JP6733195B2 - Optical scanning device - Google Patents

Description

The present invention relates to an optical scanning device .

An optical scanning device is known that includes a light source, a mirror that reflects the light emitted from the light source while rotating, and an optical sensor that receives the reflected light from the mirror and detects the mirror angle (for example, patents). Reference 1).

JP-A-11-203701

In the optical scanning device as described above, when a mirror unit including a mirror is miniaturized as a configuration different from a light source or the like, it is difficult to miniaturize the mirror unit if an optical sensor used for detecting the mirror angle is provided in the mirror unit. Could be.

The present invention provides an optical scanning device having a mirror unit that can be miniaturized.

According to the optical scanning device according to one aspect of the present invention, the mirror that reflects the irradiation light from the light source while rotating and scans the object with the scanning light that reflects the irradiation light from the light source; A mirror unit having a first reflecting member that is provided within a scanning range of and that reflects the scanning light ;
And a light receiving portion provided outside the mirror unit,
The reflected light reflected by the first reflecting member toward the mirror is reflected by the mirror and guided to the light receiving unit.

According to an embodiment of the present invention, an optical scanning device having a mirror unit that can be miniaturized is provided.

It is a figure which illustrates the schematic structure of the optical scanning device in 1st Embodiment. It is a figure which illustrates a mode that a mirror rotates. It is a figure for demonstrating the mirror angle detection method. It is a figure which illustrates the schematic structure of the optical scanning device in 2nd Embodiment. It is a figure which illustrates the schematic structure of the optical scanning device in 3rd Embodiment.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components may be denoted by the same reference numerals and redundant description may be omitted.

[First Embodiment]
FIG. 1 is a diagram illustrating a schematic configuration of an optical scanning device 100 according to the first embodiment.

As shown in FIG. 1, the optical scanning device 100 includes a light source 101, a half mirror 102, an optical fiber 103, a photodetector 105, a mirror unit 110, a processing device 120, a capacitance detection unit 130, and a display device 140. ..

The light source 101 is, for example, a laser diode, and emits laser light toward the optical fiber 103. The light source 101 is not limited to the laser diode as long as it can irradiate the mirror unit 110 with light through the optical fiber 103.

The half mirror 102 transmits the laser light emitted from the light source 101 and reflects the reflected light emitted from the optical fiber 103. Laser light emitted from the light source 101 passes through the half mirror 102 and enters the optical fiber 103.

The optical fiber 103 guides the laser light emitted from the light source 101 to the mirror unit 110. Further, the optical fiber 103 guides the reflected light reflected by the mirror unit 110 in a direction opposite to the laser light emitted from the light source 101. The optical fiber 103 is provided with fiber collimators 104 at both ends so that the light emitted from the ends becomes parallel light.

As shown in FIG. 1, the mirror unit 110 has a mirror 111, a drive electrode 113, and a reflection member 117. In FIG. 1, the mirror unit 110 is enlarged to show the schematic configuration of the mirror unit 110. The mirror unit 110 is provided, for example, at the tip of the optical fiber 103 (the portion from which the laser light emitted from the light source 101 is emitted).

The mirror 111 is provided at a position where the laser light of the light source 101 guided to the optical fiber 103 is irradiated, and reflects the laser light emitted from the light source 101 toward the object 500. The mirror 111 is, for example, a MEMS (micro electro mechanical system) mirror, and is formed on the semiconductor substrate together with the drive electrode 113. The mirror 111 is formed so as to be rotatable about a shaft 112 in the arrow direction shown in FIG. The mirror 111 is connected to a DC power supply 114 and a DC voltage is applied.

The drive electrode 113 is formed on the semiconductor substrate together with the mirror 111. The drive electrode 113 is connected to the AC power supply 115 and is applied with an AC voltage. When an AC voltage is applied from the AC power supply 115 to the drive electrode 113, the mirror 111 periodically rotates about the axis 112 within a predetermined angle range as indicated by an arrow in FIG.

FIG. 2 is a diagram illustrating how the mirror 111 rotates.

When an AC voltage is applied to the drive electrode 113, the mirror 111 moves as shown in FIGS. 2B and 2C with the position shown in FIG. 2A as the center (mirror angle: 0 degree). , And rotates periodically about a shaft 112 within a predetermined angle range (mirror angle: ±θ). The mirror 111 rotates as shown in FIG. 2 to scan within a predetermined scanning range (scanning angle: ±θ) with the scanning light that reflects the laser light emitted from the light source 101.

As shown in FIG. 1, the laser light (scanning light) reflected by the mirror 111 periodically reciprocates within the scanning range indicated by the broken line to scan the surface of the object 500. A reflecting member 117 is provided within the scanning range of the scanning light.

The reflecting member 117 is formed of a material that reflects light, such as resin or metal. Reflected light reflected by the reflecting member 117 and the object 500 toward the mirror 111 is reflected by the mirror 111 and enters the optical fiber 103. The reflected light from the reflecting member 117 and the object 500 that has entered the optical fiber 103 is emitted from the optical fiber 103, reflected by the half mirror 102, and guided to the photodetector 105.

The photodetector 105 is a photodiode, for example, and outputs a photodetection signal according to the amount of received light. The photodetector 105 is provided at a position where the reflected light from the half mirror 102 is received, and outputs a photodetection signal according to the amount of received light to the processing device 120.

The processing device 120 includes an angle detection unit 121 and an image processing unit 122. The processing device 120 has, for example, a CPU, a ROM, a RAM, and the like. Each function of the processing device 120 is implemented, for example, by the CPU executing a program stored in the ROM in cooperation with the RAM.

The angle detection unit 121 detects the mirror angle of the mirror 111 based on the light detection signal output from the light detector 105 and the electrostatic capacitance detected by the electrostatic capacitance detection unit 130. The electrostatic capacitance detection unit 130 detects the electrostatic capacitance between the mirror 111 and the drive electrode 113, and outputs the detected value to the processing device 120.

FIG. 3 is a diagram for explaining a mirror angle detection method in the angle detection unit 121.

The graph of FIG. 3A shows the change over time of the mirror angle θ of the mirror 111. The graph of FIG. 3B shows the photodetection signal output from the photodetector 105 when the mirror 111 rotates as shown in FIG. In the graph of FIG. 3C, the value of the electrostatic capacitance detected by the electrostatic capacitance detection unit 130 when the mirror 111 rotates as shown in FIG. ing.

The mirror 111 in the present embodiment periodically rotates within a range of a mirror angle θ of −10 degrees to +10 degrees, as shown in FIG. 3A, for example. The reflecting member 117 is provided at a position where the scanning light is incident when the mirror angle θ is around −8 degrees, for example. With such a configuration, as shown in FIG. 3B, a peak appears in the light detection signal when the mirror angle θ is −8 degrees.

Further, as shown in FIG. 3C, the electrostatic capacitance between the mirror 111 and the drive electrode 113 is maximum when the mirror angle θ at which the distance between the mirror 111 and the drive electrode 113 is minimum is 0 degree. It becomes a value. Further, the electrostatic capacitance has a minimum value when the mirror angle θ at which the distance between the mirror 111 and the drive electrode 113 is maximum is −10 degrees and +10 degrees.

Here, the memory of the processing device 120 stores the relationship between the electrostatic capacitance C and the mirror angle θ shown by the solid line in FIG. The angle detection unit 121 makes the capacitance C′ detected by the capacitance detection unit 130 indicated by the broken line in FIG. 3 equal to the capacitance C indicated by the solid line in FIG. 3C. The calibration described below is performed.

The angle detection unit 121, for example, _{adjusts the} capacitance C- ₈ ′ when the light detection signal exceeds the reference value v to be equal to the preset capacitance C- _8. A correction coefficient of the electrostatic capacitance C′ detected by 130 is obtained. The angle detection unit 121 corrects the electrostatic capacitance C′ detected by the electrostatic capacitance detection unit 130 so as to be equal to the electrostatic capacitance C shown by the solid line in FIG. 3C, using the obtained correction coefficient. To do.

The angle detection unit 121 corrects the electrostatic capacitance C′ detected by the electrostatic capacitance detection unit 130 as described above, and based on the relationship between the electrostatic capacitance C and the mirror angle θ stored in the memory, The mirror angle θ corresponding to the corrected capacitance C is calculated.

When the angle detection unit 121 obtains the mirror angle θ of the mirror 111, the image processing unit 122 causes the scan image of the object 500 based on the mirror angle θ of the mirror 111 and the light detection signal output from the photodetector 105. To generate. The image processing unit 122, for example, in a mirror angle range where the reflecting member 117 is not provided (for example, -7 degrees to +7 degrees when the reflecting member 117 is provided at the position of the mirror angle (-8 degrees)). A scan image of the object 500 is generated based on the light detection signal.

The display device 140 is, for example, a liquid crystal display, and displays the scan image generated by the image processing unit 122 of the processing device 120. The user of the optical scanning device 100 can confirm the surface of the object 500 from the scan image displayed on the display device 140.

As described above, according to the first embodiment, the reflected light from the reflecting member 117 provided in the mirror unit 110 is detected outside the mirror unit 110, so that the mirror angle θ of the mirror 111 is changed. You can ask. Therefore, since it is not necessary to provide the photodetector 105 in the mirror unit 110 to detect the angle of the mirror 111, the mirror unit 110 can be downsized.

The reflecting member 117 may be made of a material that transmits light in a predetermined wavelength range. Since the reflecting member 117 transmits light, the scanning range of the object 500 can be expanded. For example, when the mirror 111 rotates from −10 degrees to +10 degrees as described above, if the reflection member 117 is provided at a position where the scanning light is reflected at a mirror angle θ of −8 degrees, the scanning range of the target object 500. Is narrower than the scanning range at a mirror angle θ of −7 degrees to +7 degrees. However, since the reflection member 117 transmits light, the scanning range of the object 500 can be expanded from −10 degrees, which is the scanning range of the scanning light, to +10 degrees.

[Second Embodiment]
Next, a second embodiment will be described based on the drawings. The description of the same components as those of the above-described embodiment will be omitted.

FIG. 4 is a diagram illustrating a schematic configuration of the optical scanning device 200 according to the second embodiment.

As shown in FIG. 4, the mirror unit 210 of the optical scanning device 200 according to the second embodiment includes a reflecting member 117 as a first reflecting member and reflecting members 118a and 118b as second reflecting members.

Here, the electrostatic capacitance between the mirror 111 and the drive electrode 113 detected by the electrostatic capacitance detection unit 130 has the same magnitude when the mirror angle θ is −8 degrees and +8 degrees, for example. Therefore, when the angle detection unit 121 obtains the mirror angle θ based on the electrostatic capacitance, it may not be possible to determine in which direction the mirror 111 is rotating.

Therefore, in the mirror unit 210 according to the second embodiment, one reflecting member 117 as the first reflecting member and two reflecting members 118a and 118b as the second reflecting member are opposite to each other in the scanning range of the scanning light. It is provided near the end on the side.

With such a configuration, for example, when the mirror 111 rotates in the counterclockwise direction in FIG. 4 and scanning light enters the reflecting member 117, one peak exceeding the reference value v is present in the photodetection signal in the photodetector 105. appear. Further, for example, when the mirror 111 rotates in the clockwise direction in FIG. 4 and scanning light enters the reflecting members 118a and 118b, two peaks exceeding the reference value v appear in the photodetection signal in the photodetector 105.

The angle detection unit 121, for example, moves the rotation direction of the mirror 111 that rotates periodically when the light detection signal exceeds the reference value v once within a predetermined time or when the light detection signal reaches the reference value within the predetermined time. It can be determined based on the elapsed time from when v is exceeded twice.

Therefore, the angle detection unit 121 can accurately detect the mirror angle θ of the mirror 111 based on the capacitance detected by the capacitance detection unit 130 and the rotation direction of the mirror 111. ..

As described above, according to the second embodiment, the mirror unit 210 can be downsized and the mirror angle θ of the mirror 111 can be detected more accurately.

In the above-described second embodiment, one reflecting member 117 is provided as the first reflecting member and two reflecting members 118a and 118b are provided as the second reflecting member, but the first reflecting member and the second reflecting member are provided. The number of reflecting members provided as is not limited to the configuration illustrated in the present embodiment. If the number of reflecting members provided as the first reflecting member and the number of reflecting members provided as the second reflecting member are different, the rotation direction of the mirror 111 can be determined in the same manner as the above-described method.

Further, the reflecting members provided as the first reflecting member and the second reflecting member may be formed of a material that transmits a predetermined wavelength range. The scanning range of the object 500 can be expanded by allowing each reflecting member to transmit light.

[Third Embodiment]
Next, a third embodiment will be described based on the drawings. The description of the same components as those of the above-described embodiment will be omitted.

FIG. 5 is a diagram illustrating a schematic configuration of the optical scanning device 300 according to the third embodiment.

As shown in FIG. 5, the mirror unit 310 of the optical scanning device 300 according to the third embodiment has a first reflecting member 119a and a second reflecting member 119b.

The 1st reflective member 119a and the 2nd reflective member 119b reflect the light of a different wavelength range, respectively. The first reflection member 119a and the second reflection member 119b are, for example, wavelength conversion elements that convert the wavelength range of scanning light into different wavelength ranges and reflect the converted wavelength ranges. In addition, the first reflecting member 119a and the second reflecting member 119b are respectively provided in the vicinity of the ends on the opposite sides in the scanning range of the scanning light.

With such a configuration, for example, when the mirror 111 rotates counterclockwise in FIG. 5 and the scanning light enters the first reflecting member 119a, a peak appears in the photodetection signal in the photodetector 105. Further, for example, when the mirror 111 rotates clockwise in FIG. 5 and the scanning light is incident on the second reflecting member 119b, the scanning light is incident on the first reflecting member 119a in the light detection signal of the photodetector 105. A peak having a different maximum value from the case appears.

The angle detection unit 121 changes the rotation direction of the mirror 111, which rotates periodically, from the time when the peak of the light detection signal is detected by the reflected light from the first reflection member 119a or the second reflection member 119b. It can be determined based on the elapsed time. By comparing the maximum values of the peaks appearing in the light detection signal, the peak of the light detection signal due to the reflected light of the first reflecting member 119a and the peak of the light detection signal due to the reflected light of the second reflecting member 119b are both It can be determined whether or not it is caused by the reflected light from the reflecting member.

Therefore, the angle detection unit 121 can accurately detect the mirror angle θ of the mirror 111 based on the capacitance detected by the capacitance detection unit 130 and the rotation direction of the mirror 111. ..

The first reflection member 119a and the second reflection member 119b may be formed of a material that transmits a predetermined wavelength range. The scanning range of the object 500 can be expanded by allowing each reflecting member to transmit light.

Further, a plurality of light receiving portions including a half mirror and a photodetector are provided between the light source 101 and the optical fiber 103, and the reflected light from the first reflecting member 119a and the reflected light from the second reflecting member 119b are respectively received differently. It may be detected by the section. The light receiving unit that detects the reflected light from the first reflecting member 119a is provided with a half mirror that reflects the light in the wavelength range corresponding to the reflected light from the first reflecting member 119a. Further, the light receiving unit that detects the reflected light from the second reflecting member 119b is provided with a half mirror that reflects the light in the wavelength range corresponding to the reflected light from the second reflecting member 119b. With such a configuration, the detection accuracy of the reflected light from the first reflecting member 119a and the reflected light from the second reflecting member 119b is improved, and the mirror angle θ of the mirror 111 can be detected more accurately.

Although the mirror unit and the optical scanning device according to the embodiment have been described above, the present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention. The dimensions of each part in the above-described embodiment are not limited to the exemplified values.

100, 200, 300 Optical scanning device 105 Photodetector (light receiving part)
110, 210, 310 Mirror unit 111 Mirror 117 Reflecting member (first reflecting member)
118a, 118b Reflecting member (second reflecting member)
119a 1st reflection member 119b 2nd reflection member 121 Angle detection part 500 Object

Claims (12)

A mirror that reflects the irradiation light from the light source while rotating and scans the object with the scanning light that reflects the irradiation light from the light source; and a mirror provided in the scanning range of the scanning light to reflect the scanning light. A mirror unit having a first reflecting member ;
And a light receiving portion provided outside the mirror unit,
An optical scanning device in which reflected light reflected by the first reflecting member toward the mirror is reflected by the mirror and guided to the light receiving unit. The first reflecting member transmits light in a predetermined wavelength range ,
The optical scanning device according to claim 1. Have a second reflecting member for reflecting said scanning light provided to a position different from the first reflecting member in the scanning range of the scanning light,
The number of the light receiving units is one or more,
The light receiving unit detects the reflected light from the second reflecting member,
The optical scanning device according to claim 1. The second reflecting member transmits light in a predetermined wavelength range ,
The optical scanning device according to claim 3. The first reflecting member and the second reflecting member include different numbers of reflecting members ,
The optical scanning device according to claim 3 or 4. The first reflecting member and the second reflecting member reflect light in different wavelength ranges ,
The optical scanning device according to claim 3 or 4. Having, an angle detector for detecting the angle of the mirror on the basis of a signal output from the pre-Symbol light receiving unit,
The optical scanning device according to claim 1 . A capacitance detection unit for detecting a capacitance between the mirror and a drive electrode of the mirror,
The optical scanning according to claim 7, wherein the angle detection unit detects an angle of the mirror based on a signal output from the light receiving unit and a capacitance detected by the capacitance detection unit. apparatus. The light receiving unit outputs a signal according to the amount of light received,
The first reflecting member is located between the object and the mirror,
The optical scanning device according to claim 1. The optical scanning device according to claim 1, further comprising an optical fiber that guides the reflected light reflected and incident on the mirror to the light receiving unit. A half mirror that reflects the reflected light emitted from the optical fiber and guides it to the light receiving unit;
The optical scanning device according to claim 10, wherein the irradiation light is transmitted through the half mirror and is incident on the optical fiber. The optical scanning device according to claim 11, wherein fiber collimators are provided at both ends of the optical fiber.

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