JP2008241986A - Fixing structure for frame of lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing structure for a frame of a lens unit, the structure being designed so that, in an image reader with a lens unit directly fixed to the body frame of the image reader, the lens unit can be fixed in two steps, one for relatively loose fixing when the position of the lens unit is adjusted and the other for secure fixing after the position adjustment, without applying such external force as adversely affecting the positioning of the lens unit. <P>SOLUTION: The fixing structure is for the frame of the lens unit through which an image reading light passes. The fixing structure has a fixing force switching means by which force for fixing the lens unit in the frame can be switched in two or more steps while being fixed in the frame. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure in which a lens unit for forming an image of a document on an image sensor, a photosensitive member, or a polygon mirror is fixed to a frame of an image reading apparatus main body, and in particular, a lens for simplifying the structure. The present invention relates to a structure for fixing the unit to the frame.

  Conventionally, in a copying machine, a printer, an image scanner, a facsimile machine, and the like, an imaging lens is used to form an image of an original on an image sensor, a photoconductor or a polygon mirror.

  FIG. 5 shows a schematic longitudinal section of an image reading apparatus in a copying machine as an example of an image forming apparatus to which the present invention is applied. The reflected light from the document D illuminated by the light source L provided under the platen glass G is reflected by the first mirror M1, the second mirror M2, and the third mirror M3 as shown by the one-dot chain line, The light is collected by the lens unit 1, imaged on the image sensor S, and converted into an electric signal by the image sensor S. If the copying machine is a digital copying machine, it is then converted to a digital signal.

  At this time, the light source L scans in parallel with the document D on the platen glass G, whereby image data over the entire surface of the document D is acquired. The scanning may be performed by moving the light source L or the original D side.

  In FIG. 5, the image of the document D on the platen glass G is reduced to 1 / N (magnification) by the lens unit 1 and formed on the image sensor S. The lens unit 1 is attached to the image reading apparatus of the copying machine main body via a support stand or the like. However, since the image is reduced as described above, if the mounting position of the lens unit 1 is not accurate, a particularly good resolution MTF ( Modulation Transfer Function) characteristics cannot be obtained. Therefore, the lens unit 1 needs to be positioned highly.

Therefore, in the conventional image forming apparatus, when the image reading apparatus is assembled, the position of the lens unit 1 is moved in the direction of the optical axis of the unit mainly for the purpose of adjusting the magnification in the main scanning direction. It is fixed to the frame after accurately determining.
For example, in the image reading apparatus described in Patent Document 1, the lens unit is fixed to an intermediate mounting base using a spring, and the position of the intermediate mounting base is moved precisely in the optical axis direction to thereby fix the lens unit. The mounting position of is set with high accuracy.
JP-A-6-332077

However, in the spread type image forming apparatus, in terms of cost, the intermediate mounting base as described above is not provided, and the lens unit is directly attached to the main body frame of the image reading apparatus. Fine adjustments cannot be made by moving the intermediate mounting base.
Further, in the popular type image forming apparatus as the object of the present invention, the lens unit is attached to a part of the main body frame as described above, but the lens unit can be easily moved when positioning the lens unit. When positioning the lens unit while fixing it to the support base with a moderate gripping force, and then fixing the lens unit to the main body frame in earnest, it is necessary to fix the lens unit with a considerable force so as not to move semipermanently. However, a method in which the operator simply positions the lens unit while keeping the lens unit movable by hand, and then performs a fixing operation such as releasing the hand or tightening the screw while holding the lens unit by hand. Then, there is a problem that the lens unit that has been positioned is moved and the positioning accuracy cannot be kept high, that is, the position of the lens unit that has been positioned once is incorrect again.
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a comparatively easy adjustment of the position of the lens unit in an image reading apparatus that directly fixes the lens unit to the main body frame of the image reading apparatus. By providing a lens unit frame mounting structure that can be fixed in two stages: loose fixing and secure fixing after position adjustment, without applying external force that may cause the lens unit positioning to go wrong. is there.

In order to achieve the above object, the present invention provides a structure for fixing a lens unit to a frame through which image reading light passes, and a force for fixing the lens unit to the frame while the lens unit is fixed to the frame. This is a fixing structure for a frame of a lens unit provided with fixing force switching means for switching between two or more stages.
In this way, the lens unit can be switched with a weak fixing force that can be positioned, and the lens unit can be fixed to the frame with a strong fixing force semipermanently while the lens unit is fixed to the frame. , Once set, the lens unit can be accurately set without changing the position again. Moreover, such a configuration is extremely simple and can be manufactured at low cost.

As a specific example of the fixing force switching means, a first band shape for fixing the lens unit sandwiched between the frames by engaging with the frame by engaging portions provided at both ends is fixed to the frame. It is a member, Comprising: It can comprise as a 1st band-shaped member provided with two or more engagement parts in the longitudinal direction of this 1st band-shaped member at least at one end side.
Since the fixing force can be changed simply by switching the engaging portion, it can be configured very inexpensively.
As another specific example, the fixing force switching means has a second band shape for fixing a lens unit sandwiched between the frame by fixing both ends to the frame with screws. A second band-shaped member, wherein two or more screw insertion holes for inserting the screws are formed at different positions in the longitudinal direction of the second band-shaped member, at least one of the ends. Can be considered. Also in this case, the fixing force can be switched simply by tightening the screw, so that the object can be achieved at a very low cost as a structure.
Such a frame can be configured as a frame of the image reading apparatus or a support member fixed to the frame.
In this case, the image forming apparatus including the image reading device may be a copying machine, a facsimile, or an image scanner.

  According to the present invention, it is possible to switch between fixing the lens unit with a weak fixing force capable of positioning and fixing the lens unit to the frame with a semi-permanently strong fixing force while fixing the lens unit to the frame. As a result, the position of the lens unit once positioned can be set accurately without changing again. Moreover, such a configuration is extremely simple and can be manufactured at low cost.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
1 is an exploded perspective view of the lens unit fixing structure according to the embodiment of the present invention, FIG. 2 is a partial perspective view showing a mounting state of the fixing structure shown in FIG. 1, and FIG. 3 is another embodiment. FIG. 4 is a plan view of a band-like member used in the above embodiment, and FIG. 5 is a conceptual diagram showing a schematic configuration of an image reading apparatus as the background of the present invention. is there.
As shown in FIG. 1, the lens unit 1 to which the fixing structure according to this embodiment is applied is cylindrical, and the lens unit 1 is mounted on a support base 5 that forms a part of the frame of the image reading apparatus body. A mounting seat 7 for the lens unit 1 having a semicircular arc cross section is formed. The arc of the mounting seat 7 of the lens unit 1 is configured to be the same or substantially the same as the arc of the outer surface of the lens unit 1, and when the lens unit 1 is mounted on the mounting seat 7 as shown in FIG. Is designed so that the optical axis of the optical axis coincides exactly with the optical axis of the designed image sensor S.

FIG. 4A shows a first band-shaped member 10a that forms part of the fixing force switching means used in the lens unit fixing structure according to this embodiment. The first band-shaped member 10a is provided with two engaging portions 14a and 15a having different longitudinal positions of the first band-shaped member 10a at one end 12a. One engaging portion 16a is formed at the other end of the first band-shaped member 10a. In addition, as shown in FIG. 4, the band-shaped member 10a has an opening K1 as shown in FIG. 4, and can be easily bent along the lens unit 1 when attached to the support base 5 described later. It has been taken care of.
Further, an engaged portion 18a that can be engaged with the engaging portion 14a or 15a of the first band-shaped member 10a is further adjacent to one side of the mounting seat 7 and is adjacent to the other side of the mounting seat 7. Is formed with an engaged portion 19a engageable with the engaging portion 16a of the first band-shaped member 10a.
Since the engaging portions 14a to 16a are simple notches as shown in FIG. 4, the engaged portions 18a and 19a that engage with the engaging portions 14a to 16a may be simple protrusions that mesh with the notches.
When the mounting position of the lens unit 1 is adjusted, the engagement portion 16a of the first band-shaped member 10a is engaged with the engaged portion 19a as indicated by an arrow X in FIG. When the joining portion 14a is engaged with the engaged portion 18a, the lens unit 1 is temporarily fixed between the first band-shaped member 10a and the mounting seat 7 of the support base 5 (with a relatively loose force). Accordingly, the lens unit 1 is not detached from the mounting seat 7, but is movable along the central axis of the arc-shaped cross section of the mounting seat 7, that is, along the optical axis of the lens unit 1, that is, position adjustment. The lens unit 1 is fixed in a possible state.
Further, with the engaging portion 16a engaged with the engaged portion 19a, that is, with the lens unit 1 fixed to the support base 5, the outer engaging portion 14a with respect to the engaged portion 18a. When the inner engagement portion 15a is engaged with the engaged portion 18a by releasing the engagement, the lens unit is interposed between the first band-shaped member 10a and the mounting seat 7 of the support base 5. 1 is fixed (fixed with a strong force), whereby the lens unit 1 is firmly fixed to the mounting seat 7.
The loose temporary fixing of the lens unit 1 to the mounting seat 7 and the tight fixed fixing as described above are the distance L1 between the engaging portions 16a-15a and the engaging portions 16a-14a of the first band-shaped member 10a. This is caused by the difference from the distance L2.
In the lens unit mounting structure according to this embodiment, by switching the engaging portion 14a of the first band-shaped member 10a engaged with the engaged portion 18a on the main body frame side to the engaging portion 15a as described above, Only the fixing force of the lens unit 1 by the band-shaped member 10a is switched. This switching is achieved only by the operation of pushing the end portion 12a of the first band-shaped member into the back of the engaged portion 18a with the tip of the driver or an appropriate jig or the like. The fixed state of the lens unit 1 by the band-shaped member 10a is not loosened, or the first band-shaped member 10a is not displaced in the direction of the optical axis of the lens unit 1, and the position of the lens unit 1 whose position has been adjusted is adjusted. Thus, the problem that has occurred in the prior art such that the first band-like member 10a is displaced due to the re-mounting operation and is out of position is solved.
In the above embodiment, there are two engaging portions 14a and 15a formed at the end 12a of the first band-like member 10a. However, this is an example, and three or more engaging portions are provided. It is also possible to form a part. There is no problem even if two or more engaging portions 16a are formed. By forming a large number of engaging portions in this way, the distances L1 and L2 between the engaging portions can be further increased. In this case, the outer diameter of the lens unit 1 and the engaged portion 18a- A plurality of image reading devices having different distances 19a can be handled by one band-like member, which contributes to cost reduction.

FIG. 4B shows a second band-shaped member 10b that forms part of the fixing force switching means used in the lens unit fixing structure according to another embodiment. The second band-shaped member 10b is provided with two screw insertion holes 14b, 15b at different positions in the longitudinal direction of the second band-shaped member 10b at one end 12b. One screw insertion hole 16b is formed at the other end of the second band-shaped member 10b. As shown in FIG. 4, the band-shaped member 10b is also formed with an opening K2 in a substantially central portion, and can be easily bent along the lens unit 1 when attached to the support base 5 described later. It has been taken care of.
Further, in accordance with the structure of the second band-shaped member 10b, a screw inserted into the screw insertion holes 14b and 15b of the first band-shaped member can be mounted on one side of the mounting seat 7. The screw holes 18b and 20b are formed on the other side of the mounting seat 7, and a screw hole 19b into which a screw inserted into the screw insertion hole 16b of the second band-shaped member 10b can be mounted is formed. Yes.
When positioning the lens unit 1, the second band-shaped member 10b is placed along the support base 5 as shown in FIG. 3, and the screw B1 inserted into the screw insertion hole 16b is tightened into the screw insertion hole 19b. The screw inserted into the screw insertion hole 14b is tightened into the screw hole 18b. At this time, the lens unit 1 is temporarily fixed (relatively loosely fixed) between the second band-shaped member 10b and the mounting seat 7 of the support base 5, whereby the lens unit 1 is detached from the mounting seat 7. However, the position of the lens unit 1 in the axial direction can be freely adjusted by being able to move along the central axis of the cylindrical recess constituting the mounting seat 7, that is, along the optical axis of the lens unit 1.
Further, one end of the screw is fixed to the support base 5 with the screw B1 inserted into the screw insertion hole 16b, and the end 12b is fixed to the support base 5 with the screw B2 inserted into the outer screw insertion hole 14b. In this state, that is, while the lens unit 1 is fixed to the support base 5, the screw B3 is inserted into the inner screw insertion hole 15b, and the screw B3 is tightened into the screw hole 20b. The lens unit 1 is permanently fixed (fixed with a strong force) between the member 10b and the mounting seat 7 of the support base 5, whereby the lens unit 1 is firmly fixed to the mounting seat 7.
The loose temporary fixing to the mounting seat 7 of the lens unit 1 as described above and the tight fixed fixing are the distance L3 of the screw insertion hole 16b-14b in the second band-shaped member 10a and the engagement portions 16a-14a. This is caused by the difference from the distance L4.
In the lens unit mounting structure according to this embodiment, the fixing force is simply switched from temporary fixing to main fixing by simply tightening the screw B3 where the screws B1 and B2 are temporarily fixed as described above. I can do it. In this way, while maintaining the temporarily fixed state, it is possible to switch from temporary fixing to main fixing by simply tightening the screw B3. At this time, the lens unit 1 is fixed by the second band-shaped member 10b. Is not loosened or the second band-shaped member 10b is not displaced in the direction of the optical axis of the lens unit 1, so that the position of the lens unit 1 whose position has been adjusted is changed from the temporarily fixed state to the permanently fixed state. This eliminates the problem that has arisen in the prior art such that the position is shifted due to the change in position and the position is distorted.
In the above embodiment, there are two screw insertion holes 14b and 15b formed in the end 12a of the second band-shaped member 10b. However, this is an example, and there are three or more engaging portions. It is also possible to form There is no problem even if two or more screw insertion holes 16b are formed. By forming a number of combinations of the engaging portions in this way, the distances L3 and L4 between the engaging portions can be further increased, and a plurality of lens units having different outer shapes and different distances between the non-engaging portions. This image reading apparatus can be handled with one band-like member, which contributes to cost reduction. Further, the screw insertion holes 14b, 15b, 16b may be long holes.
In principle, the frame is configured as a frame of the image reading apparatus as described above. However, in some cases, the frame may be configured by a support member fixed to the frame.
In the above embodiment, the image forming apparatus provided with the image reading device is a copying machine. However, even if this is a printer, a facsimile, or an image scanner, the actual state of the invention does not change.

The disassembled perspective view of the lens unit fixing structure which concerns on embodiment of this invention. The partial perspective view which shows the attachment state of the attachment structure shown in FIG. The partial perspective view which shows the attachment structure of the lens unit concerning other embodiment. The top view of the band-shaped member used for both embodiment. 1 is a conceptual diagram showing a schematic configuration of an image reading apparatus as a background of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lens unit 5 ... Support stand 7 ... Mounting seat 10a ... 1st band-shaped member 10b ... 2nd band-shaped member 12a, 12b ... End part 14a, 15a, 16a ... Engagement part 18a, 19a ... Engagement Part 14b, 15b, 16b ... Screw insertion hole B1, B2, B3 ... Screw 18b, 19b, 20b ... Screw hole

Claims (5)

In the fixed structure to the frame of the lens unit through which the image reading light passes,
A fixing structure of the lens unit with respect to the frame, comprising fixing force switching means for switching the force for fixing the lens unit to the frame in two or more stages while the lens unit is fixed to the frame.   The fixing force switching means is a first band-shaped member that fixes the lens unit sandwiched between the frames by engaging with the frame by engaging portions provided at both ends. 2. The lens unit fixed to the frame according to claim 1, wherein at least one engagement portion on one end side includes two or more first band members provided at different positions in the longitudinal direction of the first band member. Construction.   The fixing force switching means is a second band-shaped member that fixes the lens unit sandwiched between the frame by fixing both ends to the frame with screws, and is at least one of The screw insertion hole for inserting the screw at one end includes a second band-shaped member formed by two or more at different positions in the longitudinal direction of the second band-shaped member. Fixed structure to the lens unit frame.   The structure for fixing a lens unit to a frame according to claim 1, wherein the frame is a frame of an image reading device or a support member fixed to the frame.   The lens unit frame fixing structure according to claim 4, wherein the image forming apparatus including the image reading device is a copying machine, a printer, a facsimile, or an image scanner.

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