Movement speed calculation device and movement speed calculation method

Abstract

To provide a movement speed calculation device capable of calculating a movement speed of an object to be measured without using light transmitted through the object to be measured.SOLUTION: A movement speed calculation device 20 comprises: a light quantity distribution signal acquisition unit 22 that acquires light quantity distribution signals corresponding to images of reflected light captured at two different times t1, t2 from a photodetector 14, on which reflected light including light unevenness from a side surface 51 of a moving object to be measured 50 is imaged by an imaging lens 13; a movement amount calculation unit 24 that calculates a movement pixel amount Δi within a difference Δt between the two times t1, t2 from the light quantity distribution signals at the two different times t1, t2 acquired by the light quantity distribution signal acquisition unit 22; and a speed calculation unit 26 that calculates a movement speed of the object to be measured 50 based on a lateral magnification m of the imaging lens 13, a pixel pitch p of the photodetector 14, the difference Δt, and the movement pixel amount ΔI.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a movement speed calculation device and a movement speed calculation method. [Background technology]

[0002] Patent Document 1 discloses a speed measuring device that measures the moving speed of an object to be measured in a non-contact manner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 158465 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0004] The speed measuring device disclosed in Patent Document 1 measures the moving speed of a moving translucent object by transmitting light irradiated from a light source through the object. In such a speed measuring device employing a transmission method, a light source and a polarizing plate, etc. must be provided on one side of the translucent object, while a polarizing plate, an imaging optical system, a spatial filter, a photodetector, etc. must be provided on the other side of the object to be measured. For this reason, the speed measuring device disclosed in Patent Document 1 may be large in size.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a movement speed calculation device that can calculate the movement speed of an object to be measured without using light transmitted through the object. [Means for solving the problem]

[0006] The movement speed calculation device according to the present disclosure includes a light intensity distribution signal acquisition unit that acquires light intensity distribution signals corresponding to images of reflected light captured at two different times from a photodetector on which reflected light including light unevenness from the side of a moving object to be measured is imaged by an imaging lens; a movement amount calculation unit that calculates the amount of movement of pixels within the difference between the two times from the light intensity distribution signals at the two different times acquired by the light intensity distribution signal acquisition unit; and a speed calculation unit that calculates the movement speed of the object to be measured based on the lateral magnification of the imaging lens, the pixel pitch of the photodetector, the difference, and the movement pixel amount. [Effects of the Invention]

[0007] According to the present disclosure, the moving speed of an object to be measured can be calculated without using light transmitted through the object to be measured. [Brief explanation of the drawings]

[0008] [Figure 1] 1A is a schematic configuration diagram of a speed measurement device to which a travel speed calculation device according to Embodiment 1 is applied, and FIG 1B is a side view of the speed measurement device as seen from the downstream side in the direction of travel of an object to be measured. [Figure 2] 1 is a block diagram of a moving speed calculation device according to a first embodiment. [Figure 3] 4 is a flowchart showing the operation of the moving speed calculation device according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] Embodiment 1 A moving speed calculation device 20 according to the first embodiment will be described with reference to FIGS. 1 to 3. FIG.

[0011] First, the configuration of a speed measurement device 10 to which a travel speed calculation device 20 according to the first embodiment is applied will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of the speed measurement device 10 to which a travel speed calculation device 20 according to the first embodiment is applied.

[0012] The velocity measuring device 10 shown in Fig. 1 uses an optical method to measure the moving velocity of a sheet-like object 50 in a non-contact manner. Possible optical methods for measuring the moving velocity of the object 50 in a non-contact manner include a template matching method, a spatial filter method, and a laser Doppler method. Arrow A in Fig. 1 indicates the moving direction of the object 50. The object 50 moves along its length.

[0013] The object to be measured 50 is made of, for example, a transparent or semi-transparent material, such as a transparent film, a transparent sheet, or a transparent substrate.

[0014] Here, the side surface 51 of the object to be measured 50 is a rough surface. This side surface 51 is rough because it is not subjected to mirror finishing. Alternatively, the side surface 51 is rough because it is subjected to roughening finishing. Therefore, the reflected light reflected by the side surface 51 has light unevenness according to the surface roughness, and the light intensity of the reflected light is improved. Light unevenness means that there is variation in brightness. In this case, of the side surfaces 51 on both the left and right sides of the object to be measured 50, at least the side surface 51 on the side irradiated with light from the light source 11, which will be described later, needs to be a rough surface.

[0015] Note that a pattern may be applied using ink or the like to the side surface 51. By adopting a side surface 51 with a pattern applied in this way, the reflected light will have uneven light according to the density of the pattern, thereby improving the light intensity of the reflected light.

[0016] As shown in FIG. 1, the speed measuring device 10 includes a light source 11, an illumination lens 12, an imaging lens 13, and a photodetector 14.

[0017] The light source 11 irradiates light toward one side surface 51 of the moving object to be measured 50. The intensity of the light emitted from the light source 11 is, for example, constant. The light source 11 is, for example, a light emitting diode, a semiconductor laser, or a halogen bulb.

[0018] Illumination lens 12 converts the light emitted from light source 11 into parallel light. Illumination lens 12 then illuminates the parallel light onto side surface 51 of object to be measured 50 within a predetermined range and at a predetermined illumination angle. Therefore, the light emitted from light source 11 is irradiated onto side surface 51 of object to be measured 50 via illumination lens 12.

[0019] The imaging lens 13 receives light reflected from the side surface 51 of the object to be measured 50, and forms an image of the received reflected light on the photodetector 14. The imaging lens 13 has, for example, a first lens 13a, a second lens 13b, and an aperture 13c.

[0020] First lens 13a is disposed so that its optical axis is perpendicular to side surface 51 of object to be measured 50. First lens 13a collects the reflected light reflected from side surface 51, which is parallel light.

[0021] Second lens 13b is disposed so that its optical axis is perpendicular to side surface 51 of object to be measured 50. The optical axis of first lens 13a and the optical axis of second lens 13b are aligned. Second lens 13b collimates the chief ray of the reflected light collected by first lens 13a, and forms an image of the parallel light on photodetector 14.

[0022] Aperture 13c is disposed between first lens 13a and second lens 13b. Aperture 13c is provided at the focal position of first lens 13a. Therefore, aperture 13c is an opening that allows the reflected light collected by first lens 13a to have a desired light intensity and a desired depth of field, and allows the rays of the reflected light to pass toward second lens 13b.

[0023] The photodetector 14 is, for example, a one-dimensionally arranged array sensor or line sensor, or a two-dimensionally arranged array sensor or image sensor. Reflected light containing light unevenness according to the surface roughness of the side surface 51 is imaged on the photodetector 14. The photodetector 14 captures the imaged reflected light containing light unevenness at times t1 and t2. The photodetector 14 also outputs light intensity distribution signals corresponding to the imaged imaging surfaces at times t1 and t2. These light intensity distribution signals are obtained by photoelectrically converting the imaged surface, and have distributions according to the light unevenness of the reflected light.

[0024] Note that times t1 and t2 are different from each other. The time that elapses from time t1 to time t2 is very short. The time difference between time t1 and time t2 is indicated as Δt.

[0025] Next, the configuration of the traveling speed calculation device 20 applied to the speed measurement device 10 will be described with reference to Fig. 2. Fig. 2 is a block diagram of the traveling speed calculation device 20 according to the first embodiment.

[0026] The moving speed calculation device 20 corresponds to the central processing unit of the speed measurement device 10. The moving speed calculation device 20 has a light control unit 21, a light quantity distribution signal acquisition unit 22, a light quantity distribution signal storage unit 23, a moving amount calculation unit 24, a measurement constant storage unit 25, a speed calculation unit 26, and an output unit 27.

[0027] The light control unit 21 controls the turning on and off of the light source 11. When the light control unit 21 turns on the light source 11, it outputs an acquisition command signal to the light quantity distribution signal acquisition unit 22. The light control unit 21 is previously input with the times t1 and t2 and the difference Δt.

[0028] When the light intensity distribution signal acquisition unit 22 receives an acquisition command signal from the light control unit 21, it acquires a light intensity distribution signal of the image plane of the reflected light including light unevenness, which is captured by the photodetector 14 at times t1 and t2.

[0029] The light intensity distribution signal storage unit 23 stores at least the light intensity distribution signal at time t1 out of the light intensity distribution signals at times t1 and t2 acquired by the light intensity distribution signal acquisition unit 22.

[0030] The movement amount calculation unit 24 acquires the light intensity distribution signals at times t1 and t2 from the light intensity distribution signal storage unit 23. Alternatively, the movement amount calculation unit 24 acquires the light intensity distribution signal at time t1 from the light intensity distribution signal storage unit 23, and acquires the light intensity distribution signal at time t2 from the light intensity distribution signal acquisition unit 22. Furthermore, the movement amount calculation unit 24 uses the light intensity distribution signals at times t1 and t2 to calculate the amount of movement Δi of pixels that has moved within the difference Δt, using a template matching method such as phase-only correlation.

[0031] The measurement constant storage unit 25 stores in advance the lateral magnification m of the imaging lens 13 and the pixel pitch p of the photodetector 14. The measurement constant storage unit 25 may also store in advance the difference Δt.

[0032] Velocity calculation unit 26 obtains difference Δt from light control unit 21. Velocity calculation unit 26 obtains movement pixel amount Δi from movement amount calculation unit 24. Velocity calculation unit 26 obtains lateral magnification m of imaging lens 13 and pixel pitch p of photodetector 14 from measurement constant storage unit 25. Then, velocity calculation unit 26 calculates the movement velocity of object 50 based on difference Δt, movement pixel amount Δi, lateral magnification m, and pixel pitch p.

[0033] Here, assuming that the moving speed of the object to be measured 50 is v, the speed calculation unit 26 calculates the moving speed v using the following equation (1). v=m(p×Δi / Δt) (1)

[0034] For example, the velocity calculation unit 26 performs phase-only correlation processing on two uneven light images at times t1 and t2. The coordinates of the correlation peak value obtained by this processing correspond to the relative positional deviation between the two uneven light images. Therefore, the moving velocity v of the measured object 50 can be calculated using equation (1).

[0035] Although the phase-only correlation method is used as the template matching method, it is also possible to use the normalized cross-correlation method, the sum-of-squared difference method, the sum-of-absolute-value difference method, etc. Furthermore, it is also possible to use the spatial filter method or the laser Doppler method instead of the template matching method.

[0036] The output unit 27 acquires the moving speed of the object to be measured 50 from the speed calculation unit 26. The output unit 27 also outputs the moving speed of the object to be measured 50 to a display unit or the like.

[0037] Next, the operation of the travel speed calculation device 20 will be described with reference to Fig. 3. Fig. 3 is a flow diagram showing the operation of the travel speed calculation device 20 according to the first embodiment.

[0038] In step ST11, the lateral magnification m of the imaging lens 13 and the pixel pitch p of the photodetector 14 are stored in the measurement constant storage unit 25.

[0039] In step ST12, the light control unit 21 controls the light source 11. The light source 11 irradiates light via the illumination lens 12 toward the side surface 51 of the moving object 50 to be measured.

[0040] In step ST13, the light control unit 21 controls the light intensity distribution signal acquisition unit 22. The light intensity distribution signal acquisition unit 22 acquires a light intensity distribution signal from the photodetector 14 at time t1.

[0041] In step ST14, the light intensity distribution signal at time t1 acquired by the light intensity distribution signal acquisition unit 22 is stored in the light intensity distribution signal storage unit .

[0042] In step ST15, the light control unit 21 controls the light intensity distribution signal acquisition unit 22. The light intensity distribution signal acquisition unit 22 acquires a light intensity distribution signal from the photodetector 14 at time t2.

[0043] In step ST16, the movement amount calculation unit 24 calculates the amount of movement Δi of pixels that has moved within the difference Δt using the light intensity distribution signals at times t1 and t2.

[0044] In step ST17, the velocity calculation unit 26 calculates the moving velocity v of the object to be measured 50 based on the difference Δt, the moving pixel amount Δi, the lateral magnification m, and the pixel pitch p.

[0045] In step ST18, the output unit 27 outputs the moving speed v of the object to be measured 50 calculated by the speed calculation unit 26. Then, the operation of the moving speed calculation device 20 ends.

[0046] As described above, the movement speed calculation device 20 according to the first embodiment includes a light intensity distribution signal acquisition unit 22 that acquires light intensity distribution signals corresponding to images of reflected light captured at two different times t1 and t2 from the photodetector 14, on which reflected light including light unevenness from the side surface 51 of the moving object 50 is imaged by the imaging lens 13, a movement amount calculation unit 24 that calculates a movement pixel amount Δi of movement within a difference Δt between the two times t1 and t2 from the light intensity distribution signals at the two different times t1 and t2 acquired by the light intensity distribution signal acquisition unit 22, and a speed calculation unit 26 that calculates the movement speed of the object 50 based on the lateral magnification m of the imaging lens 13, the pixel pitch p of the photodetector 14, the difference Δt, and the movement pixel amount ΔI. Therefore, the movement speed calculation device 20 can calculate the movement speed of the object 50 without using light transmitted through the object 50. As a result, by applying the moving speed calculation device 20 to the speed measurement device 10, the speed measurement device 10 can be made smaller.

[0047] In the travel speed calculation device 20 according to the first embodiment, the side surface 51 of the object to be measured 50 is a rough surface. Therefore, the travel speed calculation device 20 can make the reflected light from the side surface 51 include light unevenness, thereby improving the light intensity of the reflected light. As a result, the travel speed calculation device 20 can use a light quantity distribution signal with improved signal intensity, and can calculate the speed of the object to be measured 50 with high accuracy.

[0048] Furthermore, in the travel speed calculation device 20 according to the first embodiment, a pattern is provided on the side surface 51 of the object to be measured 50. Therefore, the travel speed calculation device 20 can make the reflected light from the side surface 51 include light unevenness, thereby improving the light intensity of the reflected light. As a result, the travel speed calculation device 20 can use a light quantity distribution signal with improved signal intensity, thereby enabling the speed of the object to be measured 50 to be calculated with high accuracy.

[0049] It should be noted that, within the scope of the present disclosure, any of the components of the embodiments may be modified or omitted. [Explanation of symbols]

[0050] 10 Speed ​​measuring device 11 Light source 12 Lighting lens 13 Imaging lens 13a First lens 13b Second lens 13c aperture 14 Photodetector 20 Movement speed calculation device 21 Light control unit 22 Light intensity distribution signal acquisition section 23 Light intensity distribution signal storage section 24 Travel amount calculation section 25 Measurement constant memory section 26 Speed ​​calculation section 27 Output section 50 Object to be measured 51 Side

Claims

1. a light intensity distribution signal acquisition unit that acquires light intensity distribution signals corresponding to images of reflected light captured at two different times from a photodetector on which reflected light including light unevenness from a side surface of a moving object to be measured is imaged by an imaging lens; a movement amount calculation unit that calculates a movement pixel amount within a difference between two times from the light intensity distribution signals at two different times acquired by the light intensity distribution signal acquisition unit; a speed calculation unit that calculates the moving speed of the object to be measured based on the lateral magnification of the imaging lens, the pixel pitch of the photodetector, the difference, and the amount of moving pixels. A movement speed calculation device characterized by:

2. The side surface of the object to be measured is rough.

2. The moving speed calculation device according to claim 1.

3. The side surface of the object to be measured is provided with a pattern.

2. The moving speed calculation device according to claim 1.

4. a step in which a light intensity distribution signal acquiring unit acquires light intensity distribution signals corresponding to images of reflected light captured at two different times from a photodetector on which reflected light including light unevenness from a side surface of a moving object to be measured is imaged by an imaging lens; a movement amount calculation unit calculating, from the light intensity distribution signals at two different times acquired by the light intensity distribution signal acquisition unit, an amount of movement of pixels within a difference between the two times; a speed calculation unit calculating the moving speed of the object to be measured based on the lateral magnification of the imaging lens, the pixel pitch of the photodetector, the difference, and the moving pixel amount. A movement speed calculation method characterized by:

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