JP2007155467A - Light beam scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light beam scanner for highly accurately detecting the position of an original point of a light polarization element. <P>SOLUTION: This light beam scanner 1 comprises a light source device 10, a transmissive light polarization disk 30 equipped with light scanning areas 36 where the outgoing direction of a light beam L0 changes depending on the incoming position of a light beam outputted from the source device 10, and a drive device for rotatively driving the polarization disk 30. On the polarization disk 30, an output area 82 for original point position detection is formed for outputting the incoming light beam L0 in a direction different from that of the scanning areas 36, and a photo-detector 81 for original point position detection is disposed in a direction in which the light beam is outputted from the output area 82. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light beam scanning apparatus that scans a light beam in a predetermined direction.

  The light beam scanning device is widely used in image forming devices such as laser printers, digital copying machines, facsimiles, bar code reading devices, inter-vehicle distance measuring devices, and monitoring devices. Among these devices, for example, in a conventional light beam scanning device used for an inter-vehicle distance measuring device or a monitoring device, a light beam emitted from a light source is deflected by a light deflecting element such as a polygon mirror, and a predetermined angle range is obtained. The scanning beam is emitted as a scanning beam, and the return light reflected by the preceding vehicle or the like is received by a photodetector to detect the presence of the preceding vehicle and the distance from the preceding vehicle (for example, Patent Document 1).

In such a light beam scanning device, in order to detect the direction in which the preceding vehicle is present, it is necessary to detect the emission direction of the light beam emitted from the light deflection element, which is the origin position of the light deflection element. Need to be monitored. Conventionally, a magnetic sensor, a photo interrupter, or the like is used for monitoring the origin position.
Japanese Patent Laid-Open No. 11-326499

  However, when a magnetic sensor is used for the detection of the origin position, there is a problem that variation in the detection of the origin position due to a temperature change cannot be avoided due to the characteristics of the magnetic sensor. When a magnetic sensor is used to detect the origin position, a magnetic pattern is provided on the light deflection element, while a magnetic sensor is disposed on the apparatus body side, and the magnetic pattern approaches or separates from the magnetic sensor. Since the origin position of the light deflection element is set by the output change, the variation in the mounting position of the magnetic sensor is directly detected as an origin position detection error, and there is a problem that the accuracy is low.

  Also, when a photo interrupter is used for detecting the origin position, a light shielding magnetic pattern is provided on the light deflection element, while a light emitting element and a light receiving element are arranged on the apparatus main body side, and the light shielding magnetic pattern passes the optical path of the photo interrupter. Since the timing for blocking is detected, the variation in the mounting position of the light emitting element and the light receiving element becomes the detection error of the origin position as it is, and there is a problem that the accuracy is low. Furthermore, when a photo interrupter is used to detect the origin position, a light emitting diode is used as a light source for origin position detection separately from a laser light emitting element as a light beam light source. In the case of driving the light emitting elements in a pulsed manner, there is a problem that it is impossible to avoid the occurrence of detection errors due to deviations in the light emission timing between these light emitting elements.

  In view of the above problems, an object of the present invention is to provide a light beam scanning apparatus capable of performing the origin position of a light deflection element with high accuracy.

  In order to solve the above problems, in the present invention, a light source device, a light deflection element in which the emission direction of the light beam changes depending on the incident position of the light beam emitted from the light source device, and the light deflection element are driven. And a driving device that changes the incident position of the light beam with respect to the light deflection element, the light deflection element includes a light scanning region that scans the incident light beam over a predetermined angular range, An origin position detecting exit area for emitting the incident light beam in a direction different from the scanning direction of the optical scanning area is formed, and the origin position detecting light is emitted in the direction in which the light beam is emitted from the origin position detecting exit area. A detector is arranged.

  In the present invention, an optical scanning area is formed in the optical deflection element, and an origin position detection emitting area for emitting an incident light beam in a direction different from the optical scanning area is formed. When the origin position detection emission region arrives at the incident position of the emitted light beam, the light beam emitted from the origin position detection emission region is detected by the origin position detection photodetector. For this reason, since the origin position of the light deflection element can be reliably detected, the direction in which the light beam is emitted from the light beam scanning device at each time point can be grasped with reference to this origin position. In addition, unless the origin position detection exit region arrives at the incident position of the light beam emitted from the light source device, the light beam is not emitted from the light deflection element toward the origin position detection photodetector. Unlike the case where an interrupter is used, the origin of the light deflection element can be detected even if the position accuracy of the light detector for origin position detection is low, as long as the light beam emitted from the origin area detection exit area can be detected. The position can be detected reliably.

  In the present invention, it is preferable that the light beam emitted from the origin position detection emission region reaches the origin position detection photodetector in an unfocused state. With this configuration, when the light beam emitted from the origin position detection emission region reaches the origin position detection photodetector, the diameter of the light beam is large. For this reason, since the area | region which can detect the light beam radiate | emitted from the origin position detection exit area | region is wide, the position accuracy calculated | required by the origin position detection photodetector can further be eased.

  In the present invention, the optical deflection element is, for example, a disk-shaped optical deflection disk that is rotationally driven by the driving device. In this case, the optical deflection disk has the optical scanning area formed on the disk surface over a predetermined angular range, and the origin position detection emission area is formed at an angular position on the disk surface avoiding the optical scanning area. ing. If comprised in this way, since the drive device should just rotate and drive a disk-shaped optical deflection | deviation disk, the structure of a drive device can be simplified compared with a linear motion system.

  In the present invention, as the optical deflection disk, a reflective optical deflection disk in which the direction in which the light beam is reflected differs depending on the angular position where the light beam is incident in the optical scanning region can be adopted. However, it is preferable that the optical deflection disk is, for example, a transmissive optical deflection disk in which the direction in which the light beam is refracted differs depending on the angular position where the light beam is incident in the optical scanning region. With such a transmissive optical deflection disk, it is not necessary to arrange a light source device in the light beam emitting direction, and thus the light beam scanning device can be miniaturized.

  In this case, it is preferable that the origin position detection emission region refracts and emits a light beam in a direction different from the optical scanning region. That is, it is preferable that both the light scanning region and the origin position detecting exit region deflect the light beam by refraction. If comprised in this way, the said optical deflection | deviation disk can be comprised as an integral resin disk also including the said optical scanning area | region and the said origin position detection emission area | region. In this case, when the optical deflection disk is configured, the optical deflection disk can be manufactured by cutting and grinding the disk-shaped translucent substrate. Further, the optical deflection disk can be formed as an integral resin molded product including the optical scanning area and the origin position detection emission area. According to such a configuration, the optical deflection disk can be mass-produced at low cost. can do.

  In the present invention, it is preferable to use a photodiode as the origin position detection photodetector. Since the photodiode has a high response speed, it is suitable for detecting the origin position.

  In the present invention, an optical scanning area is formed in the optical deflecting element, and an origin position detection emitting area for emitting an incident light beam in a direction different from the optical scanning area is formed. When the origin position detection emission region arrives at the incident position of the light beam, the light beam emitted from the origin position detection emission region is detected by the origin position detection photodetector. For this reason, since the origin position of the light deflection element can be reliably detected, the direction in which the light beam is emitted from the light beam scanning device at each time point can be grasped with reference to this origin position. In addition, unless the origin position detection exit region arrives at the incident position of the light beam emitted from the light source device, the light beam is not emitted from the light deflection element toward the origin position detection photodetector. Unlike the case where an interrupter is used, the origin of the light deflection element can be detected even if the position accuracy of the light detector for origin position detection is low, as long as the light beam emitted from the origin area detection exit area can be detected. The position can be detected reliably.

  A light beam scanning apparatus to which the present invention is applied will be described below with reference to the drawings.

[Embodiment 1]
(overall structure)
FIG. 1 is an explanatory diagram showing a schematic side view schematically showing a schematic configuration of a light beam scanning apparatus to which the present invention is applied. FIG. 2 is an explanatory view showing the principle of a light beam scanning apparatus to which the present invention is applied. 3A, 3B, 3C, and 3D are a plan view, a cross-sectional view, and a cross-sectional view, respectively, of a transmissive optical deflection disk used in a light beam scanning apparatus to which the present invention is applied. It is Y sectional drawing and ZZ sectional drawing.

  A light beam scanning apparatus 1 shown in FIG. 1 generally rotates a light source device 10, a transmissive light deflection disk 30 that can deflect a light beam L0 emitted from the light source device 10, and the transmissive light deflection disk 30. A driving device for driving and an origin detection mechanism 8 to be described later are provided. The light source device 10 includes a laser diode 13 as a light source, and an optical system 19 that guides the laser light L0 emitted from the laser diode 13 as predetermined convergent light. The driving device 4 includes a synchronous motor 40, and the rotation output portion of the synchronous motor 40 is fitted in the center hole 31 of the transmissive optical deflection disk 30 to hold the transmissive optical deflection disk 30. In FIG. 1, the transmission type optical deflection disk 30 is shown to be directly driven by the synchronous motor 40, but a transmission mechanism for transmitting the rotation of the synchronous motor 40 to the driving device 4 is provided. A configuration in which the transmissive light deflection disk 30 is rotationally driven through a mechanism may be employed. The synchronous motor 40 may be an external synchronous motor such as a stepping motor, or an internal synchronous motor such as a brushless motor or a DC commutator motor. As the synchronous motor 40, a synchronous motor using an AC power source, an AC inductance / capacitor motor, or the like may be used.

  2 and 3A, the transmissive light deflection disk 30 has a disk shape made of a translucent material such as polycarbonate resin or acrylic resin, and is an upper surface opposite to the side on which the light source device 10 is disposed. The optical scanning region 36 is formed over a predetermined region in the circumferential direction. In this embodiment, the optical scanning region 36 is formed over a range of 3/4 circumference of the transmissive optical deflection disk 30. Here, in the light scanning region 36 of the transmissive light deflection disk 30, the emission direction of the light beam changes depending on the incident position of the light beam L 0 emitted from the light source device 10.

  That is, the optical scanning area 36 of the transmissive optical deflection disk 30 is divided into a plurality of optical deflection areas 32 a, 32 b,... (Hereinafter referred to as the optical deflection area 32) in the circumferential direction around the center hole 31. Each of the plurality of light deflection regions 32 is formed such that inclined surfaces 33a, 33b,... (Hereinafter referred to as inclined surfaces 33) that refract the incident light beam are inclined in the radial direction. ing. For this reason, as shown in FIGS. 3B, 3C, and 3D, the radial cross section of each light deflection region 32 is formed in a wedge shape, and the radial cross section of each light deflection region 32 is It is formed in the trapezoid shape which makes an inner peripheral side and an outer peripheral side parallel. In addition, in each of the plurality of light deflection regions 32, the inclination angles of the plurality of inclined surfaces 33 are different between adjacent inclined surfaces.

Here, when the inclination angle of the inclined surface 33 is θw, the scanning angle of the light beam emitted from the transmissive optical deflection disk 30 is θs (see FIG. 1), and the refractive index of the transmissive optical deflection disk 30 is n,
sin (θw + θs) = n · sin θw
The inclined surface 33 is formed so as to satisfy this relationship. In this equation, n is the refraction angle of the material constituting the transmissive optical deflection disk 30. For example, when n = 1.51862, and the scanning angle θs is 10 °, the inclination angle θs is 18. The angle may be set to 02 °.

  Furthermore, in this embodiment, the inclination angle θw of the inclined surface 33 of the adjacent light deflection region 32 is gradually increased or decreased. For example, as shown in FIGS. 3B, 3C, and 3D, the inclination angles θwa, θwb, and θwc of the inclined surfaces 33a, 33b, and 33c of the adjacent light deflection regions 32a, 32b, and 32c are gradually increased. It has come to increase. Further, the inclined surface 33 of the light deflection region 32 includes a surface that is lowered from the inner peripheral side toward the outer peripheral side, and a surface that is lowered from the outer peripheral side toward the inner peripheral side. Parallel planes are also included. That is, a surface with a sign of θw of + and a surface of − are included, and a surface with θw of 0 ° is also included.

  In such a transmissive optical deflection disk 30, the number of light deflection regions 32 is determined by the number of light beam scanning points. For example, the number of light deflection regions 32 is 201 and the light beam scanning range is ± 10 °. In this case, the scanning resolution of the light beam is 0.1 °. Further, for example, if the size of the light beam of the transmissive light deflection disk 30 at the position where the light beam is transmitted is 40 mm, the circumferential width at the light beam transmission position of one light deflection region 32 is 0.63 mm. Become.

  Such a transmissive light deflection disk 30 may be produced by directly manufacturing a translucent resin disk by ultra-precision machining such as cutting, or by using a mold in consideration of production cost. Also good. Here, the inclined surface 33 is formed only on the upper surface located on the emission side of the transmissive optical deflection disk 30, and the lower surface on the incident side is formed in a planar shape. Therefore, when the transmissive optical deflection disk 30 is manufactured using a mold, the mold can be easily manufactured because only one surface of the mold is required to be processed. Further, when the transmissive light deflection disk 30 is manufactured by directly cutting a transparent resin, the lower surface is flat, so that the material can be easily fixed and processed easily. Note that if the transmissive light deflection disk 30 is subjected to an antireflection treatment by a thin film or a fine structure, return light that causes variations in the output of the light source device 10 can be reduced. Further, since the transmittance is improved, the loss of the light amount from the light source device 10 can be reduced.

(Configuration of origin detection mechanism 8)
1, 2, and 3 (a) again, an optical scanning region 36 is formed on the upper surface of the transmissive optical deflection disk 30 used in the light beam scanning apparatus 1 of the present embodiment over a range of 3/4 of its circumference. In addition, the remaining range of about ¼ is a flat region 38 parallel to the lower surface. Further, a triangular prism-shaped prism portion 37 is formed at the center position in the circumferential direction of the flat region 38 and has two inclined surfaces 371 and 372 extending in the radial direction in the circumferential direction. In the prism portion 37, the two inclined surfaces 371 and 372 and the ridge line portion where the inclined surfaces 371 and 372 are connected are not inclined in the radial direction of the transmissive optical deflection disk 30.

  In the transmissive light deflection disk 30 configured as described above, one of the two inclined surfaces 371 and 372 constituting the prism portion 37 is used as the origin position detecting emission region 82 as described below. . First, in the transmissive optical deflection disk 30, the inclined surface 33 formed in the optical scanning region 36 is inclined in the radial direction of the transmissive optical deflection disk 30, so that the light beam emitted from the light source device 10 is In the optical scanning region 36, the light is not deflected in the circumferential direction of the transmissive light deflection disk 30 but is deflected in the radial direction of the transmissive light deflection disk 30. The plurality of light deflection regions 32 of the optical scanning region 36 include an inclined surface 33 having an inclination angle of 0 °, that is, a surface parallel to the lower surface of the transmissive light deflection disk 30. The light beam L0 emitted from 10 is not deflected in the circumferential direction of the transmissive light deflection disk 30, but is emitted in a direction perpendicular to the lower surface of the transmissive light deflection disk 30.

  On the other hand, the inclined surface 371 constituting the origin position detecting emission region 82 in the prism portion 37 is not inclined in the radial direction of the transmissive light deflection disk 30 but inclined in the circumferential direction of the transmissive light deflection disk 30. For this reason, the light beam L0 emitted from the light source device 10 is not deflected in the radial direction of the transmissive light deflection disk 30 in the origin position detection emission region 82, and the circumferential direction (tangential line) of the transmissive light deflection disk 30 is not affected. Direction).

  Further, in this embodiment, the light source L 10 for detecting the origin position is formed of a photodiode in the direction in which the light beam L 0 emitted from the light source device 10 is deflected and emitted by the origin position detecting exit area 82 of the transmissive optical deflection disk 30. A container 81 is arranged. Thus, in this embodiment, the origin position detection mechanism 8 is configured by the origin position detection emission area 82 and the origin position detection photodetector 81 of the transmissive optical deflection disk 30. Note that a phototransistor may be used as the origin position detection photodetector 81.

(Operation of the light beam scanning apparatus 1)
4A, 4B, and 4C are explanatory views schematically showing the operation principle of the light beam scanning apparatus to which the present invention is applied. In the light beam scanning device 1 of the present embodiment, first, as shown in FIG. 4A, when the light beam L0 emitted from the light source device 10 enters the light scanning region 36 of the transmissive light deflection disk 30, the arrow As indicated by L1, the light beam L0 is deflected and emitted in a direction corresponding to the inclination angle of the inclined surface 33 at the position where the light beam L0 is incident in the optical scanning region 36. Here, since the inclination angle of the inclined surface 33 differs depending on the light deflection region 32, the direction emitted from the transmission type optical deflection disk 30 is transmitted along with the rotation of the transmission type optical deflection disk 30 to the arrow CW. The light beam that changes in the radial direction of the mold light deflection disk 30 and is emitted from the light source device 10 is scanned over a predetermined angular range θ0 in the radial direction of the transmission light deflection disk 30.

  Next, the transmissive light deflection disk 30 rotates in the direction of arrow CW, and the light beam L0 emitted from the light source device 10 is used to detect the origin position of the transmissive light deflection disk 30 as shown in FIG. When incident on the emission area 82 (slope 371), the origin position detection emission area 82 is inclined to one side in the circumferential direction of the transmissive optical deflection disk 30, so that the light beam L0 emitted from the light source device 10 is obtained. Is deflected and emitted in one circumferential direction of the transmissive optical deflection disk 30, that is, in the direction in which the origin position detecting photodetector 81 is disposed, as indicated by an arrow L2. As a result, it is detected from the detection result of the origin position detection light detector 81 that the origin position detection exit area 82 of the transmissive optical deflection disk 30 has arrived at the exit position of the light beam L0 from the light source device 10. Can do. Here, the light beam emitted from the origin position detection emission region 82 reaches the origin position detection photodetector 81 in an unfocused state.

  When the light beam L0 emitted from the light source device 10 is incident on the other inclined surface 372 of the prism portion 37 of the transmissive light deflection disk 30, this inclined surface 372 is on the other side in the circumferential direction of the transmissive light deflection disk 30. That is, it is deflected to the side opposite to the side where the origin position detecting photodetector 81 is arranged and emitted, and thus is not used for detecting the origin position.

  When the transmissive light deflection disk 30 rotates and the light beam L0 emitted from the light source device 10 enters the flat region 38 of the transmissive light deflection disk 30, as shown in FIG. The light beam L0 emitted from the apparatus 10 is not deflected and is emitted in a direction perpendicular to the lower surface of the transmissive light deflection disk 30, as indicated by an arrow L3, and thus is not used for detecting the origin position. .

(Main effects of this form)
As described above, in the present embodiment, the light scanning region 36 is formed on the transmissive light deflection disk 30 and the origin position detection emitting region for emitting the incident light beam in a direction different from the light scanning region 36. 82 is formed, and when the origin position detecting exit area 82 arrives at the incident position of the light beam L0 emitted from the light source device 10, the light beam emitted from the origin position detecting exit area 82 is It is detected by the position detection photodetector 81. For this reason, since the origin position of the transmissive light deflection disk 30 can be reliably detected, the direction in which the light beam is emitted from the light beam scanning device 1 at each time point can be grasped with reference to this origin position. Therefore, when the light beam scanning device 1 of the present embodiment is used for an inter-vehicle distance measuring device or a monitoring device, the direction in which the preceding vehicle is located can be reliably detected.

  Further, as long as the origin position detection emission region 82 does not arrive at the incident position of the light beam L0 emitted from the light source device 10, the light beam is emitted from the transmission light deflection disk 30 toward the origin position detection photodetector 81. Therefore, unlike the case where a magnetic sensor or a photo interrupter is used, the position accuracy of the origin position detection photodetector 81 is sufficient if the light beam emitted from the origin position detection exit area 82 can be detected. Even if it is low, the origin position of the transmissive light deflection disk 30 can be reliably detected. In particular, in this embodiment, the light beam emitted from the origin position detection emission region 82 reaches the origin position detection photodetector 81 in a non-focused state. For this reason, when the light beam emitted from the origin position detection emission region 82 reaches the origin position detection photodetector 81, the diameter of the light beam is large. For this reason, since the area | region which can detect the light beam radiate | emitted from the origin position detection emission area | region 82 is wide, the position accuracy calculated | required by the origin position detection photodetector 81 can further be relieve | moderated.

  Furthermore, in this embodiment, since the light beam L0 emitted from the light source device 10 is directly used for the origin position detection as it is, the detection accuracy is high. Further, since the laser diode 13 is used as the light source, it is possible to increase the S / N ratio, and the reaction speed is fast. Thereby, detection stability improves remarkably.

  Further, in this embodiment, a disc-shaped transmission type optical deflection disk 30 is used as the optical deflection element. For this reason, the drive device 4 only needs to drive the transmission type optical deflection disk 30 to rotate, so that the configuration of the drive device can be simplified as compared with the direct acting system. In addition, since the transmissive optical deflection disk 30 is used as the optical deflection element, the light source device 10 is arranged in the light beam emitting direction, unlike the case where the reflective optical deflection element is used as the optical deflection element. Since it is not necessary, the light beam scanning device 1 can be downsized.

  Furthermore, in this embodiment, both the light scanning region 36 and the origin position detecting exit region 82 deflect the light beam by refraction. For this reason, unlike the case where the optical scanning area 36 is a transmissive type and the origin position detecting emission area 82 is a reflective type, the entire transmissive optical deflection disk 30 made of resin can be used. For this reason, in constructing the transmission type optical deflection disk 30, the optical deflection disk can be manufactured by cutting and grinding the disk-shaped transparent substrate. Further, the transmission type optical deflection disk 30 can be formed as an integral resin molded product, and according to such a configuration, it can be mass-produced at low cost. In either case, since the optical scanning area 36 and the origin position detection emission area 82 can be integrally formed with the transmissive optical deflection disk 30, the origin position does not fluctuate, and therefore the origin position must be adjusted for each solid. There is no. In addition, even if the environmental temperature varies, the light source is common and the relative position between the light scanning area 36 and the origin position detection emission area 82 does not change, so that the origin position can be reliably detected.

  In this embodiment, since the photodiode is used as the origin position detection photodetector 81, the response speed is high, which is suitable for the detection of the origin position.

(Specific configuration of light beam scanning device)
FIGS. 5A, 5B, and 5C are a plan view, a right side cross-sectional view, and a front cross-sectional view, respectively, showing a specific configuration of a light beam scanning apparatus to which the present invention is applied. 6 (a) and 6 (b) are explanatory views showing the operation principle of the light beam scanning device shown in FIG.

  In this embodiment, as shown in FIG. 5, when the light beam scanning apparatus 1 is configured, a light source device 10, a transmissive light deflection disk 30 as a light deflection element, and a transmissive light deflection disk are provided on a common base 51. An origin detection mechanism 8 that includes a synchronous motor 40 (drive device) that rotates the axis 30 around the axis and that includes an origin position detection exit area 82 and an origin position detection photodetector 81 of the transmissive optical deflection disk 30 is provided. It is configured.

  Also in the example shown here, the synchronous motor 40 is a stepping motor, and includes an annular stator 41, a rotor magnet 42 disposed inside the annular stator 41, and a rotating shaft 43. On the outer peripheral surface of the rotor magnet 42, S poles and N poles are alternately arranged in the circumferential direction. The rotating shaft 43 is supported on the base 51 via a bearing 52 made of a ball bearing at the base end side, and supported on the upper plate 54 via a bearing 53 made of a ball bearing. Here, the upper plate 54 is fixed with screws 55 at a predetermined interval with respect to the base 51, and between the base 51 and the upper plate 54 with a predetermined interval with respect to the base 51 and the upper plate. The middle plate 56 is fixed with screws 57. A hole through which the rotation shaft 43 passes is formed in the middle plate 56. Between the bearing 52 and the base 51, a coil spring 58 for applying pressure to the bearing 52 made of a ball bearing is disposed. Accordingly, when the synchronous motor 40 is energized, the rotating shaft 43 rotates around the axis, and the transmission type optical deflection disk 30 rotates.

  On the other hand, in the base 51, on the side of the region where the synchronous motor 40 is disposed, there is a mounting portion of the light source device 10, and there is a cover in which an opening for securing an optical path is formed on the upper surface portion. 71 is attached so as to be substantially perpendicular to the rear surface of the transmissive light deflection disk 30. Below the cover 71, there are a wiring board 11, a holder 12, a laser diode 13, a disk-shaped gear 14 arranged around the laser diode 13, a diaphragm 15, a collimating lens 16, a washer 17, and a coil spring 18 in this order. It is installed.

  A total reflection mirror 61 that reflects the light beam emitted from the transmissive light deflection disk 30 in a direction of about 90 ° is disposed above the cover 71 and the transmissive light deflection disk 30. Is held by a mirror holder 62. On the optical path of the light beam reflected from the total reflection mirror 61, a divergence angle adjusting lens 63 held by a pressing spring 64 is disposed. The divergence angle adjusting lens 63 includes a cylindrical lens, a toric lens, a toroidal lens, and the like.

  In the present embodiment, when the light beam scanning apparatus 1 forms the origin detection mechanism 8, the origin position detection emission area 82 is formed on the transmission type optical deflection disk 30, while the laser diode 13, the collimating lens 16, An origin position detecting light detector 81 is arranged at a position deviating from the optical path defined by the reflecting mirror 61 and the divergence angle adjusting lens 63. Here, the origin position detection light detector 81 is positioned in the emission direction of the light beam from the origin position detection emission region 82 of the transmissive optical deflection disk 30.

  In the light beam scanning apparatus 1 configured as described above, when the light beam is irradiated from the light source device 10 to the transmissive light deflection disk 30 rotated by the synchronous motor 40, as shown in FIGS. 6 (a) and 6 (b). Perform the action. First, as shown in FIG. 6A, when the light beam L0 emitted from the light source device 10 enters the origin position detection exit area 82, as described with reference to FIG. The light beam L0 emitted from the light source device 10 is refracted by the detection emission region 82 and is emitted toward the origin position detection photodetector 81 as indicated by an arrow L2. Accordingly, the origin position of the transmissive optical deflection disk 30 can be detected by detecting the light beam by the origin position detecting photodetector 81. On the other hand, as shown in FIG. 6B, when the light beam L0 emitted from the light source device 10 enters the optical scanning region 36 of the transmissive optical deflection disk 30, as described with reference to FIG. In addition, the light beam L0 is deflected in the radial direction of the transmissive light deflection disk 30 by the inclined surface 33 of the light scanning region 36, then reflected by the total reflection mirror 61, and as scanning light through the divergence angle adjusting lens 63. Emitted.

  When the return light reflected by the monitoring object is detected by the monitoring photodetector mounted on the light beam scanning device 1 or the monitoring photodetector disposed outside the light beam scanning device, the transmission type is detected. Based on the elapsed time since the origin position of the light deflection disk 30 was detected, it is possible to determine in which direction the laser beam is emitted from the light beam scanning device 1, and the direction in which the monitoring object is located is determined. Can be detected.

[Other embodiments]
In the above embodiment, the refractive light scanning area 36 is formed on the transmissive light deflection disk 30 and the refracting origin position detecting emission area is provided on the transmissive light deflection disk 30. A reflection-type origin position detection exit region may be provided on the transmission type optical deflection disk 30 provided with 36.

  In the above embodiment, the transmissive optical deflection disk 30 is used as the optical deflection element. However, the reflective optical deflection in which the direction in which the light beam is reflected differs depending on the angular position where the light beam is incident in the optical scanning region. A disk may be used. In this case, for example, a reflective optical deflection disk is formed by forming a reflective layer on the upper surface of the transmissive optical deflection disk 30 shown in FIG. 2, and a light beam is emitted from the light source device toward the upper surface of the reflective optical deflection disk. What is necessary is just to emit. The light source device may emit a light beam from the lower surface side of the reflective light deflection disk toward the reflective layer on the upper surface. Further, when forming the origin position detection emission area on such a transmission type optical deflection disk, a transmission type origin position detection emission area may be provided.

  In the above embodiment, the deflecting disk having the optical scanning area on the disk surface is used as the optical deflecting element. However, an optical deflecting element having the optical scanning area on the side surface is used like a polygon mirror. In this case, an origin position detecting emission region may be provided on a part of the side surface.

  Furthermore, the present invention may be applied to a light beam scanning device using not only a rotationally driven type but also a reciprocating linearly driven optical deflection element.

  Furthermore, in the above-described embodiment, the light beam scanning device used for the inter-vehicle distance measuring device and the monitoring device has been described as an example. Also good.

It is explanatory drawing which shows the schematic side view which shows typically schematic structure of the light beam scanning apparatus to which this invention is applied. It is explanatory drawing which shows the principle of the light beam scanning apparatus to which this invention is applied. (A), (b), (c), and (d) are a plan view, a XX cross-sectional view, and a YY cross-section, respectively, of a transmissive optical deflection disk used in a light beam scanning apparatus to which the present invention is applied. It is a figure and a ZZ sectional view. (A), (b), (c) is explanatory drawing which shows typically the operation principle of the light beam scanning apparatus to which this invention is applied. (A), (b), (c) is the top view, right side sectional drawing, and front sectional drawing which show the specific structure of the light beam scanning device to which this invention is applied, respectively. (A), (b) is explanatory drawing which shows the principle of operation of the light beam scanning apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light beam scanning device 4 Drive device 8 Origin position detection mechanism 10 Light source device 13 Laser diode 30 Transmission type optical deflection disk (optical deflection element)
37 Prism section 40 Synchronous motor 81 Origin position detection photodetector 82 Origin position detection exit area 371 One slope of the prism section

Claims (8)

A light source device, a light deflection element in which an emission direction of the light beam changes depending on an incident position of the light beam emitted from the light source device, and an incident position of the light beam with respect to the light deflection element by driving the light deflection element A light beam scanning device having a driving device for changing
The optical deflection element includes an optical scanning region that scans an incident light beam over a predetermined angle range, and an origin position detection emitting region that emits the incident light beam in a direction different from the scanning direction of the optical scanning region. Formed,
An optical beam scanning apparatus, wherein an optical detector for detecting an origin position is arranged in a direction in which a light beam is emitted from the origin position detecting emission area.   2. The light beam scanning apparatus according to claim 1, wherein the light beam emitted from the origin position detection emission region reaches the origin position detection photodetector in a non-focused state. 3. The optical deflection element according to claim 1, wherein the optical deflection element is a disc-shaped optical deflection disk that is rotationally driven by the driving device.
In the optical deflection disk, the optical scanning area is formed over a predetermined angle range on the disk surface, and the origin position detecting emission area is formed at an angular position on the disk surface avoiding the optical scanning area. A light beam scanning device characterized by the above.   4. The light beam scanning device according to claim 3, wherein the light deflection disk is a transmissive light deflection element in which a direction in which the light beam is refracted differs depending on an angular position where the light beam is incident in the light scanning region.   5. The light beam scanning apparatus according to claim 4, wherein the origin position detection emission region refracts the light beam in a direction different from that of the light scanning region.   6. The light beam scanning apparatus according to claim 5, wherein the optical deflection disk is an integral resin disk including the optical scanning area and the origin position detecting emission area.   6. The light beam scanning apparatus according to claim 5, wherein the optical deflection disk is an integral resin molded product including the optical scanning area and the origin position detecting emission area.   8. The light beam scanning apparatus according to claim 1, wherein the origin position detection photodetector is a photodiode.

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