JP2000075226A - Multibeam scanner and its light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce the fluctuation in the pitch of a scanning line caused by an environmental change such as temperature and humidity by setting an adhesive coating area on the peripheral surface part of a coupling lens held by a holder under 1/2 of the entire periphery of the peripheral surface part of the lens. SOLUTION: A coupling lens 2b is stuck and fixed on a holding part 8c2 in which the cross-sectional shape of a holder 8 is an arc, with an adhesive 8e. An adhesive coating area that the peripheral surface part of the lens 2b is coated with the adhesive 8e is set to be under 1/2 of the entire periphery of the peripheral surface part. Then, the lens 2b is held up and down by a jig for holding 10 and its position in an optical axis direction is adjusted with respect to the holding part 8c2 to adjust positional relation between the light emitting part of a light source and the optical axis. In this case, since the adhesive coating area is under 1/2 of the entire periphery of the peripheral surface part of the lens, a situation that the adhesive 8e is stuck to the jig 10 to disturb adjusting operation is prevented even though the lens 2b is held by the jig 10. When the positional adjustment is completed, the adhesive 8e is irradiated with ultraviolet rays U.V to be cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a multi-beam scanning device and a light source device thereof.

[0002]

2. Description of the Related Art Optical scanning devices are widely known in relation to LBPs, digital copiers, PPFs and the like. In recent years, the speed of the optical scanning device has been increasingly required. In order to realize high-speed scanning by the conventionally known one-beam scanning, it is necessary to increase the rotation of the deflector. High-speed rotatable deflectors are expensive in themselves,
Since a soundproof means for reducing noise such as wind noise caused by high-speed rotation is required, the cost of the optical scanning device is greatly increased.
As a scanning method capable of increasing the scanning speed without increasing the rotation of the optical deflector, a multi-beam scanning method for simultaneously scanning a plurality of scanning lines by simultaneously deflecting a plurality of light beams is being put into practical use. In a multi-beam scanning device, in view of the low cost and compactness of the device, it is desirable that the optical system provided on the optical path from the light source to the surface to be scanned is "shared as much as possible for a plurality of light beams". As described above, when the optical system is shared by a plurality of light beams, it is necessary to perform “beam combining” in order to make the light paths of the light beams emitted from the plurality of light sources close to each other. 2. Description of the Related Art As a light source device for performing beam combining, conventionally, a device that combines two light beams using a λ / 2 plate and a polarization combining element is known. That is, the polarization directions of the light beams emitted from the two light sources are set to be parallel to each other, and the polarization plane of one of the light beams is rotated by 90 degrees with a λ / 2 plate, so that the polarization directions of the two light beams are orthogonal to each other. As described above, two light beams whose polarization planes are orthogonal to each other are made incident on the polarization combining element, and beam combining is performed by utilizing the fact that one light beam transmits through the same element and the other light beam is reflected by the element. Since the “λ / 2 plate and the polarizing optical element” required for such beam combining are expensive, the cost of the light source device is increased. In addition, the λ / 2 plate and the polarizing optical element need to be arranged with high accuracy, and assembling to the light source device is troublesome, and it is difficult to increase the efficiency of assembling the light source device.

FIG. 10 shows a method of performing beam combining without using expensive optical elements such as a λ / 2 plate and a polarizing optical element.
A method as shown in (a) is intended. The divergent luminous flux emitted from the semiconductor lasers 1a and 1b as light sources is coupled to a coupling lens 2 provided for each light source.
a and 2b, each of which is converted into a "luminous flux form suitable for the following optical system" and the aperture 3
After the beam shaping, the beam is shaped in a sub-scanning direction (a direction originally defined on the surface to be scanned, but in a sub-scanning direction on an optical path from the light source to the surface to be scanned) by the cylinder lens 4 common to the light beams. The corresponding direction is also referred to as the sub-scanning direction, and similarly, the direction corresponding to the main scanning direction on the optical path from the light source to the surface to be scanned is also referred to as the main scanning direction. Then, a long line image is formed in the main scanning direction. These two line images are separated from each other in the sub-scanning direction (the direction orthogonal to the drawing in FIG. 10A). The principal rays of the light beams coupled by the coupling lenses 2a and 2b gradually approach the deflecting / reflecting surface side in the main scanning direction (in a plane parallel to the drawing) as shown in FIG. In the vicinity of the reflecting surface 5A,
They cross each other in the main scanning direction. When each coupled light beam is viewed from the sub-scanning direction, the angle formed by each light beam from the intersection to the light source side is called an "open angle" between the light beams. Each light beam reflected by the deflecting / reflecting surface 5A is deflected at a constant angular velocity with the rotation of the deflector 5 at a constant speed.
(A lens system is illustrated, but a concave mirror or the like can be used.) The light is focused as a light spot on the surface 7 to be scanned. A similar configuration is also disclosed in Japanese Patent Application Laid-Open No. 9-145024. By the way, in order to realize good optical characteristics for a plurality of light beams, the "open angle" of the plurality of light beams
Needs to be as small as possible. For this purpose, the coupling lens is preferably directly and adjustably bonded to the holder. If the coupling lens is directly adhered to the holder, a lens cell of the coupling lens is not required, so that a plurality of couplings can be brought close to each other. Also, by adjusting the bonding position of the coupling lens at the time of bonding, the amount of separation of the light spot on the surface to be scanned in the sub-scanning direction, that is, the scanning line pitch can be adjusted. Is unnecessary, and the interval between the light sources can be reduced. JP-A-9-146
In the light source device described in Japanese Patent No. 024, the position of the light source is adjusted. However, the position of the light source must be adjusted for each substrate on which a drive circuit or the like is loaded, and the adjustment becomes large. The two light spots are separated from each other in the sub-scanning direction, and simultaneously scan two scanning lines on the surface 7 to be scanned. The scanned surface 7 is substantially the surface of a photoconductive photoconductor.

The beam combining as shown in FIG. 10A can be easily applied even if the number of light sources is three or more. Hereinafter, for the sake of specificity, the case where the number of light sources is 2 will be described as an example. In the beam combining as shown in FIG. 10A, the semiconductor lasers 1a and 1b, which are light sources, and the coupling lens 2
A holder as shown in FIG. 10B is considered as a holder for holding a and 2b. Although the holder 8 also holds the aperture 3 in this example, the holding of the aperture 3 may be performed by another means. FIG. 10 (c)
Shows a state in which the holder 8 is viewed from the front side (the side from which the coupled light beam is emitted). FIG. 10B,
Referring to (c), the holder 8 has a base 8A having a substantially rectangular shape, and a cylindrical portion 8B protruding from the center thereof.
The projection 8C protrudes from the cylindrical portion 8B. A semiconductor laser 1 as a light source is provided on the cylindrical portion 8B.
Holes 1a1 and 1b1 for press-fitting and fixing a and 1b are formed. The semiconductor lasers 1a and 1b are provided together with a drive circuit (not shown) on the substrate 9, and are pressed into the holes 1a1 and 1b1 from the rear surface of the base 8A of the holder 8 and fixed. Then, the base 8A is fixed and integrated with the substrate 9.
As shown in FIG. 10C, holes 1a1 and
The portion connected to 1b1 is the cylinder surfaces 8c1 and 8c2. Each of the cylinder axes of these cylinder surfaces is configured to "slowly narrow toward the deflector side". That is, the cylinder surfaces have an “open angle”. The coupling lenses 2a and 2b are respectively connected to the semiconductor laser 1
The positions are adjusted in the optical axis direction and the optical axis orthogonal direction with respect to a and 1b, and fixed to the cylinder surfaces 8c1 and 8c2 using an adhesive. At this time, the adhesive also has a function of performing “position adjustment in the direction orthogonal to the optical axis” of each coupling lens. The technique of adjusting and fixing the position of the coupling lens with an adhesive as described above is known from Japanese Patent Application Laid-Open No. 8-72300, etc., in connection with a single-beam optical scanning device.

FIG. 10D shows a state in which the coupling lens 2b is properly fixed to the cylinder surface 8c2. The adhesive 8e is applied to the peripheral surface of the coupling lens 2b (a so-called “edge surface”), and the application area extends over “substantially half the circumference of the lens peripheral surface”. FIG.
In (d), the symbol AX represents the coupling lens 2b.
The symbol q indicates the position of the “light emitting section” of the semiconductor laser 1b. In order to “separate light spots in the sub-scanning direction” on the surface to be scanned, the optical axis AX and the light emitting section q are separated from each other in the sub-scanning direction (up and down direction in the figure) (the semiconductor laser 1 and the cup). In the relationship with the ring lens 2a, the "shift direction" is reversed.) The hole 1b1 in the holder 8 is drilled so that the position of the light emitting section q is at an appropriate position when the semiconductor laser 2b is press-fitted and fixed in the hole 1b1 if the "position of the light emitting section" is appropriate. In such a case, FIG.
As shown in (d), the coupling lens 2 b is
If it is appropriately held at b1, the positional relationship between the optical axis AX and the light emitting unit q is as designed. The same applies to the mounting of the semiconductor laser 1a and the coupling lens 2a. In practice, the position of the light emitting portion of a semiconductor laser as a light source varies among individual semiconductor lasers. FIG. 10E shows that the position of the light emitting portion q of the semiconductor laser 1b is shifted from the original design position, and the coupling lens 2 is relatively positioned with respect to the position of the light emitting portion q.
The state where the position of the optical axis AX of b is adjusted is shown. FIG.
The position of the coupling lens 2b is slightly displaced upward in the figure as compared to the “proper mounting state” of the coupling lens 2b shown in FIG. At this time, the adjustment of the positional relationship of the coupling lens 2b with respect to the cylinder surface 8c2 is performed by the adhesive 8e. That is, FIG.
In order to realize the mounting position as shown in FIG.
In FIG. 10E, the thickness of “e” gradually increases from the upper side of the figure to the lower side of the figure “counterclockwise”.
As described above, the positional relationship between the optical axis AX of the coupling lens and the light emitting portion q can be adjusted by the thickness of the adhesive 8e. However, the coupling lens fixed in this manner has the following problems. .

That is, the adhesive 8e is mainly composed of resin, and changes in volume when the temperature and humidity of the environment change. FIG. 10F shows a state in which the coupling lens 2b is attached as shown in FIG. 10E (shown by a broken line), and the temperature and humidity increase, the adhesive 8e causes a volume change, and the coupling lens 2b is displaced. (Solid line). Since the semiconductor laser 1b is press-fitted into the hole 1b1, the position of the light emitting section q does not change even if the temperature and humidity change. On the other hand, since the coupling lens 2b is fixed to the holder 8 by the adhesive 8e, the coupling lens 2b is displaced if the adhesive 8e changes in volume. At this time, since the thickness of the adhesive 8e is non-uniform as shown in FIG. 8E, the amount of change in the volume of the adhesive is proportional to the thickness of the adhesive. For this reason, the displacement of the optical axis of the coupling lens 2b occurs so that the optical axis AX is displaced to the optical axis AX ′, and the shift amount Δ in the sub-scanning direction between the optical axis AX ′ and the light emitting section q is An appropriate shift amount between the axis AX and the light emitting portion q: becomes larger than δ. Assuming that the combined lateral magnification of the image forming optical system (coupling lens, cylinder lens, scanning image forming optical system) between the light source and the surface to be scanned is βs, the light spot position is caused by the displacement of the coupling lens. Is enlarged by “βs (Δ−δ)” times in the sub-scanning direction. In such a case, the amount of separation of the two light spots on the surface to be scanned in the sub-scanning direction changes, so that the scanning line pitch in multi-beam scanning varies, which adversely affects the recorded image.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to effectively reduce the fluctuation of the scanning line pitch due to the above-mentioned causes in a multi-beam scanning apparatus.

[0008]

According to the light source device of the present invention, the divergent light beams emitted from a plurality of light sources are coupled by coupling lenses respectively corresponding to the light sources, and the light beams passing through the respective coupling lenses are coupled. Deflecting light at a constant angular velocity by a deflector having a deflecting / reflecting surface, and condensing a plurality of deflected light beams on the surface to be scanned by a common scanning optical system as light spots separated from each other in the sub-scanning direction. The light source device used in the “multi-beam scanning device that simultaneously scans a plurality of scanning lines at substantially the same speed”. Claim 1
The light source device described includes a plurality of light sources, a plurality of coupling lenses, and one or more holders. "Multiple light sources"
Each emit a divergent beam. Each coupling lens of the “plurality of coupling lenses” corresponds to each of the light sources and couples a light beam from the corresponding light source.
The coupling action may be such that the coupled light beam becomes a parallel light beam, or a weakly divergent or weakly converging light beam. The correspondence between the light source and the coupling lens may be a one-to-one correspondence, or a plurality of coupling lenses may correspond to one light source. The “holder” holds one or more pairs of a light source and a coupling lens (corresponding to the light source). As described above, when two or more coupling lenses correspond to one light source, the light sources forming a pair with the coupling lens are common to the two or more pairs. The positional relationship between the light source held by the holder and the coupling lens is determined so that the principal ray of the light beam coupled by each coupling lens gradually approaches the deflector side in the main scanning direction. That is, the principal ray of the coupled light beam forms the above-mentioned “open angle” in the main scanning direction. The holder has a “holding portion”, and each coupling lens is fixed to the holding portion by an adhesive. The cross-sectional shape of the holding portion may be an arc shape,
A shape similar to that may be used. At this time, the adhesive application area on the peripheral surface of the coupling lens held by the holder is “less than の of the entire circumference of the lens peripheral surface”.

In the light source device according to the first aspect, the length of the adhesive layer applied to the peripheral surface of the coupling lens projected in the main scanning direction is L1, and the length of the adhesive layer projected in the sub-scanning direction is L2. Sometimes, these magnitude relations are expressed as “L2> L1”.
(Claim 2). Further, in the light source device according to claim 1 or 2, at least two light sources and a coupling lens corresponding to each of the light sources can be held in a common holder (claim 3). Two coupling lenses can be attached to the “same projection formed on the holder” (claim 4), and two coupling lenses can be attached to “different projections formed on the same holder, Each coupling lens may be on the same side with respect to each projection ". Claim 1
In the light source device according to any one of Items 5, the center of the adhesive layer for fixing at least two coupling lenses to the holder in the sub-scanning direction is a plane including the optical axes of the two coupling lenses. Of the adhesive layer for fixing at least two coupling lenses to the holder, and the adhesive layer in the sub-scanning direction is made substantially identical in cross section. The positions of the agent layers can be substantially the same (claim 7).
The light source device according to any one of claims 3 to 7, wherein each holding portion is a cylinder surface in the common holder,
The radii of curvature can be made substantially the same (claim 8). Also, the bonding surfaces of the holding portions of the holder that hold the two or more coupling lenses are separated from each other in the main scanning direction by an “open angle (the bonding surfaces open in the main scanning direction from the coupling lens side to the light source side). Angle). " Alternatively, when the cross-sectional shape of the holder of the holder is arc-shaped, the center line of curvature of the holder having the arc-shaped cross-section can be shifted from the position of the light-emitting portion of the light source held by the holder. This “shift” is performed at least in the main scanning direction. In this case, the optical axes of the coupling lenses can be set parallel to each other. In this case, by adjusting the rotation of the holder, the distance between the light spots in the sub-scanning direction can be adjusted and set.
Is the main scanning direction in a state before the rotation adjustment is performed. Any one of claims 1 to 10 above.
In the light source device described in the above, the principal ray of the light flux coupled by each coupling lens gradually approaches the deflector side in the main scanning direction and intersects in the main scanning direction in the vicinity of the deflecting reflection surface of the deflector. (Claim 11). In the light source device according to any one of the first to eleventh aspects, an adhesive for bonding and fixing each coupling lens to the holder can be “ultraviolet curable resin” (claim 12).

Further, in the light source device according to any one of the first to twelfth aspects, one holder holds a plurality of pairs of a light source and a corresponding coupling lens, and holds the holder in at least the sub-scanning direction. And a rotation adjustment mechanism for the holder, which is rotatable about a rotation axis substantially perpendicular to the main scanning direction and not parallel to the main scanning direction. In this case, a holder holding member that holds the holder rotatably around a predetermined rotation axis, and a holder that is provided so that one end is locked by the holder and the other end is in contact with the holder holding member, and the holder is bent so that the holder is bent. A spring member for applying a rotation moment in a predetermined direction around the rotation axis, and an adjustment mechanism for preventing rotation of the holder due to the rotation moment by the spring member and adjusting the rotation state of the holder. Item 14). In this case, after adjusting the rotational position of the holder, the position of the holder can be fixed by the adjusting mechanism (claim 15), or the rotational position of the holder can be switched by the adjusting mechanism according to the pixel density. (Claim 16). The multi-beam scanning apparatus according to the present invention is configured such that “divergent light beams emitted from a plurality of light sources are coupled by coupling lenses respectively corresponding to the light sources, and the light beams passing through each coupling lens are deflected by a deflector having a deflective reflection surface. A plurality of deflected light beams are condensed on the scanned surface by a common scanning optical system as light spots separated from each other in the sub-scanning direction, and a plurality of scanning lines on the scanned surface are simultaneously and simultaneously deflected. 2. A multi-beam scanning device that scans at substantially constant speed, wherein the light source device is a light source device.
A light source device according to any one of (6) is used (claim 17). As the “light source”, a semiconductor laser or an LED can be used. Of course, a desirable light source is a semiconductor laser. The "coupling effect" by the coupling lens can be appropriately set by the design of the subsequent optical system in which the light beam from the light source is coupled. As described above, the light beam transmitted through the coupling lens becomes a parallel light beam. Or a weakly divergent light beam or a weakly convergent light beam. In addition to using a polygon mirror as a "deflector",
A rotating two-sided mirror or a rotating single-sided mirror can be used. The “scanning optical system” may be constituted by one or more lenses, or may be constituted by one or more concave mirrors.
One or more concave mirrors and one or more lenses or one or more concave mirrors and one
Conventionally known appropriate ones such as the combination of the above plane mirrors can be used.

[0011]

Embodiments of the present invention will be described below. As described above, in the present invention, "the light source and the corresponding coupling lens pair" may be three or more pairs. Further, the “light source and coupling lens pair” held by the holder may be one pair or three or more pairs. Hereinafter, an embodiment will be described in which there are two pairs of a light source and a coupling lens, and these two pairs are held by the same holder. It is assumed that the form of the multi-beam scanning device conforms to the case described earlier with reference to FIG. That is, in the embodiment described below, the multi-beam scanning device couples each divergent light beam radiated from the plurality of light sources 1a and 1b by the coupling lenses 2a and 2b corresponding to the light sources individually. The luminous flux passing through the coupling lens is transmitted to the deflecting / reflecting surface 5A
Are deflected at a uniform angular velocity by a deflector 5 having a
This is a multi-beam scanning apparatus that condenses light spots separated from each other in the sub-scanning direction and simultaneously scans a plurality of scanning lines on a surface to be scanned at substantially the same speed. The light source device includes a plurality of light sources 1a and 1b, a plurality of coupling lenses 2 and 2b respectively corresponding to the light sources, and one or more holders 8 holding one or more pairs of the light source and the coupling lens. Then, the positional relationship between the light source held by the holder 8 and the coupling lens is set such that the principal ray of the light beam coupled by each coupling lens gradually approaches the deflector side in the main scanning direction. A light source device,
Each coupling lens is fixed to the holding portion of the holder 8 with an adhesive.

FIG. 1 is an explanatory diagram showing only the characteristic portions of the light source device according to the first aspect. To avoid clutter,
The same reference numerals as those in FIG. 10 are used for those which do not seem to be confused. FIG. 1A shows a state in which the coupling lens 2b is adhered and fixed to the holding portion 8c2 having the arc-shaped cross section of the holder 8 with an adhesive 8e. As shown in the figure, the “adhesive application area” on the peripheral surface of the coupling lens 2b to which the adhesive 8e is applied is less than の of the entire circumference of the peripheral surface. The adhesive 8e for bonding and fixing the coupling lens 2b to the holder is “ultraviolet curable resin” (claim 12). The coupling lens 2b having the adhesive 8e applied to the peripheral surface is held from above and below by a holding jig 10, the position in the optical axis direction is adjusted with respect to the holding portion 8c2, and the light emitting portion of the light source 1b (shown in the figure). ) And the optical axis are adjusted. At this time, since the adhesive application area is “less than の of the entire circumference of the lens peripheral portion”,
As shown in the figure, even when the coupling lens 2b is held by the holding jig 10, the adhesive 8e does not adhere to the holding jig 10 and does not hinder the adjustment operation. When the position adjustment is completed, as shown in FIG. By irradiating V, the adhesive 8e is cured. Thus, the coupling lens 2b
It is adhesively fixed to the holding portion 8c2. Although not shown,
Needless to say, the bonding and fixing of the coupling lens 2a are performed in the same manner.

In FIG. 1A, the light emitting portion of a semiconductor laser 1b (see FIG. 10) as a light source is at a "designed position with respect to the holder", and the coupling lens 2b is also positioned with respect to the holding portion 8c2. It is attached at the "design position". At this time, the layer thickness of the adhesive 8e is “almost uniform”, and when the temperature and humidity change, the coupling lens 2
The optical axis b is displaced in the left-right direction (main scanning direction) in FIG. 1A, but is not displaced in the sub-scanning direction (vertical direction in the drawing). The coupling lenses 2b and 2a (not shown)
When displaced in the main scanning direction, the positional relationship between the two light spots on the surface to be scanned also changes in the main scanning direction. However, each deflected light beam by the deflector is separately detected by the photodetector (so-called “synchronous detection”) while being deflected toward the writing scanning unit, and the timing of starting writing for each deflected light beam is determined based on the detection result. Since it is determined, there is no practical problem even if the positional relationship of the light spot changes in the main scanning direction.
FIGS. 1B and 1C show that the light emitting portion of the semiconductor laser 1 b
It is shifted from the design position, and according to this "shift",
The case where the position of the optical axis AX of the coupling lens 2b is adjusted is shown. In these cases, the layer thickness of the adhesive 8e is not uniform, but the difference in the layer thickness is not so large because the adhesive application area is less than half of the entire circumference of the lens. The displacement of the optical axis AX of the coupling lens due to the volume change of the layer of the adhesive 8e due to the change of
In the direction of arrow A1 (including a slightly upward displacement component) or arrow A2 (including a downward downward displacement component), the optical axis displacement in the sub-scanning direction (interval of the light spot in the sub-scanning direction) Is very small, so that the scanning line pitch is not greatly disturbed.

FIG. 2 shows an embodiment of the invention according to the second aspect of the invention, showing only the characteristic portions. That is, when the length of the layer of the adhesive 8e applied to the peripheral surface of the coupling lens 2b projected in the main scanning direction is L1 and the length of the layer projected in the sub-scanning direction is L2, the magnitude relation between these is as follows. "L2>L1". The same applies to the coupling lens 2b not shown. By doing so, the amount of movement of the coupling lens 2b (2a) in the sub-scanning direction due to environmental changes such as temperature becomes smaller than the amount of movement in the main scanning direction, and the amount of deviation of the scanning line pitch on the surface to be scanned. Becomes smaller. In the embodiment described with reference to FIGS. 1 and 2, two light sources (semiconductor lasers 1a and 1b not shown) and two coupling lenses 2a and 2b are provided as shown in FIG.
The common holder 8 is provided (claim 3). By providing the light source and the coupling lens on a common holder, the relative positional relationship between each light source and each coupling lens is less likely to change, and the amount of displacement between the light spots on the surface to be scanned is reduced. If the light source is the light source and the coupling lens is the coupling lens, and each is provided in a separate holder, if one or both of the two holders are deformed, each light source and each coupling lens There is a possibility that the relative positional relationship changes greatly, and the deviation amount of the positional relationship between the light spots on the surface to be scanned also increases. In the embodiment shown in FIGS. 1 and 2, both coupling lenses (the coupling lens 2b is shown) are attached to the same projection 8c of the holder 8 as shown in FIG. (Claim 4). In this case, when the projection 8c is deformed (for example, thermal deformation due to heat generated by the semiconductor laser), the two coupling lenses move in the same direction, so that relative positional fluctuation between the coupling lenses is caused. Is smaller, and the amount of shift between the light spots on the surface to be scanned is smaller. In the embodiment shown in FIG. 3, two coupling lenses 2a and 2b
Different projections 80a, 80 formed on the same holder
b, the coupling lenses 2a and 2b are mounted on the same side (the right holding portion in the figure) with respect to the projections 80a and 80b (claim 5). In this case, the adhesives 8e1, 8e
2, the coupling lenses 2a, 2b
Move in the same direction, so the coupling lens 2
Variations in the relative positions a and 2b are reduced, and the amount of change in the positional relationship between the light spots on the surface to be scanned can be reduced. In FIG. 4, the coupling lenses 2a and 2b are provided on holding portions 8c1 and 8c2 of the common projection 8c of the holder. In this case, the adhesives 8e1, 8e2
When the layer thickness of the light spot changes, the separation amount of the light spot in the main scanning direction changes, but the separation amount in the sub-scanning direction hardly changes, so that the scanning line pitch does not change. In the embodiment shown in FIGS. 3 and 4, two coupling lenses 2
adhesives 8e1 and 8e for fixing a and 2b to the holder
The center of the two layers in the sub-scanning direction is located near a plane S including the optical axes AXa and AXb of the two coupling lenses 2a and 2b (claim 6). By doing so, even if the shape of the layer of the adhesives 8e1 and 8e2 changes due to environmental changes such as temperature, the coupling lenses 2a and 2b
Is small in the sub-scanning direction, and the displacement of the positional relationship between the light spots on the surface to be scanned can be reduced.

As shown in FIG. 5B, even if the layers of the adhesives 8e1 and 8e2 for adhering and fixing the coupling lenses 2a and 2b to the holding portions of the projecting portions of the holder have substantially the same sectional shape, Is different in the sub-scanning direction as shown in the figure, the direction of displacement of the coupling lenses 2a and 2b (indicated by arrows) when there is an environmental change such as temperature.
Is reversed, the change in the relative positional relationship between the coupling lenses 2a and 2b increases in the sub-scanning direction, and the distance between the light spots in the sub-scanning direction changes, so that the scanning line pitch changes. However, as shown in FIG.
The shapes of the layers of the adhesives 8e1 and 8e2 are substantially the same in the sub-scanning direction (claim 7). Therefore, the relative position fluctuation of the coupling lenses 2a and 2b due to the environmental fluctuation can be reduced, and the shift amount of the light spots on the surface to be scanned can be reduced. Incidentally, in the embodiment shown in FIGS. 3 and 4, the “adhesives 8 e 1 and 8 e
The two layers have substantially the same shape, and the position of the adhesive layer is substantially the same in the sub-scanning direction. "
The condition in claim 7 is satisfied. In the embodiment shown in FIGS. 3, 4 and 5, each of the holding portions 801 and 802 (FIG. 3), 8c1 and 8c2 (FIGS. 4 and 4) in the "common holder" for holding the coupling lenses 2a and 2b.
FIG. 5) shows a "cylinder surface", whose radius of curvature is substantially the same (claim 8). In this way, the shapes of the two adhesive layers can be made substantially the same, and the relative position fluctuation of the coupling lenses 2a and 2b due to environmental fluctuations such as temperature decreases, and the light spot on the surface to be scanned Can be reduced. In each of the embodiments described above, the holder is the same as the holder 8 shown in FIG. 10, and the coupling lenses 2a, 2 held by the holder.
The optical axis b gradually approaches the main scanning direction toward the deflector. The bonding surface of the holder of the holder has an "open angle" in the main scanning direction. That is, the shape of the holder is determined so that the optical axes of the coupling lenses 2a and 2b gradually approach the deflector in the main scanning direction (claim 9). Coupling lenses 2a, 2b
The optical axis gradually approaches the main scanning direction toward the deflector side by the method of "realizing by the form of the holder" and by "deforming the thickness of the adhesive layer" It is possible to do. However, if the thickness of the adhesive layer is uneven, the displacement of the coupling lens increases due to environmental fluctuations such as temperature, and the displacement of the light spots on the surface to be scanned increases. As shown in FIG. 10, by making the holding portions 8c1 and 8c2 of the holder 8 gradually approach the deflector side in the main scanning direction, the thickness of the adhesive layer can be made uniform, and the temperature and the like can be increased. By reducing the relative position fluctuation of the coupling lenses 2a and 2b due to environmental fluctuation,
The amount of deviation between light spots on the surface to be scanned can be reduced. In addition, the optical axis of the coupling lens and the position of the light emitting portion can be substantially matched in the main scanning direction, and “wavefront aberration can be reduced”, so that a good light spot diameter can be obtained.

The principal ray of the light beam coupled by the coupling lenses 2a and 2b is directed toward the deflector side.
In order to gradually approach the main scanning direction, FIG.
As shown in (a), as the optical axes of the coupling lenses 2a and 2b move toward the deflector 5 in the main scanning direction,
In addition to the method of determining the holding mode of the holder 8 so as to be “close to each other”, there is a method as shown in FIG. In FIG. 6A, the “left-right direction is the main scanning direction”, and the direction orthogonal to the drawing is the sub-scanning direction. Coupling lenses 2a, 2b
Are arranged with the optical axes AXa and AXb parallel to each other,
The light emitting units q1 and q2 of the light source (semiconductor laser) are shifted from the optical axis in the main scanning direction. Even if you do this,
The principal rays of the coupled light fluxes approach each other as they approach the deflector. 6B and 6C, the horizontal direction is the main scanning direction, and the vertical direction is the sub-scanning direction. The positions of the light emitting portions q1 and q2 of the light source may be shifted from the optical axes AXa and AXb “only in the main scanning direction” as shown in FIG. Axis A
Xa and AXb may be shifted “in both the main and sub-scanning directions”.

However, in the case of FIG. 6B, the optical axes AXa, AXa,
When the AXb and the light emitting units q1 and q2 are arranged in a line in the main scanning direction, the light spot formed on the surface to be scanned does not separate in the sub scanning direction. In such a case, the arrangement direction of the optical axes AXa and AXb and the light emitting units q1 and q2 is set to “finite with respect to the main scanning direction” by adjusting the rotation state of the holder as described in claim 13 described later. In such a manner that the two light spots are separated in the sub-scanning direction. In the case shown in FIG. 6C, two light spots on the surface to be scanned are separated in the main and sub scanning directions. In this case, the separation amount of the light spot in the sub-scanning direction can be adjusted by adjusting the “shift in the sub-scanning direction” of the light emitting units q1 and q2 from the optical axes AXa and AXb. By using the adjustment of the rotation position of the holder, the separation amount of the light spot in the sub-scanning direction can be adjusted or switched. As described with reference to FIG. 6, the coupling is performed by making the optical axes of the coupling lenses 2a and 2b parallel to each other and displacing the light emitting portion of the light source from the optical axis of the coupling lens in the main scanning direction. The principal ray of each light beam can be made closer to each other as it goes to the deflector side.However, as a method of setting the positional relationship between each light emitting unit and the coupling lens as described above, the coupling lens is bonded to the holder. A method of shifting the optical axis of the coupling lens by making the thickness of the adhesive layer uneven is considered. But,
If the thickness of the adhesive layer is made uneven, the displacement of the coupling lens due to environmental fluctuations such as temperature increases, and the amount of displacement between the light spots on the surface to be scanned increases. However, as in the tenth aspect of the present invention, the center of curvature of the "holding portion having an arc-shaped cross section" of the holder is shifted from the position of the light emitting portion of the light source held by the holder at least in the main scanning direction. If, for example, the adhesive layer can be made uniform, the relative position fluctuation of the coupling lens due to environmental fluctuations such as temperature is reduced,
The amount of deviation between light spots on the surface to be scanned can be reduced. In the light source device of the present invention, the principal rays of the light beam coupled by the coupling lenses gradually approach the deflector side in the main scanning direction, and these principal rays are shown in FIG. As described above, it is preferable that the light beams intersect in the main scanning direction in the vicinity of the deflecting reflection surface of the deflector. In this case, the coupled light fluxes also “intersect in the main scanning direction near the deflection / reflection surface”, so that the deflection / reflection surface of the deflector can be reduced, and the size of the deflector itself can be reduced. Because it becomes.

FIG. 7 is a view for explaining an embodiment of the light source device according to the thirteenth aspect. The holder holding the semiconductor lasers 1a and 1b (not shown) as the light source, the coupling lenses 2a and 2b, and the aperture (not shown) has the cylindrical portion 8B as an immovable member (in this example, an optical element to which the holder can be attached). (Circular hole) of the wall portion 90 of the system housing) from the outside so as to be rotatable, and the axis of the cylindrical portion 8B (the direction orthogonal to the drawing).
It is rotatable around. In the cylindrical portion 8B,
A spring member 100 is wound. Spring member 100
Is locked by a locking portion 8D formed in the cylindrical portion 8B, and the other end is elastically pressed against the bottom surface 91 of the immovable member. The resilient force of the spring member 100 causes the holder 8 to apply a “clockwise rotational moment to the immovable member”.
By acting on the holder 8, the rotational position of the holder 8 can be adjusted. That is, in the embodiment shown in FIG. 7A, one holder 8 holds a plurality of pairs of a light source and a corresponding coupling lens, and the holder 8 is “at least substantially orthogonal to the sub-scanning direction. , A rotation axis that is not parallel to the main scanning direction ”and a rotation adjustment mechanism for the holder (spring member 100 and an appropriate mechanism for applying force: F). FIG. 7B shows a light spot SPa (a light spot formed by a light beam from the light source 1a) and a light spot SPb (a light spot formed by a light beam from the light source 1b) formed on the surface to be scanned. Holder 8
Is rotated as described above, the light spots SPa, S
Since the angle θ formed by the arrangement direction of Pb and the main scanning direction can be changed, the “holder 8”
Adjustment of Rotational Position of Scanning Line ", the scanning line pitch: P can be adjusted.

If the scanning line pitch: P is uniquely set, as shown in FIG.
The tip of the adjusting screw 93 screwed into the holder 8 is brought into contact with an engaging projection 8E formed on the base of the holder 8, and by adjusting the adjusting screw 93, the holder 8 (clockwise rotation moment is generated by a spring member (not shown)). The given scanning line pitch may be set by adjusting the rotational position (given). That is,
In the embodiment shown in FIG. 8, the light source device has a holder holding member (an immovable member such as the above-described housing) for holding the holder 8 rotatably around a predetermined rotation axis, and one end fixed to the holder 8. A spring member (the above-described spring) is provided so that the other end thereof abuts on the holder holding member, and which bends to apply a rotational moment to the holder in a predetermined direction around a rotation axis (in a direction perpendicular to the drawing). Members 100) and adjusting mechanisms 8E and 9 for preventing the holder from rotating due to the rotating moment by the spring member and adjusting the rotation state of the holder.
2, 93 (claim 14). The adjusting screw 9
After adjustment, 3 can be fixed with an adhesive or the like as necessary (claim 15). With such a configuration, the number of components is small, and the scanning line pitch can be adjusted with high accuracy with a simple configuration.

Alternatively, as shown in FIG. 9, a stepping motor 95 is attached to an engagement protrusion 8E 'provided at the base of the holder 8 to which a clockwise rotational moment is applied.
If the actuator 96 is brought into contact with the actuator 96 and the rotation state of the holder 8 is adjusted by the stepping motor 95 according to the pixel density, the scanning line pitch can be switched according to the pixel density with a simple configuration. That is, in the embodiment of FIG. 9, the rotation state of the holder is adjusted by the adjusting mechanisms 95 and 96.
Switching is performed according to the pixel density (claim 16).

It is apparent that the light source devices described in the various embodiments can be used as the light source device of the multi-beam scanning device shown in FIG. This is an embodiment of the beam scanning device (claim 17).

[0022]

As described above, according to the present invention, a novel multi-beam scanning device and its light source device can be realized. In the light source device according to the present invention, even if the volume of the adhesive layer for bonding and fixing the coupling lens to the holder changes due to changes in temperature and humidity, the influence on the scanning line pitch is small. Therefore, according to the multi-beam scanning device of the present invention using such a light source device, good optical scanning can always be performed regardless of environmental fluctuations such as temperature and humidity.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a characteristic portion of an embodiment of a light source device according to the first aspect of the present invention.

FIG. 2 is a view for explaining a characteristic portion of the light source device according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining a characteristic portion of the light source device according to the first embodiment of the present invention.

FIG. 4 is a view for explaining a characteristic portion of the light source device according to the sixth embodiment of the present invention.

FIG. 5 is a diagram for explaining a characteristic portion of the light source device according to the sixth embodiment of the present invention;

FIG. 6 shows a first embodiment of the light source device according to the tenth aspect of the present invention.
It is a figure for explaining the characteristic part of a form.

FIG. 7 is a view for explaining an embodiment of the light source device according to the present invention.

FIG. 8 is a view for explaining one embodiment of the light source device according to the invention described in claim 15;

FIG. 9 is a view for explaining one embodiment of the light source device of the invention according to claim 16;

FIG. 10 is a diagram for explaining a multi-beam scanning device and a problem to be solved by the invention.

[Explanation of symbols]

 2b Coupling lens 8c Projecting part of holder 8C2 Holding part of holder 8e Adhesive (ultraviolet curable resin)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomohiro Nakajima 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H045 BA22 DA02 DA04

Claims (17)

[Claims] A divergent light beam emitted from a plurality of light sources is coupled by a coupling lens corresponding to each of the light sources, and a light beam passing through each coupling lens is subjected to uniform angular velocity by a deflector having a deflecting / reflecting surface. And a plurality of deflected light beams are scanned on the surface to be scanned by a common scanning optical system.
In a multi-beam scanning apparatus that converges as light spots separated from each other in the sub-scanning direction and scans a plurality of scanning lines on the surface to be scanned simultaneously and at a substantially constant speed, A plurality of coupling lenses and a pair of a light source and a coupling lens
One or more holders for holding pairs or more, and the holders are held by the holders so that the principal ray of the light flux coupled by each coupling lens gradually approaches the deflector side in the main scanning direction. A light source device for setting a positional relationship between a light source and a coupling lens, wherein each coupling lens is fixed to a holding portion of the holder by an adhesive, and a periphery of the coupling lens held by the holder. A light source device, wherein an adhesive application area of a surface portion is less than half of an entire circumference of the peripheral surface portion. 2. The light source device according to claim 1, wherein the length of the adhesive layer applied to the peripheral surface of the coupling lens projected in the main scanning direction is L1, and the length of the adhesive layer projected in the sub-scanning direction is L1. A light source device characterized by satisfying L2> L1 when L2. 3. The light source device according to claim 1, wherein at least two light sources and a coupling lens corresponding to each of the light sources are held by a common holder. 4. The light source device according to claim 3, wherein the two coupling lenses are mounted on the same projection formed on the holder. 5. The light source device according to claim 3, wherein the two coupling lenses are mounted on different projections formed on the holder, and each coupling lens is mounted on the same side with respect to each projection. A light source device characterized by being obtained. 6. The light source device according to claim 1, wherein the center of the adhesive layer for fixing at least two coupling lenses to the holder in the sub-scanning direction is the two cups. A light source device located near a plane including an optical axis of a ring lens. 7. The light source device according to claim 1, wherein a cross-sectional shape of an adhesive layer for fixing at least two coupling lenses to the holder is substantially the same, and in a sub-scanning direction. A light source device, wherein the positions of the adhesive layers are substantially the same. 8. The light source device according to claim 3, wherein each holding portion of the common holder is a cylinder surface, and the radii of curvature are substantially the same. 9. The divergent light beams emitted from a plurality of light sources are coupled by coupling lenses respectively corresponding to the light sources, and the light beams passing through the respective coupling lenses are subjected to uniform angular velocity by a deflector having a deflecting / reflecting surface. And a plurality of deflected light beams are scanned on the surface to be scanned by a common scanning optical system.
In a multi-beam scanning apparatus that converges as light spots separated from each other in the sub-scanning direction and scans a plurality of scanning lines on the surface to be scanned simultaneously and at a substantially constant speed, a plurality of light sources and a light source corresponding to each of the light sources are provided. A plurality of coupling lenses and a pair of a light source and a coupling lens
One or more holders for holding pairs or more, and the holders are held by the holders so that the principal ray of the light flux coupled by each coupling lens gradually approaches the deflector side in the main scanning direction. A light source device for setting a positional relationship between a light source and a coupling lens, wherein each coupling lens is fixed to a holder of the holder by an adhesive, and the holder of the holder is arranged in a main scanning direction. A light source device having an opening angle. 10. A divergent light beam emitted from a plurality of light sources,
Coupling is performed by a coupling lens corresponding to each of the light sources, and the light flux passing through each coupling lens is deflected at a uniform angular velocity by a deflector having a deflecting reflection surface,
A multi-scan device that converges a plurality of deflected light beams on a surface to be scanned by a common scanning optical system as light spots separated from each other in a sub-scanning direction, and simultaneously scans a plurality of scanning lines on the surface to be scanned at substantially the same speed. In the beam scanning apparatus, a plurality of light sources, a plurality of coupling lenses respectively corresponding to the light sources, and a pair of the light source and the coupling lens are included in one beam.
One or more holders for holding pairs or more, and the holders are held by the holders so that the principal ray of the light flux coupled by each coupling lens gradually approaches the deflector side in the main scanning direction. A light source device for setting a positional relationship between a light source and a coupling lens, wherein each coupling lens is fixed to a holding portion of the holder by an adhesive, and the holding portion of the holder has an arc-shaped cross section. A light source device, wherein a center line of curvature of the holding portion is displaced from a light emitting portion position of the light source held by the holder at least in a main scanning direction. 11. The light source device according to any one of claims 1 to 10, wherein the principal ray of the light beam coupled by each coupling lens gradually approaches the deflector side in the main scanning direction; A light source device intersecting in the main scanning direction near a deflecting reflection surface of a deflector. 12. The light source device according to claim 1, wherein the adhesive for adhering and fixing each coupling lens to the holder is an ultraviolet curable resin. 13. The light source device according to claim 1, wherein one holder holds a plurality of pairs of a light source and a corresponding coupling lens, and said holder is at least a sub-type. A light source device that is rotatable about a rotation axis that is substantially perpendicular to the scanning direction and is not parallel to the main scanning direction, and has a rotation adjustment mechanism for the holder. 14. The light source device according to claim 13, wherein a holder holding member for holding the holder rotatably around a predetermined rotation axis, one end of which is locked by the holder, and the other end of which is held by the holder holding member. A spring member that is provided so as to be in contact with and bends to apply a rotational moment in a predetermined direction around the rotation axis to the holder by bending, and prevents the holder from rotating due to the rotational moment by the spring member, and A light source device comprising: an adjustment mechanism that adjusts a rotation state of the light source. 15. The light source device according to claim 14, wherein after adjusting the rotational position of the holder, the position of the holder is fixed by an adjusting mechanism. 16. The light source device according to claim 14, wherein a rotation state of the holder is switched by an adjustment mechanism according to a pixel density. 17. Each divergent light beam emitted from a plurality of light sources,
Coupling is performed by a coupling lens corresponding to each of the light sources, and the light flux passing through each coupling lens is deflected at a uniform angular velocity by a deflector having a deflecting reflection surface,
A multi-scan device that converges a plurality of deflected light beams on a surface to be scanned by a common scanning optical system as light spots separated from each other in a sub-scanning direction, and simultaneously scans a plurality of scanning lines on the surface to be scanned at substantially the same speed. A beam scanning device, wherein the light source device according to any one of claims 1 to 16 is used as a light source device.