JPS62238514A - Light beam scanner - Google Patents

Abstract

PURPOSE:To adjust a scan length by varying a deflection angle of a light beam by a rotary polygon mirror, in accordance with expansion and contraction of a scan distance required for the light beam by a size variation of a recording medium, by providing plural rotary polygon mirrors whose number of faces is different from each other. CONSTITUTION:The titled scanner contains a light source optical system 1 for emitting a light beam, at least two pieces of rotary polygon mirrors 10, 12 having each different number of faces, an incident optical path switching optical system 6 for making an incident light beam incident selectively on one of the rotary polygon mirrors 10, 12, a reflecting optical path switching optical system 30 for setting the reflecting optical beams which have been reflected and deflected by the rotary polygon mirrors 10, 12, into a prescribed plane, respectively, and a scanning lens system 32 which has been placed in an optical path of the reflected light beams which have been set in the prescribed plane by this optical system 30. It can be applied suitably to a device for reading a radiation image which has been recorded in a cumulative phosphor for showing an accelerated phosphorescence property. In this way, even if a size of a body to be scanned is varied, an effective scan time rate is held high, and a light beam scan can be executed efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light beam scanning device, and more particularly to a light beam scanning device for reading and recording image information.

[Technical background]

2. Description of the Related Art A light beam scanning device is known in which a light beam emitted from a light source such as a laser oscillator is reflected and deflected by a rotating polygon mirror to scan an object to be scanned. When applied to an image information recording device, this device modulates a light beam in correspondence with an image information signal using, for example, an acousto-optic modulator (AOM), and scans a recording medium including a photosensitive material etc. with the modulated light. Image information can be recorded. In addition, when applied to an image information reading (reproduction) device, the recording medium on which image information is recorded is scanned with a light beam, and the transmitted light, reflected light, or emitted light is detected. can read image information. In particular, when reading a radiation image recorded on a stimulable phosphor sheet that exhibits so-called photostimulability, a laser beam is used as excitation light to irradiate the phosphor and scan it to generate a brightness corresponding to the recorded image information. By photoelectrically reading the exhaustion light, an image signal of the bond image can be obtained, and the image signal can be reproduced as a visible image using a CRT display device, a laser printer, or the like.

By the way, the dimensions of the recording medium may change depending on the type of subject, but conventionally recording media of different dimensions are scanned with a light beam deflected by the same rotating polygon mirror, so recording media of small dimensions can be scanned. There was a problem that the effective scanning time rate decreased when scanning. for example,
Regular octahedral rotating polygon mirror and focal length f = 324 m
The distance L+ corresponding to the long side of the 84th plate with a scanning lens of m
When scanning =364ffIII+, the deflection angle θ1 of the light beam is θ+=64.4°, and the deflection angle of the light beam by one surface of the regular octahedral rotating mirror is 360°Xi/8X2=90°. Therefore, the effective scanning time rate is 64.4°/9 Q, O.

#0.72.

On the other hand, using the above rotating polygon mirror and scanning lens, 85
When scanning a distance L2 = 257 mm corresponding to the long side of the plate, the deflection angle θ2 of the light beam is as follows, and the effective scanning time rate is 45.5°/90.0°ζ0.51.

The present invention was developed in view of the problem that the effective scanning time rate decreases depending on the dimensions of the object to be scanned, as described above, and it is possible to maintain a high effective scanning time rate even if the dimensions of the object to be scanned change. An object of the present invention is to provide a light beam scanning device that can efficiently perform light beam scanning.

[Structure of the invention]

The features of the configuration of the present invention for achieving the above object include: a light source optical system that emits a light beam; at least two rotating polygon mirrors having different numbers of surfaces; an incident optical path switching optical system that selectively inputs the reflected optical beam into either one of the above-mentioned reflected optical paths; It includes a scanning lens system disposed in the optical path of the reflected light beam set within a certain plane by a switching optical system, and a radiation image recorded on a stimulable stimulable phosphor. This can be suitably applied to reading devices and the like.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

In the first embodiment, as shown in FIG. 1, an incident beam optical path switching oscillating mirror 6 having a horizontal oscillating axis is disposed on the optical path of the emitted beam 2 of the light source device 1. The swinging mirror 6 has a first swinging position shown by a solid line in FIG. 1 and a second swinging position shown by a dotted line in FIG.
It is swingable so as to assume a swinging position.

On the other hand, the regular octahedral rotating mirror IO and the regular dodecahedral rotating mirror 12 are attached to the same vertical rotating shaft 14 at appropriate positions, and the reflected beam 16 by the swinging mirror 6 at the first swinging position
A mirror 20 is arranged on the optical path of the beam 16, and the beam 16 is incident on the reflecting surface of the regular octahedral rotating mirror 10. Further, a mirror 24 is disposed on the optical path of the beam 22 reflected by the swing mirror 6 at the second swing position, and the beam 22 is made incident on the reflection surface of the regular dodecahedral rotating mirror 12.

A mirror 26 is arranged on the optical path of the reflected beam 42 reflected by the rotating mirror 10, and a mirror 28 is arranged on the optical path of the reflected beam 44 reflected by the rotating mirror 12. A reflected beam optical path switching oscillating mirror 30 is arranged at the intersection of the reflected beams 42 and 44 by the mirrors 26 and 28. The reflected beam optical path switching swing mirror 30 sets the reflected beam 42 within a predetermined plane. The first indicated by a solid line
It is swingable so as to take a swinging position and a second swinging position shown by a dotted line in which the reflected beam 44 is set within the predetermined plane. The scanning lens 32 is placed on the optical path of the beam 34 reflected by the swinging mirror 30.

The scanning lens 32 is formed to have Fθ characteristics and focuses the reflected beam 34 onto the object to be scanned 4o.

With the above configuration, when the incident light beam swinging mirror 6 and the reflected beam swinging mirror 3o are each in the first swinging position, the light beam 42 emitted from the light source device 1 is reflected by the swinging mirror 6, It is reflected by the mirror 2° and is incident on the rotating mirror 10, and is reflected by the rotating mirror l.

The light beam reflected and deflected by is reflected by the mirror 26, and then enters the scanning lens 32 by the swinging mirror 3o, and scans the object to be scanned 4o.

Further, when the incident beam swinging mirror 6 and the reflected beam swinging mirror 30 are respectively at the second swinging position, the light beam 42 emitted from the light source device l is reflected by the swinging mirror 6 and enters the mirror 24, The light is reflected by the mirror 24 and enters the rotating mirror 12 .

The light beam reflected and deflected by the rotating mirror 12 is reflected by the mirror 2
After being reflected by 8, the beam is incident on a scanning lens 32 by an oscillating mirror 30, and scans an object 40 to be scanned.

By the way, in the above-mentioned embodiment, as is well known, each of the reflecting surfaces of the rotating mirror 10, 12 is normally tilted at slightly different angles, and there is a problem in that the scanning position by the light beam varies. Therefore, as shown by the two-dot chain line in FIG.
In addition, a convex cylindrical lens 51 having power in a direction perpendicular to the scanning direction of the light beam is provided between the scanning lens 32 and the object to be scanned 40 to eliminate the influence of variations in the tilt of the rotating mirror 10.12 in each direction. It is preferable to correct it. In this case, instead of separately providing the convex cylindrical lens 51, the scanning lens 32 may be constructed from a toric lens system.

The second embodiment is shown in FIG. 2, but the light source section, scanning lens, and recording medium section common to the first embodiment are omitted. An input beam optical path switching oscillating mirror 106 is placed on the emitted beam 102 emitted from the light source device, and a regular dodecahedral rotating mirror 112 and a regular octahedral rotating mirror 110 are placed on the optical path of the beam reflected by this, and their rotation axes are parallel to each other. It is arranged so that

The swinging mirror 106 has a beam 10 shown in solid line in Figure 2.
2 toward the rotating mirror 112;
It is swingable between a second swing position, indicated by a dotted line, in which the beam 102 is reflected toward a rotating mirror 110.

A mirror 126 is disposed on the optical path of the reflected beam 144 reflected by the rotating mirror 112, and a mirror 128 is disposed on the optical path of the reflected beam 144 reflected by the rotating mirror 110.
is placed. A reflected beam optical path switching oscillating mirror 30 is arranged at the intersection of the reflected beams A 144 and 146, and the oscillating mirror 130 makes the beam 146 reflected by the rotating mirror 110 incident on the scanning lens 32. and a second position shown by a solid line in which the beam 144 reflected by the rotating mirror 112 is made incident on the scanning lens 32.

In this embodiment as well, by switching the first and second positions of the swinging mirrors 106 and 130, the light beam 102 is moved to the rotation axis 1.
10 or 112 to be deflected.

In the two embodiments described above, the optical path of the beam is switched using a swinging mirror, but it can also be switched using an acousto-optic deflection element (AOD).

〔Effect of the invention〕

As described above, since the present invention is configured by providing a plurality of rotating polygon mirrors with different numbers of surfaces, the rotation polygon mirror can accommodate the expansion and contraction of the required scanning distance of the light beam due to changes in the dimensions of the recording medium. The scanning length can be adjusted by changing the deflection angle of the beam, which has the effect of maintaining a high effective scanning time rate of the light beam.

For example, considering the numerical example described in the [Technical Background] section, the deflection angle of the light beam by one surface of a regular dodecahedral rotating polygon mirror is 360° x 1/12 x 2 = 6
Since it is 0°, the effective scanning time rate when the scanning length L1 = 257nu++ is 45.5°/60° = 0.76
This is a significant increase compared to 0.51 for a regular octahedral rotating polygon mirror, making it excellent.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an optical system according to a first embodiment of the present invention, and FIG. 2 is a plan view of an optical system according to a second embodiment. 1... Light source device, 6.106... Swinging mirror for changing the optical path of the incident beam 10.110... Regular octahedral rotating mirror 12.112
・・・・・・Regular dodecahedral rotating mirror 20.24.26.28
, 126. 128...Mirror 30.130...Reflected beam optical path switching swinging mirror 32...Scanning lens

Claims (4)

[Claims] (1) A light source optical system that emits a light beam, at least two rotating polygon mirrors having different numbers of surfaces, and an input optical path switching optical system that selectively makes the incident light beam enter one of the rotating polygon mirrors. , a reflection optical path switching optical system that sets each reflected light beam reflected and deflected by a rotating polygon mirror within a fixed plane, and a reflection optical path switching optical system that sets each reflected light beam reflected and deflected by a rotating polygon mirror within a fixed plane. 1. A light beam scanning device comprising: a scanning lens system disposed in an optical path of a light beam. (2) The light beam scanning device according to claim (1), wherein the incident optical path switching optical system and the reflective optical path switching optical system include a swinging mirror. (3) The incident optical path switching optical system and the reflective optical path switching optical system include an acousto-optic deflection element.
The light beam scanning device according to item 1). (4) The light beam scanning device according to claim (1), wherein the scanning lens system is configured to have fθ characteristics.