JPS61184416A - Optical displacement meter - Google Patents

Abstract

PURPOSE:To enhance measuring accuracy as possible, by optically and electrically canceling the change in the spot diameter and light quantity distribution of a light spot source. CONSTITUTION:The luminous flux I irradiated from a light spot source is held to an almost normal distribution state and, when said luminous flux irradiates the colored part 40 of an article 21 to be measured accompanied by a color, said luminous flux is irregularly reflected on the surface thereof to be respectively formed into images on first and second light detection elements 26, 28. At this time, the luminous intensity distributions of the first and second light detection elements 26, 28 comes to distribution states shown by Ia, Ib by the absorption of a color and points confirmed as light spots come to Ya, Yb and the optical positional dimension and quantity of light are adjusted to Ia=Ib and confirmation points are brought to Ya=Yb (at the time of displacement=0) and the effect by a color is canceled.

Description

[Detailed Description of the Invention] [Industrial Fields of Application] This invention is used, for example, in counter devices for newspaper off-wheels that detect displacement and deformation of colored printed matter such as patterns and letters, and beer bottle label detection devices. Regarding optical displacement meters.

[Prior Art] Generally, this type of optical displacement meter, such as a light spot detection displacement meter (optical micro), uses a semiconductor laser, LED, etc. as a light point source 1, as shown in FIG. [The light from 1 is focused and irradiated onto the surface of the object to be measured 3 via the illumination lens 2. Then, the scattered light reflected by the object to be measured 3 is reflected onto a photodetecting element 5 called an optical position sensor via an imaging lens 4 attached at an angle θ with respect to the irradiated light beam. Form a light spot into an image. This light spot image is moved on the photodetector element 5 according to the movement of the reflection spot on the light flux axis. Corresponding to this movement, the photodetecting element 5 has electrodes on both sides thereof, and carriers generated by the incident light beam become a current source 1, which is inversely proportional to the resistance between the point of incidence and the electrodes. The signals i1 and i2 are extracted as distributed signals i1 and i2. These signals i1 and i2 are converted by a current-to-voltage converter 6.7, then passed through adders and subtracters 8 and 9, and outputted as reference signals by a divider 10.

[Problems to be Solved by the Invention] However, when the above-mentioned optical displacement meter measures colored objects such as printed matter, due to its configuration, the light beam area focused on the surface of the treasure 3 to be measured is the light spot i11. For example, 80u!
In the case of n or more, the halftone dot (color) of the printed matter is 20 to 30tII
Since n is large, light is absorbed within the area of the light beam irradiated onto the surface of the object 3 with halftone dots, and the reflected illuminance distribution changes depending on the position of the halftone dots. According to this, when light with a reflected illuminance distribution that changes depending on the halftone dots is imaged on the photodetecting element 5, the halftone dots are moved even on the object to be measured which does not displace in the irradiation direction, so that the light in the image formation is There was a problem in that the illuminance distribution changed and a signal was generated as if it had been displaced in the irradiation direction, leading to malfunction.

[Means and effects for solving the problems] This invention was made in view of the above circumstances, and includes a light point source that irradiates an object to be measured with irradiation light, and a light point source that emits light reflected from the object to be measured. a first optical system including a first photodetecting element that has a predetermined illuminance distribution and forms an image at a reflected light spot according to a change in the imaging position with respect to the irradiation direction; and a second optical system comprising a second photodetecting element that forms an image of the light at a fixed imaging position with respect to the irradiation direction at a reflected light point having the same illuminance distribution as that of the first optical system; and a means for detecting a difference in the image forming position taken out according to the image forming positions of the first and second photodetecting elements to cancel movement due to a change in the illuminance distribution of the object to be measured, The purpose of the present invention is to provide an optical displacement meter that is configured to optically and electrically cancel changes in color, spot diameter of a light point source, and light intensity distribution, and is capable of improving measurement accuracy as much as possible. shall be.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a device for counting the number of sheets of a commercial offset printing press to which an optical displacement meter according to the present invention is applied. A point source of light is arranged. This light spot 7112
0 obtains the irradiation light by its drive circuit, and between the object to be measured 21 there is a light projecting lens that collects the irradiation light to the minimum area on the object to be measured 21 and controls the intensity of the light beam. 22 and a half mirror 23 called a beam splitter.
An optical system is constructed in which the Among these, the half mirror 23 allows the irradiation light beam to pass through, and specularly reflects the light that is diffusely reflected by hitting the surface of the object to be measured 21, and the reflected light, that is, the light in the direction perpendicular to the object to be measured 21, is attenuated. It passes through the optical filter 24 and the imaging lens 25 to form an image on the first photodetecting element 26 provided on the spatial plane formed by the optical axis, and also aligns the optical axis in the θ direction with respect to the beam axis of the irradiated light. intersect with the object to be measured 21 and the half mirror
It is arranged so that the optical axes reflected by 23 are all located on the same plane. The diffusely reflected light from the object to be measured 21 traveling on the optical axis in the θ direction passes through the imaging lens 27 and is imaged on the second photodetecting element 28 provided on the spatial plane formed by the optical axis. Ru.

Here, one end of each of the first and second photodetecting elements 26, 28 is connected to the first differential amplifier 31 via a current-voltage converter 29, 30, and the other end thereof is connected to the first differential amplifier 31 through a current-voltage converter 29, 30, and - a second differential amplifier 34 via a voltage converter 32.33;
connected to. These first and second differential amplifiers 31 and 34 are connected to a divider 37 via adders and subtracters 35 and 36, respectively, and this divider 37 detects a level difference in the printed matter within the range of the normal signal. counter 3 for pulse counting via a comparator 38 with a possible threshold value
Connected to 9.

In the above configuration, the operation will be explained. That is, the first and second photodetecting elements 26 and 28 are imaged so that the illuminance distribution of the light irradiated by the light point source 20 and reflected by the object to be measured 21 becomes the same image. Then, these first and second
Predetermined carriers are generated in the photodetecting elements 26 and 28 according to their imaging positions, and current signals r ai,
+a2. i bl.

Ib2 are respectively taken out, and these current signals 1a1゜i a2 . i bl, i b2 are current-to-voltage converters 29, 30, 32, 33, respectively, and voltage signals va
l, v a2°vbl, vb2. This voltage signal val.

ya2. vbl, vb2 are the voltages v1=vai-Vbl and v2=va at the first and second differential amplifiers 31.34.
2-vb2 and the above-mentioned first and second signals.
After canceling the movement due to the illuminance distribution change in the light spot imaged on the photodetecting elements 26 and 28, the subtracter 36 calculates vl.
-v2, the adder 35 converts the signals to vl +v2, and the divider 37 converts them into regular signals of O to 1. Here, this normal signal O~1v is converted into pulses by a comparator 38, which is given a threshold within its range that can detect a level difference between the two printed matter to be measured, and then the number of pulses is counted by a counter. It is counted as 39.

Here, the optical effect of canceling the above-mentioned color will be explained. That is, as shown in FIGS. 1 and 2, the irradiation light flux I from the light point source 20 has a substantially normal distribution, and when the light is irradiated onto the colored part 40 of the colored object 21, it is diffusely reflected on the surface. Said No. 1 and second photodetector element 26
．． 28, respectively, as described above. At that time, each illuminance distribution of the first and second photodetecting elements 26 and 28 becomes a distribution state such as la and Ib due to color absorption, and the points recognized as light spots become ya and Yb,
The optical one-position dimension and light intensity are adjusted to 1a-Ib, and the recognition point is set as Ya=Yb (provided that displacement=0), and the influence of color is canceled. Therefore, the amount of displacement to be canceled is such that the entire image (illuminance distribution 1a) formed on the first photodetecting element 26 is moved over the first photodetecting element 26, and the amount of displacement is Since the light spot (illuminance distribution 1b) on the photodetecting element 28 is in a vertical state and is immovable, these first and second photodetecting elements 26.
28 signals to the first and second differential amplifiers 3.
1.34.

It goes without saying that the present invention is not limited to the above embodiments, and that various modifications can be made without departing from the spirit of the invention.

[Effects of the Invention] As detailed above, according to the present invention, there is provided a light point source that irradiates an object to be measured with irradiation light, and a light point source that emits light reflected from the object to be measured so as to have a predetermined illuminance distribution. , a first optical system including a first photodetecting element that forms an image at a reflected light point according to a change in the imaging position with respect to the irradiation direction; and a first optical system that collects the reflected light from the object to be measured. a second optical system comprising a second photodetection element that forms an image at a fixed imaging position with respect to the irradiation direction at a reflected light point with the same illuminance distribution; and the first and second photodetection elements. By detecting the difference in the image forming position taken out according to the image forming position of the object and canceling the movement caused by the change in the illuminance distribution of the object to be measured, the color and the spot diameter of the light point source can be adjusted. Since it is configured to optically and electrically cancel changes in the light amount distribution, it is possible to provide an optical displacement meter that can improve measurement accuracy as much as possible.

[Brief explanation of drawings]

FIG. 1 is a configuration explanatory diagram showing a device for counting the number of sheets of a commercial offset printing press using an optical displacement meter according to an embodiment of the present invention, and FIG. 2 explains the operation of the main parts of FIG. 1. FIG. 3 is a configuration diagram showing a conventional light spot detector. 20... Light point source, 21... Printing material, 23... Half mirror 124... Neutral density filter, 25... Imaging lens, 26... First photodetecting element, 27... ...Imaging lens, 28...Second photodetection element, 29.30,
32° 33... Current-voltage converter, 31... First differential amplifier, 34... Second differential amplifier, 35...
Adder, 36... Subtractor, 37... Divider, 38.
...Comparator, 39...Counter, 40...Colored part. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1 Figure 2z Figure 3

Claims (1)

[Claims] A light point source that irradiates an object to be measured with irradiation light, and the reflected light from the object to be measured is formed into a reflected light point having a predetermined illuminance distribution and corresponding to a change in the imaging position with respect to the irradiation direction. a first optical system equipped with a first photodetecting element that detects the light reflected from the object to be measured; A second optical system including a second photodetection element that forms an image at the image position, and detects a difference between the image formation positions taken out according to the image formation positions of the first and second photodetection elements. and a means for canceling the movement of the object to be measured due to a change in illuminance distribution.