JPH10177030A - Rotary direction detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary direction detection device for accurately determining a phase difference between output signals of a photo interrupter with an inexpensive device configuration. SOLUTION: The device has a reflection sheet 12, which is provided on the surface of a rotator, which orthogonal crosses the center axis and where a reflection part 12a and a non-reflection part 12b are alternately arranged at a region divided into n equal portions at an equal angle interval with the center axis as the center for detecting the rotary direction of the rotator that rotates with the center axis as the center, two photo interrupters 13a and 13b, which are provided opposite to the reflection sheet 12 and are located with an approximately 90 deg. with the center axis as the center, and a detection part for detecting the rotary direction of the rotator based on the reception signal of the photo interrupters 13a and 13b, where n is an even number that is equal or more than 10 in that the remainder obtained by dividing (n/2) by 4 is either 1 or 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation direction detecting device for detecting a rotation direction of a tape reel in an AV apparatus using a magnetic tape as a recording medium, for example.

[0002]

2. Description of the Related Art Conventionally, in an AV device such as an audio device or a video device using a tape-shaped recording medium, the rotation direction of a tape reel is detected in order to control the back tension of the tape. As shown in FIG. 6, for example, the detection of the rotation direction of the tape reel is performed by the reflection sheet 2 attached to the lower surface of the reel base 1 and the photo interrupters 3a and 3b arranged on the printed wiring board 4. And a processing unit for processing the detection signals of the photo interrupters 3a and 3b. On the lower surface of the reflection sheet 2, reflection portions 2a and non-reflection portions 2b are arranged in a pattern shown in FIG.

In this tape reel rotation direction detecting device,
When the reflecting section 2a of the reflecting sheet 2 is located at a position facing the photo interrupters 3a and 3b, the light beam emitted from the photo interrupters 3a and 3b is reflected by the reflecting section 2a, and the reflected light is transmitted to the light receiving section. Detected.
As a result, the output signals from the light receiving sections of the photo interrupters 3a and 3b become low level, for example. On the other hand, when the non-reflection portion 2b of the reflection sheet 2 is located at a position facing the photo interrupters 3a and 3b, the light beam emitted from the photo interrupters 3a and 3b
b, and the light beam is not detected by the light receiving unit.
As a result, the output signals from the light receiving sections of the photo interrupters 3a and 3b become, for example, high level.

[0006] In the examples shown in FIGS. 6 and 7, on the surface of the reflecting sheet 2, reflecting portions 2 a and non-reflecting portions 2 b are alternately arranged in the circumferential direction at intervals of about 45 °. ing. Further, the photo interrupters 3a and 3b are arranged at intervals of about 112.5 ° on a predetermined circumference centered on the rotation center of the reflection sheet 2. The waveforms of the output signals S3a and S3b of the photo interrupters 3a and 3b when the reflection sheet 2 is rotated at a constant rotation speed are as shown in FIGS. 8A and 8B, for example. FIG.
As shown in (A) and (B), the output signal S3a and the output signal S3b are out of phase by about 90 °. As described above, the phase difference of 90 ° is determined by the output signal S3a and the output signal S3b.
Is required to detect the rotation direction of the reflection sheet 12.

[0005] In the tape reel rotation direction detecting device, the data processing section determines from the output signals S3a and S3b shown in FIGS. 8A and 8B whether or not the reflection sheet 2 is rotated rightward as shown in FIG. I do. That is, the reflection sheet 2 is
8A, the output signal S3 shown in FIG.
The level of the output signal S3b at the time of the rise of “a” becomes a low level. On the other hand, if the reflection sheet 2 rotates counterclockwise as shown in FIG. 6, the level of the output signal S3b at the time of rising of the output signal S3a shown in FIG. Therefore, the rotation direction of the reflection sheet 2 is determined by detecting the level of the output signal S3b when the output signal S3a rises in the data processing unit.

[0006]

However, in the conventional tape reel rotation direction detecting device described above, the sheet 2
Are arranged at 45 ° intervals, the photointerrupter 3a and the photointerrupter 3b are separated from each other by about 112.5 ° on a predetermined circumference centered on the rotation center of the reflection sheet 2. Although it is necessary to arrange them at intervals, in the manufacturing process of the tape reel rotation direction detecting device, the photo interrupters 3a,
It is very difficult to mount (arrange) the 3b at an interval of about 112.5 °, and there is a problem that the positioning accuracy is low, and the manufacturing is complicated and the price is high.

This is because mounting control in an automatic insertion machine is usually performed using a rectangular coordinate system, and thus is suitable for mounting the photointerrupters 3a and 3b at intervals of about 112.5 °. Because there is no. Such a problem is that the comb-shaped circular member is attached to the lower surface of the tape reel, and when the tooth portion passes, the light beam from the light emitting portion is blocked by the tooth portion, and the portion other than the tooth portion passes. This also occurs in a tape reel rotation direction detecting device in which the light emitting unit and the light receiving unit are arranged so that the light beam from the light emitting unit reaches the light receiving unit when the light is emitted.

By the way, the photo interrupters 3a, 3b
There is a special photo-interrupter that combines the output signals into one package and outputs a phase difference of 90 ° between the output signals, but it is not only expensive but also the photo-interrupters 3a and 3b
There is a problem that the user cannot arbitrarily determine the number of pulses and the rotation diameter included in the output signal in one rotation.

The above-described problem of the tape reel rotation direction detecting device similarly occurs when detecting the rotation direction of various rotating bodies.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has as its object to provide a rotation direction detecting device capable of determining a phase difference between output signals of a photointerrupter with high accuracy with an inexpensive device configuration. .

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art and to achieve the above-mentioned object, a rotation direction detecting device according to the present invention comprises a rotating direction of a rotating body rotating about a central axis. A rotation direction detecting device, which is provided on a surface of the rotating body orthogonal to the center axis, and is provided with a light reflection portion and a light non-reflection in a region equally divided by n at equal angular intervals around the center axis. Light reflecting means in which the parts are alternately arranged,
At least two light emitting / receiving means provided opposite to the light reflecting means and located at about 90 ° intervals about the central axis, based on a light receiving result in the light emitting / receiving means,
Detecting means for detecting the direction of rotation of the rotating body, wherein n is an even number of 10 or more such that the remainder when (n / 2) is divided by 4 is 1 or 3.

Also, in the rotation direction detecting device according to the present invention, specifically, the detecting means detects the level of the light receiving signal of the other light emitting / receiving means at the timing when the level of the light receiving signal of the one light emitting / receiving means switches. The rotation direction of the rotating body is detected accordingly.

In the rotation direction detecting device according to the present invention, when the light reflecting portion of the light reflecting means is located at a position facing the light emitting and receiving means, the light emitted by the light emitting and receiving means is received. On the other hand, when the light non-reflecting portion of the light reflecting means is located at a position facing the light emitting and receiving means, the light emitted by the light emitting and receiving means is not received.

In the rotation direction detecting device according to the present invention, the light reflecting portion and the light non-reflecting portion of the light reflecting means are formed at equal angular intervals around the center axis at equal intervals.
By setting n to be an even number of 10 or more such that a remainder obtained by dividing (n / 2) by 4 is 1 or 3, two light emitting / receiving means are arranged at intervals of about 90 ° about the center axis. Then, the light receiving signals corresponding to the light receiving results from the two light emitting and receiving means can have a phase difference of 90 °. As described above, since the two light emitting and receiving means are arranged at intervals of about 90 ° about the center axis, during the manufacturing process,
An automatic insertion machine employing a rectangular coordinate system can position the light emitting and receiving means with high accuracy at low cost.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Hereinafter, a tape reel rotation direction detecting device according to an embodiment of the present invention will be described. This tape reel rotation direction detection device is incorporated in an AV device using a magnetic tape such as an audio device or a video device, and detects a rotation direction of the tape reel in order to appropriately control the back tension of the magnetic tape.

FIG. 1 is a side view of a reel base 11 around which a reflection sheet 12 of a tape reel rotation direction detecting device 10 according to the present embodiment is fixed, FIG. 2 is a front view of the reflection sheet 12, and FIG. FIG. 3 is a circuit diagram of a detection circuit 14 of the reel rotation direction detection device 10. As shown in FIG. 2, the reflection sheet 12 fixed to the lower surface of the reel base 11 opposite to the printed wiring board 4 has, for example, a circular shape. Is divided into Reflecting portions 12a and non-reflecting portions 12b are alternately assigned to the ten equally divided regions along the circumferential direction. The surface of the reflection sheet 12 is formed, for example, by pasting a silver seal on the substrate, applying black silk printing to the non-reflection section 12b, and exposing the silver seal to the reflection section 12b. .

The photo-interrupters 13a and 13a are provided on the printed wiring board 4 at 90 ° intervals about the rotation center of the reflection sheet 12 so as to face the reflection sheet 12.
b is provided. The distance between the reflection sheet 12 and the photo interrupters 13a and 13b is, for example, about 0.9 mm. As shown in FIG. 3, the photo interrupters 13a,
Is composed of an infrared light emitting diode 21a and a phototransistor 22a. Also, the photo interrupter 1
3b, comprises an infrared light emitting diode 21b and a phototransistor 22b.

In the phototransistors 22a and 22b, the infrared rays from the infrared light emitting diodes 21a and 21b are reflected by the reflecting portion 12b of the reflecting sheet 12, and when the reflected light is received, the potential of the collector is changed from a high level to a low level. Drop to level. Here, the photointerrupters 13a, 1a when the reflection sheet 12 is rotated at a constant rotation speed
The waveforms of the output signals S13a and S13b of 3b are as shown in FIGS. 4A and 4B when the reflection sheet 12 is clockwise in FIG. At this time, the phase of the output signal S13a leads the phase of the output signal S13b by about 90 °. When the reflection sheet 12 is counterclockwise in FIG. 2, the waveforms of the output signals S13a and S13b are as shown in FIG.
As shown in FIG. At this time, the output signal S13a
Is delayed by about 90 ° with respect to the phase of the output signal S13b. In this example, while the reflection sheet 12 makes one rotation, pulses of five cycles are generated in the output signals S13a and S13b.

In the detection circuit 14, as shown in FIG. 3, the collector of the phototransistor 22a is connected to the base of the transistor 23, and the collector of the transistor 23 is connected to the clock of the flip-flop (FF) 25 via the point P. (CK) terminal. The collector of the phototransistor 22b is connected to the base of the transistor 24, and the collector of the transistor 24 is connected to the D terminal of the flip-flop (FF) 25 via the point Q.

In the detection circuit 14, when the output signal S13a is at a high level, the output signal S13a goes low, and the output signal S13a
When the signal is at a low level, a signal that goes to a high level appears at point P. When the output signal S13b is at a high level, the signal goes to a low level, and when the output signal S13b is at a low level, a signal that goes to a high level appears at a point Q.

The levels at the points P and Q are input to the flip-flop 25, and the level at the point Q when the level at the point P rises is latched by the flip-flop 25 and appears at the output terminal Q. The level appearing at the output terminal Q indicates the rotation direction of the reflection sheet 12. Specifically, when the output terminal Q is at a low level, the reflection sheet 12 is clockwise as shown in FIG. 2, and when the output terminal Q is at a high level, the reflection sheet 12 is counterclockwise as shown in FIG. From the frequency of the signal generated at point P,
Rotation speed information is obtained.

In the tape reel rotation direction detecting device 10,
The reflection sheet 12 rotates according to the rotation of the reel base 11. Then, output signals S13a and S13 as shown in FIG. 4 corresponding to the rotation of the reflection sheet 12 are output from the photo interrupters 13a and 13b and input to the detection circuit 14. The detection circuit 14 outputs a signal of a level corresponding to the output signals S13a and S13b from the output terminal Q of the flip-flop 25. If the output terminal Q is at a low level, the reflection sheet 12 is detected to be clockwise as shown in FIG. 2, and if the output terminal Q is at a high level, the reflection sheet 12 is detected to be counterclockwise as shown in FIG.

As described above, in the tape reel rotation direction detecting device 10, the photo interrupters 13 a and 13 b are arranged at 90 ° intervals around the rotation center of the reflection sheet 12.
Is provided. Therefore, in the manufacturing process of the device, using an automatic insertion machine that performs positioning using a rectangular coordinate system,
The photo interrupters 13a and 13b can be mounted at high positioning accuracy and at low cost. Further, even when a printed wiring board is used, the positioning of the photo interrupters 13a and 13b can be easily performed.

Second Embodiment A tape reel rotation direction detecting device according to the second embodiment is basically the same as the tape reel rotation direction detecting device 10 according to the first embodiment described above. Are different. FIG. 5 is a front view of the reflection sheet 42. As shown in FIG. 5, the reflection sheet 42 has a circular shape, for example, and this circular area is divided into 14 equal areas having the same central angle. In these 14 equal areas,
The reflecting portion 42a and the non-reflecting portion 4 are alternately arranged along the circumferential direction.
2b is allocated. The surface of the reflection sheet 42
For example, a silver seal is attached to the substrate, and the non-reflective portion 42b
Is subjected to black silk printing, and the reflective portion 42b is formed by exposing the silver seal as it is. In this example, while the reflection sheet 42 makes one rotation, pulses of seven cycles are generated in the output signals S13a and S13b.

Also with this tape reel rotation direction detecting device, by providing photointerrupters 13a and 13b at intervals of 90 ° about the rotation center of the reflection sheet 12, a 90 ° angle between the output signals of the photointerrupters 13a and 13b can be obtained. It can have a phase difference. for that reason,
The same effect as the tape reel rotation direction detecting device 10 of the first embodiment can be obtained by this tape reel rotation direction detecting device.

By the way, when the photo interrupters 13a and 13b are arranged at an angular interval of 90 ° about the center of rotation of the reflection sheet, the photo interrupters 13a and 13b
The pattern of the reflection portion and the non-reflection portion of the reflection sheet capable of causing a phase difference of 90 ° between the output signals of 13b satisfies the following conditions.

(Condition) When the reflection sheet is equally divided into n at equal center angles, the remainder obtained by dividing (n / 2) by 4 is 1 or 3. Here, n is an even number of 10 or more.

Therefore, the photo interrupters 13a, 1
3b are fixedly arranged at 90 ° angular intervals as shown in FIG. 2 and FIG.
When it is desired to increase or decrease the number of cycles per rotation of the output signal, the value of n may be increased or decreased so as to satisfy the above condition. In this way, if only the pattern of the reflection part and the non-reflection part formed on the reflection sheet is changed, the cycle per one rotation of the output signals of the photo interrupters 13a and 13b can be maintained without changing the arrangement of the photo interrupters 13a and 13b. You can change the number. Therefore, the labor and cost associated with the change in the number of cycles can be reduced.

In the first embodiment, the condition n = 10 is satisfied.
And the second embodiment is a case where n = 14.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the case where the present invention is applied to the tape reel rotation direction detecting device has been exemplified. However, the present invention can be applied to a case where the rotation direction of another rotating body is detected. Also, the photo interrupters 13a and 13b
In addition to the detection circuit shown in FIG. 3 which detects the rotation direction using the output signals S13a and S13b of FIG.

[0031]

As described above, according to the rotation direction detecting device of the present invention, the rotation direction of the rotating body can be detected with high accuracy with an inexpensive device configuration.

[Brief description of the drawings]

FIG. 1 is a side view of a periphery of a reel base to which a reflection sheet of a tape reel rotation direction detecting device according to a first embodiment of the present invention is fixed.

FIG. 2 is a front view of the reflection sheet shown in FIG.

FIG. 3 is a circuit diagram of a detection circuit of the tape reel rotation direction detection device.

4A is a waveform diagram of an output signal of a first photointerrupter, and FIG. 4B is a waveform diagram of an output signal of a second photointerrupter when a reflection sheet is clockwise. FIG. 4C is a waveform diagram of an output signal of the second photointerrupter when the reflection sheet is counterclockwise.

FIG. 5 is a front view of a reflection sheet of a tape reel rotation direction detecting device according to a second embodiment of the present invention.

FIG. 6 is a side view of the periphery of a reel base to which a reflection sheet of the conventional tape reel rotation direction detecting device is fixed.

FIG. 7 is a front view of the reflection sheet shown in FIG. 6;

8A is a waveform diagram of an output signal of the first photo-interrupter shown in FIG. 6, and FIG. 8B is a diagram of the second photo-interrupter shown in FIG. 6 when the reflection sheet is clockwise. It is a waveform diagram of an output signal.

[Explanation of symbols]

4 Printed wiring board, 11 Reel base, 12, 42 Reflective sheet, 12a, 42a Reflector, 12b, 42b
Non-reflection part, 13a, 13b ... photo interrupter, 25
…flip flop

Claims (4)

[Claims] 1. A rotation direction detection device for detecting a rotation direction of a rotating body that rotates about a central axis, the rotation direction detecting apparatus being provided on a surface of the rotating body that is orthogonal to the central axis and having equal angular intervals about the central axis. A light reflecting means in which light reflecting parts and light non-reflecting parts are alternately arranged in an area equally divided by n; and provided opposite to the light reflecting means, and located at intervals of about 90 ° about the central axis. At least two light emitting and receiving means; and detecting means for detecting a rotation direction of the rotating body based on a light receiving result of the light emitting and receiving means, wherein n is obtained by dividing (n / 2) by 4. The rotation direction detection device is an even number of 10 or more in which the remainder is 1 or 3. 2. The apparatus according to claim 1, wherein said detecting means detects a rotation direction of said rotating body in accordance with a level of a light receiving signal of said other light emitting and receiving means at a timing when a level of a light receiving signal of said one light emitting and receiving means switches. 3. The rotation direction detecting device according to 1. 3. The rotation direction detecting device according to claim 1, further comprising a rotation speed detecting means for detecting a rotation speed of the rotating body based on a frequency of a light receiving signal according to the light receiving result. 4. The rotation direction detecting device according to claim 1, wherein the rotating body is a reel base on which a magnetic tape is wound, and detects a rotation direction of the reel base.