JPS6040904A - Length measuring device - Google Patents

Abstract

PURPOSE:To make it possible to perform correct measurement of length all the time even if radiation energy and the like are changed, by receiving the radiation energy and the like from a material to be measured, and adequately correcting the set value in correspondence with a peak value. CONSTITUTION:Radiation energy L corresponding to a length W from a body 1, which is changed by wavelength and temperature, is received by an image sensor 4. A peak value VP of the light is detected by a peak value detecting circuit 5. A set value VT, which is corrected in correspondence with the peak value VP through a setting device 6, is determined as VT=alphaVP. The number of picture elements (a) of the value of the received light, which is higher than the set value, from the image sensor is counted by a counter 9 through a comparator circuit 8. Thus the length W is measured. In this constitution, the set value is corrected in correspondence with the peak value. Therefore, the correct length measurement can be performed all the time, even though radiation energy is changed due to temperature change and the like and the magnitude of signal leakage is changed due to mutual interference among the picture elements of the sensor. When light is received from a light source, which is shielded by the material to be measured, the same procedure can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention relates to a length measuring device using an image sensor such as a COD.

(2) Prior Art Conventionally, as shown in FIGS. 1 and 2, a detector uses one or two image sensors such as CCDs to measure the length W of an object to be measured 1. I went to 2. For example, in Figure 1, the total number of pixels of the image sensor is No.
, the corresponding length is N, then the length W of the object to be measured 1 is calculated by W-Wo''N/No.

However, as shown in FIG. 4, the radiant energy L (A, T) of the measured object 1 for one pixel number N is (>,:
The wavelength (T: temperature) and the measured temperature (T) greatly change the signal level, and the thickness of signal leakage caused by mutual interference between pixels of the image sensor also changes. Therefore, the set value vT'
If the value of the measured object 1 is set to a low constant value, the measured object 1 will be
However, the length w' is measured from the number of pixels N' which is larger than the actual number N of pixels, which leads to an error.

Conversely, if the set value vT" is set to a high constant value.

Changes in the temperature of the object to be measured or changes in the sight of the light source directed to the object to be measured will result in a measurement shorter than the actual length.

(3) Purpose of the Invention In view of two or more points, the purpose of the present invention is to provide a length measuring device that can accurately measure even if the radiant energy from the object to be measured or the output light of the light source changes. It is to be.

(4) Embodiment of the Invention FIG. 5 is an explanatory diagram showing an embodiment of the invention.

In the figure, 1 is the radiant energy L (on, T).

An object to be measured has a width W. 3 is an optical system that makes radiant energy from the weight of the object to be measured incident on an image sensor 4 such as a CCD. 5 is a peak that detects the peak value of the output of the image sensor 4. A detection circuit 6 is a setting device such as a variable resistor that multiplies the peak value ■P of the peak detection circuit 5 by a predetermined value α (α<1) to obtain a set value αVp.

7 is a level selection circuit that selects the larger of the output αVp of the setting device 6 and the lower limit setting value (constant value) VZ used when the level of radiant energy becomes extremely small;
8 compares the set value vT (usually avP) of the level selection circuit 7 and the output of the image sensor 4, and
For example, when the output of D-A is large, it is converted into an output analog signal.
It is a converter.

The operation is as follows.

Radiant energy corresponding to the length W from the object to be measured 1 is received by the image sensor 4 via the optical system 3, and the image sensor 4 generates an output as shown in FIG. The peak value vP of this image sensor 4 is determined by the peak detection circuit 5.
is detected by the setter 6 and multiplied by a predetermined value α to obtain αVp.
Then, the level selection circuit 7 compares it with the lower limit setting value VZ, and since αVp is normally equal to VZ, the setting value for length measurement is set as vT=αVp. The comparison circuit 8 compares the set value VT with the output of the image sensor 4, and generates an output when the output of the image sensor 4 is equal to the set value vT. This output is counted by a counter 9.

Measurement is performed using this count value N as the length W of the object to be measured 1. The output of the counter 9 is outputted as an analog signal by a DA converter 10 as required.

In this way, the setting (threshold) value for length measurement is changed to avP according to the peak value Vp of the image sensor 4, and even if the peak value Vp changes and the leakage value also changes, the set value is always maintained. is greater than the leakage value and will not cause erroneous measurements.

The length measuring means such as the peak detecting means, the comparison circuit 8 and the counter 9 shown in FIG. 5 may perform A-to-D conversion of the image sensor output and perform arithmetic processing using a central processing unit such as a microcomputer.

FIG. 6 shows another embodiment using a light source, in which the light from the light source 11 partially blocked by the object to be measured 1 is transmitted to the optical system 3.
The light is incident on the image sensor 4.

An output signal as shown in FIG. 7 is obtained. The measurement circuit is almost the same as that shown in Fig. 5, and for the total number of pixels of the image sensor 4,
If the number of pixels above the set value VT = αVp is NI and No, then the length of the object to be measured 1 is N = No (N l + N
t) Please ask. In this case, even if the sight of the light source ii changes due to deterioration or the like, - a predetermined times the peak value Vp, α
Since Vp is used as the set value VT, there is no effect of changes in the amount of light, and accurate measurement is always possible.

(5) Summary of the Invention As described above, the present invention uses a peak detection means to detect the peak value of an image sensor that receives radiant energy from an object to be measured and light that is partially blocked by the object to be measured. The measuring means is a length measuring device that measures the length of the object based on a set value obtained by multiplying the output of the peak detecting means by a predetermined value.

(6) Effects of the Invention Since the set value is always corrected to the optimum value according to the peak value, it is possible to always measure the correct length regardless of the influence of leakage, etc.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 5, and FIG. 6 are configuration explanatory diagrams, FIG. 3, and FIG. 4 showing an embodiment according to the present invention. FIG. 7 is a waveform diagram for explaining the operation. Engineering...Object to be measured, 4...Image sensor, 5...
・P, T, 6.1. Definitely. , 401. Ratio□2. Groove 1. . δ Counter patent applicant Chino Seisakusho Co., Ltd.

Claims (1)

[Claims] 1. An image sensor that receives radiant energy from an object to be measured or light from a light source that is partially inserted into the object to be measured, and a peak detection means for detecting the peak value of the image sensor. A length measuring device comprising: and a measuring means for measuring the length of an object to be measured based on a set value obtained by multiplying the output of the peak detecting means by a predetermined value. 2. The length measuring device according to claim 1, wherein the measuring means selects and uses the larger of the output of the peak detecting means and a constant value.