JPS6352066A - Revolution indicator - Google Patents

Abstract

PURPOSE:To measure an accurate rotating speed by processing an image without adding any special body to a rotary body by rotating a still image pickup camera which is installed so that the rotary body is put in the visual field plural times. CONSTITUTION:The video signal of the still image pickup camera 1 installed in front of the rotary body 8 is converted by an A/D converter 2 into a digital signal, which is stored in one of image memories 3, 4, and 9. The rotary body; 8 is provided with a mark 8a at a position other than the center and a mark 8b in the center. The video signal is read twice or three times so as to measure the rotating speed of the rotary body 8. A 1st read signal is stored in the memory 3, a 2nd signal is stored in the memory; 4, and a 3rd signal is stored in the memory; 9. Those signals are inputted to an image processing part 5 to read the positions of the marks 8a and 8b. Those read data are inputted to an arithmetic processing part 6 to calculate the rotating speed, and the calculation result is inputted to and displayed on a display part 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field This invention relates to a tachometer that measures the rotational speed of a rotating body.

(b1 Summary of the Invention The tachometer according to the present invention is provided with a still image camera that takes a still image of a rotating body that has a mark at one point off the center,
This static imaging camera continuously photographs the rotating body multiple times. The rotational speed of the rotating body is determined based on the position of the mark on the rotating body in these images.

This makes it possible to accurately measure the rotational speed without adding any special object to the rotating body.

fc) Prior Art Conventionally, there are the following means for measuring the rotational speed of a rotating object (rotating body).

A device in which a magnet is attached to a part of a zero-rotating body, a magnetic head is installed near the rotating body, and one rotation is counted each time the magnetic head detects the magnet.

■Means for measuring rotational speed by installing a rotary encoder, which consists of a rotating plate with multiple slits and a photo sensor that detects the slits, on a rotating body.

(d1 Problem to be solved by the invention)However, all of the above means require some kind of object to be attached to the rotating body, which takes time and effort to measure, and the object must be attachable. There was a drawback that the object to be measured was restricted.

This invention was made in view of these problems, and an object of the present invention is to provide a tachometer that can accurately measure rotational speed through image processing without adding any special object to the rotating body. shall be.

(e) Means for Solving the Problems This invention relates to a tachometer that measures the rotational speed of a rotating body marked at a point off the center, and that captures a still image of the rotating body. The present invention is characterized in that it includes a camera, means for repeatedly operating the still imaging camera at regular intervals, and means for calculating a rotational speed based on the position of the mark in each image taken.

(f) Function In the tachometer of the present invention, a still imaging camera is installed so that the rotating body is within the field of view, and this still imaging camera is operated multiple times (twice or three times).

The rotation angle of the rotor is determined from the position of the mark of the rotor photographed on the screen output by this operation, and the rotation speed of the rotor is calculated from this rotation angle and the operation interval of the still imaging camera. The calculated rotational speed is output to a display device or the like.

(gl Embodiment FIG. 4 is a diagram showing a schematic structure of a still imaging camera 1 used in a tachometer according to an embodiment of the present invention.As this still imaging camera 1, for example, the (
(Patent Application No. 101740/1988) "Still Imaging Camera" is used. A frame transfer type CCD image sensor (hereinafter simply referred to as rccDJ) 10 is installed behind the lens 14, which is an optical system. This CCD10 consists of an imaging section 1), a storage section 12, and a horizontal shift register 13, and the imaging section 1) faces the lens 14. An amplifier 17 that amplifies the output signal is connected to the horizontal shift register 13, and a signal processing section 18 that edits the amplified signal as a video signal is connected to the amplifier 17. The video signal output by the signal processing section 18 is input to an image processing device or the like. On the other hand, a driver 15 is connected to each part of C0DIO, and movement of signals (charges) in CCD10 is performed based on commands (clock signals) from this driver 15. A controller 16 is connected to the driver 15. This controller 16 determines the timing of outputting the clock signal and outputs the clock signal to the driver 15.
control.

Outside light is imaged by the lens 14 on the imaging section 1) of the CGDIO, and charges are accumulated in each cell according to the density of the image. The charges transferred to the storage unit 12 are transferred to the storage unit 12 every l/60 seconds), and the charges transferred to the storage unit 12 are transferred to the horizontal shift register 1.
3, the data is output one column (one scanning line) at a time.

Here, the exposure method of the still imaging camera 1 will be explained with reference to the exposure timing chart of FIG. Since a typical video device is set to process 60 fields of screen per second, the still imaging camera 1, which is a video camera, also operates with 1/60 second as one cycle to comply with the specifications. Since the lens 14 does not have a mechanical shack, it continues to be exposed for 1/60 second. Therefore, in this device, the charges accumulated in the imaging section 1) are cleared once during a 1/60 second cycle, and the charges accumulated from the time of clearing until the end of the cycle are transferred to the accumulation section 12 as image data. I have to. If there is a sufficient amount of light on the subject, a sufficient image can be obtained with exposure for this amount of time. By doing so, the exposure time (shutter speed) in each cycle (field) can be made shorter than 1/60 second without adding any mechanical components. As a result, if the exposure time is 1) 500 seconds, for example, even when a rotating object is photographed, a still image of the object, that is, a clear image without blur, can be obtained.

FIG. 1 is a diagram showing the configuration of a tachometer according to an embodiment of the present invention using the still imaging camera 1. As shown in FIG. A video signal (output of the signal processing section 18) from the still imaging camera 1 installed in front of the rotating body 8 is input to the A/D converter 2.

The A/D converter converts the video signal input as an analog signal into a digital signal, and stores two image memories A3. Store it in either image memo + J B 4 or image memory C9. Note that the rotating body 8 is provided with a mark 8a at a position other than the center of rotation (preferably at the periphery). Furthermore, a center mark 8b may be provided at the center of rotation.

Here, the video signal is read two or three times to measure the rotational speed of the rotating body 8. That is, when the center position of the rotating body 8 is known from the beginning, the rotation angle can be determined by two readings, but if the center position is not known, the center position can be determined by three readings, and the rotation angle can also be calculated. I will have to figure it out. Therefore, if the center position of the rotating body 8 is set in advance in the device, the reading will be performed twice if the center mark 8b is located at the center position of the rotating body 8; otherwise, reading will be performed twice.
times reading is done.

The first signal read in the above operation is stored in the memory A3, the next signal is stored in the memory B4, and when the third reading is performed, the signal is stored in the image memory C9. These signals are input to the image processing section 5, and the positions of the mark 8a and center mark 8b are read. This read data is input to the arithmetic processing section 6 to calculate the rotational speed. The calculation results are input to the display section 7 and displayed.

In FIGS. 2 and 3, the image memo 1JA3. B4,C
FIG. 2 shows an image of the rotating body 8 stored in 9, which shows the case where the center mark 8b is not attached to the rotating body 8, and (4
), (81, fc) are stored.

Further, FIG. 3 shows a case where a center mark 8b is attached to the rotating body 8, and two images Kl and (B) are stored.

If three images are stored, i.e. mark 8
If three movement positions of a are stored, the rotation angle can be determined because the circumcenter of the triangle formed by connecting the respective marks with a straight line is the center of rotation of the rotating body 8. When the center mark 8b is attached, the rotation angle can be easily determined from the two images.

The obtained rotation angle per field interval is θ(r
ad, ), the rotational speed R (=number of rotations per unit time: rpm) can be determined by π.

The controller 16 corresponds to the "means for repeatedly operating a still imaging camera at regular intervals" of the present invention, and the image processing section 5 and the arithmetic processing section 6 correspond to "the position of the mark of each photographed image" of the present invention. means for calculating rotational speed based on

In this embodiment, the still imaging camera 1 is installed in front of the rotating body 8, but even if it is not in front, the direction of the camera and the inclination of the rotating body 8 can be easily measured and set by arithmetic processing. Accurate rotation speed can be determined.

Further, instead of providing the mark 8a on the rotating body 8 solely for measuring the rotational speed, a pattern or the like originally provided on the rotating body 8 may be used as the mark.

Therefore, the rotational speed of any rotating body can be measured as long as it has a mark and its orientation with respect to the still imaging camera 1 can be determined.

Note that in this embodiment, a still imaging camera 1 whose shutter speed was substantially increased by charge accumulation time control was used as the still imaging camera 1, but a camera having a mechanical shutter (including a liquid crystal shutter, etc.) may also be used. good.

(h) Effects of the Invention According to this invention, by using a still imaging camera, it becomes possible to take a clear image of an object moving at high speed without blurring, and It becomes possible to automatically calculate the rotational speed of the rotating body based on the position of the mark on the retracting body.

This makes it possible to measure the accurate rotational speed with a fully automated device without adding any special objects to the rotating body, and configures a system that inputs this data to the control unit, etc. This makes it possible to apply it to various automatic control fields.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a tachometer according to an embodiment of the present invention, FIG. A diagram showing an image of a rotating body photographed by a camera, FIG. 4 is a diagram showing a schematic configuration of the still imaging camera, and FIG. 5 is an exposure timing chart of the still imaging camera. 1-Still imaging camera, 2-A/D converter, 3.4.9-
Image memory, 5-image processing unit, 6-arithmetic processing unit, 1O-
C.C.D. 16-Controller.

Claims (1)

[Claims] (1) A tachometer that measures the rotational speed of a rotating body marked at a point outside the center, comprising a still imaging camera that takes a still image of the rotating body, and a static imaging camera that repeatedly shoots the static imaging camera at regular intervals. A tachometer comprising means for operating the mark and means for calculating a rotational speed based on the position of the mark in each photographed image.