JPS625604Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a photoelectric measuring device.

2. Description of the Related Art There is an apparatus that measures the dimensions of an object by arranging a large number of photoelectric elements in a line, projecting the shadow of the object to be measured onto the photoelectric elements, and counting the number of light-receiving elements that are receiving or not receiving light. The present invention is aimed at this type of device, and aims to enable correct dimensions to be measured even when the object to be measured is moving.

FIG. 1 shows one embodiment of the present invention, and a general explanation will first be given with reference to FIG. 1st
In the figure, 1 is a round bar whose diameter is to be measured, and it is being transported in a direction perpendicular to the plane of the figure, and the diameter is measured while being transported. 2 and 3 are light sources, and 4 and 5 are collimator lenses that convert the light emitted from the light sources 2 and 3 into a parallel beam of light and project it onto the round bar 1. 6 and 7 are imaging lenses that form images of the side lines of the round rod 1 onto photoelectric photoreceptors 8 and 9.
Therefore, the silhouette of a round bar is reflected on the photoreceptors 8 and 9. The photoreceptors 8 and 9 are constructed by arranging a large number of photoelectric elements in a line and scanning the elements to sequentially extract the photoelectric output. The scanning time is
Products with a speed of about 700 μS are commercially available (for example,
(What are called CCD elements, etc.) Photoreceptor 8, 9
When scanned, the output of each light receiving element is taken out in order, and an output consisting of a pulse train is obtained. If each light receiving element does not receive light, the output is 0 (or small), so when the number of pulses above a certain level is counted by level selection, a round bar is determined from the distance between the light receiving elements 8 and 9 and the above counted value. 1 diameter is calculated.

By the way, the round bar is being transported and is slightly swaying up and down.
Also, since the thickness is changing, the side line (one line on the surface in the axial direction) of the round bar is moving up and down in the plane of the figure. Assume that the speed of this movement is 1 m/s. This speed is slow, but 1mm in 1mS
will be moved. Therefore, if we decide to scan the photoreceptors 8 and 9 by first scanning 8 and then scanning 9, it will take a maximum of 0.7 mS at the time when the boundary of the silhouette of the round bar projected on 8 and 9 is scanned. There was a misalignment and the lateral line had moved by 0.7mm, which led to the measurement.
There will be an error of 0.7mm. The purpose of the present invention is to eliminate measurement errors that occur in this way.

To achieve the above object, the photoreceptors 8 and 9 may be scanned simultaneously. For this purpose, it is sufficient to apply a common scanning pulse signal to the two photoreceptors.
However, in this case, since the pulse phases of the two pulse train signals output from the two photoreceptors match, it is not possible to simply add them and count them with one counter. That is, in FIG. 2, a is the photoreceptor 8.
The output pulse b is the output pulse of the photoreceptor 9, and the section T corresponds to one scan. The diameter of the round bar 1 is determined by counting the pulses of both pulse trains a and b separately and subtracting the sum from a certain constant. Now, two pulse trains a and b
If we count and add each separately, counter 2
, one digital adder is required. If we use one counter and input two pulse trains a and b into one counter through an OR circuit in order to eliminate the need for a digital adder, the pulses ABC and Ni will overlap in Figure 2, which is correct. Unable to count. The second purpose of this invention is to
The object of the present invention is to enable simultaneous scanning of two photoreceptors without an adder. The present invention will be explained below with reference to Examples.

In FIG. 1, 12 is a clock pulse generator, 10 and 11 are driving circuits for the photoreceptors 8 and 9, and the photoreceptors 8 and 9 receive clock pulses from 12.
Scan 9. Since 10 and 11 receive a common clock pulse, 8 and 9 are scanned completely synchronously. Reference numerals 13 and 14 indicate level comparators, which extract only those output pulses having a certain level or higher (corresponding to the output of the light-receiving element outside the silhouette of the round bar) from the output pulses 8 and 9. 8 and 9 are scanned in synchronization with each other, the outputs of the comparators 13 and 14 are as shown in FIG. 2a and b, respectively. 15 and 16 are conversion circuits mainly composed of differentiating circuits, and 15 is a comparator 1.
The output pulse of 3 (Figure 2a) is differentiated and only its rising portion is extracted as a positive pulse, and the output is as shown in Figure 2c, and the leading edge of each pulse is as shown in Figure 2a. coincides with the leading edge of each pulse. The conversion circuit 16 is a circuit that differentiates the output pulse of the comparator 14 (FIG. 2b), inverts only the falling part, and outputs the inverted signal, and the output pulse is as shown in FIG. 2d.
As shown in FIG. 2b, its leading edge coincides with the trailing edge of each pulse in FIG. 2b. Therefore, the output pulses of the conversion circuits 15 and 16 are out of phase with each other. Of course, the width of the output pulses of the conversion circuits 15 and 16 is narrower than the width of the input pulses to the same circuits. More specifically, the positive outputs of the conversion circuits 15 and 16 (this is a sharp spike-like signal) trigger the monomulti circuits 17 and 18, and the outputs of the converters 17 and 18 are shown in Figures 2c and d.
The pulse shown in is obtained. Reference numeral 19 denotes an OR circuit through which both the pulses shown in FIG. 2c and d are input to the counter 20. This input pulse is shown in FIG. 2e. The count on the counter is the total number of light-receiving elements in the photoreceptors 8 and 9, and the diameter of the round bar 1 is obtained by subtracting this from a certain constant number, which is displayed on the display 21.

In the embodiment described above, a photoreceptor with a large number of photodetectors arranged in a row is scanned and the length of the light receiving range is converted into the number of pulses. The present invention can be applied even when using the principle of determining the length by measuring the time during which the above-mentioned light beam is blocked by the object to be measured (the time during which light cannot be received) in the image plane by the number of pulses in a pulse train of a constant period. Needless to say. Further, the number of photoreceptors is not limited to two, but may include three or more depending on the size of the object to be measured.

Since the present invention has the above-described configuration, it is possible to perform measurements with good accuracy even when the object to be measured is moving.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a time chart of signals showing the operation of the same embodiment. 1...Object to be measured, 8, 9...Photoreceptor, 12...
Clock pulse generator, 19...OR circuit, 20
……counter.

Claims (1)

[Scope of utility model registration request] In a configuration in which light is applied to an object to be measured and the length of a portion of the object to be measured that is illuminated or not illuminated by light is converted into a pulse train signal and counted, one edge of the object to be measured is used. In order to calculate the sum of the number of pulses obtained in each scan by scanning the shaded part of the edge and the shaded part of the other edge separately, scan the above two parts in synchronization with each other, and A device that detects the rising edge of the pulse train signal obtained by scanning and outputs a pulse, a device that detects the falling edge of the pulse train signal obtained by scanning the other part and outputs the pulse, and an OR circuit for the output pulses of both devices. A dimension measuring device that is equipped with a counter that applies voltage through the counter, and calculates and displays the dimensions of an object to be measured based on the output of the counter.