JPS5827432Y2 - Tape amount display device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tape amount display device used in tape recorders, VTRs, etc.

Conventionally, there is a device of this kind that detects the number of revolutions of a reel stand and determines the amount of tape from the number of revolutions.

For example, it has been proposed to detect the rotational speed of the take-up reel and supply reel electrically or optically, find the ratio of these rotational speeds, and convert this into voltage to swing the meter. .

However, with this device, it is necessary to install detection elements on the take-up reel side and the supply reel side, and the amount of tape is displayed using voltage, which tends to cause errors, and the display is unstable and difficult to read accurately. It had drawbacks.

The present invention can eliminate the above-mentioned drawbacks by providing a pair of discs that rotate in synchronization with the supply reel and the take-up reel, and providing a plurality of slits in one disc, and A shirt piece is provided that overlaps a part of the slit, so that the light from the light emitting element passes through the slit and is received by the photoelectric conversion element, and the output of this photoelectric conversion element is digitally processed to reduce the amount of tape. This is what I asked for.

First, a first embodiment of the present invention will be described with reference to the drawings.

1 and 2, a tape 1 is unwound from a supply reel 2, passed through a guide roller 3, a magnetic head 4, a pinch roller 5, and a capstan 6, and then wound onto a take-up reel 7.

Note that 1a indicates the tape wound on the supply reel 2;
b shows the tape wound on the take-up reel 7.

A disk 9 is fixed to the shaft 8 of the supply reel 2 so as to rotate together with the supply reel 2.

For example, 300 slits 10 are provided at the peripheral edge of this disk 9.
is provided.

A disk 13 provided with a shirt flap piece 12 is fixed to the shaft 11 of the take-up reel 7 so as to rotate together with the take-up reel 7.

The shirt flap piece 12 is configured to always cover a part of the slit 10 of the disc 9.

A light emitting element 14 such as a light emitting diode or a lamp, and a photoelectric conversion element 15 such as a phototransistor are arranged facing each other on both sides of the portion where the shirt flap piece 12 and a part of the slit 10 of the disk 10 overlap.

Next, the operation of the above configuration will be explained with reference to FIGS. 3 and 4.

When the tape 1 runs at a predetermined speed in recording or playback mode and is wound from the supply reel 2 onto the take-up reel T, and the disks 9 and 13 rotate accordingly, a substantially sinusoidal waveform is generated from the photoelectric conversion element 15. An output signal is obtained.

This output signal is waveform-shaped by the Schmitt circuit 16, and
A signal Sa shown in FIG. 4A is obtained.

In FIG. 4A, tl is the time for the portion between each slit 10 to pass above the photoelectric conversion element 15, and t2 is the time for the shirt shirt piece 12 to pass above the photoelectric conversion element 15.

This signal Sa is applied to the counter 17 and also to the gate signal separation circuit 18.

This gate signal separation circuit 18 is composed of, for example, a Miller integration circuit.

Here, if the shutter angle α2 is made larger to some extent than the angle α1 between the slits in FIG. A gate signal Sb as shown in FIG. 4B is obtained from the circuit.

The counter 17 is operated by this gate signal Sb, and the signal S
When a is counted, the counted value represents the number of revolutions of the supply reel 2 during one rotation of the take-up reel 7.

A predetermined calculation is performed in the calculation circuit 19 based on this count value, and the remaining amount of tape 1a on the supply reel 2 is displayed on the display 20 based on the calculation output.

The above calculation is performed based on the following formula.

However, T8 is the remaining amount of tape, which is expressed as the play time (running time when running at a predetermined speed) of the tape 1a on the supply reel 2.

r Radius of Nireel hub, θT Nishishata opening angle, T:
,, total play time, L: total tape length, N2 number of slits counted, t: tape thickness, Ns total number of 10 slits.

In the above calculation formula, all data except N is known data, and by substituting N, the remaining amount of tape can be determined as play time.

By using a microprocessor as the arithmetic circuit 19, when the above data is different, for example, the tape thickness t
, tape length L, etc., if these data are input in some form from the outside, calculations can be performed based on the new data.

Furthermore, if the tape speed differs due to fast forwarding, rewinding, etc., the time constant of the Miller integration circuit may be changed by switching.

Next, a second embodiment will be described.

In this embodiment, the remaining amount of tape can be displayed during fast forwarding and rewinding without using a Miller integration circuit.

In this embodiment, the disk 9 shown in FIG. 1 is made of a semi-transparent material, and a slit 10 is provided therein.

According to the above configuration, the quadruple conversion element 15 includes the shirt shirt piece 1
Since light is always irradiated through the semi-transparent disk 9 except when the light beam 2 passes, a current of level a shown in FIG. 6A flows.

Therefore, when the disks 9 and 13 rotate, this photoelectric conversion element 1
5, a substantially sinusoidal signal S superimposed on level a is obtained.

This signal S is applied to Schmitt circuits 21 and 22 shown in FIG.
are added to each.

The Schmitt circuit 21 has a trigger level of level a, and the Schmitt circuit 22 has a trigger level of level b, which is lower than the above a in FIG. 6A.

Therefore, from the Schmitt circuit 21, the signal S shown in FIG.
a is obtained and this signal Sa is added to the counter 17.

A signal Sb shown in FIG. 6C is obtained from the Schmitt circuit 22 as a gate signal, and this signal Sb causes the counter 1 to
7 is operated.

Based on the count value of the counter 17, calculation is performed according to the above formula, and the remaining amount of tape is displayed as play time on the display 20.

According to the above, without using the Miller integration circuit, the gate signal S
b can be obtained.

Next, third and fourth embodiments will be described.

In the first and second embodiments described above, if the distance between the supply reel 2 and the take-up reel 7 is large, the disk 9
, 13 becomes large, making it difficult to install them.

The third and fourth embodiments solve this problem.

FIG. 7 shows a third embodiment, in which a supply rule 2 and a disc 9 provided with a slit 10 are fixed to a shaft 8 so as to be rotated together.

A disc 13 provided with a shirt flap piece 12 and a pulley 23 are integrally provided on this shaft 8 and are rotatable with respect to this shaft 8 .

The rotation of the take-up reel 7 is connected to the pulley 23 by a rubber belt 24.
It is designed to be transmitted via.

Furthermore, a light emitting element 14 and a photoelectric conversion element 15 are disposed to face each other on both sides of a portion where the shirt flap piece 12 and a portion of the slit 10 overlap.

FIG. 8 shows a fourth embodiment, in which a shaft 25 is provided separately from the supply reel 2 and the take-up reel 7, and the shaft 25 has two boots IJ 26 and 27 arranged in upper and lower stages. and are provided so as to be freely rotatable with respect to each other.

A disc 9 having a slit 10 is provided on the pulley 26 so as to rotate integrally with the pulley 26, and the rotation of the supply reel 7 is transmitted via a rubber belt 28.

The pulley 27 is provided with a disk 13 provided with a shirt flap 12 so as to rotate integrally with the boot IJ 27, and the rotation of the take-up reel 7 is transmitted via a rubber belt 29. There is.

According to the configurations shown in FIGS. 7 and 8, since the rotations of the supply reel 2 and the take-up reel 7 are collected at one location and detected, the sizes of the disks 9 and 13 can be freely selected. This is especially advantageous for models in which the distance between the supply reel 2 and the take-up reel 7 is large.

In each of the above embodiments, the amount of tape used can be known by providing the disk 13 on the supply reel 2 side and the disk 9 on the take-up reel 7 side.

As described above, the present invention includes a disk 9 that rotates in synchronization with the rotation of the supply reel 2 and a disk 13 that rotates in synchronization with the rotation of the take-up reel 7, and one disk has a plurality of In addition to providing the slit 10, a shirt flap piece 12 covering a part of the plurality of slits is provided on the other disc, and a light emitting element 14 and a photoelectric conversion element 15 are placed on both sides of the portion where the shirt flap piece and a part of the slit overlap. a detection circuit 18.22 for detecting a period during which light from the light emitting element is not blocked by the shirt shirt piece from the output of the photoelectric conversion element; A counter 17 that counts the pulses Sa obtained from
The present invention relates to a tape amount display device characterized in that it is provided with: and an arithmetic circuit 19 that performs a predetermined calculation based on the count value of the counter to calculate the tape amount.

Therefore, according to the present invention, the rotational speed ratio between the supply reel and the take-up reel can be detected using one light emitting element and one photoelectric conversion element.

Furthermore, since the output of the photoelectric conversion element is digitally processed, an output indicating the amount of tape can be obtained in an accurate and easy-to-read form, and the circuit can be easily integrated into an IC.

Even if the tape is used halfway, the amount of tape can be determined by running the tape a little depending on whether it is running at a constant speed in the forward direction, fast forwarding, or rewinding.

[Brief explanation of the drawing]

Figures 1 to 4 show the first embodiment of the present invention, where Figure 1 is an exploded plan and perspective view of the main parts, Figure 2 is a plan view of the main parts, and Figure 3 is the circuit. System diagram, Figures 4A and 4B are waveform diagrams of each part in Figure 3, Figures 5 and 6 show the second embodiment, Figure 5 is a circuit diagram, Figure 6A, B and C are waveform diagrams of each part in FIG. 5, FIG. 7 is a side view of the main part showing the third embodiment, and FIG. 8 is a plan view of the main part showing the fourth embodiment. In addition, in the symbols used in the drawings, 1 indicates tape;
2 is a supply reel, 7 is a take-up reel, 9 is a disc, 10 is a slit, 12 is a shirt piece, 13 is a disc, 14 is a light emitting element, and 15 is a photoelectric conversion element.

Claims (1)

[Scope of utility model registration request] A disc that rotates in synchronization with the rotation of the supply reel and a disc that rotates in synchronization with the rotation of the take-up reel are provided, one disc is provided with a plurality of slits, and the other disc is provided with the plurality of slits. A shirt flap piece covering a part of the slit is provided, a light emitting element and a photoelectric conversion element are provided on both sides of a portion where this shirt flap piece and a part of the slit overlap, and light from the light emitting element is crushed by the shirt flap piece. a detection circuit that detects a period during which the photoelectric conversion element is not activated from the output of the photoelectric conversion element; a counter that is operated by the detection signal of this detection circuit and counts the pulses obtained from the photoelectric conversion element; 1. A tape amount display device comprising: an arithmetic circuit that performs calculations to calculate a tape amount.