JP2006256063A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus whose dimensions is kept constant by using the same housing, even if an LD (laser diode) is changed, and which reduces the kinds of densities of an ND (neutral density) filter. <P>SOLUTION: The ND filter 20, and a cylinder lens 22, which is held on a holder 32 capable of being positionally adjusted in the direction of an optical axis, are provided on a sub-chassis 26 which is fitted into a plurality of positioning parts 30, provided in a frame 24, by means of a positioning guide 28. Since a lens-barrel 15 for holding a CML (collimator lens) 17 becomes longer than a lens-barrel 14 when an LD 13 with a spreading angle smaller than that of an LD 12 is used, a position of a leading end of the lens-barrel 15 is shifted to the side of the ND filer 20 with respect to a position of a leading end of the lens-barrel 14. The ND filter 20 and the cylinder lens 22 are moved by distances A and B equal to a distance C from the leading end of the lens-barrel 14 to that of the lens-barrel 15, so that interference between the lens-barrel 15, and the ND filter 20 and the cylinder lens 22 can be avoided, and so that the amount of the adjustment of the cylinder lens 22 can be secured. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image recording apparatus.

  Conventionally, there has been proposed an apparatus for recording a color image on a silver rolled photosensitive material using a plurality of lasers having different wavelengths using the same scanning optical system. In this case, when an LD (laser diode) is used as the light source, direct modulation with intensity and pulse width is possible, so that an external modulation element such as an AOM is not required, and the size and cost can be reduced. In addition, the photosensitive material achieves good color reproducibility by having spectral characteristics having sharp peaks corresponding to a plurality of different wavelengths. However, since LDs have large variations in divergence angles and wavelengths even within the same product, it is necessary to adjust the amount of light for each unit. Here, if the light amount adjustment is performed with the LD drive current, the modulation characteristics change in addition to the droop and mode hop, and sufficient gradation characteristics cannot be obtained. Therefore, it is desirable to separately provide a light amount adjusting means such as an ND filter filter. As the ND filter, a vapor deposition type is used from the viewpoint of durability, but flare light may be generated on the recording surface due to the influence of the surface reflection, and the image quality may be deteriorated. For this reason, it is desirable that the ND filter be arranged on the upstream side as much as possible so that the reflected light is not diffused into the unit. Therefore, the arrangement of the optical members from the light source to the deflector is optimal in the order of LD, collimator lens, aperture, ND filter, and cylinder lens.

  In the prior art, a collimator lens having a certain predetermined focal length has been used. When a collimator lens having a certain focal length is used for an LD having a certain wavelength, the divergence angle of the LD varies due to manufacturing variations of the LD, so that a predetermined amount of light cannot be obtained. In addition, there was variation in the divergence angle between LDs having different wavelengths, and a predetermined amount of light could not be obtained.

  In addition, as shown in FIG. 9B, the LD 206W having a wide divergence angle needs to set the CML 214 to a short focus in order to ensure a substantially equivalent amount of light as shown in FIG. 9A, and the sub-scan magnification (cylinder lens focal length). / CML focal length) increases, the adjustment amount of the cylinder lens 212 is insufficient when the astigmatic difference between the LD 202 and the LD 206W is equal. If the CML 214 remains at a long focal point, the amount of light captured by the CML 214 decreases as shown in FIG. 9B, and the exposure amount is insufficient.

  As described above, it is difficult to respond to a second source (substitute equivalent) product or a discon (discontinued) when designed for an LD having a specific beam divergence angle.

  Also, when the solid dispersion of the LD divergence angle is large, the transmitted light amount of the CML decreases if the divergence angle is large.

  Furthermore, when an ND filter is used as the light amount adjusting means, it is necessary to independently adjust the light amount of the LD corresponding to the three colors of YMC when forming a color image, and the ND filter according to the spread angle and wavelength variation of each LD. Since this is necessary, there are many types of transmission density of the ND filter to be used, and when the LD is changed, the wavelength range is different.

  As an alternative to an ND filter, a polarization scanning device that adjusts the reflectance of a folding mirror and adjusts the amount of laser light has been proposed (see, for example, Patent Document 1).

However, the function of the aperture and the ND filter is given to the mirror, and the balance of the laser light intensity of each color is not corrected.
JP-A-6-51223 (Pages 2-5, Fig. 1)

  In view of the above facts, the present invention has an object to provide an image recording apparatus that uses the same housing even when the LD is changed, keeps the dimensions of the apparatus constant, and reduces the density type of the ND filter. To do.

  The image recording apparatus according to claim 1, wherein a light source comprising a laser diode, a deflector for deflecting laser light emitted from the light source in a main scanning direction, and a collimator lens that makes the beam emitted from the light source substantially parallel light An exposure optical system for focusing the beam in the vicinity of the deflection surface of the deflector in the sub-scanning direction, and a scanning optical system for condensing the laser light deflected by the deflector. The collimator lenses having different focal lengths are selected so that the amount of the parallel light is substantially constant regardless of the beam divergence angle of the laser diode.

  In the invention with the above configuration, when using LDs having different beam divergence angles, it is possible to keep the collimated light beam substantially constant by selecting an optimum one from a plurality of collimator lenses having different focal lengths. It is not necessary to project the mounting position of the light source unit to the outside of the housing of the light source unit, so that the outer dimensions of the housing of the light source unit can be maintained.

  The image recording apparatus according to claim 2, further comprising a position changing unit that includes a light amount adjusting unit for the beam, and changes a mounting position of the light amount adjusting unit in response to a movement of a collimator lens position accompanying the replacement of the collimator lens. It is characterized by that.

  In the invention with the above configuration, even when the collimator lens is replaced and the total length of the collimator lens barrel becomes long, the tip of the barrel and the ND filter may interfere with each other by changing the mounting position of the ND filter by the position moving means. Therefore, even if LDs having different beam divergence angles are used, the same light source unit housing can be used.

  The image recording apparatus according to claim 3 includes a scanning optical system including a plurality of light sources including laser diodes having different wavelengths, a beam deflecting unit, a scanning optical unit, and a folding mirror, and the folding mirror is provided for each light source. It is characterized in that it has a spectral reflection characteristic that corrects the difference in intensity of the collimator lens emission according to the required amount on the recording surface.

  In the invention with the above configuration, for example, instead of changing the transmission density range of the ND filter used for each color light source in scan exposure in which recording is performed at wavelengths corresponding to three colors of YMC, the reflectivity of the folding mirror has wavelength dependency. By reducing the reflectance of a specific color, it is possible to align the transmission density range of the ND filter necessary for each color. Thereby, the kind of ND filter required in order to adjust the light quantity of each color can be restrained few.

  According to a fourth aspect of the present invention, the folding mirror is composed of a plurality of mirrors having the same spectral reflection characteristics.

  In the invention with the above configuration, the spectral reflection characteristics given to the folding mirror are not sharp in sharp cut, but the spectral reflection characteristics required by using a plurality of the same mirrors having gentle characteristics can be obtained. . As a result, it is possible to maintain a stable reflectance without overcoating the mirror coating.

  The image recording apparatus according to claim 5 includes a scanning optical system including a plurality of light sources composed of laser diodes having different wavelengths, a beam deflecting unit, a scanning optical unit, and a folding mirror, and the folding mirror is provided for each light source. It is characterized in that it has a spectral reflection characteristic that corrects the difference in intensity of the collimator lens emission according to the required amount on the recording surface.

  In the invention with the above configuration, when using LDs having different beam divergence angles, it is possible to keep the collimated light beam substantially constant by selecting an optimum one from a plurality of collimator lenses having different focal lengths. It is not necessary to project the mounting position of the light source unit to the outside of the housing of the light source unit, so that the outer dimensions of the housing of the light source unit can be maintained, and the light source of each color can be used in scan exposure for recording at wavelengths corresponding to, for example, YMC three colors Instead of changing the transmission density range of the ND filter used for each color, the reflectance of the folding mirror is made wavelength dependent, and the reflectance of the specific color is lowered by reducing the reflectance of a specific color. Can be aligned. Thereby, the kind of ND filter required in order to adjust the light quantity of each color can be restrained few.

  The image recording apparatus according to claim 6 is characterized in that the folding mirror includes a plurality of mirrors having the same spectral reflection characteristic.

  In the invention with the above configuration, the spectral reflection characteristic provided to the folding mirror is not steep, and the spectral reflection characteristic obtained by using a plurality of the same mirrors having a gradual characteristic can be obtained. As a result, it is possible to maintain a stable reflectance without overcoating the mirror coating.

  Since the present invention has the above-described configuration, the same housing can be used even when the LD is changed, and the image recording apparatus can be configured to keep the apparatus size constant and reduce the density type of the ND filter. .

  FIG. 1 is a sectional view of an image forming apparatus using the image recording apparatus according to the first embodiment.

  As shown in FIG. 1, the image forming apparatus 110 exposes the photosensitive material 114 by the image recording apparatus 10 in accordance with the input image data, and transfers the exposed image of the photosensitive material 114 to the image receiving material 116 by heating and pressing. Then, an image corresponding to the image recorded on the original is formed on the image receiving material 116. The photosensitive material 114 and the image receiving material 116 that are recording materials are respectively accommodated in the light-shielding magazines 170 and 172 and loaded into the image forming apparatus 110.

  First, the outline of the image forming apparatus 110 will be described.

  The image forming apparatus 110 includes a casing 112 configured in a box shape as a whole, and a photosensitive material magazine 170 is disposed in the casing 112 as a light-shielding magazine for storing the photosensitive material 114. The photosensitive material 114 is accommodated and loaded in the photosensitive material magazine 170 while being wound in a roll shape. At this time, in the photosensitive material magazine 170, the outlet of the photosensitive material 114 is directed upward. A nip roller 118 and a cutter 120 are provided above the photosensitive material magazine 170 loaded in the casing 112, and the photosensitive material 114 drawn from the photosensitive material magazine 170 is cut into a predetermined length.

  Further, the image recording apparatus 10 is provided above the photosensitive material magazine 170, and conveying roller pairs 126 and 128 are provided to face the image recording apparatus 10. The photosensitive material 114 drawn out from the photosensitive material magazine 170 is conveyed near the image recording apparatus 10 by a pair of conveying rollers 126 and 128 with the photosensitive surface directed toward the image recording apparatus 10.

  As will be described later, the image recording apparatus 10 is provided with three color LDs (laser diodes), a lens unit, a polygon mirror, a mirror unit, and the like, and the light emitted from the three color LDs is disposed between the conveying roller pairs 126 and 128. Irradiate toward the exposure position P. As a result, the photosensitive material 114 is scanned and exposed by light emitted from the image recording device 124 when passing through the exposure position P between the pair of conveying rollers 126 and 128.

  A water application unit 130 is provided above the image recording apparatus 10. The photosensitive material 114 that has passed through the exposure position P is transported by a transport turn section 132 formed by a plurality of roller pairs, and the photosensitive surface is directed upward from the left side of the water application section 130 (left side of the paper in FIG. 1). In this state, the water is applied to the water application unit 130. The water application unit 130 uniformly applies water used as an image forming solvent to the photosensitive surface of the photosensitive material 114.

  On the other hand, the image forming apparatus 110 is loaded with a receiving material magazine 172 that is a light-blocking magazine for storing a roll-shaped image receiving material 116 at the upper left end of the casing 112. The image receiving material 116 accommodated in the receiving material magazine 172 is coated with a dye fixing material having a mordant on the image forming surface, and the receiving material magazine 172 has the outlet of the receiving material material 116 directed rightward on the paper surface. The image receiving material 116 is loaded so that the image forming surface is drawn downward.

  A nip roller 134 and a cutter 136 are provided to face the drawer opening of the receiving material magazine 172. The image receiving material 116 that is sandwiched and drawn from the receiving material magazine 172 by the nip roller 134 is cut into a predetermined length by the cutter 136. The image receiving material 116 is loaded with a size smaller than the width of the photosensitive material 114, and the length cut by the cutter 136 is shorter than the cutting length of the photosensitive material 114.

  The image receiving material 116 drawn out from the receiving material magazine 172 and cut to a predetermined length is conveyed above the water application unit 130 by a conveying unit 138 constituted by a plurality of roller pairs.

  A thermal development transfer unit 140 is provided at the right end of the casing 112 along the vertical direction (the vertical direction of the paper in FIG. 1). The heat development transfer unit 140 is provided with a pair of rollers 142 and 144 on the top and bottom, and an endless belt 146 is wound around the rollers 142 and 144 in pairs. The endless belt 146 is rotationally driven by driving of the roller pairs 144 and 146.

  The photosensitive material 114 delivered from the water application unit 130 is guided by the guide unit 148 between the endless belts 146 wound around the roller pair 142. The image receiving material 116 conveyed by the conveying unit 138 is sent between the endless belt 146 in synchronization with the conveyance of the photosensitive material 114. Thus, the photosensitive material 114 and the image receiving material 116 are inserted and sandwiched between the endless belt 146 with the photosensitive surface of the photosensitive material 114 and the image forming surface of the image receiving material 116 facing each other.

  Within the loop of one endless belt 146, a heating plate 150 formed in a flat plate shape is disposed along the vertical direction. The heating plate 150 heats the endless belt 146 facing between the roller pairs 142 and 144. As a result, the photosensitive material 114 and the image receiving material 16 that are sandwiched between the endless belts 146 and conveyed from the roller pair 142 to the roller pair 144 are heated while being sandwiched between the endless belts 146 (heating pressure contact). The image formed on the photosensitive material 114 is transferred to the image receiving material 116. The endless belt 146 is temporarily stopped when the photosensitive material 114 and the image receiving material 116 are sandwiched between the endless belt 146 and the photosensitive material 114 and the image receiving material 116 are completely accommodated between the pair of endless belts 146. And the image receiving material 116 are sufficiently heated and pressed. When the photosensitive material 114 is heated, the movable dye is released and transferred to the image receiving material 116, and is fixed by the dye fixing layer of the image receiving material 116, and an image corresponding to the exposure is formed on the image receiving material 116.

  A peeling claw 152 is provided at the lower end portion of the endless belt 146, and a waste sensitive material container 154 is provided at the side of the peeling claw 152. The photosensitive material 114 and the image receiving material 116 that are nipped and conveyed by the endless belt 146 are peeled off from the image receiving material 116 by the peeling claw 152 when the photosensitive material 114 and the image receiving material 116 are fed out between the endless belts 146. The photosensitive material 114 peeled off from the image receiving material 116 is transported toward the waste sensitive material container 154 by a roller pair 156 provided on the side of the peeling claw 152.

  The waste sensitive material container 154 includes a drum 158 and an endless belt 160 wound around the drum 158. The belt 160 is wound around the drum 158 so that a part on the side of the peeling claw 152 is opened, and the drum 158 also rotates as the belt 160 rotates.

  The photosensitive material 114 peeled from the image receiving material 116 is guided to a winding start position of the belt 160 around the drum 158, is sandwiched between the belt 160 and the drum 158, wound around the drum 158, and sequentially accumulated.

  The bottom of one casing 112 is provided with a conveyance unit 162 that horizontally conveys the image receiving material 116 fed from between the endless belts 146. The image receiving material 116 from which the photosensitive material 114 has been peeled off is provided in the conveyance unit 160. , And sent out to the tray 164 provided on the side wall of the casing 112 for accumulation.

  FIG. 2 shows a cross-sectional view of the image recording apparatus according to the first embodiment.

  As shown in FIG. 2, the image recording apparatus 10 includes a laser diode (hereinafter referred to as LD) 12 held by a mounting portion 18 and a lens barrel 14 of a collimator lens (hereinafter referred to as CML) 16 on a frame 24. An ND filter 20 and a cylinder lens 22 held on a holder 32 whose position can be adjusted in the optical axis direction are placed on a sub chassis 26 fitted to a plurality of positioning portions 30 provided on the frame 24 by positioning guides 28. And.

  Laser light emitted from the LD 12 becomes substantially parallel light by the CML 16, the amount of light is adjusted by the ND filter 20, and the light is guided to a polygon mirror (not shown) through the cylinder lens 22.

  At this time, when the spread angle of the LD 12 is narrow, it is necessary to set the collimator lens (hereinafter referred to as CML) 16 to a long focal point in order to ensure the collimating diameter. When the CML 16 is moved to the ND filter 20 side, the ND filter 20 and further the cylinder lens. The LD 12 having a narrow divergence angle due to space interference due to interference with the 22 cannot be used, or the LD 12 needs to be moved outward.

  If the spread angle of the LD 12 is wide, the CML 17 needs to be set to a short focus in order to secure the amount of captured light, and the sub-scanning magnification (cylinder lens focal length / CML focal length) increases. Insufficient quantity. Furthermore, if the CML 17 remains at a long focal point, the amount of light captured by the CML 17 decreases and the exposure amount is insufficient.

  The semiconductor laser used in the present embodiment includes a thin active layer 42 at the center of the chip 40 that emits laser light inside the LD 12 as shown in FIG. 3, and emits laser light from the end face of the active layer 42. 3A, light in a direction perpendicular to the active layer 42 spreads from the light emitting point 44 at an angle θ⊥, and light parallel to the active layer 42 as shown in FIG. Spread with //. Usually, the angle θ⊥ is about 2.5 to 6 times θ //, and the beam spot is an ellipse.

  Since the light emission point 44 exists on the surface of the chip 40 and the light emission point 46 exists inside the chip, the laser light is emitted from different portions of the active layer 42 of the chip 40 depending on the vertical direction and the horizontal direction. It cannot be corrected as parallel light. That is, in the laser light corrected by the CML 16, only one of the vertical direction and the horizontal direction becomes parallel, and the other converges or diverges. Therefore, as shown in FIG. 4A, the laser light parallel to the active layer 42 is paralleled by the CML 16, but the laser light perpendicular to the active layer 42 is corrected by the CML 17 as shown in FIG. It will not be parallel.

  In the present invention, as shown in FIG. 4, the laser light emitted from the light emitting point 46 of the chip 40 spreads at an angle θ //, becomes substantially parallel light by the CML 16, passes through the cylinder lens 22, and travels to a polygon mirror (not shown).

  Laser light emitted from the light emitting point 44 spreads at an angle θ⊥, passes through the CML 16, is refracted by the cylinder lens 22, is deflected by the polygon mirror 52, and forms an image on the photosensitive material 114.

At this time, the distance Δa between the light emitting point 44 and the light emitting point 46 is referred to as an astigmatic difference. Since this Δa differs depending on the LD, it is necessary to adjust the astigmatic difference for each LD by moving the cylinder lens 22. That is, as shown in FIG. 4, the laser light emitted from the chip 40 passes through the CML 16, the light amount is adjusted by the ND filter 20, and then passes through the cylinder lens 22 in the main scanning direction, that is, the direction perpendicular to the conveyance direction of the photosensitive material 114. (Arrow) is scanned by a polygon mirror, but it is necessary to move the cylinder lens 22 in accordance with Δa to adjust the astigmatic difference for each LD.

  For this reason, a space for adjusting the position of the cylinder lens 22 must be secured between the ND filter 20 and the ND filter 20. However, when the LD 13 having a small spread angle is used as described above, the lens barrel 15 that holds the CML 17 is longer than the lens barrel 14, so that the tip position is closer to the ND filter 20 than the tip position of the lens barrel 14. shift.

  For example, when the CML 16 having a focal length of 15 mm is used when the spread angle of the LD 12 is θ⊥25 to 40 °, and the CML 17 having a focal length of 23 mm is used when the spread angle of the LD 13 is 20 ° to 35 °, the CML 17 is held. The lens barrel 15 is about 5 mm longer than the lens barrel 14 holding the CML 16 and may interfere with the ND filter.

  Here, when the LD 13 having a narrower laser beam spread angle than the LD 12 is used, it cannot be used because the dimensions are not suitable conventionally, or the LD 13 is retracted to the outside of the frame 24 to increase the optical path length, thereby affecting the influence of the spread angle. A correction method can be considered.

  In contrast, in this embodiment, as shown in FIG. 2B, the ND filter 20 and the cylinder lens 22 are separated by a distance A equal to a distance C (here, 5 mm) from the tip of the lens barrel 14 to the tip of the lens barrel 15. And B (5 mm) are moved to avoid interference between the lens barrel 15, the ND filter 20, and the cylinder lens 22, and an adjustment amount of the cylinder lens 22 is secured.

  When the focal length of the cylinder lens is 360 mm and the astigmatic difference is 15 μm, the astigmatism adjustment amount in CML16 is (360/15) ^ 2 × 15 μm = 8.6 mm, but the necessary adjustment amount in CML17 is (360/23) ^ Since 2 × 15 μm = 3.7 mm, the adjustment amount of the cylinder lens 22 can be secured even if the ND filter 20 is moved by the distance B.

  That is, the ND filter 20 and the cylinder lens 22 are fixed on the sub chassis 26, and the sub chassis 26 is fitted to the positioning portion 30 </ b> A by the positioning guide 28. A positioning portion 30B is provided at a location extending 5 mm from the positioning portion 30A in the optical axis direction. By fitting the positioning guide 28 of the sub chassis 26, the ND filter 20 and the cylinder lens 22 together with the sub chassis 26 are connected to the lens barrel. Retract 15 mm from the tip of 15. Thereby, the distance between the lens barrel 15, the ND filter 20, and the cylinder lens 22 can be ensured to be equal to the distance when the lens barrel 14 of FIG.

  As a result, even when LD 13 having a different laser beam spread angle is used, LD 13 does not protrude to the outside of frame 24, and the external dimensions are not changed, so that it can be attached to the same casing without change. Further, the ND filter 20 and the lens barrel 15 do not interfere with each other and the adjustment amount of the cylinder lens 22 is not insufficient.

  In addition, when a color image is formed using a plurality of LDs, the appropriate focal length of the collimator lens is different for each LD, so that the sub chassis 26 can be adjusted for each LD as a separate component for each LD. Good. In this case, if the linear expansion coefficient differs between the housing and the chassis, distortion due to temperature changes may occur. Therefore, materials with the same or similar linear expansion coefficient, such as BMC (Bulk Molding Compound) and aluminum, BMC and BMC It is desirable to form the chassis with the housing.

  FIG. 6 is a perspective view of the light source unit of the image recording apparatus according to the first embodiment.

  As shown in FIG. 6, in an optical system for forming a color image by exposing a photosensitive material 148 by a polygon mirror 52 via folding mirrors 50A and 50B using three color LD light sources 12Y, 12M, and 12C. The ND filters 20Y, 20M, and 20C that adjust the light amounts of the light sources 12Y, 12M, and 12C according to the divergence angles and wavelengths are necessary.

  This is because when the light output of the LD is adjusted, the modulation characteristic and the droop characteristic change, and therefore it is desirable to adjust the light quantity of the LD with an ND filter in color image formation.

  Conventionally, for example, 8 types of ND filters with a transmittance of 21 to 99% for Y (wavelength 810 nm), 5 types of 6 to 15% for M (670 nm), and 43 to 99% for C (750 nm) 5 types, a total of 13 types were required, and the required range of transmittance was wide. This is because the sensitivity of the photosensitive material and the spread angles of 12Y, 12M, and 12C are different. An ND filter having a low transmittance is used for 12M, which has a high sensitivity for the photosensitive material, and a transmittance is used for 12Y and 12C, which has a low sensitivity for the photosensitive material. This is because the light amounts of the three colors are each optimized by combining ND filters having a high value.

  Therefore, in this application, instead of the conventional silver-coated mirror (having a flat spectral reflectance at a wavelength of 450 nm or more), a mirror with a reduced reflectance on the short wavelength side is used, and the reflectance of the mirror is changed depending on the color. Thus, by adjusting the light intensity of each color to the characteristics of the photosensitive material, a large number of ND filters that have been necessary in the past can be dispensed with, and a small number of ND filters having approximate transmittances can be used.

  The mirror coating film is made into a multilayer, and the refractive index and film thickness of each layer are optimized, so that an infrared LD mirror having spectral transmission characteristics as shown in FIG. 7 is used as the folding mirror 50A or 50B. By using it, the spectral reflection characteristics as shown in FIG. 8 can be obtained as a whole. As a result, the reflectance of 670 nm (M) is lowered, so that the ND filters necessary for aligning the light intensities of the respective colors can be unified to those of 810 nm (Y). You can reduce the type and number.

  In addition, by using mirrors with moderate characteristics for 50A and 50B, it is possible to obtain stable spectral reflection characteristics without any difficulty in the manufacturing quality of the mirrors.

  Since the present embodiment is configured as described above, the types of ND filters used can be reduced.

2 is a cross-sectional view of an exposure optical system of the image forming apparatus according to the first embodiment. FIG. 2 is a cross-sectional view of an exposure optical system of the image recording apparatus according to the first embodiment. FIG. It is a perspective view of LD concerning this Embodiment 1. FIG. It is the side view and top view of the exposure optical system which concern on this Embodiment 1. FIG. 1 is a perspective view of an exposure optical system according to Embodiment 1. FIG. 1 is a schematic diagram of an exposure optical system according to Embodiment 1. FIG. FIG. 6 is a spectral transmission characteristic diagram of the mirror according to the first embodiment. It is a spectral reflection characteristic view of the mirror according to the first embodiment. It is sectional drawing of the exposure optical system of the conventional image recording apparatus.

Explanation of symbols

10 Image recording device 12 LD
14 Tube 16 CML
18 Mounting portion 20 ND filter 22 Cylinder lens 24 Frame 26 Sub chassis 28 Positioning guide 30 Positioning portion 40 Chip 42 Active layer 50 Mirror 52 Polygon mirror

Claims (6)

A light source consisting of a laser diode;
A deflector for deflecting laser light emitted from the light source in the main scanning direction;
A collimator lens that makes the beam emitted from the light source substantially parallel light;
An exposure optical system for focusing the beam in the vicinity of the deflecting surface of the deflector in the sub-scanning direction with the beam substantially parallel light in the main scanning direction;
A scanning optical system for condensing the laser beam deflected by the deflector,
The image recording apparatus, wherein the collimator lenses having different focal lengths are selected so that the amount of the parallel light is substantially constant regardless of the beam divergence angle of the laser diode. 2. The apparatus according to claim 1, further comprising a position changing unit that includes a light amount adjusting unit for the beam, and changes a mounting position of the light amount adjusting unit in response to a movement of a collimator lens position associated with the replacement of the collimator lens. Image recording device. A scanning optical system including a plurality of light sources composed of laser diodes having different wavelengths, beam deflecting means, scanning optical means, and a folding mirror,
The image recording apparatus according to claim 1, wherein the folding mirror has a spectral reflection characteristic that corrects a difference in intensity of the collimator lens emitted from each light source according to a required amount on the recording surface. The image recording apparatus according to claim 3, wherein the folding mirror includes a plurality of mirrors having the same spectral reflection characteristic. A scanning optical system including a plurality of light sources composed of laser diodes having different wavelengths, beam deflecting means, scanning optical means, and a folding mirror,
3. The image recording apparatus according to claim 1, wherein the folding mirror has a spectral reflection characteristic that corrects a difference in intensity emitted from the collimator lens for each light source according to a necessary amount on a recording surface. . The image recording apparatus according to claim 5, wherein the folding mirror includes a plurality of mirrors having the same spectral reflection characteristic.

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