JPS6278967A - Optical beam scanning device - Google Patents

Abstract

PURPOSE:To position a main scanning direction of a scanning sheet on a holding surface and to effectively plate the scanning sheet at a prescribed position on specific holding surface by disposing a positioning means consisting of a guide plate and a siding plate. CONSTITUTION:When a recording member 5 is carried on a holding surface 11a by carrying rollers 17A, 17B, and a positioning in a subscanning direction by a sheet stop plate 21 is completed, a siding plate 23 is rotated, and a siding plate 24 makes the recording member 5 abut on the guide plate 23 to perform the positioning in a main scanning direction. Namely, the recording member 5 includes a collecting position of an optical beam 2 and is disposed on a position on a plane inclined by angle equal to an incident angle to a subscanning mirror 10 of the optical beam 2 with respect to the incident optical beam 2 and permitting the incidence of the reflected optical beam 2. When the recording by the optical beam 2 is completed, the siding plate 24 is retired again, the sheet stop plate 21 rotates centering a rotating axis and retired, and the siding plate 24 drops along the holding surface 11a again by a dead weight. Carrying out rollers 22A, 22B are rotated and carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a light beam scanning device that scans a light beam with an optical deflector, and more particularly! Light beam scanning 4At that can reduce the size and cost of the entire VAm
This is related to a.

(Technical Background of the Invention and Prior Art) Conventionally, a light beam scanning device that deflects a light beam with an optical deflector and scans a scanning sheet relatively two-dimensionally has been used in various scanning recording devices, scanning reading devices, etc. Widely used in equipment, etc. Two-dimensional scanning of the light beam in these light beam scanning devices involves deflecting the light beam with an optical deflector to cause the scanning sheet to be scanned in the main scan direction, and moving the light beam and the scanning sheet relative to each other in the main scanning direction. This is performed by moving in a substantially orthogonal sub-scanning direction.

However, in the conventional apparatus, a problem arises in that the means for performing the sub-scanning makes the apparatus large and expensive. Hereinafter, problems with the conventional light beam scanning device will be explained with reference to FIG.

In the light beam scanning device shown in FIG.
The light beam 102 emitted from the point 01 enters the rotating polygon mirror 103, which is an optical deflector, and as the rotating polygon mirror 103 rotates in the six directions of arrows, the light beam 102 is reflected by anti-tJ1? ; Directed to A. The light beam 102 reflected by the rotating polygon mirror 103 passes through an fθ lens 104, which is an imaging lens, provided on the optical path.
After passing through, the scanning sheet 105 is main scanned in the direction of arrow B. The scanning sheet 105 is held in the main scanning direction as the rotating drum 106 rotates while being held between a rotating drum 10G rotating in the direction of arrow C and a pair of rollers 107A and 107B provided on the rotating drum 106. The sub-scanning is carried out by being conveyed in the direction of the arrow, which is substantially perpendicular to the arrow. Therefore, the light beam 102 is thus conveyed (sub-scanned) in the direction of the arrow on the scanning sheet 10.
5 is repeatedly scanned in the direction of arrow B, the sheet 105 is two-dimensionally scanned, and the scanned sheet 105 is
The light beam 102 is scanned over substantially the entire surface.

However, in the above device, sub-scanning is performed by moving the scanning sheet 105;
In order to suppress load fluctuations on the motor 108 as much as possible during sub-scanning to prevent sub-scanning unevenness, the scanning sheet is placed before and after the scanning position by the light beam 102 as shown in the figure.
It is necessary to provide a space in which one scanning sheet can be placed on each of the scanning sheets, such as by arranging supporting stands 109 and 110 that support the scanning sheets 105. For this reason, the above-mentioned apparatus requires a space having a length of two or more scanning sheets in the sub-scanning direction, resulting in an increase in the size of the entire apparatus. Further, the rotating drum 106 that conveys the scanning sheet 10:) has a width larger than the width of the scanning sheet in order to stably convey the scanning sheet, and a motor 108 that rotates the rotating drum 106. is further provided in the width direction of the rotating drum 106, so the device described in E is also large in the main scanning direction.

Furthermore, in order to scan the scanning sheet 105 with high precision while conveying the scanning sheet 105, it is necessary to
It is necessary to strictly control the motor 108 so that the motor 105 can be transported at a constant speed in the correct direction with high precision, and since high-precision motors that can be controlled as described above are expensive, the cost of the entire device is low. There is also the problem that the amount increases significantly. Furthermore, the rollers 107A and 107B are essential in order to stably convey the scanning sheet 105;
13, the scanning sheet 105
Scanning can be performed at both ends of the sub-scanning direction.
If the device is a light beam recording device, there is also the inconvenience that the request for black edges at both ends cannot be met.

(Purpose of the invention) The present invention has been made in view of the above-mentioned problems. The purpose of this invention is to solve the problem and provide a compact and inexpensive light beam scanning device.

(Structure of the Invention) The light beam scanning device of the present invention is a main scanning optical deflector that is provided on the optical path of a light beam emitted from a beam light source and deflects the light beam.

An imaging lens capable of focusing the light beam on a predetermined straight line, which is provided on the optical path of the light beam deflected by the main scanning optical deflector; an elongated sub-scanning mirror that is located on the optical path, extends in the main scanning direction, is inclined with respect to the optical path of the light beam, and is movable in the optical axis direction of the imaging lens; On a plane formed by a straight line locus that moves with the movement of the sub-scanning mirror in the optical axis direction and is located at a position conjugate with a straight line on which the light beam is imaged with respect to the sub-scanning mirror. The first feature is that it includes a scanning sheet holding means for holding a scanning sheet.

That is, in the light beam scanning device of the present invention, the light beam deflected in the main scanning direction is reflected by the sub-scanning mirror and made incident on the scanning sheet, and the DI constant scanning is performed by moving the sub-scanning mirror. Since the scanning sheet is fixed by the scanning sheet holding means, there is no need to make the device large in the sub-scanning direction, unlike when carrying the scanning sheet for sub-scanning, making the entire device compact. be able to. In addition, the motor that moves the sub-scanning mirror for sub-scanning does not undergo load fluctuations unlike when conveying a scanning sheet, so it is easy to control, and a relatively inexpensive motor can be used. It is possible to reduce the manufacturing cost of the device.

By the way, as mentioned above, in the vA@ of the present invention, scanning of the light beam is performed on the scanning sheet held by the scanning sheet holding means, so the scanning sheet is accurately positioned on the holding surface of the scanning sheet holding means. It is necessary to

Therefore, the light beam scanning device of the present invention has a guide plate and a scanning sheet holding means provided on one side end of the scanning sheet holding means so as to protrude upward as a means for positioning the scanning sheet on the holding surface in the main scanning direction. A first position provided near the other side edge of the scanning sheet and pushing the side edge of the scanning sheet on the scanning sheet holding means to bring the scanning sheet into contact with the guide plate, and a second position of retreating from the side edge of the scanning sheet. The second feature is that it has a side plate that can be positioned in different positions.

(Actual #i Embodiment) Hereinafter, the actual mts embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view showing an outline of a light beam recording device which is an embodiment of the light beam scanning device of the present invention.

A light beam 2 emitted from a laser light source 1 enters a modulator 6 which is modulated by a modulator drive circuit 7 based on a signal emitted from an image signal output circuit 8 that outputs an image signal, and then is modulated. The light is incident on the rotating polygon mirror 3, which is a main scanning optical deflector, and is deflected in the direction of the arrow. As the laser light source 1, in addition to an H8-N e laser, an Ar laser, etc., a laser light source formed by a combination of a semiconductor laser and a beam shaping optical system is used. Furthermore, when using a laser light source capable of direct modulation such as a semiconductor laser, the modulator 6 is not particularly provided in the optical path of the light beam 2, and the laser light source is directly controlled to modulate the light beam 2. You can also do it. Further, as the main scanning optical deflector, other types of optical deflectors such as a galvanometer mirror or an acousto-optic deflector (AOD) may be used in place of the above-mentioned rotating polygon mirror.

The light beam deflected by the rotating polygon mirror 3 passes through a main scanning imaging lens 4 such as an fθ lens provided on the optical path, and then is driven by a motor 9 at a low speed to align the optical axis of the imaging lens. A reflective surface 10a of a long sub-scanning mirror 10 extending in the main scanning direction and moving linearly in the direction of arrow C.
incident on and reflected. In addition, this sub-scanning mirror 10
Light beam 2 reflected by the sub-scanning mirror below
On the optical path, a sheet-like recording material 5 such as a photosensitive film or photographic paper is placed at a predetermined angle with respect to the incident light beam so as to have a specific relationship with the sub-scanning mirror 10, as will be described in detail later. Recording body holding means 11 having an inclined holding surface 11a
Supported by This holding means 11 is formed, for example, by processing a plate-shaped object or by integrally molding a synthetic resin or the like.

When the recording medium 5 is held on the recording medium holding means 11 as described above, the light beam 2 is deflected by the rotating polygon mirror 3.
performs main scanning on the recording medium 5 in the direction of arrow B. The imaging lens 4 converges the light beam 2 onto the recording medium 5 and scans the light beam deflected at a constant angular velocity by the rotating polygon mirror 3 on the flat recording medium 5 at a constant velocity. It's a lens.

Further, in the illustrated recording apparatus, sub-scanning is performed by moving the a1 scanning mirror 10 with respect to the recording body 5. Next, the relationship between the sub-scanning mirror 10 and the recording medium 5 and the mechanism of sub-scanning will be described with reference to FIG. 2, which is a conceptual side view of the apparatus shown in FIG. 1.

The light beam 2 reflected and deflected by the rotating polygon mirror 3 passes through the imaging lens 4 provided on the optical path, as described above. This imaging lens 4 is capable of focusing the incident light beam on a predetermined imaging position P1 located on a straight line perpendicular to the paper surface of FIG. On the optical path of the light beam 2 that has passed through the imaging lens 4, the elongated sub-scanning mirror 10 is stepped, as described above. The sub-scanning mirror 10 is provided to be inclined with respect to the optical path of the light beam 2 so that the beam 2 is incident at an incident angle α, and the light beam 2 is reflected downward by the sub-scanning mirror 10 . The light beam 2 reflected by the sub-scanning mirror 10 forms an image at an image-forming position J3 located at a position conjugate with the image-forming position V1PI with respect to the sub-scanning mirror 10. The imaging position P2 of the light beam 2 reflected by the sub-scanning mirror 10 changes as the sub-scanning mirror 10 moves in the direction of arrow C. The image forming position P1 is held on a plane formed by the locus of the image forming position P2, which is at a position that is ahead of the image forming position P1 with respect to the changing sub-scanning mirror 10. However, the recording body 5 includes the focal point PL of the light beam 2, and is tilted at an angle α equal to the incident angle α of the front beam 2 on the sub-scanning mirror 10. The light beam 2 reflected by the sub-scanning mirror 10 is placed on the plane at a position that allows the light beam 2 reflected by the sub-scanning mirror 10 to be incident thereon.

As described above, the sub-scanning mirror 10 includes one ii
While recording image information on the a'& body, the sub-scanning mirror gradually moves linearly in the direction of the arrow C by a range S sufficient for the light beam 2 to scan the entire surface of the recording medium. By the movement of 10, the main scanning line formed by the light beam 2 on the recording medium 5 is gradually moved in the direction of the arrow, thereby performing sub-scanning.

Therefore, the light beam 2 is two-dimensionally scanned over the entire surface of the recording medium 5 by the rotating polygonal mirror 3 and the sub-scanning mirror 10.

The movement of the sub-scanning mirror 10 is carried out by, for example, as shown in FIG. , 1
D
This is done by moving the mirror support portion 115a connected to the wires 14 provided at both ends of the J-scanning mirror on the guide rail 15b. The sub-scanning mirror 10 can be moved by various means depending on the design of the apparatus, such as movement using a linear motor, in addition to the above-mentioned wire drive.

As described above, when the sub-scanning mirror 10 moves within a predetermined range at a predetermined speed and the necessary image information is recorded over the entire surface of the recording medium, the sub-scanning mirror 10 moves in the opposite direction to the moving direction. direction and returned to the initial position in preparation for recording on the next recording medium.

In this embodiment, as shown in FIG. The starting position is determined.

At the same time, the sub-scanning mirror 10 is moved from the initial position in the direction of arrow C to detect that the light beam 2 has reached the end of the recording medium 5, and at this point the modulator 6 is activated based on the image signal. Then, the light beam 2 is modulated and image recording on the recording medium 5 is started.

As described above, in the apparatus of the present invention, sub-scanning is performed by fixing the recording medium 5 and moving the sub-scanning mirror 10 to move the light beam 2. Therefore, when moving the recording medium side, In comparison, the size of the device in the n1 scanning direction can be reduced to less than half. In addition, the r
The length of the IIj scanning mirror 1o in the main scanning direction is sufficient as long as it is long enough to allow the incidence of the light beam 2, and it is sufficient that it is shorter than the length of the main scanning line on the recording medium 5. Therefore, even if the sub-scanning mirror 10 and the mirror moving means are combined, it is sufficiently possible to make the length shorter than the length of the recording medium holding means 11 in the main scanning direction. It is also compact in direction.

Further, the motor 9 that drives the sub-scanning mirror 1o is 0.
Since load fluctuations do not occur, control is easy and a relatively inexpensive motor can be used. Further, since the recording medium 5 held by the sheet holding means 11 can be irradiated with the light beam 2 from the front end to the rear end in the sub-scanning direction to perform recording on the entire surface of the recording medium, both ends of the recording medium 5 can be It is also easy to make it black.

Note that depending on the type of recording body, the recording body 5 may be the recording body holding means 1.
If the recording medium does not adapt well to the holding surface 11a of the holding surface 11a and is difficult to maintain in a flat state, the recording medium may be suctioned onto the holding surface 11a using suction means in the recording medium holding means 11.

By the way, as mentioned above, in the apparatus of this embodiment,
Since the recording medium 5 is held by the recording medium holding means 11 when recording with a light beam is performed, the recording medium 5 needs to be accurately positioned on the holding surface 11a of the recording medium holding means. Therefore, the above-mentioned apparatus is provided with positioning means for positioning the recording medium in the main scanning direction after the recording medium is carried onto the holding surface. Below, referring mainly to FIG. 1, FIG. 3 which is a schematic side view of an apparatus not shown in FIG. A specific example of loading and unloading the recording medium will be explained.

A pair of carry-in rollers 17A and 17B, which serve as a means for carrying in the recording body, are provided near the upper end of the ftJ recording body holding means 11 (
is being pulled. These carry-in rollers 17A, 17B are used to pick up recording bodies one by one from a magazine 18 in which a plurality of recording bodies are stored, as shown in FIG. Thereafter, the recording medium 5 falling while being guided by the guide plate 19 is grasped and rotated in the direction of the arrow E+ force to carry the recording medium 5 along the holding surface 11a.

The carry-in rollers 17A and 17B feed the recording medium in the direction of the arrow F+ force by their rotation, and carry the recording medium 5 along the holding surface 11a to a position just before a predetermined position on the holding surface 11a. In addition, the holding surface 11a allows the recording medium 5 to fall under its own weight along the holding surface 11a due to its inclination and friction with the recording medium 5. is the carry-in roller 17Δ.

When separated from 17B, it falls under its own weight along the holding surface 11a in the direction of arrow F2, as shown in FIG. 3(b).

At the lower end of the recording medium holding means 11, one end protrudes above the holding surface 11a. E. For example, there are two sheet stop plates 21 that can take a first position where the recording body 5 comes into contact with the tip of the falling recording body 5 and stops the recording body 5 at a predetermined position, and a second position where it retreats from the holding surface 11a. It is provided,
When the recording medium 5 is carried in by the carry-in rollers 17A and 17B and falls under its own weight, the recording medium 5 that is at the first position and falls under its own weight is stopped at a predetermined position, as shown in FIG. 3(b). urge In this way, the recording medium 5 is brought into contact with the sheet stop plate 21 and stopped, thereby positioning the recording medium 5 in the sub-scanning direction.

Furthermore, a guide plate 23 that projects upward is provided at one end of the recording medium holding means 11, as shown in FIG.
A width plate 24 is provided at the other end of the recording medium holding means 11 for positioning the recording medium 5 in the main scanning direction by bringing the recording medium 5 into contact with the guide plate 23. The abutment plate 24 is a driving means 2 such as a rotary solenoid or a motor.
5, a first position shown by a solid line in FIG.
The recording medium 5 is rotated 4rJ from the side edge of the recording medium 5 to a second position indicated by a broken line in the figure, and is retracted from the side edge thereof.

17B onto the holding surface 11a, and until the sheet stop plate 21 finishes positioning the recording medium in the sub-scanning direction, the width shifting plate 24 is in the second position as shown in FIG. 4(a). However, when the positioning of the recording medium 5 in the sub-scanning direction is completed, the width unevenness plate 23 rotates in the plane of the arrow Gll as shown in FIG. 1, and as shown in FIG.
reach the position. In this first position, the width shifting plate 24 pushes the recording medium 5 toward the guide plate 23, brings the side edge of the recording medium 5 into contact with the guide plate 23, and positions the recording medium 5 in the main scanning direction. In addition to the above-mentioned rotation using a rotary solenoid, the position of the width shifting plate 24 may be moved linearly in the direction of arrow 02 using a linear solenoid 25', as shown in FIG. , any movement that can take the first and second positions described above may be used. Further, a plurality of width shifting plates 24 may be provided, and their length, shape, etc. can be arbitrarily set according to the size of the recording medium, etc. The shape of the guide plate may also be formed by discontinuously disposing a plurality of plate-like members as shown in FIG.

As described above, when the positioning of the recording medium 5 in the main scanning direction and the sub-scanning direction is completed, two-dimensional scanning by the light beam 2 is performed in this state as shown in FIG. 3(C).

When the recording by the light beam 2 is completed, the width plate 24
is retreated to the second position again, and the seat stop plate 21 is
As shown in FIG. 3(d), it rotates in the direction of arrow H about the rotation axis 21a and withdraws from the holding surface 11a.
, IyI moves to the second position, and the recording medium 5 falls again along the holding surface 11a in the direction of arrow F3 due to its own weight. A pair of carry-out rollers 22A and 22B are provided near the lower end of the record body holding means 11, and are a pair of carry-out rollers 22A and 22B, which are carrying-out means for grasping and carrying out the leading edge of the record body 5 falling under its own weight. 5 are these delivery rollers 22A, 22B
As shown in FIG. 3(e), by rotating these carry-out rollers 22A and 22B in the direction of arrow E2, it is moved in the direction of arrow F4 and carried out to the outside of the recording apparatus. Note that the recording medium discharged from the apparatus is carried into, for example, an automatic developing machine or a receiving magazine, and the carrying-out rollers 22A and 223 may also serve as entrance rollers of the automatic developing machine. When the recording medium 5 is thus carried out of the apparatus, the sheet stop plate 21 rotates in the direction opposite to the direction of the arrow 11 and returns to the first position in preparation for carrying in a new recording medium. As shown by the broken line in FIG. 3(e), a detector 26 such as a reflective photointerrupter or a limit switch is provided near (inside) the sheet stop plate 21 in the recording medium holding means 11. The device 26 detects that the rear end of the recording medium 5 has been carried out from the apparatus and generates a detection signal, and based on this detection signal, the sheet stop plate 21 is moved from the second position to the first position. You can also move it.

Further, the positioning of the recording medium in the sub-scanning direction on the holding surface 11a can also be performed using a member other than the sheet stop plate 21 described above. For example, the inclination of the holding surface 11a with respect to the horizontal plane is relatively small, and the recording medium 5
If the weight does not fall on the holding surface 1a, as shown in FIG.
It is also possible to provide a recording medium feed roller 27 that can take a second position of retreating from 1a, and to position the recording medium using this feed roller 27. The positioning of the recording medium using the recording medium feed roller 27 will be explained with reference to FIG.

As shown in FIG. 8(a), when the recording medium 5 is conveyed to the front of the predetermined position on the holding surface by the conveyance rollers 17A and 17F3, the recording medium feed roller 27
It has retreated to the position shown in Figure 8 (b).
), the recording body 5
comes into contact with. At this first position, the recording medium feed roller 27 rotates in the direction of arrow 11, as shown in FIG. 8(C), and moves the recording medium 5 in the direction of arrow F2. The recording medium holding means 11 has the leading end of the recording medium 5 positioned at a predetermined position where the recording medium 5 is placed. A detector 28 is provided at a portion J5, and when the recording medium 5 reaches a predetermined position in the sub-scanning direction, this detector F1i2B detects the leading edge of the recording medium 5 and issues a detection signal, and the recording medium feed roller 27 stops rotating when this detection signal is sent, and stops the recording medium 5 at a predetermined position. When the positioning of the recording body 5 in the sub-scanning direction is completed in this way, the width shifting plate 24 and the guide plate 2 as described above are moved.
Then, as shown in FIG. 8(d), the recording body feed roller 27 retreats to the second position, and recording with the light beam 2 is performed. When the recording by the light beam 2 is completed, as shown in FIG. 8(0), the recording material feed roller 27 rises again to the first position and rotates, moving the recording material 5 in the direction of arrow E3 and moving the recording material 5 to the carry-out roller. The tips 22A and 22B are gripped to carry out the recording medium 5. In addition, to carry out the recording body 5, move the recording body feed roller 27 in the opposite direction of the arrow 11 direction, ie, the arrow ■2.
The recording medium is rotated in the direction of
Move the recording medium to the 1713 side and transfer it to the carry-in rollers 11△, 1
7B, and these carry-in rollers 17A and 17B are reversed in the direction of arrow E3 and used as carry-out rollers.

In the following, the light beam scanning device of the present invention has been explained by taking the light beam recording device as an example. Radiation image information recording and reproducing system (Unexamined Japanese Patent Publication No. 55-
No. 12429, No. 56-11395.

It can be applied to various light beam reading 5A stomachs, such as the radiation image information reading device used in Japanese Patent No. 56-11397, etc.), and the above-mentioned effects can be achieved in the same way in the light beam reading device. In this case, light is reflected on the scanning sheet in conjunction with the movement of the sub-scanning mirror 10.

The light detection means for detecting the transmitted light, the emitted light, etc. may be moved opposite to the scanning line.

(Effects of the Invention) As explained above, according to the light beam scanning device of the present invention, by performing sub-scanning with the scanning sheet fixed,
The entire device can be downsized, especially in the sub-scanning direction.

Also, sub-scan in the sub-scanning direction.

The motor that moves the mirror is easy to control because there is no load fluctuation, and a motor that is cheaper than the motor used to move the scanning sheet side can be used. yJ construction cost is reduced.

In general, since the apparatus of the present invention is provided with the positioning means consisting of the guide plate and the width shifting plate, the scanning sheet can be positioned on the holding surface in the main scanning direction, and the scanning sheet can be positioned on the holding surface. This makes it possible to reliably position it at a predetermined position.

[Brief explanation of drawings]

Fig. 1 is an example of the present invention! A perspective view showing the outline of the optical beam recording device by i@, Figure 2 is a conceptual side view of Figure 1 explaining the sub-scanning of the above device, Figures 3 (a) to (e) are A schematic side view illustrating the loading and unloading of the recording medium into the above apparatus and positioning in the sub-scanning direction. FIGS. 4(a) and 4(b) are schematic side views illustrating the positioning of the recording medium in the main scanning direction at the 5A position. A plan view, FIG. 5 is a perspective view showing an actual embodiment of the width plate used in the present invention, FIG. 6 is a perspective view showing an embodiment of the guide plate used in the present invention, and FIG. 7 is a record view. A plan view showing a recording medium holding means provided with a recording body feeding roller, FIGS. FIG. 2 is a perspective view without showing the outline of the scanning device. 1... Beam light source 2... Light beam 3...
Rotating polygon mirror 4... Imaging lens 5... Recording body 10... Sub-scanning mirror 11... Recording body holding means 23... Guide plate 24... Width uneven plate Fig. 2 Figure 4 Figure 5 1n

Claims (1)

[Claims] A light beam emitted from a beam source is caused to scan a scanning sheet in a main scanning direction, and the light beam and the scanning sheet are relatively moved in a sub-scanning direction substantially orthogonal to the main scanning direction. In the light beam scanning device that moves the light beam to two-dimensionally scan the light beam on the scanning sheet, the main scanning device is provided on the optical path of the light beam emitted from the beam source and deflects the light beam. a light deflector; an imaging lens that is provided on the optical path of the light beam deflected by the main scanning light deflector and is capable of focusing the light beam on a predetermined straight line; a light beam that passes through the imaging lens; an elongated sub-scan that is located on the optical path of the light beam, extends in the main scanning direction, is inclined with respect to the optical path of the light beam, and is movable in the optical axis direction of the imaging lens; and a linear locus that moves with the movement of the sub-scanning mirror in the optical axis direction and is located at a position conjugate with the straight line on which the light beam is imaged with respect to the sub-scanning mirror. A scanning sheet holding means for holding the scanning sheet is provided on a plane, a guide plate provided protruding upward at one end of the scanning sheet holding means, and a guide plate provided near the other end of the scanning sheet holding means. and a first position in which the side edge of the scanning sheet on the scanning sheet holding means is pushed to bring the scanning sheet into contact with the guide plate, and a second position in which the scanning sheet is retreated from the side edge of the scanning sheet. A light beam scanning device characterized by having a width plate.