JPS59122909A - Rotary phase detector - Google Patents

Abstract

PURPOSE:To make detecting accuracy high, by providing a plurality of detecting means, which detects the rotating phase of a rotary body together with a plurality of parts to be detected that are provided in the rotary body, with the phase relationship with respect to the parts to be detected being shifted. CONSTITUTION:In a rotary phase detector for VTR, the following parts are provided: a capstan motor 1; a flywheel 3, which is attached to a capstan output shaft 2; cut in parts 3a, which are provided at the outer periphery of the flywheel 3; light shielding parts; light emitting elements 5, 7, and 9, which are arranged so that the phase relationship with the cut in parts 3a is shifted by every 1/3 the width of the cut in part 3a; and light receiving elements 6, 8, and 10, which are provided so as to face the light emitting elements under the elements. When the light receiving elements 6, 8, and 10 receive the light from the light emitting elements 5, 7, and 9 through the cut in parts 3a, ''H'' is outputted. When the light is shielded by the light shielding parts 3b, ''L'' is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intermittent recording type magnetic recording/playback device (hereinafter referred to as V
This invention relates to a rotational phase detector which is used in a motor vehicle (hereinafter referred to as TR), etc., and which improves the accuracy of detecting the rotational phase of a capstor/output shaft, etc.

In general, in intermittent recording VTRs, long-term recording is performed using ci.
In order to achieve high performance, the magnetic tape is run intermittently, and recording is performed while the magnetic tape is running. In order to perform this intermittent running with high precision, a magnetic tape is required.
It is necessary to accurately detect the running distance of the magnetic tape, and for this purpose, the phase of the capstan output shaft that runs the magnetic tape is detected.

In a conventional VTR rotational phase detector, for example, a flywheel is provided on the capstor/output shaft, a plurality of notched recesses are formed in the flywheel, and a light emitting element and a light receiving element are arranged facing each other across the notched recesses. and an element,
Phase detection was performed by dividing one rotation from the detection pulse of the light receiving element by the number of four notches. However, in such conventional devices, even if a large number of notch recesses are formed in order to improve detection accuracy, there is a physical limit to the number, and therefore there is also a limit to the detection accuracy. Therefore, in conventional intermittent recording type VTRs, the traveling distance of a magnetic tape cannot be accurately detected when a large amount of magnetic tape is being driven, so that accurate recording cannot be performed. This was done in order to eliminate the drawbacks of the conventional ones, in which a plurality of sensing parts provided on a rotating body and a detection means for detecting the rotational phase of the rotating body are provided with a plurality of detection means with different phase relationships with respect to the sensing parts. It is an object of the present invention to provide a rotary phase detector that can significantly improve detection accuracy without physical constraints.

An embodiment of the F1 invention will be described below with reference to the drawings.

1 and 2 show a rotational phase detector of a VTK according to an embodiment of the present invention, in which (1) shows a cab stan motor for running a magnetic tape, and (2) shows this cab stan motor. (1) is a fixed capstan output shaft, (3) is a flywheel attached to this capstan output dm+21, (3a) and (3b) are notches provided on the outer periphery of this flywheel (3) The portion (detected portion) and the light speed 1 portion, +51, (71, i9) are the phase relationship with the cut portion (3a) above the outer periphery of the flywheel (3) as shown in the figure, respectively. 1
Light-emitting elements arranged by /3 and ゛C, +61゜+8
1 and (11 are light receiving elements provided below the outer periphery of the flywheel (3) to face the respective light emitting elements +51 (71+91).

Here, the light receiving element (6) t8) fiG outputs "H" when it receives the light emitted from the light emitting element (5) (71+91) through the notch (3a), and the light is transmitted to the light S When it is cut off at the disconnection section (3b), it outputs "L".

FIG. 2 shows an electrical connection diagram of the above device.

In addition, Fig. 3 shows the above three light receiving elements 16+ +810Ω.
shows output signal waveforms a, b, and c. According to this diagram,
Due to the arrangement of the light receiving elements t61 t8) tlG, the trough waveform 3. b.

C is also 1/3 of the circumferential angle of the notch (3a) (that is, 1/2 of the circumference T of each waveform). You can see that there is a difference.

Pulse signals a and b shown in FIG. 3 are improved in this way.
, c can be used to divide the angular range corresponding to the above-mentioned opening T into six regions 1 to 3 and detect the rotational position with high accuracy.

That is, for example, the cutoff portion (3) of the flywheel (3)
If the number of a) is 30, the 0th rotation 1cllT of the 3 sets of light detection means can be divided into 6 regions as described above, so one revolution of the motor can be divided into 30 K 6 = 180. It can be detected and the detection accuracy is extremely high.

Therefore, in a long-duration VTR, it is possible to control the travel distance of the capstan with three times the accuracy of the conventional technology, and it is possible to perform recording without disturbing the reproduced image.

In addition, in the above implementation sequence (V), a light emitting element and a light receiving element were used as the detection means for detecting the rotational phase, but by using other intelligent means that can obtain a similar signal,
It is possible to obtain similar detection accuracy.

As described above, according to the present invention, a detection means for detecting the rotational phase of the rotary body is provided with a plurality of detected parts provided on a rotary body, and a plurality of detecting means are arranged so that the phase relationship of the housing with respect to the detected parts is shifted. This has the effect of greatly increasing detection accuracy without physical constraints.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts of a VTK rotational phase detector according to an embodiment of the present invention, FIG. 2 is a #L electrical diagram of the detector, and FIG. 3 is an output signal waveform diagram of the detector. It is. (2)...Capstan output I[ll, t3)...
Flywheel, (3a)... cutoff section (!detection section)
, 151 (7) +91 , +61 +81LI
O)... Light emission, light reception SF (detection means). Note that the same reference numerals in the drawings indicate the same or equivalent parts. Agent Nobu S No - Figure 1 Figure 2

Claims (1)

[Claims] (1) In a rotational phase detector that detects the phase of a rotating body, a plurality of detected parts are provided at equal intervals on the outer circumference of the rotating body, and a plurality of detected parts near the outer periphery of the rotary body are connected to the one detected part. 1. A rotary phase detector comprising a plurality of detection means arranged with a shifted phase relationship.