JP2002267908A - Optical unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical unit which can decrease the number of components, the component cost, and the assembly man-hour. SOLUTION: An image reading optical unit 1 comprises a read lens 31, a photodetecting element array 32 which receives read original information through the read lens and photoelectrically converts it, and a base 33 which holds the read lens 31 and the photodetecting element array 32, and a holding part of the read lens 31 is formed of a groove 34 formed on the top surface of the base 33, and at least one read lens 31 is fixed in the groove 34. The fixation is performed, for example, with an adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital copying machine,
Facsimile, scanner, printing machine, barcode reader,
In addition, the present invention relates to an optical unit applicable to various devices including an image sensor and an image input device using the optical unit.

[0002]

2. Description of the Related Art Digital copiers, facsimiles,
2. Description of the Related Art An image input device including an image pickup device including a light receiving element array for photoelectrically converting document information is widely used in scanners and other devices having an image reading function. FIG. 13 is an explanatory diagram showing the principle of this type of image input device. In FIG. 13, the image input device 100
A transparent substrate 4, also called a contact glass, on which the original 6 is placed is fitted into the upper part of the housing 2. Case 2
A light source 10 is provided therein, and the original 6 is passed through the transparent substrate 4.
To illuminate with light from an oblique direction. The optical unit 1 is attached to a lower part of the housing 2. Optical unit 1
Is a lens barrel 12, a lens group 14 held in the lens barrel 12, a circuit board 16 fixed to the lower end surface of the lens barrel 12, and the lens group 14 of the circuit board 16. CCD as an image sensor mounted on the opposite surface
(Charge Coupled Device) 18. .

[0003] In the housing 2, first and second two long mirrors 8 and 20 are attached with their longitudinal directions parallel to the surface of the transparent substrate 4. Illumination light from the light source 10 irradiates the document 6 placed on the transparent substrate 4 and is reflected on the printing surface of the document 6. The reflected light from the document 6 is further reflected in the order of the second mirror 20 and the first mirror 8 and enters the optical unit 1. The reflected light that has entered the optical unit 1 reaches the CCD 18 through the lens group 14. Thus, the image of the document 6 is moved by the lens group 14 to the CCD 1.
The CCD 18 outputs a signal corresponding to the original image. Thus, this type of device has a C
The image of the original is linked to an image sensor such as a CD18,
Since the image signal is output from the image sensor, it is called an image input device. The image input device functions as a reading device of an image forming apparatus such as a copying machine, a facsimile, and a printer if the signal is subjected to an exposure process of an electrophotographic process. That is, by scanning the surface of the photoconductor with a light beam whose intensity changes according to the signal, an electrostatic latent image corresponding to the signal can be formed on the surface of the photoconductor. Alternatively, there are various modes of use, such as inputting the signal to a computer and performing image processing.

FIG. 14 is a view conceptually showing the optical unit 1 in the image input apparatus 100. In FIG. 14, the optical unit 1 includes a lens barrel 12 for holding a reading lens group 14, a circuit board 16 on which a CCD 18 as an image sensor is mounted, and a base 19 for holding these lens barrel 12 and the circuit board 16. It is mainly composed. Then, the CCD 18 extends on the extension of the optical axis of the lens group 14.
The center is located. The lens barrel 12 is fixed to a base 19 by a Ω-shaped holder 15. However,
The lens barrel 12 can be rotated around the optical axis of the lens group 14 before being fixed to the base 19.

In the image input apparatus 100 described with reference to FIGS. 13 and 14, the image of the original must be faithfully formed on the light receiving surface of the CCD 18. Therefore, as shown in FIG.
The circuit board 16 on which the CCD 18 is mounted and the circuit board 16 are arranged on a base 19 so that the rotational position of the lens barrel 12 can be adjusted so that a document image can be faithfully formed on the CCD 18. In this type of image input device 100, C
A line CCD is often used as the CD 18.
The line CCD is configured to read a document in a line.

The optical unit 1 configured as described above is
A production place where the lens group 14 is assembled to the lens barrel 12, and the lens barrel 12 and the circuit board 16 on the base 19.
May differ from the production site. When the lens group 14 is attached to the lens barrel 12, eccentricity occurs for each lens unit and eccentricity occurs due to assembly accuracy of each lens. Therefore, when the lens barrel 12 is fixed to the base 19 when the lens barrel 12 is fixed to the base 19 with the outer periphery of the lens barrel 12 as a reference, the eccentricity of the lens group 14 remains without being corrected, and the line CCD is left on the line CCD. Is a factor of deteriorating the imaging performance at

Ideally, on a line CCD, the optical performance near the image height 0, that is, near the center, and the optical performance on the plus image height side and the minus image height side are ideal. Therefore, the outer peripheral portion of the lens barrel 12 on the base 19 is configured to be rotatable along the inner periphery of the holder 15. By doing so, the lens barrel 12 can be rotated, and when the lens barrel 12 is rotated, the lens group 14 can be integrally rotated. Thereby, the lens group 14 also rotates around the optical axis. that time,
Since the imaging performance at each image height position fluctuates, the rotational position of the lens barrel 12 that can obtain the same optical performance near the image height 0, the plus image height, and the minus image height is detected. Then, the lens barrel 12 is fixed to the base 19 at that position.

On the other hand, MT is used as a scale for evaluating optical performance.
There is F. FIG. 15 shows an MTF vs. defocus curve. Curve A shows the MTF vs. defocus curve near the image height 0, curve B shows the MTF vs. defocus curve on the plus side of the image height. If the field curvature has asymmetry due to the eccentricity of the lens, as shown in the MTF vs. defocus curve shown in FIG. 15A, the MTF on the plus image height side and the minus image height side near the image height 0 is a boundary. Vs. defocus curve A,
B and C are shifted up and down, and the defocus position of the peak of each curve is largely shifted. As a result, the depth at the MTF standard value becomes shallow.

In the process of assembling the optical unit 1, as described above, the lens barrel 12 is rotated about the optical axis of the lens group 14 with respect to the CCD 18, as shown in FIG.
As shown in (b), the peak of the MTF versus defocus curve on the plus side and the minus side on the image height near the image height 0 can be made almost the same level, and the peak position of each curve can be changed. You can get closer. As a result, M
The depth at the TF standard value becomes deep. At this rotational position, the lens barrel 12 is fixed, and the relative positional relationship between the CCD 18 and the lens barrel 12 is maintained.

[0010]

As described above, in a conventional optical unit or an image input apparatus using the same, a production place for assembling a lens group to a lens barrel and a pedestal are provided. The production site where the lens barrel and the circuit board are fixed may be different from each other, and therefore, there is a problem that the number of parts tends to increase and the parts cost increases. In addition, when the number of components increases, the accuracy deteriorates due to the accumulation of the accuracy errors of the components, so that it is necessary to allocate tolerances to the components. As a result, adjustment standards for fixing the circuit board on which the CCD is mounted on the cradle and the lens barrel may eventually be narrowed, increasing not only the component costs but also the assembly adjustment costs.

As an optical unit of this kind, Japanese Patent Application Laid-Open No. 9-61239 discloses an invention in which the optical unit is sealed to eliminate the need for a glass for sealing a CCD package. And CCD
No particular mention was made of the adjustment of

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide an optical unit capable of reducing the number of parts, the cost of parts, and the number of assembling steps.

Further, by reducing the number of parts, the tolerance distribution is made more advantageous, and by making the tolerance distribution more advantageous, it is possible to increase the adjustment standard, thereby reducing the assembly adjustment cost. Is to provide.

[0014]

In order to achieve the above object, the present invention provides a reading lens, a light receiving element array to which read original information is incident via the reading lens and performs photoelectric conversion, and the reading lens. And an optical unit for reading an image comprising a base holding the light receiving element array, wherein a holding portion of the reading lens is formed in a groove shape on an upper surface of the base, and at least one of the reading lenses is formed in the groove shape. It is characterized by being fixed to the formed holding portion.

In this case, it is preferable to provide an adjustment mechanism for performing adjustment when fixing the lens to the holding section. Further, it is desirable that the fixing of the lens to the holding portion is performed via an adhesive.

It is to be noted that the fixing of the lens via the adhesive is performed at two positions symmetrical with respect to a side surface of the lens and a line passing through the center of the lens perpendicular to the optical axis. , Less mess after bonding. To fix the reading lens, a surface facing the mounting member of the reading lens is formed in a planar shape, and an adhesive is filled and adhered to the portion formed in the planar shape, and if it is fixed, the optical accuracy with less displacement is reduced. Can be provided.

Further, supporting means for supporting the light receiving element array movably along the optical axis in a state perpendicular to the optical axis of the reading lens, and supporting the light receiving element array along the optical axis of the reading lens. It is preferable to provide an adjusting mechanism that includes an adjusting unit that adjusts the focal position by moving the light receiving spur at the focal point of the reading lens. At this time, a support means for rotatably supporting one end of the light receiving element array on a base with one end of the light receiving element array as a fulcrum, and adjusting the eccentricity of the reading lens with respect to the optical axis by moving the other end side of the light receiving element array with respect to the fulcrum. It is desirable that the adjustment means can also adjust the inclination of the reading lens with respect to the optical axis.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a perspective view showing the structure of an optical unit according to a first embodiment of the present invention, and FIG.
Is a plan view. In the following description, the same reference numerals are given to the same components, and the duplicate description will be omitted.
Further, the image input device itself is the same as that described with reference to FIG. 13 described above, and thus redundant description will be omitted.

The optical unit 1 according to the present embodiment is shown in FIG.
As shown in FIG. 1, the optical system comprises a reading lens (group) 31, a light receiving element array 32, and a base 33 holding these. The base 33 is formed with a groove 34 along the optical path and an enlarged groove 34 a which extends in a fan shape on the extension of the groove, and a circuit board 30 for holding the light receiving element array 32 is provided. The reading lens 31 is held in the groove 34,
The groove 34 functions as a lens holding unit. As a method for holding the lens, a method in which the lens is directly fixed to the inner surface of the groove 34 by an adhesive or a ring-shaped mounting groove 35 is perpendicular to the axial direction of the groove 34 as shown in FIG. A method is used in which a large-diameter narrow groove 35 is formed by the inner surface of the lens, and the outer peripheral portion of the reading lens 31 is inserted into the narrow groove 35 and fixed by an adhesive. Needless to say, this fixing may be a strong fitting without using an adhesive. In this embodiment, the reading lens 31 does not enter the lens barrel as in the above-described conventional example, but is merely mounted in the groove 34 or the narrow groove 35 of the base 33 whose upper surface is opened. It goes without saying that the fixing method may be different for each lens.

The other parts, which are not particularly described, have the same configuration as the above-mentioned conventional example, and therefore, duplicate description will be omitted.

<Second Embodiment> FIG. 3 is a plan view showing an optical unit 1 according to a second embodiment. In this embodiment, at least one of the plurality of reading lenses can be fixed with the inclination of the lens adjusted with respect to the optical axis of the reading optical system in order to approach the desired optical performance. It was made.

That is, when assembling the plurality of lenses constituting the reading lens 31 on the base 33, the lens 31a having little influence on the optical performance is assembled with mechanical accuracy, and the lens 31b having a great influence on the optical performance can be adjusted. By doing so, the optical performance of the entire reading lens 31 can be set to a desired value.

FIG. 3 shows an example in which the arm 36 is extended from the side surface of the lens 31b to be adjusted, and adjustment is performed using the arm 36. When the arm 36 is provided in this manner, the side on which the arm 36 is not provided is located on the groove 3 of the base 33.
5, the end on the same side is brought into contact with the base 33, and this arm is used as a fulcrum, and the arm 36 is moved in the direction of the arrow in the drawing, whereby the inclination with respect to the optical axis can be adjusted.
In addition, for adjustment, the adjusting member 3
7 may be provided. As the adjusting member 37, for example, a screw member or the like can be used.

On the other hand, in order to assemble and adjust the lens 31c having no arm on the side surface to the base 33, for example, an arm 38a such as an adjuster or an adjusting jig 38 is used to adjust the lens 31c.
Need to be chucked and the desired adjustments made. FIG.
Is an example in which an arm 38a such as an adjusting device or an adjusting jig 38 is processed so as to easily chuck the side surface of the lens 31c, and the lens 31c is adjusted so that sufficient friction is obtained between the arm 38a and the lens 31c. The surface roughness of the side surface 31c 'is increased.

Other parts, which are not particularly described, have the same configuration as those of the above-described conventional example and the first embodiment.

<Third Embodiment> FIGS. 5 and 6 show a third embodiment.
It is a top view showing optical unit 1 concerning an embodiment.
In this embodiment, at least one lens 31 is fixed with the adhesive 35a when fixing the lens 31 in the narrow groove 35 described above.

There are roughly two methods for fixing with the adhesive 35a. One is a method called an adhesion bonding method in which only the portions where the bonding locations are in contact with each other as shown in FIG. 5, and the other is a method in which a gap is formed in the bonding locations as shown in FIG. However, there is a method called filling bonding in which the space therebetween is filled with an adhesive 35a and bonded. In any case, it is necessary to perform the above-mentioned adjustment before bonding, and after the adjustment, hold the lens 31 and the narrow groove 35 or the base 33 until they are fixed by the adhesive 35a so that the relative positions of the narrow groove 35 and the base 33 are not disturbed. Of course there are.

Other parts not particularly described are constructed in the same manner as in the above-described conventional example and the first embodiment.

<Fourth Embodiment> FIG. 7 is a sectional view showing a main part of an optical unit 1 according to a fourth embodiment.

In this embodiment, a more specific bonding position is specified with respect to the adhesive fixing method in the third embodiment. That is, this is an example in which, when the lens 31 is bonded and fixed to the groove 34 or the narrow groove 35 of the base 33, two symmetrical portions on the side surface of the lens 31 are bonded and fixed. More specifically, in this embodiment, the filling and bonding of the third embodiment shown in FIG. 6 is performed at two symmetrical positions with respect to the vertical line L passing through the center of the lens 31 in FIG. Adhesion at such a position makes it difficult for positional displacement to occur due to adhesive curing or environmental fluctuations. On the other hand, as shown in FIG. 8A, when the number of bonding points is one, even if bonding is performed in consideration of the center of gravity of the lens 31, as shown in FIG. The displacement causes a displacement, and it becomes impossible to obtain desired characteristics.

Other parts not particularly described are configured in the same manner as in the above-described conventional example and the first embodiment.

<Fifth Embodiment> FIG. 9 is a plan view showing an optical unit 1 according to a fifth embodiment.

In this embodiment, the light receiving element array 32
Is an example of adjusting the focal position of the incident light that enters the line sensor from the reading lens 31 by adjusting the position of. That is, in order to obtain the above-described reading characteristics of the reading lens 31, it is necessary to position the light receiving element array 32 at a good image forming position. In the fifth embodiment, the light receiving element array 3
2 is an example in which it can be adjusted in a direction perpendicular to the optical axis of the reading lens 31.

In this example, the circuit board 30 of the light receiving element array 32 is slidably held, and the focus position adjusting member 39 is disposed at the center of the circuit board 30, that is, substantially on the optical axis of the reading lens 31. ing. The focus position adjusting member 39 is of a screw type, and by rotating a screw 39a, the circuit board 30, that is, the light receiving element array 32 is rotated.
Can be moved in parallel in a direction perpendicular to the optical axis. Note that the circuit board 30 itself is held perpendicular to the base 33, and moves in parallel while maintaining this state.

Other parts not particularly described are configured in the same manner as in the above-described conventional example and the first embodiment. It is desirable that this adjustment mechanism be used together with the lens adjustment mechanism as in the second embodiment.

<Sixth Embodiment> FIG. 10 is a plan view showing an optical unit 1 according to a sixth embodiment.

In this embodiment, the light receiving element array 32
This is an example in which the inclination of the circuit board 30 is adjusted to adjust the eccentricity with respect to the incident light from the reading lens 31 to the line sensor. That is, in order to obtain the above-described reading characteristics of the reading lens 31, it is necessary to make light incident on each light receiving element of the light receiving element array 32 under the same conditions. In the sixth embodiment, the light receiving element array 32 is
This is an example in which the inclination with respect to the optical axis can be adjusted.

In this example, a pivot 40 is provided at one end of the circuit board 30 of the light receiving element array 32, and the pivot 40
This is an example in which one end is rotatably supported with respect to and the eccentric position adjusting member 41 is arranged on the other end side. This eccentricity adjusting member 41
Is a screw type, and the circuit board 30 can be inclined with respect to the optical axis by rotating the screw 41a. The circuit board 30 itself is held vertically with respect to the base 33.
3 move on.

The other parts which are not particularly described are constructed in the same manner as in the above-described conventional example and the first embodiment. The adjusting mechanism is a lens adjusting mechanism as in the second embodiment and a light receiving element array 32 as in the fifth embodiment.
It is desirable to use together with the adjustment mechanism of (1).

What is important for the image reading apparatus is the reading lens 31.
And the light receiving element array 32 that photoelectrically converts the document information. This position accuracy is determined when the light receiving element array 32 has one reading line as shown in the explanatory diagram of FIG.
Position accuracy of several μ units is required at positions with five degrees of freedom of x, y, z, α, and β. In order to read a color image, a three-line light receiving element array or the like in which pixels having spectral sensitivity peaks in red, green, and blue are arranged in three rows for each color is used, and x, y, z, α, β, and γ are used. The position accuracy of several μ units is required at the position having six degrees of freedom.

Such positional accuracy can be ensured by using the three mechanisms of the above-described lens adjusting mechanism, light receiving element array parallel position adjusting mechanism, and light receiving element array eccentricity adjusting mechanism.

<Seventh Embodiment> FIG. 12 is a sectional view showing a state of a lens mounting portion of an optical unit 1 according to a seventh embodiment.

In this embodiment, a flat portion 31a is formed on the edge of the reading lens 31, and an adhesive 35a is filled between the flat portion 31a and the grooves 34 and 35 provided on the base 33 to fix the reading lens 31. This is an example. At least one of the lenses to be assembled is formed into such a shape, and is attached to the base 33 via an adhesive, so that the attachment strength can be improved.

The other parts which are not particularly described have the same construction as those of the above-described conventional example and the first embodiment.

[0046]

As described above, according to the present invention, the following effects can be obtained.

According to the first aspect of the present invention, since the lens barrel of the reading lens becomes unnecessary, the number of parts can be reduced, and the cost of parts can be reduced. Further, since the number of parts is small, it is possible to omit redundant adjustment and assembling work, and it is possible to reduce assembly and adjustment costs by reducing man-hours. Furthermore, by reducing the number of parts, the number of parts to which tolerances are assigned is reduced, and accordingly, the adjustment range of each part is widened, or the adjustment accuracy is loosened, and adjustment is facilitated.

According to the second aspect of the present invention, since the adjustment mechanism for adjusting the lens at the time of fixing is provided, it is possible to adjust the lens and then fix it, thereby bringing the optical performance close to a desired value. be able to.

According to the third aspect of the present invention, since an adhesive is used to fix the lens, the work of assembling and fixing the lens becomes easy.

According to the fourth aspect of the present invention, since the bonding points are two symmetrical points, it is possible to minimize the occurrence of displacement due to adhesive curing or environmental fluctuation.

According to the fifth aspect of the present invention, since the flat portion is formed on the side surface of the reading lens, and the flat portion and the member are attached via the adhesive, the mounting strength can be improved. it can.

According to the sixth aspect of the invention, the relative distance between the reading lens and the light receiving element array can be adjusted in accordance with the state of the assembled reading lens, so that the desired performance of the reading lens is obtained. It becomes possible.

According to the seventh aspect of the present invention, the eccentricity of the light receiving element array can be adjusted in accordance with the state of the assembled reading lens, so that the desired performance of the reading lens can be obtained. Become.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical unit according to a first embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a plan view of an optical unit according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a modification of the second embodiment of the present invention.

FIG. 5 is a plan view of an optical unit according to a third embodiment of the present invention.

FIG. 6 is a plan view of an optical unit according to a modification of the third embodiment of the present invention.

FIG. 7 is a sectional view showing a lens bonding portion of an optical unit according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing a comparative example with respect to the fourth embodiment.

FIG. 9 is a plan view of an optical unit according to a fifth embodiment of the present invention.

FIG. 10 is a plan view of an optical unit according to a sixth embodiment of the present invention.

FIG. 11 is a diagram for explaining the necessity of adjusting a reading lens, a light receiving element array, and an optical axis.

FIG. 12 is a plan view of an optical unit according to a seventh embodiment of the present invention.

FIG. 13 is a cross-sectional view illustrating a schematic configuration of a conventional image reading apparatus.

FIG. 14 is a perspective view of an optical unit according to a conventional example.

FIG. 15 is a diagram illustrating a relationship between MTF and defocus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical unit 31 Reading lens (group) 31a, 31b Reading lens 32 Light receiving element array 33 Base 34 Groove 35 Narrow groove 35a Adhesive 36 Arm 37 Adjusting member 39 Focus position adjusting member 40 Rotating fulcrum 41 Eccentricity adjusting member

Continued on the front page F term (reference) 2H044 AA02 AA13 AA16 AA17 AC01 AE06 5C051 AA01 BA03 DA03 DB01 DB04 DB22 DB35 FA01

Claims (7)

[Claims] 1. An image reading apparatus comprising: a reading lens; a light receiving element array to which read original information is incident via the reading lens and photoelectrically converts the information; and a base holding the reading lens and the light receiving element array. In the optical unit, the holding portion of the reading lens is formed in a groove shape on the upper surface of the base, and at least one of the reading lenses is fixed to the holding portion formed in the groove shape. Optical unit. 2. The optical unit according to claim 1, further comprising an adjustment mechanism for performing adjustment when fixing the lens to the holding section. 3. The optical unit according to claim 1, wherein the fixing of the lens to the holding portion is performed via an adhesive. 4. The fixing of the lens through the adhesive is performed at two points symmetrical with respect to a side surface of the lens and a line passing through the center of the lens perpendicular to the optical axis. The optical unit according to claim 3, wherein: 5. The optical unit according to claim 4, wherein a side portion of the lens fixed by the adhesive is formed in a flat shape. 6. A support means for supporting the light receiving element array movably along the optical axis in a state perpendicular to the optical axis of the reading lens, and supporting the light receiving element array along the optical axis of the reading lens. The optical unit according to claim 1, further comprising an adjustment unit configured to adjust the focal position by moving the optical unit. 7. A support means for rotatably supporting one end of the light receiving element array on a base with one end of the light receiving element array as a fulcrum, and moving the other end of the light receiving element array with respect to the fulcrum to decenter the reading lens with respect to the optical axis. The optical unit according to any one of claims 1 to 6, further comprising an adjusting unit configured to adjust the distance.