing such as calculation or conversion, so the configuration can be extremely simplified and high-speed processing is possible. It is. In addition, by performing the linear approximation in detail, the measurement time unit can be reduced to an extremely small time K.
It has the advantage of being able to be configured up to

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
Ea operation for illumination, Figure 3 is as follows:
FIG. 3 is a characteristic curve diagram showing the running time of the tape as a reel shaft rotation period harameter. 3...Detection device 5...Pulse generation circuit 6.
... Selection circuit 7 ... Counting circuit and above Applicant: Japan Precision Circuits Co., Ltd. No. 1
Figure 2-Exhibition

Claims (1)

[Scope of Claims] A pulse generation circuit that approximates a characteristic curve of tape running time expressed as a parameter with the rotation period of the reel shaft and generates clock pulses of frequencies corresponding to the slopes of the straight lines of a plurality of holes, said reel shaft; a detection device that detects the rotation of the detection pulse and generates a detection pulse tube; a selection circuit that sequentially selects each of the clock pulses after a lapse of time corresponding to a forging rotation period of the reel shaft from the arrival of the detection pulse; A tape running time meter* device comprising a stitch count circuit that counts the clock pulses selected by the selection circuit until the next detection pulse is detected.