Optical scanner for monochrome use and monochrome image formation device

Abstract

To provide an optical scanner for monochrome use and a monochrome image formation device that for obtaining a desired optical characteristic when the optical scanner for monochrome use is converted.SOLUTION: An optical scanner for monochrome use mounted in a monochrome image formation device comprises a scanning lens 6K which is an optical element that guides light from a light source 2K deflected and scanned by a polygon mirror 5a acting as a deflector, onto a photoreceptor and forms an image thereon. A foundation part 9 on which the scanning lens 6K is mounted has a same shape to the scanning lens 6K and is made of the same or a similar material as the scanning lens 6K.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a monochrome optical scanning device and a monochrome image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art Monochrome optical scanning devices have been known which are equipped with optical elements that guide light from a light source, which has been deflected and scanned by a deflector, onto a photosensitive member to form an image, and which are mounted in monochrome image forming apparatuses.

[0003] Patent Document 1 describes a two-color optical scanning device in which scanning lenses, which are optical elements, are stacked one above the other. This two-color optical scanning device has a red scanning lens on the bottom and a black scanning lens on the top, with the black scanning lens on the top mounted on the red scanning lens. When converting a two-color optical scanning device into a monochrome optical scanning device, the component on which the black scanning lens is mounted is changed from the red scanning lens on the bottom to a spacer serving as a base. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a risk that the desired optical characteristics may not be obtained in the converted monochrome optical scanning device. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a monochrome optical scanning device that is installed in a monochrome image forming device and that includes an optical element that guides light from a light source that has been deflected and scanned by a deflector onto a photosensitive element to form an image, wherein the base on which the optical element is placed has the same shape as the optical element and is made of the same or similar material as the material of the optical element. [Effects of the Invention]

[0006] According to the present invention, desired optical characteristics can be obtained in a converted monochrome optical scanning device. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a monochrome image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram of a color image forming apparatus capable of transferring to a monochrome image forming apparatus according to the present embodiment. [Figure 3] FIG. 2 is a schematic diagram of a monochrome optical scanning device mounted in the monochrome image forming apparatus of the present embodiment. [Figure 4] FIG. 2 is a schematic diagram of a color optical scanning device that can be converted into a monochrome optical scanning device according to the present embodiment. [Figure 5] 5 is a perspective view showing the periphery of a scanning lens of the color optical scanning device shown in FIG. 4. [Figure 6] FIG. 3 is a schematic diagram of a holding mechanism that holds a scanning lens. [Figure 7] FIG. 2 is a schematic perspective view of the scanning lens and its surroundings in the monochrome optical scanning device of the present embodiment. [Figure 8] FIG. 10 is a perspective view showing an example of providing an identification mark on a non-standard scanning lens used as a base portion. [Figure 9] FIG. 10 is a perspective view showing an example in which a C-color scanning lens of a color optical scanning device is used as a base portion in a monochrome optical scanning device. DETAILED DESCRIPTION OF THE INVENTION

[0008] The best mode for carrying out the present invention will be described below with reference to the drawings. Note that a person skilled in the art can easily modify or alter the present invention within the scope of the claims to create other embodiments, and these modifications and alterations are included within the scope of the claims. The following description is an example of the best mode for carrying out the present invention and does not limit the scope of the claims.

[0009] FIG. 1 is a schematic diagram of a monochrome image forming apparatus according to this embodiment. The monochrome image forming apparatus 1 shown in FIG. 1 is a conversion of the color image forming apparatus 100 shown in FIG. 2. The color image forming apparatus 100 is converted into the monochrome image forming apparatus 1 without the color imaging units 104Y, 104M, and 104C and the color toner bottles 106Y, 106M, and 106C. The monochrome image forming apparatus 1 shares components, systems, and functions with the color image forming apparatus 100, reducing the need for new resources and lowering the cost of the apparatus. Furthermore, the monochrome image forming apparatus of this embodiment can be easily recycled from a monochrome image forming apparatus to a color image forming apparatus, and vice versa.

[0010] 1 includes an image forming unit 115, a paper feed unit 118, and an image reading device 119 that reads an image of a document on which an image is to be formed. The image reading device 119 is disposed above the image forming unit 115, and includes a document transport unit 110 and a scanner unit 102. The paper feed unit 118 is disposed below the image forming unit 115, and includes two feed trays 112 and 113 that accommodate sheets P.

[0011] The image forming section 115 includes a black image forming unit 104K, an intermediate transfer belt 178 serving as an intermediate transfer body, a monochrome optical scanning device 103, and a secondary transfer roller 189. Above the secondary transfer roller 189, a fixing section 120 that fixes the image on the sheet P is provided.

[0012] The imaging unit 104K is provided with a charging device that applies an electric charge to the surface of the photoreceptor 105K, a developing device that develops the latent image formed on the surface of the photoreceptor 105K with black toner to form a toner image, and a cleaning device that cleans the surface of the photoreceptor 105K after the toner image is transferred.

[0013] Next, an example of the operation of the monochrome image forming apparatus 1 of this embodiment will be described. First, the document D is transported (fed) from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 110, and passes over the scanner unit 102. At this time, the scanner unit 102 optically reads the image information of the document D passing above it.

[0014] The optical image information read by the scanner unit 102 is converted into an electrical signal and then transmitted to the monochrome optical scanning device 103. From the monochrome optical scanning device 103, a laser beam based on the image information of the electrical signal is emitted onto the photosensitive element 105K, and an exposure process is carried out.

[0015] In the imaging unit 104K, a charging process, an exposure process, and a development process are performed on the photosensitive member 105K, and a desired image is formed on the photosensitive member 105K. The image formed on the photosensitive member 105K is then transferred as a monochrome image onto the intermediate transfer belt 178. The monochrome image formed on the intermediate transfer belt 178 is transferred, at a position facing the secondary transfer roller 189 (secondary transfer nip), onto the sheet P that has been fed and conveyed from one of the two feed trays 112, 113 to the sheet feeding path K0 by the feed roller 197. The sheet P onto which the monochrome image has been transferred is conveyed to the position of the fixing unit 120, and the monochrome image transferred to the front surface is fixed onto the sheet P (a fixing process).

[0016] The sheet P after the image is formed by the image forming unit 115 (printed sheet P) passes through a first sheet discharge path K1 (sheet discharge path) of the lateral protrusion 116 and is discharged from a first sheet discharge outlet H1 (sheet discharge outlet) by a first discharge roller 131. Then, the sheet P is stacked on a first sheet placement section 134 (sheet placement section) in the first space W1.

[0017] When a "duplex printing mode" is selected, which prints on both sides (front and back sides) of the sheet P, the sheet P, after the fixing process on the front side, is guided to the second sheet discharge path K2 (sheet relay path) by the operation of the switching claw. The sheet P guided to the second sheet discharge path K2 is then guided to the sheet reversal path K3. At this time, the rear end of the sheet P is held between the second discharge rollers 132 (reversal rollers), and the other part is discharged from the second sheet discharge opening H2 into the second space W2. The sheet P is then switched back by the reverse rotation of the second discharge rollers 132 and conveyed toward the duplex conveyance path K4.

[0018] The sheet P guided to the double-sided conveying path K4 is conveyed again toward the position of the secondary transfer nip (secondary transfer roller 189). At the position of the secondary transfer nip, an image is formed (printed) on the back side of the sheet P by the same image forming process (image forming operation) as described above. The sheet then undergoes a fixing process in the fixing unit 120, passes through the first sheet discharge path K1, and is discharged from the first sheet discharge outlet H1 into the first space W1, and is stacked on the first sheet loading unit 134.

[0019] FIG. 3 is a schematic diagram of the monochrome optical scanning device 103 mounted in the monochrome image forming apparatus of this embodiment. The monochrome optical scanning device of this embodiment is a device converted from a color optical scanning device 103' (an optical scanning device installed in the color image forming apparatus 100 shown in FIG. 2) shown in FIG. 4. The color light sources 2Y, 2M, and 2C and the color optical elements 3Y-8Y, 3M-8M, and 3C-8M are not installed, and the color optical scanning device 103' is converted to a monochrome optical scanning device. The monochrome optical scanning device 103 shares at least the housing 10, the black light source 2K, and the black optical elements 3K-8K with the color optical scanning device 103'. This reduces the need for new resources and reduces the cost of the device. Furthermore, recyclability is improved, from the monochrome optical scanning device 103 to the color optical scanning device 103' and from the color optical scanning device to the monochrome optical scanning device.

[0020] 3 includes a housing 10, a light source 2K, a collimator lens 3K, a cylindrical lens 4K, a polygon scanner 5, a scanning lens 6K, a first reflecting mirror 7K, and a second reflecting mirror 8K. The polygon scanner 5 includes a polygon mirror 5a serving as a deflector having six mirror surfaces, a polygon motor that rotates the polygon mirror 5a, and a control board that controls the polygon motor.

[0021] The light beam Lk emitted from the light source 2K is converted from a divergent light beam into a parallel light beam by the collimator lens 3K, and then passes through the cylindrical lens 4K to be focused in the sub-scanning direction (the direction corresponding to the direction of movement of the photosensitive body surface on the photosensitive body surface).

[0022] The light beam that passes through the cylindrical lens 4K is deflected in the main scanning direction (the direction corresponding to the axial direction on the surface of the photosensitive member) while being reflected by one of the mirror surfaces formed on each side of the polygon mirror 5a, which is rotated at high speed by a polygon motor. The speed of movement in the deflection direction of the light deflected in the main scanning direction at a constant angular velocity by the polygon mirror 5a is converted to a constant speed by a scanning lens 6K, which is an optical element. The scanning lens 6K also focuses the light deflected in the main scanning direction in the sub-scanning direction, correcting the tilt of the mirror surface of the polygon mirror 5a, known as plane tilt. The light beam Lk that passes through the scanning lens 6K is reflected by a first reflecting mirror 7K and a second reflecting mirror 8K, and is then directed to the surface of the photosensitive member 105K (see FIG. 1).

[0023] FIG. 5 is a perspective view showing the periphery of the scanning lens of the color optical scanning device 103' shown in FIG. 5, between the light source and the scanning lens of the color optical scanning device 103', an optical system for K color is disposed above an optical system for C color, and the scanning lens 6K for K color is mounted and fixed on the scanning lens for C color. The upper scanning lens 6K for K color and the lower scanning lens 6C for C color are made of the same material and have the same shape.

[0024] The high-speed rotation of the polygon mirror generates heat in the bearings that support the rotation axis 5c of the polygon mirror. This heats the area around the polygon mirror, causing the scanning lenses 6C and 6K to thermally expand. In the color optical scanning device 103', the positioning and optical characteristics of each optical element, including the scanning lenses, are designed so that the desired optical characteristics can be obtained even if the orientation of the scanning lenses 6C and 6K changes due to thermal expansion of the scanning lenses.

[0025] When converting the color optical scanning device 103' into a monochrome optical scanning device 103, if the component on which the K scanning lens 6K is mounted is changed from the lower C scanning lens to a base made of a different material and shape than the scanning lens, the following problem may occur. That is, when the periphery of the polygon mirror is heated and the base thermally expands, the base thermally expands in a different way than the C scanning lens 6C, and the posture and vertical position of the scanning lens 6K differ from when it was mounted on the C scanning lens 6C. As a result, the angle of incidence of light incident on the scanning lens 6K during thermal expansion differs between monochrome and color scanning. This causes a problem in that the desired optical characteristics of the K scanning lens 6K when the temperature inside the device rises, which are obtained in the color scanning device, may not be obtained when the device is converted into a monochrome scanning device.

[0026] Therefore, for example, when converting a color optical scanning device into a monochrome optical scanning device, it is possible to hold the scanning lens 6K with a holding mechanism 17 as shown in FIG. 6 to suppress changes in the posture of the scanning lens 6K due to an increase in device temperature. Specifically, the holding mechanism 17 shown in FIG. 6 is composed of a lower sheet metal member 11, an upper sheet metal member 12, and a spacing member 13. Both ends of the lower sheet metal member 11 and the upper sheet metal member 12 in the longitudinal direction (main scanning direction) are fastened to the spacing member 13. The distance between the lower sheet metal member 11 and the upper sheet metal member 12 is set equal to or lower than the height of the scanning lens 6K in the sub-scanning direction (up-down direction), and the scanning lens 6K is sandwiched and fixed between the lower sheet metal member 11 and the upper sheet metal member 12. The lower sheet metal member 11 and the upper sheet metal member 12 are fixed to the spacing member 13 using separate screws. The spacing member 13 is molded from a material with the same linear expansion coefficient as the scanning lens 6K. This reduces the difference in the amount of thermal deformation between the scanning lens 6K and each sheet metal member, and maintains a constant compressive stress on the scanning lens 6K even when the temperature inside the device changes, thereby preventing changes in the posture of the scanning lens 6K when the temperature inside the device rises.

[0027] However, when converting the configuration shown in FIG. 6 from color to monochrome, a separate holding mechanism must be prepared for monochrome use, which may result in insufficient reduction in new resource input and cost reduction of the device.

[0028] When converting from color to monochrome, it is possible to install only the lower C optical system and write the K latent image using this lower C optical system. However, this would require changing the system and functions, which could result in insufficient reduction in new resource investment and cost reduction for the device. In other words, when converting from color to monochrome, by placing the K optical system in the same position as the K optical system in color, the system and functions used to create monochrome images can be reused exactly for color, thereby reducing new resource investment and reducing device costs.

[0029] Therefore, the monochrome optical scanning device 103 of this embodiment uses a base on which the scanning lens 6K is mounted and fixed that has the same shape as the scanning lens 6K and is made of the same or similar material as the scanning lens 6K. FIG. 7 is a schematic perspective view of the scanning lens and its surroundings of the monochrome optical scanning device 103 of this embodiment. 7, in this embodiment, a scanning lens whose optical characteristics become out of specification during manufacturing or reuse / recycle is used as the base 9. This allows the shape and material of the base 9 to be the same as those of the scanning lens 6K.

[0030] In this way, by using a non-standard scanning lens for the base 9 on which the K scanning lens 6K is mounted, the shape and material of the base 9 can be made the same as those of the scanning lens 6K. As described above, in a color optical scanning device, the C scanning lens 6C on which the K scanning lens 6K is mounted has the same shape and material as the K scanning lens 6K. Therefore, by using a non-standard scanning lens for the base 9 on which the K scanning lens 6K is mounted and making it the same shape and material as the K scanning lens, the C scanning lens 6C can also be made the same shape and material as those of the K scanning lens. This allows the thermal expansion of the base 9 to be similar to that of the C scanning lens 6C on which the K scanning lens 6K is mounted in a color optical scanning device. This allows the posture, etc., of the scanning lens 6K mounted on the base 9 of this monochrome optical scanning device converted from a color optical scanning device when the temperature inside the device rises to be the same as that of the color optical scanning device, and desired optical characteristics can be obtained. Furthermore, by using a non-standard scanning lens, which would have been discarded in the past, as the base 9, it is possible to reduce costs and conserve resources by reducing the amount of material used.

[0031] In order to distinguish between a scanning lens with non-standard optical characteristics used as the base 9 and the K-color scanning lens 6K when assembling them, an identification mark 15 may be attached to the non-standard scanning lens used as the base 9, as shown in Fig. 8. In the example of Fig. 8, a black line is drawn on the exit surface of the scanning lens as the identification mark 15. In this way, by attaching the identification mark 15 to the non-standard scanning lens of the base 9, it is possible to prevent the non-standard scanning lens from being assembled as the K-color scanning lens.

[0032] As shown in FIG. 8, it is preferable to provide an identification mark 15 on the exit surface or entrance surface of the scanning lens in the base portion. By providing the identification mark 15 at the light transmitting portion of the entrance surface or exit surface of the scanning lens in the base portion, the identification mark 15 can prevent light from passing through the scanning lens. As a result, even if a non-standard scanning lens is mistakenly assembled as a K-color scanning lens, it will be detected as an abnormality in the characteristic value inspection process and the product (image forming apparatus) guarantee process. This makes it possible to detect the occurrence of incorrect assembly. The position where the identification mark 15 is formed is not limited to the entrance surface or exit surface of the scanning lens, and the shape and color of the identification mark 15 are not limited to those shown in FIG.

[0033] 9, a color polygon scanner having two stages of polygon mirrors 5a, 5b may be used for monochrome transfer as is. Also, as shown in FIG. 9, the C-color scanning lens 6C used in the color optical scanning device 103' may be reused as the base 9. Note that the M-color scanning lens and the Y-color scanning lens have the same shape and are made of the same material as the C-color scanning lens, so the M-color scanning lens 6M and the Y-color scanning lens 6Y may be reused as the base.

[0034] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and unless otherwise specifically limited in the above description, various modifications and variations are possible within the spirit and scope of the present invention as set forth in the claims.

[0035] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) In a monochrome optical scanning device 103 mounted on a monochrome image forming device 1, the device is equipped with an optical element such as a scanning lens 6K that guides light from a light source, which has been deflected and scanned by a deflector such as a polygon mirror 5a, onto a photosensitive member to form an image. The base 9 on which the optical element is placed has the same shape as the optical element and is made of the same or similar material as the material of the optical element. Generally, in a multi-color optical scanning device such as a two-color optical scanning device, the lower optical element on which the upper optical element is placed has the same shape as the upper optical element and is made of the same or the same type of material. When the deflector rotates at high speed, the bearing that supports the rotating shaft to which the deflector is fixed generates heat, causing the temperature inside the device to rise. In Patent Document 1, when converting a multi-color optical scanning device into a monochrome optical scanning device, if the component on which the upper optical elements are mounted is changed from the lower optical elements to a base, such as a spacer, that has a different shape or material than the lower optical elements, the following problem occurs. If the base has a different shape or material than the lower optical elements, the thermal expansion of the upper optical elements when the temperature inside the device rises will differ from that of the lower optical elements. As a result, the posture of the upper optical elements when the temperature inside the monochrome optical scanning device rises will differ from when the device was used as a multi-color optical scanning device. This causes the angle of incidence of light incident on the optical elements to differ between monochrome and multi-color use, potentially resulting in a problem in which the desired optical characteristics of the upper optical elements when the temperature inside the device rises, achieved in multi-color use, may not be achieved when converted into monochrome use. In contrast, in aspect 1, by using a base made of the same or similar material as the optical element and having the same shape as the optical element, the thermal expansion of the base can be made approximately the same as that of the optical element below, which has the same shape and is made of the same or similar material as the optical element and on which the optical element is placed when used as a multi-color optical scanning device. As a result, when the device is converted from multi-color use to monochrome use, the posture of the optical element placed on the base when the temperature inside the device rises can be made the same as in the multi-color optical scanning device, and desired optical characteristics can be obtained.

[0036] (Aspect 2) In the first embodiment, the base 9 is an optical element such as a scanning lens whose optical characteristics are out of spec. As a result, as described in the embodiment, optical elements such as non-standard scanning lenses that would have been discarded in the past can be used as the base, thereby reducing costs and saving resources by reducing the amount of material used.

[0037] (Aspect 3) In the first embodiment, the base portion 9 is an optical element such as a scanning lens 6C used in a color optical scanning device 103' that performs optical scanning on a plurality of photosensitive members. According to this, the base portion on which the optical element such as the scanning lens is placed can be made of the same material as or of the same type as the optical element and can have the same shape as the optical element.

[0038] (Aspect 4) In any of the embodiments 1 to 3, the housing 10 containing the light source 2, a deflector such as a polygon mirror, and optical elements such as a scanning lens 6 is the housing of a color optical scanning device mounted in a color image forming apparatus that performs optical scanning on multiple photosensitive elements. This allows the housing to be common between color and monochrome printers, reducing the amount of resources used and the cost of the device. It also improves recyclability from color to monochrome and vice versa.

[0039] (Aspect 5) In any of the first to fourth aspects, the base portion is provided with a marking that identifies it as a base portion. As described in the embodiment, this allows the base part, which is made of the same or similar material as the optical element serving as the scanning lens and has the same shape as the optical element, to be distinguished from the optical element by the identification mark, thereby preventing the base part from being mistakenly assembled as the optical element.

[0040] (Aspect 6) In a monochrome image forming apparatus that forms a monochrome image by irradiating the surface of a photosensitive member with light using an optical scanning means to form a latent image on the surface of the photosensitive member, and finally transferring the image obtained by developing the latent image onto a recording material, the optical scanning means uses an optical scanning device of any of aspects 1 to 5. This makes it possible to form a good monochrome image. [Explanation of symbols]

[0041] 1: Monochrome image forming device 2:Light source 3: Collimating lens 4: Cylindrical lens 5: Polygon scanner 5a: Polygon mirror 5b: Polygon mirror 5c: Rotation axis 6: Scanning lens 7: First reflecting mirror 8: Second reflecting mirror 9: Base 10: Housing 11: Lower sheet metal member 12: Upper sheet metal member 13: Spacing member 15: Identification mark 100: Color image forming apparatus 103: Monochrome optical scanning device 103': Color optical scanning device 105: Photoreceptor [Prior art documents] [Patent documents]

[0042] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-278207

Claims

1. A monochrome optical scanning device equipped in a monochrome image forming apparatus includes an optical element that guides light from a light source, which is deflected and scanned by a deflector, onto a photosensitive member to form an image, A monochrome optical scanning device, characterized in that a base portion on which the optical element is placed has the same shape as the optical element and is made of the same or similar material as the material of the optical element.

2. 2. The monochrome optical scanning device according to claim 1, The monochrome optical scanning device is characterized in that the base portion is an optical element having non-standard optical characteristics.

3. 2. The monochrome optical scanning device according to claim 1, The monochrome optical scanning device is characterized in that the base portion is an optical element used in a color optical scanning device that performs optical scanning on a plurality of photosensitive members.

4. 2. The monochrome optical scanning device according to claim 1, A monochrome optical scanning device, characterized in that the housing for accommodating the light source, the deflector, and the optical element is the housing of a color optical scanning device that performs optical scanning on a plurality of photosensitive bodies.

5. 2. The monochrome optical scanning device according to claim 1, A monochrome optical scanning device, characterized in that the base portion is provided with a marking that identifies it as being for use with a base.

6. A monochrome image forming apparatus in which a latent image is formed on the surface of a photosensitive member by irradiating the surface of the photosensitive member with light using an optical scanning means, and the image obtained by developing the latent image is finally transferred onto a recording material to form a monochrome image, 2. A monochrome image forming apparatus using the monochrome optical scanning device of claim 1 as said optical scanning means.

Images