JPH04344408A - Dimension measuring instrument - Google Patents

Abstract

PURPOSE:To provide a dimension measuring instrument for measuring the dimension of the outer diameter of the like of an object to be measured disposed in a light path or crossing the light path and detecting a position in which the object to be measured is disposed or a position of a parallel ray crossed by the object to be measured in the direction of the light path. CONSTITUTION:The shadow of an object 10 to be measured disposed in one end of a measuring range along a light path allowing the object 10 to be measured to be disposed is adjusted to be projected on a camera element 15 under the imaging condition better than the shadow of the object to be measured disposed in the other position within the measuring range. A second light source 17 is disposed to form a second parallel ray advancing obliquely in relation to a parallel ray for measuring the dimension of the object 10 to be measured.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a
Alternatively, the present invention relates to a dimension measuring device that measures the outer diameter of an object to be measured that traverses an optical path.

0002

2. Description of the Related Art Conventionally, as a method for measuring the outer diameter of an object to be measured in a non-contact manner, for example, a method of measuring by scanning with a galvanometer mirror is known. In addition, as a non-contact measurement method that does not have a moving part such as a galvanometer mirror, the shadow of the object to be measured is projected onto an imaging device such as a CCD, and the dimensions of the shadow projected onto this imaging device are determined. A method of determining the dimensions of the object to be measured can be considered (see Japanese Patent Application No. 200103/1999).

FIG. 7 is a schematic configuration diagram showing an example of a dimension measuring device that measures the outer diameter of an object to be measured by projecting the shadow of the object onto an image pickup element. The light 12 emitted from the light source 11 is converted into parallel light 1 by the collimator lens 13.
2', and this parallel light 12' is guided onto the one-dimensional CCD 15 via the light receiving lens 14. Also, the parallel light 12 sandwiched between the collimator lens 13 and the light receiving lens 14
The object to be measured 10 is configured to pass through the optical path '.

In the dimension measuring instrument configured as described above, when the object to be measured 10 enters the optical path of the parallel light 12' as shown in FIG. and find the dimension d of the shadow,
Based on this dimension d, the focal length of the light receiving lens 14 and the CC
The outer diameter dimension D of the object to be measured 10 is determined by taking into consideration the arrangement position of D15, etc.

[0005]

In the dimension measuring instrument configured as shown in FIG. 7, the object to be measured 10 does not always cross a fixed position between the collimator lens 13 and the light receiving lens 14; For example, it is possible to cross the position A or position C shown by the dashed line in FIG. 7, and in this case, it is desired to measure not only the outer diameter of the object 10 but also its passing position.

[0006] In view of the above circumstances, the present invention has been developed by placing an object to be measured in the middle of parallel light as shown in FIG. In a dimension measuring device configured to determine the dimensions of the object to be measured by projecting it onto an image sensor, the position of the object to be measured is also detected in the optical path direction of the parallel light that is placed or traversed by the object to be measured. The purpose is to provide a dimension measuring instrument that can measure dimensions.

[0007]

[Means for Solving the Problems] A first dimension measuring device of the present invention for achieving the above object includes a light source, a collimating optical system that converts the light emitted from the light source into parallel light, and an image sensor. a light-receiving optical system that projects a shadow of the object placed in the optical path of the parallel light onto the image sensor; and a light receiving optical system that projects the shadow of the object placed in the optical path of the parallel light onto the image sensor; In the dimension measuring device, the shadow of the object placed at one end of the measurement range along the optical path of the parallel light, in which placement of the object to be measured is allowed, Adjusted so that the shadow of the object to be measured is projected onto the image sensor in a better image formation state than the shadow of the object placed at other positions within the measurement range,
The apparatus is characterized in that it includes a position calculation means for determining the placement position of the object to be measured within the measurement range based on the imaging state of the shadow projected onto the image sensor.

A second dimension measuring device of the present invention for achieving the above object includes a light source, a collimating optical system that converts the light emitted from the light source into parallel light, an imaging element, and a collimating optical system that converts the light emitted from the light source into parallel light. a light-receiving optical system that projects a shadow of an object to be measured placed in an optical path onto the image pickup device; and a dimension for determining the dimensions of the object to be measured by determining the dimensions of the shadow projected onto the image pickup device. a second light source arranged such that the collimating optical system forms a second parallel light that travels obliquely with respect to the parallel light; and a second light source that is emitted from the light source. a difference in the position of a shadow on the imaging device of the object to be measured formed by the light emitted from the second light source and the position of a shadow on the imaging device of the object to be measured formed by the light emitted from the second light source; The apparatus is characterized by comprising a position calculation means for determining the arrangement position of the object to be measured in the direction along the optical path of the parallel light based on the above.

Here, the "placement of the object to be measured" in the first and second dimension measuring instruments refers to the case where the object to be measured does not need to stop at that position, but is placed instantaneously, that is, the object to be measured does not need to stop at that position. This is a concept that includes passing through.

0010

[Operation] The light source is not an ideal point light source, for example, 200μ
Even with a very small light source such as an LED having a size of approximately m square, when the light emitted from this light source is converted into parallel light by a collimating optical system, this parallel light will not become perfectly parallel light. Therefore, the blur of the shadow of the object projected onto the image sensor through the light receiving optical system differs depending on the position along the optical path of the parallel light.

The first dimension measuring instrument of the present invention was completed by considering this point, and the object to be measured is placed at one end of the measuring range along the optical path of the parallel light, where the object to be measured is allowed to be placed. Adjustments are made so that the shadow of the object to be measured is projected onto the image sensor in a better image formation state than the shadow of the object to be measured placed at other positions within this measurement range. As you move from one end of the range to the other, the shadow on the image sensor of the object placed at that position gradually becomes blurred, so by detecting the degree of blur, the position of the object to be measured can be determined. It becomes possible to know.

Furthermore, the second dimension measuring instrument of the present invention is configured to more actively include a second light source and to obliquely irradiate the object to be measured with the second parallel light from the second light source. Therefore, depending on where the object to be measured is placed within the measurement range, the projection position of the shadow of the object to be measured on the image sensor due to the light emitted from the second light source differs.
Therefore, by detecting this difference in projection position, it is possible to know the placement position of the object to be measured.

[0013]

[Examples] Examples of the present invention will be described below. FIG. 1 is a schematic diagram of an optical system of an embodiment of the first dimension measuring device of the present invention. Each component corresponding to each component of the dimension measuring instrument shown in FIG. 7 has a number assigned in FIG.
The same numbers and symbols as the symbols will be given, and the explanation will be omitted.

It is assumed that the object to be measured 10 crosses an arbitrary position within a measurement range L between two positions A and C shown by a dashed line in the figure. At this time, the focal length of the light receiving lens 14,
Assuming that the light-receiving lens 14 and the CCD 15 are arranged at position A or to the left of the position A as shown in FIG. Select and adjust so that the image is formed in the best possible focus. By doing this, the object to be measured 1
The closer 0 is to position A within the measurement range L, the better the image is formed on the CCD 15, and the closer it is to position C, the more blurred the image is formed.

FIG. 2 is a diagram schematically showing the image formation state of the shadow of the object to be measured 10 projected onto the CCD 15.
2(A), (B), and (C) show the received light signals of the CCD 15 (each point on the CCD 15) when the object to be measured 10 is placed at each position A, B, and C shown in FIG. (proportional to the amount of light irradiated on). The threshold value Th1 is set at a position slightly lower than the signal Smax corresponding to the maximum amount of light that the light emitted from the light source 11 reaches on the CCD 15 without being blocked by the object to be measured 10, and the light emitted from the light source 11 is is blocked by the object to be measured 10, and a threshold value Th2 corresponding to a signal slightly larger than the signal Smin corresponding to the minimum amount of light obtained thereby is set. The above two threshold values Th1,
Find the distance Δx while crossing Th2. In addition, in order to obtain the dimension d of the shadow of the object to be measured 10, the maximum signal Smax
A threshold value Th3 is set at the center between the minimum signal Smin and the minimum signal Smin.

FIG. 3 is a graph showing the relationship between the placement position of the object to be measured 10 and the distance Δx. Measured object 10
As the distance Δx moves from the position A to the position C side, the distance Δx becomes a larger value. Therefore, by obtaining this graph accurately in advance and obtaining the distance Δx based on the light reception signal of the CCD 15, it is possible to know where the object to be measured 10 is placed within the measurement range L.

FIG. 4 is a block diagram of a processing circuit for a light reception signal of the CCD 15 obtained using the optical system shown in FIG. The clock generation circuit 21 generates a reference clock signal CL for synchronizing the operation of this circuit, and each circuit operates according to this reference clock signal CL. The received light signal SA sequentially read out from the CCD 15 in accordance with the reference clock signal CL is converted into a digital received light signal SD by the A/D converter 22, and then converted to a digital received light signal SD by each comparator 23, 24, 2.
5 is input. Further, the CPU 26 generates signals representing the three threshold values Th1, Th2, and Th3 shown in FIG.

In the comparator 23, the input light reception signal SD
is compared with threshold value Th3, and SD ≧Th
3 or SD <Th3, the time series signal is displayed by the counter/
The signal is input to the latch 27. This counter/latch 27 starts counting the pulses of the reference clock signal CK at the timing when SD≧Th3 changes to SD<Th3, and counts the pulses until the timing changes from SD<Th3 to SD≧Th3. After this count number is latched by this counter/latch 27, the CPU
26, and the CPU 26 calculates the dimension d of the shadow of the object to be measured 10 based on this count number.

Furthermore, the comparator 24 receives the received signal S
The magnitude of D and threshold Th2 is determined, and the counter/latch 28 determines that SD<Th2 from a predetermined initial time.
The pulses up to the timing of the change are counted, and the counted number is latched and input to the subtracter 30. In addition, the comparator 25 determines the magnitude of the input light reception signal SD and the threshold Th1, and the counter/latch 29 counts pulses from a predetermined initial time to the timing when SD < Th1, and the counted number is It is latched and input to the subtracter 30.

In the subtracter 30, the counter/latch 28,2
The difference between the two count values input from 9 is calculated. This difference is input to the CPU 26. This difference corresponds to the distance Δx shown in FIG. As described above, the CPU 26 determines the dimension d of the shadow of the object to be measured 10 and the value Δ representing the degree of blur.
x is input, and the dimension D of the object to be measured 10 is determined based on this dimension d, and the placement position of the object to be measured 10 within the measurement range L is determined based on the value Δx.

FIG. 5 is a schematic diagram of the optical system of an embodiment of the second dimension measuring instrument of the present invention. In this figure, each component corresponding to each component of the optical system shown in FIG. 1 is given the same number and symbol as the number and symbol given in FIG. 1, and redundant explanation will be omitted. Here, a second light source 17 is disposed near the light source 11, and the light 18 emitted from the second light source 17 is directed slightly obliquely to the path of the parallel light 12' by the collimator lens 13. The parallel light 18' is converted into traveling parallel light 18', and after passing through the light receiving lens 14, it reaches a position on the CCD 15 that is slightly shifted from the position where the light 12 reaches.

Here, the shadow of the upper end of the object to be measured 10 shown in FIG. projected on. On the other hand, the shadow of the upper end of the object to be measured 10 due to the light 18 emitted from the light source 17 differs depending on where the object to be measured 10 is placed within the measurement range L, and for each position A, B. , C, they are projected to points yA, yB, and yC, respectively. Therefore, by finding the distance Δy=y−y0 between the projection position y0 when the light source 11 is turned on and the projection position y when the light source 17 is turned on, the object to be measured 1
The arrangement position of 0 in the optical axis direction can be determined.

FIG. 6 is a block diagram of a processing circuit for a light reception signal of the CCD 15 obtained using the optical system shown in FIG. Each timing signal and reference clock signal are transmitted from the timing generation circuit 31, and each circuit operates according to the timing signal and reference clock signal. From this timing generation circuit 31, a timing signal that turns on the light source 11 in a state where the light sources 11 and 17 are turned off is inputted to the light source 11, and the light source 11 emits light 12. In this state, the light reception signal SA is read out from the CCD 15,
The A/D converter 32 converts it into a digital light reception signal SD and inputs it to the comparator 33.

Further, the CPU 34 generates a threshold value Th3 (see FIG. 2) for determining the size of the shadow by binarizing the light reception signal read out from the CCD 15, and inputs it to the comparator 33. The comparator 33 compares the input light reception signal SD with a threshold value Th3, and the comparison results are input to two counters/latches 35 and 36.

In the counter/latch 35, SD ≧Th
From 3 to SD <Th From the moment it changes to 3, SD again ≧T
The time until the moment it turns to h3 is measured, and the dimension d of the shadow is determined from this. In addition, the counter/latch 36
Then, the time is measured from the time when the light reception signal at point y0 (see FIG. 5) is read out to the next time when the light source 11 is turned off, the light source 17 is turned on, and the light reception signal at point y is read out. This time is input to the CPU 34 and converted into a difference in shadow position Δy=y−y0.

As described above, the two light sources 11 and 17 placed at different positions are sequentially turned on to determine the dimension d of the shadow on the CCD 15 of the object to be measured 10, and the point y0
By finding the difference Δy between and point y, the shadow dimension d
The dimension D of the object to be measured 10 is determined based on the difference Δy, and the placement position of the object to be measured 10 within the measurement range L is determined based on the difference Δy.

[0027]

Effects of the Invention As explained in detail above, the first dimension measuring instrument of the present invention is capable of measuring objects to be measured placed at one end of the measurement range along the optical path of parallel light, where the placement of the object to be measured is permissible. Adjustments are made so that the shadow of the object is projected onto the image sensor in a better image formation state than the shadow of the object placed at other positions within this measurement range, so the shadow of the object is projected onto the image sensor. Based on the imaging state of the shadow of the measured object, the position of the measured object within the measurement range can be detected.

Further, the second dimension measuring device of the present invention includes a second light source arranged so as to form a second parallel light traveling obliquely with respect to the parallel light for measuring the dimension of the object to be measured. Therefore, the position of the shadow on the image sensor of the object to be measured formed by the light emitted from the light source for dimension measurement and the object to be measured formed by the light emitted from the second light source. The arrangement position of the object to be measured in the direction along the optical path of the parallel light can be determined based on the difference in the position of the shadow on the image sensor.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an optical system of an embodiment of a first dimension measuring instrument of the present invention.

FIG. 2 is a diagram schematically showing the image formation state of the shadow of the object to be measured projected onto the CCD.

FIG. 3 is a graph showing the relationship between the placement position of the object to be measured and the degree of blur on the CCD.

FIG. 4 is a block diagram of a processing circuit for a CCD light reception signal obtained using the optical system shown in FIG. 1;

FIG. 5 is a schematic configuration diagram of an optical system of an embodiment of the second dimension measuring device of the present invention.

6 is a block diagram of a processing circuit for a CCD light reception signal obtained using the optical system shown in FIG. 5. FIG.

FIG. 7 is a schematic configuration diagram illustrating an example of a dimension measuring device that determines the outer diameter of an object to be measured by projecting a shadow of the object onto an image sensor.

[Explanation of symbols]

10 Object to be measured
11 light source 12 light
12' Parallel light 13
Collimator lens 14 Light receiving lens 15 CCD
17 Second light source 18' Second parallel light 21 Clock generation circuit 22, 32 A/D converter 23, 24, 25, 33 Comparator 26, 34
CPU 27, 28, 29, 35, 36 Counter/latch 30 Subtractor

Claims (2)

[Claims] 1. A light source, a collimating optical system that converts light emitted from the light source into parallel light, an imaging device, and a method for detecting a shadow of an object to be measured placed in the optical path of the parallel light on the imaging device. A dimension measuring instrument comprising: a light receiving optical system that projects a light onto the image pickup device; and a dimension calculating means for determining the dimensions of the object by determining the dimensions of the shadow projected on the image pickup element; is allowed, and the shadow of the object placed at one end of the measurement range along the optical path of the parallel light has a better result than the shadow of the object placed at other positions within this measurement range. The arrangement position of the object to be measured within the measurement range is adjusted so that it is projected onto the image sensor in an image state, and based on the image formation state of the shadow projected onto the image sensor. A dimension measuring instrument characterized by comprising a position calculation means for determining the . 2. A light source, a collimating optical system that converts the light emitted from the light source into parallel light, an imaging device, and a method for detecting a shadow of an object to be measured placed in the optical path of the parallel light on the imaging device. A dimension measuring instrument comprising: a light receiving optical system for projecting a light onto a second light source arranged to form second parallel light that travels obliquely with respect to the parallel light; and a shadow on the image pickup device of the object formed by the light emitted from the light source. and the position of the shadow formed by the light emitted from the second light source on the image sensor of the object to be measured, based on the difference between the position of the shadow on the image sensor of the object to be measured, 1. A dimension measuring device comprising: a position calculation means for determining a directional arrangement position.