JPH0262913A - Rotation detecting device - Google Patents

Abstract

PURPOSE:To improve the resolution of the detection of rotation by disposing a disk where an N pole and an S pole are magnetized at intervals of specified angle opposed to a rotor. CONSTITUTION:A Hall element 6 is disposed by opposed to the magnetized part of the disk 2 and it makes an output signal from a magnetism sensitive element into a pulse every change of specified amplitude to output. The output signal from the Hall element 6 is supplied to a comparator 13 through an amplifier 7 and an A/D converter 11. Plural reference values corresponding to the output signal from the converter 11 are supplied to the comparator 13 from a table 14. In the comparator 13, the output signal from the A/D converter 11 is compared with plural reference values from the table 14. When the signal coincides with them, the pulse is outputted from the comparator 13. The pulse outputted from the comparator 13 is supplied to a counter 15 and the output signal from the counter 15 is supplied to a display circuit 9 so that the display of the counter is performed. The output signal from the counter 15 is made to pass a system control circuit 10 so as to detect the abnormality, etc., of the rotation of a reel 1. Thus, the resolution of the detection of rotation can be improved without lowering rotational torque.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotation detection device for transmitting a rotational motive force to a rotating body by magnetic coupling.

[Summary of the invention]

In this invention, a disk is arranged facing a rotating body and has north and south poles magnetized at predetermined angular intervals, and by rotating this disk, the rotating body is rotated.
A magnetically sensitive element is arranged opposite to the magnetized part of the disk, and the output signal of this magnetically sensitive element is converted into a pulse every time a predetermined amplitude change is output. This allows the detection resolution to be increased.

[Conventional technology]

For example, the take-up reel of a VTR must be rotating during recording, playback, rewinding, fast forwarding, and unloading. If this take-up reel is not rotating, there is a risk that the tape may become tangled or break, so it is necessary to quickly detect this and bring it to a stop state.

Conventionally, as methods for detecting the rotation of the reel, there are two methods: optically using a light-emitting element and a light-receiving element, and magnetically using a magnetically sensitive element, such as a Hall element.

By the way, there is a so-called magnetic clutch that transmits the rotational motive force to the reel by magnetic coupling, and it is conceivable to detect the rotation of the reel in this case as shown in FIG. 3.

In the figure, (1) is a reel, and this reel (1
) A disk (2) having north and south poles magnetized at predetermined angle rJJ intervals is arranged.

Further, (3) and (4) are gears, and the rotation axis of the gear (3) is common to the rotation axis of the disk (2). (5) is a motor.

In the above configuration, the gear (3) is driven by the motor (5).
.

When the disc (2) is rotated through (4), the reel (1) is rotated due to the magnetic coupling.

Further, (6) is a Hall element constituting the magnetically sensitive element, and is arranged facing the magnetized portion of the disk (2). In the illustrated example, a gear (
3) is interposed.

The output signal of the Hall element (6) is supplied to the detection circuit (8) via the amplifier (7).

In this case, when the disk (2) rotates, the magnetically sensitive element (6)
As the coil passes through the N-pole and S-pole magnetized portions of the disk (2), a sine wave signal is output. Therefore, in the detection circuit (8), for example, one pulse is generated in one period of the sine wave signal, and the rotation of the reel (1) is detected.

The output signal of this detection circuit (8) is supplied to a display circuit (9) and is used as information for counter display, tape remaining amount display, etc. Also, the output signal of the detection circuit (8) is system control (hereinafter referred to as "system control") <10
), and abnormal rotation of the reel (1) (for example, it does not rotate when it should), etc. is detected.

[Problem to be solved by the invention]

In the example shown in FIG. 3, in order to detect abnormal rotation with higher accuracy, it is necessary to increase the resolution of rotation detection. In order to increase the resolution of rotation detection, a disk (2
), but if the number of magnetized poles is increased, the rotational torque will decrease. In other words, it has been impossible to increase the resolution of rotation detection by simply increasing the number of magnetized poles of the disk (2).

Therefore, it is an object of the present invention to make it possible to increase the resolution of rotation detection without reducing the rotational torque.

Means for Solving the Two Problems] This invention provides a disc (2) facing a rotating body (1) with N poles and S poles magnetized at predetermined angular intervals; 2), in which a magnetically sensitive element, such as a Hall element (6), is arranged opposite to the magnetized portion of the disc (2), and this sensitive element is Each time the output signal of the magnetic element changes in a predetermined amplitude, it is converted into a pulse and output.

[Effect]

In the above-mentioned configuration, the output signal of the magneto-sensitive element is converted into a pulse and output every predetermined amplitude change, and one pulse is not output per period of the output signal of the magneto-sensitive element. Therefore, it is possible to increase the resolution of rotation detection without increasing the number of magnetized poles of the disk (2), that is, without reducing the rotational torque.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 3 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In the figure, the output signal of the Hall element (6) is transmitted to the comparator (1) via the amplifier (7) and A/D converter (11).
3). This comparator (13) has a plurality of reference values -En corresponding to the output signal of the A/D converter (If (sine wave signal illustrated by curve a in FIG. 2A)).

...++, F, 2. El, O, El, E2
．． = ++, En (n is a natural number), for example, RO
It is supplied from the table (14) consisting of M. Comparator (
In 13), the output signal of the A/D converter (11) is compared with a plurality of reference signals from the table (14), and when there is a match, a pulse is generated from this comparator (13). In other words, the comparator (13) generates a pulse every time the output signal of the A/D converter (11) changes in predetermined amplitude, as shown in the second l8. For example, an A/D converter (1
When the peak-to-peak value of the output signal of 1) is 750 mV, a pulse is generated every 60 mV change.

Further, the pulse output from the comparator (13) is supplied to the counter (15) as a clock. The output signal of this counter (15) is supplied to a display circuit (9) and is used as information for counter display, tape remaining amount display, etc. Further, the output signal of the counter (15) is supplied to the system controller (10), and abnormal rotation of the reel (1) is detected.

Here, the comparator (13), table (14), and counter (15) are actually the microcomputer (1
2).

This example is constructed as described above, and the rest is the same as the example shown in FIG.

In this example, the Hall element (6) is selected from the comparator (13).
A pulse is output every predetermined amplitude change of the output signal, and one pulse is not output per period of the output signal. Therefore, according to this example, the disk (2
) The resolution of rotation detection can be increased without increasing the number of magnetized poles, that is, without reducing the rotational torque. Although not described above, the disk (2) is, for example, five-pole magnetized.

In addition, in the above-mentioned Example, although the Hall element (6) was shown as the example used as a magnetically sensitive element, other magnetically sensitive elements may be used. In addition, in the above-mentioned embodiment, an example was shown in which the rotating body was the reel (1), but
The present invention can be similarly applied to other rotating bodies.

Furthermore, in the above embodiment, a pulse is output every time the amplitude changes, but the output signal of the A/D converter (11) (a sine wave shown by curve a in FIG. 2A) The pulse intervals can be made equal by decreasing the width of the amplitude change in which the pulses are output as the peak side of the signal increases.

[Effects of the Invention] According to this invention, since the output signal of the magnetically sensitive element is output as a pulse every time a predetermined amplitude change is made, it is possible to increase the resolution of rotation detection without reducing the rotation torque. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram for explaining the same, and FIG. 3 is a block diagram of an example of a rotation detecting device. (1) is a reel, (2) is a disk, (6) is a Hall element,
(11) is a to/D converter, (12) is a microcomputer, (13) is a comparator, (14) is a table, (1
5) is a counter. Deputy Attorney Hitoi Sarasada Same Litigation Hide Kuma appeared in the 1st Shinyunjin appearance! Ichii 1 structure, sense 1a Fig. 3 Example a D1 eye Fig. 1 Example 1 cause for definiteness Fig. 2

Claims (1)

[Claims of Claims] A disk having north and south poles magnetized at predetermined angular intervals is disposed facing the rotating body, and by rotating this disk, the rotating body is rotated. A rotation detection device characterized in that a magnetically sensitive element is arranged opposite to the magnetized portion of the disk, and the output signal of the magnetically sensitive element is converted into a pulse and outputted every time a predetermined amplitude change occurs. .