JP2007315804A - Surface inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface inspection device capable of performing inspection, even when the rotational speed of an inspection head varies, and capable of shortening the inspection time, without degrading inspection quality. <P>SOLUTION: The surface inspection device 1 is equipped with the inspection head 16, which can be inserted in the hole 100a of an inspection target 100 and can be rotated about an axial line AX that extends in the longitudinal direction, a linear drive mechanism 30 for linearly moving the inspection head 16 so that the inspection head 16 is relatively moved in the direction of the axial line AX, with respect to the inspection target 100, and a rotary encoder 43 for detecting the rotary position of the inspection head 16. Operation of the linear drive mechanism 30 is controlled, on the basis of the output signal of the rotary encoder 43 so that the moving quantity, related to the direction of the axial line AX per rotation of the inspection head 16, becomes constant, regardless of the rotational speed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface inspection apparatus that inspects defects such as foreign matter, nests and scratches present on the inner peripheral surface of a hole of an inspection object in which a hole is formed.

  As a surface inspection device that inspects the inner peripheral surface of an object to be inspected, for example, a cylinder liner or a cylinder bore of an internal combustion engine, the inspection light is projected onto the inner peripheral surface, and the reflected light from the inner peripheral surface By inserting a rod-shaped inspection head configured to receive the hole into the hole, and then moving the inspection head around the axis extending in the longitudinal direction while moving it forward and backward relative to the object to be inspected, the hole There is one that can inspect the inner peripheral surface (see, for example, Patent Document 1).

JP-A-11-281582

  In such a surface inspection apparatus, in order to continuously inspect the inner peripheral surface of the hole of the inspection object without unevenness, it is necessary to keep the movement amount in the axial direction per one rotation of the inspection head constant. For example, in order to keep the movement amount constant, it is conceivable to individually control the rotation speed of the inspection head and the movement speed in the axial direction. However, in that case, the movement of the inspection head in the axial direction can be started only after the rotation speed of the inspection head becomes constant. Therefore, the inspection cannot be executed during acceleration or deceleration where the rotation speed of the inspection head is not constant, and the inspection time for one inspection object is increased accordingly. Further, the inspection can be performed if the variation in the rotation speed of the inspection head is within an allowable range, but strictly speaking, the variation in the rotation speed affects the inspection result, so that the inspection accuracy is deteriorated. Patent Document 1 describes that the inspection head is gradually moved in the axial direction while rotating the inspection head to inspect the inner peripheral surface of the hole in an annular shape, but the inspection head is rotated and moved in the axial direction. There is no specific description of the relationship with.

  In view of the above, an object of the present invention is to provide a surface inspection apparatus that can perform inspection even when the rotation speed of the inspection head fluctuates and can reduce the inspection time without deteriorating the inspection accuracy.

  The surface inspection apparatus (1) of the present invention can be inserted into the hole of the object to be inspected (100) in which the hole (100a) is formed, and can be rotated around an axis (AX) extending in the longitudinal direction ( 16), moving means (30) for linearly moving the inspection head or the inspection object so that the inspection head moves relative to the inspection object in the axial direction, and the inspection head on the axis Rotation drive means (40, 71, 73 to 75) for rotating around, rotation position detection means (43) for detecting the rotation position of the inspection head, and movement in the axial direction per rotation of the inspection head The movement control means (61) for controlling the operation of the movement means based on the detection result of the rotation position detection means so that the amount is constant regardless of the rotation speed, the above-mentioned problem Resolve.

  According to this inspection apparatus, the amount of movement in the axial direction per rotation of the inspection head is constant even during acceleration or deceleration where the rotation speed of the inspection head is not constant. Therefore, even when the inspection head is accelerating or decelerating, inspection can be performed by moving the inspection head in the axial direction, so that the inspection time required for inspecting one inspection object can be shortened. Even in such a case, the movement amount in the axial direction per one rotation of the inspection head is kept constant, so that the inspection accuracy is not deteriorated. Further, it is not necessary to accurately control the inspection head so that the rotation speed of the inspection head is kept constant in order to ensure inspection accuracy, and it is sufficient if the inspection head can be rotated. Accordingly, the restriction on the configuration of the rotation driving means for rotating the inspection head is relaxed, and the selection range is expanded.

  In one aspect of the surface inspection apparatus of the present invention, the moving means includes an electric motor (35) configured such that the rotation angle is proportional to the number of pulses of the input pulse signal, and the rotational movement of the electric motor. And a conversion mechanism (34, 36) for converting the inspection head into a linear motion in the axial direction of the inspection head, and the rotational position detecting means outputs a pulse signal (Psa) corresponding to the rotational position of the inspection head. The movement control means includes signal processing means (612) for converting the frequency of the pulse signal generated by the rotational position detection means to a predetermined magnification, and the signal processing means includes The processed pulse signal (Psd2) may be supplied to the electric motor to drive the electric motor. Even in such a configuration, the movement amount in the axial direction per one rotation of the inspection head is constant regardless of the rotation speed. Therefore, even when the inspection head is being accelerated or decelerated, the inspection can be performed by moving the inspection head in the axial direction.

  The rotational driving means for rotationally driving the inspection head can be realized in various modes. As one aspect, the rotational driving means can rotate the inspection head around the axis by using the flow of air. May be configured. In this case, the rotational drive means uses the blown air to produce a rotational force generating means (71) for generating a rotational force for rotating the inspection head around the axis, and to blow air against the rotational force generating means. You may provide the ventilation means (73-75). Since such a rotational drive means rotates the inspection head using air, the air flow is used to blow off foreign matter adhering to the inner peripheral surface of the inspection object before starting the inspection. However, it has a drawback that it is more difficult to keep the rotation speed of the inspection head constant than when the inspection head is rotated by an electric motor or the like.

  In these aspects, even if the rotation speed of the inspection head is unstable, the movement amount in the axial direction per rotation of the inspection head is kept constant. Therefore, the defect can be compensated while taking advantage of the rotation driving means described above, and sufficient inspection accuracy can be secured. Although the rotational force generating means can be realized in various forms, for example, an impeller (71) attached to the inspection head may be provided as the rotational force generating means.

  In addition, in the above description, in order to make an understanding of this invention easy, the reference sign of the accompanying drawing was attached in parenthesis, but this invention is not limited to the form of illustration by it.

  As described above, according to the present invention, the amount of movement in the axial direction per rotation of the inspection head is constant regardless of the rotation speed, so that the inspection accuracy is deteriorated even if the rotation speed of the inspection head varies. I will not let you. Therefore, the inspection can be executed even when the inspection head is accelerating or decelerating, and the inspection time required for inspecting one inspection object can be shortened.

(First form)
FIG. 1 shows a schematic configuration of a surface inspection apparatus according to an embodiment of the present invention. The surface inspection apparatus 1 is an apparatus suitable for surface inspection of the inner peripheral surface of the hole 100a of the inspection object 100 such as a cylinder liner or a cylinder bore of an internal combustion engine. The surface inspection apparatus 1 controls the operation of each part of the inspection mechanism 2 that performs such inspection and outputs information on the inner peripheral surface of the hole 100a, and outputs the information output by the inspection mechanism 2. And a control unit 3 for processing. Further, the inspection mechanism 2 projects inspection light onto the inspection object 100 and receives a reflected light from the inspection object 100, and gives a predetermined operation to the detection unit 5. Drive unit 6.

  The detection unit 5 receives a laser diode (hereinafter referred to as LD) 11 as a light source of inspection light and reflected light from the inspection object 100, and the amount of the reflected light per unit time (reflected light intensity). A photodetector (hereinafter referred to as PD) 12 that outputs an electric signal having a current or voltage according to the above, a light projecting fiber 13 that guides the inspection light emitted from the LD 11 toward the inspection object 100, and the inspection object 100 A light receiving fiber 14 for guiding the reflected light from the PD 12, a holding cylinder 15 for holding the fibers 13, 14 in a bundled state, and a hollow shaft-like shape provided coaxially outside the holding cylinder 15. And an inspection head 16. At the tip of the holding cylinder 15, the inspection light guided through the light projecting fiber 13 is emitted in the form of a beam along the direction of the axis AX of the inspection head 16 (hereinafter referred to as the axial direction), and the inspection head A lens 17 is provided that collects reflected light that travels in the direction opposite to the inspection light along the 16 axial direction on the light receiving fiber 14. A mirror 18 as an optical path changing means is fixed to the tip portion (right end portion in FIG. 1) of the inspection head 16, and a light transmission window 16 a is provided on the outer periphery of the inspection head 16 so as to face the mirror 18. ing. The mirror 18 changes the optical path of the inspection light emitted from the lens 17 toward the light transmission window 16a, and travels the optical path of the reflected light incident from the light transmission window 16a into the inspection head 16 toward the lens 17. Change to

  The drive unit 6 includes a linear drive mechanism 30, a rotation drive mechanism 40, and a focus adjustment mechanism 50. The linear drive mechanism 30 is provided as a moving unit that moves the inspection head 16 in the axial direction thereof. In order to realize such a function, the linear drive mechanism 30 includes a base 31, a pair of rails 32 fixed to the base 31, and a slider 33 movable along the rail 32 in the axial direction of the inspection head 16. Further, a feed screw 34 disposed in parallel to the axis AX of the inspection head 16 and a motor 35 that rotationally drives the feed screw 34 are provided on the side of the slider 33. The slider 33 functions as a means for supporting the entire detection unit 5. That is, the LD 11 and PD are fixed to the slider 33, the inspection head 16 is attached to the slider 33 via the rotation drive mechanism 40, and the holding cylinder 15 is attached to the slider 33 via the focus adjustment mechanism 50. Further, the feed screw 34 is screwed into a nut 36 fixed to the slider 33. Therefore, when the feed screw 34 is rotationally driven by the electric motor 35, the slider 33 moves along the rail 32 in the axial direction of the inspection head 16, and accordingly, the entire detection unit 5 supported by the slider 33 is moved. It moves in the axial direction of the inspection head 16. By driving the detection unit 5 using the linear drive mechanism 30, the irradiation position of the inspection light with respect to the inner peripheral surface of the hole 100 a of the inspection object 100 can be changed with respect to the axial direction of the inspection head 16. The electric motor 35 is configured as, for example, a stepping motor that operates so that the rotation angle of the rotation shaft is proportional to the number of pulses input.

  The rotation drive mechanism 40 is provided as a rotation drive unit that rotates the inspection head 16 around the axis AX. In order to realize such a function, the rotation drive mechanism 40 includes a bearing (not shown) that supports the inspection head 16 so as to be rotatable around the axis AX, an electric motor 41 as a rotation drive source, and the electric motor 41. And a transmission mechanism 42 that transmits the rotation of the rotation to the inspection head 16. As the transmission mechanism 42, a known rotation transmission mechanism including a belt transmission device and a gear train may be used. By transmitting the rotation of the electric motor 41 to the inspection head 16 via the transmission mechanism 42, the inspection head 16 rotates around the axis AX with the mirror 18 fixed therein. By rotating the inspection head 16 using the rotation drive mechanism 40, the irradiation position of the inspection light with respect to the inner peripheral surface of the hole 100a of the inspection object 100 can be changed in the circumferential direction. Then, by combining the movement of the inspection head 16 in the axial direction and the rotation around the axis AX, the inner peripheral surface of the hole 100a of the inspection object 100 can be scanned with the inspection light over the entire surface. It becomes. Note that the holding cylinder 15 does not rotate when the inspection head 16 rotates. Furthermore, the rotary drive mechanism 40 is provided with a rotary encoder 43 that outputs a pulse signal corresponding to the rotation position of the inspection head 16. The rotary encoder 43 is attached to the inspection head 16 and rotates integrally. The rotary encoder 43 is formed with a plurality of detection holes (not shown) arranged at predetermined intervals along the circumferential direction, and detection of the disk 43a. A pulse generation unit 43b that generates a pulse corresponding to the position of the hole. The pulse signal from the rotary encoder 43 is used by the control unit 3.

  The focus adjusting mechanism 50 is provided as a focus adjusting means for driving the holding cylinder 15 in the direction of the axis AX so that the inspection light is focused on the inner peripheral surface of the hole 100a of the inspection object 100. In order to realize the function, the focus adjustment mechanism 50 is disposed between the support plate 51 fixed to the base end portion of the holding cylinder 50 and the slider 33 and the support plate 51 of the linear drive mechanism 30 to dispose the support plate 51. A rail 52 that guides in the axial direction of the inspection head 16, a feed screw 53 that is arranged parallel to the axis AX of the inspection head 16 and is screwed into the support plate 51, and an electric motor 54 that rotationally drives the feed screw 53. I have. By rotating the feed screw 53 with the electric motor 54, the support plate 51 moves along the rail 52, and the holding cylinder 15 moves in the axial direction of the inspection head 16. Thereby, the length of the optical path from the lens 17 through the mirror 18 to the inner peripheral surface of the hole 100a can be adjusted so that the inspection light is focused on the inner peripheral surface of the hole 100a of the inspection object 100.

  The control unit 3 controls the operation of each part of the inspection mechanism 2 according to instructions from the arithmetic processing unit 60 as a computer unit that executes inspection process management, measurement result processing, and the like by the surface inspection apparatus 1. Operation control unit 61, signal processing unit 62 that executes predetermined processing on the output signal of PD 12, input unit 63 for a user to input an instruction to arithmetic processing unit 60, and arithmetic processing unit 60 The output unit 64 for presenting the measurement results and the like to the user, the computer program to be executed by the arithmetic processing unit 60, and the storage unit 65 for storing the measured data and the like. The arithmetic processing unit 60, the input unit 63, the output unit 64, and the storage unit 65 can be configured using general-purpose computer equipment such as a personal computer. In this case, the input unit 63 is provided with input devices such as a keyboard and a mouse, and the output unit 64 is provided with a monitor device. An output device such as a printer may be added to the output unit 64. The storage unit 65 is a hard disk storage device or a storage device such as a semiconductor storage element capable of storing data.

  Based on various control signals from the arithmetic processing unit 60, the operation control unit 61 is configured to detect the LD 11 of the detection unit 5, the electric motor 35 of the linear drive mechanism 30, the electric motor 41 of the rotation drive mechanism 40, and the electric power of the focus adjustment mechanism 50. Each operation of the motor 54 is controlled. In addition, about control with respect to LD11 and the electric motor 54, since it is not the summary of this invention, detailed description is abbreviate | omitted. FIG. 2 is an explanatory diagram illustrating details of the operation control unit 61. When the operation control unit 61 receives the predetermined inspection start signal S output from the arithmetic processing unit 60, the operation control unit 61 causes the LD 11 to emit light with a predetermined intensity and operates the electric motor 41 of the rotation drive mechanism 40 to move the inspection head 16 along the axis AX. Rotate around. With this rotation, the rotary encoder 43 generates a pulse signal Psd1. The operation control unit 61 converts the frequency of the pulse signal Psd1 into a predetermined magnification by the signal processor 611, that is, multiplies or divides the frequency. Then, the operation control unit 61 drives the electric motor 35 by supplying the signal Psd2 converted to a predetermined magnification to the electric motor 35 of the linear drive mechanism 30, and moves the inspection head 16 linearly in the axial direction. Since the electric motor 35 is configured such that the rotation angle is proportional to the number of pulses input as described above, the linear movement amount per rotation of the inspection head 16 is independent of the rotation speed of the inspection head 16. It becomes constant. In other words, the ratio between the rotation speed of the inspection head 16 and the moving speed (feed speed) of the inspection head 16 in the axial direction by the linear drive mechanism 30 is constant. The linear movement amount per rotation of the inspection head 16 can be freely set by appropriately adjusting the magnification by which the signal processor 611 multiplies or divides the frequency.

  The signal processing unit 62 multiplies or divides the pulse signal from the rotary encoder 43 and uses it as a sampling clock in order to sample a predetermined number of signals output from the PD 12 every time the inspection head 16 rotates once. The signal sampled by the signal processing unit 62 is sent to the arithmetic processing unit 60. The arithmetic processing unit 60 generates a two-dimensional image related to the inner peripheral surface of the hole 100a of the inspection object 100 based on the signal, and determines the presence or absence of defects such as a cast hole. This determination is performed by determining whether or not a dark portion corresponding to the defect exists in the two-dimensional image. Details of the processing and details of other specific processing executed by the arithmetic processing unit 60 are described in this book. Since the relevance to the gist of the invention is weak, the description is omitted.

  According to the surface inspection apparatus 1 described above, the amount of linear movement per rotation of the inspection head 16 is constant regardless of the rotation speed of the inspection head 16, so that the rotation speed of the inspection head 16 is not constant and during acceleration or deceleration. Even so, surface inspection can be performed with the required inspection accuracy. That is, as in the embodiment in which the rotation speed of the inspection head 16 and the feeding speed of the inspection head 21 by the linear drive mechanism 30 are controlled separately, the inspection head 16 is changed until the fluctuation in the rotation speed of the inspection head 16 falls within an allowable range. There is no need to stop the linear movement. Therefore, the inspection time required for the inspection of one inspection object 100 can be shortened accordingly. In addition, since fluctuations in the rotation speed of the inspection head 16 do not affect the inspection result, accurate control of the rotation speed of the inspection head 16 is not necessary to ensure inspection accuracy. Therefore, as the electric motor 41 used for the rotation drive mechanism 40, a simple and inexpensive electric motor that can switch at least between rotation and stop can be adopted, so that the apparatus can be easily reduced in size and price.

(Second form)
Next, a second embodiment of the present invention will be described with reference to FIGS. This configuration is different from the configuration in FIG. 1 in the configuration of the inspection head and the configuration in which the inspection head is rotationally driven. In the following, the same components as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. As shown in FIGS. 3 and 4, the inspection head 216 of this embodiment does not rotate as a whole, but only the rotating part 216 </ b> A positioned at the tip rotates around the axis AX. A base portion 216 </ b> B that is the remaining portion of the inspection head 216 that does not rotate is fixed to the slider 33. As shown in FIG. 4, the rotating part 216A is attached to the base 216B with a bearing 70 interposed therebetween, and the mirror 18 is fixed in the internal space of the rotating part 216A in the same manner as in the first embodiment. A transparent window 16a is provided on the outer periphery of 216A so as to face the mirror 18. As shown in FIGS. 3 and 4, in this embodiment, the rotary encoder 43 is provided so as to output a pulse signal corresponding to the rotational position of the rotating unit 216A.

  As shown in detail in FIG. 5, in the second embodiment, an impeller 71 that generates a rotational force that rotates the rotating portion 216 </ b> A around the axis AX is provided. The impeller 71 is attached to the ceiling portion of the rotating portion 216A so as to surround the periphery of the mirror 18. A plurality of air jets 72 are opened on the outer periphery of the rotating portion 216 </ b> A so as to be aligned in the circumferential direction of the impeller 71. As shown in FIG. 4, an air passage 73 that opens toward the impeller 71 is formed between the inner peripheral surface of the base portion 216 </ b> B and the outer peripheral surface of the holding cylinder 15. As shown in FIG. 3, a supply passage 75 for introducing air pressurized by an air pump 74 is connected to the air passage 73. Air filtered by an air filter 76 is supplied to the air pump 74. Accordingly, when the air pump 74 is activated, the air guided in the air passage 73 is blown against the impeller 71 as shown by the arrow in FIG. 4, and the air is discharged from the air outlet 72. Thereby, the rotation unit 216A is driven to rotate around the axis AX. In addition, in the 2nd form, although the rotation part 216A is attached to the outer peripheral side of the base 216B, you may implement with the form which attaches the rotation part 216A to the inner peripheral side of the base 216B.

  FIG. 6 is an explanatory diagram for explaining the operation of the operation control unit 61 according to the second embodiment. As is apparent from this figure, the control performed by the operation control unit 61 is the same as that in the first embodiment except that the air pump 74 is operated to rotate the rotating unit 216A. That is, when the operation control unit 61 receives the predetermined inspection start signal S output from the arithmetic processing unit 60, the operation control unit 61 causes the LD 11 to emit light with a predetermined intensity, and operates the air pump 74 to blow air toward the impeller 71. The rotating part 216A of the inspection head 216 is rotated around the axis AX. With this rotation, the rotary encoder 43 generates a pulse signal Psd1. The operation control unit 61 converts the frequency of the pulse signal Psd1 into a predetermined magnification by the signal processor 611, that is, multiplies or divides the frequency. Then, the operation control unit 61 drives the electric motor 35 by supplying the signal Psd2 converted to the predetermined magnification to the electric motor 35 of the linear drive mechanism 30, and linearly moves the inspection head 216 in the axial direction. Thereby, the same effect as that of the first embodiment can be obtained.

  In particular, since the surface inspection apparatus 1 according to the second embodiment rotationally drives the rotating unit 216A using the air flow, it is not impossible to accurately control the rotational speed by manipulating the air flow rate. It is relatively difficult. However, by executing such control, the inspection can be carried out without requiring accurate control of the rotation speed of the rotating part 216A, that is, as long as the rotating part 216A is rotated, and there is a demand. Inspection accuracy can be sufficiently secured. Therefore, the control executed by the operation control unit 61 is suitable for the surface inspection apparatus 1 according to the second embodiment.

  In each of the above embodiments, the rotary encoder 43 corresponds to the rotational position detection means according to the present invention, the operation control unit 61 corresponds to the movement control means according to the present invention, and the signal processor 611 corresponds to the signal processing means according to the present invention. To do. The feed screw 34 and the nut 36 into which the feed screw 34 is screwed together constitute a conversion mechanism according to the present invention. In the second embodiment, the impeller 71 corresponds to the rotational force generating means of the present invention. The blowing passage 73, the air pump 74, and the supply passage 75 constitute the blowing means according to the present invention, and these and the impeller 71 constitute the rotational driving means according to the present invention.

  However, this invention is not limited to each form mentioned above, It can implement with a various form within the range of the summary of this invention. In each of the above embodiments, the slider 33 on which the inspection head 16 (or 216) is supported is moved by the linear drive mechanism 30 to inspect the stationary inspection object 100. On the contrary, The inspection head 16 (or 216) may be stationary and the inspection object 100 may be moved in the axial direction to inspect the inspection object 100. A known moving means similar to the linear drive mechanism 30 may be used as the mechanism for moving the inspection object 100.

  In addition, when the above-described rotation of the inspection head and the linear movement are not necessary, the operation control unit releases the linear movement mechanism so that the linear movement can be freely performed regardless of the rotation speed of the inspection head. May be controlled.

  In the second embodiment, the impeller 71 is provided as the rotational force generating means. However, for example, as shown in FIG. 7, the mirror 18 is rotated by forming a flap 18a extending obliquely from the edge of the mirror 18. It may be made to function as. In the case of FIG. 7, the air A is blown onto the mirror 18 to generate a rotational force around the axis AX, and the rotating unit 216 </ b> A can be rotated in one direction.

The figure which showed schematic structure of the surface inspection apparatus which concerns on one form of this invention. Explanatory drawing explaining operation | movement of the operation control part of FIG. The figure which showed schematic structure of the surface inspection apparatus which concerns on the 2nd form of this invention. The expanded cross-sectional schematic diagram which expanded the surface inspection apparatus of FIG. 3 partially. The schematic diagram which showed the inside of the rotation part which concerns on a 2nd form regarding the axial direction. Explanatory drawing explaining operation | movement of the operation control part which concerns on a 2nd form. The schematic diagram which showed the form which functions a mirror as a rotational force generation means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface inspection apparatus 16, 216 Inspection head 30 Linear drive mechanism (moving means)
34 Feed screw 35 Electric motor 36 Nut 40 Rotation drive mechanism (rotation drive means)
43 Rotary encoder (rotation position detection means)
61 Operation control unit (movement control means)
71 Impeller (Turning force generating means)
73 air passage 74 air pump 75 supply passage 100 inspection object 100a hole 611 signal processor (signal processing means)
AX axis Psa, Psd2 Pulse signal

Claims (5)

  An inspection head that can be inserted into the hole of the inspection object in which a hole is formed and is rotatable about an axis extending in the longitudinal direction, and the inspection head is moved relative to the inspection object in the axial direction. Moving means for linearly moving the inspection head or the object to be inspected, rotation driving means for rotationally driving the inspection head around the axis, rotational position detecting means for detecting the rotational position of the inspection head, A movement control means for controlling the operation of the moving means based on the detection result of the rotating position detecting means so that the moving amount in the axial direction per rotation of the inspection head is constant regardless of the rotation speed; A surface inspection apparatus comprising: The moving means includes an electric motor configured so that a rotation angle is proportional to the number of pulses of the input pulse signal, and a conversion for converting the rotational motion of the electric motor into a linear motion in the axial direction of the inspection head. A mechanism,
The rotational position detecting means is configured to generate a pulse signal corresponding to the rotational position of the inspection head; and
The movement control means includes signal processing means for converting the frequency of the pulse signal generated by the rotational position detection means to a predetermined magnification, and supplies the pulse signal processed by the signal processing means to the electric motor. The surface inspection apparatus according to claim 1, wherein the electric motor is driven.   The surface inspection apparatus according to claim 1, wherein the rotation driving unit is configured to be able to rotate the inspection head around the axis by using a flow of air.   The rotational driving means includes rotational force generating means for generating a rotational force for rotating the inspection head around the axis using the blown air, and a blowing means for blowing air to the rotational force generating means. The surface inspection apparatus according to claim 3, wherein the surface inspection apparatus is provided.   The surface inspection apparatus according to claim 4, wherein an impeller attached to the inspection head is provided as the rotational force generating means.

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