JP2002082282A - Document reading lens / Document reading lens unit / Document reading module / Document reading method / Document reading device / Image information processing device - Google Patents

Abstract

(57) [Summary] A document reading lens having a structure of 3 to 5 lenses, the number of lenses being smaller than that of a Gaussian type, and having performance equal to or higher than that of a Gaussian type. A lens for reading an image,
The front group GF is disposed on the object side, and the rear group GR is disposed on the image side. The front group GF includes two to four lenses including one or more positive lenses, and the rear group GR includes one lens. The back focus B in the actual use state is 30% or less of the total lens length A, and the air gap C between the front group GF and the rear group GR is 50% or more of the total lens length. is there.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a document reading lens, a document reading lens unit, a document reading module, a document reading method, a document reading device, and an image information processing device.

[0002]

2. Description of the Related Art Document reading lenses are used in digital copying machines and various scanners. Document scanning density is 3
00 dpi (dots per inch), 400 dpi
i, to 600 dpi, and further to 1200 dpi, and accordingly, high performance is required for the original reading lens. The "Gaussian" type, which has been widely known as a document reading lens,
High resolution can be realized with a relatively large diameter. But recently,
In order to achieve the high performance required for a document reading lens, at least six lenses are required, for example, as described in JP-A-2000-111794.

On the other hand, JP-A-7-56085 discloses that
A document reading lens intended to achieve high performance with a two-sheet configuration is described. However, the performance that can be achieved with the two-sheet configuration is naturally limited, and its use is limited to those that do not require a very high reading resolution, such as a facsimile and an image scanner.

[0004]

SUMMARY OF THE INVENTION The present invention has a structure of three to five lenses, and the number of lenses is smaller than that of a Gauss type lens.
It is another object of the present invention to realize a document reading lens having a performance equal to or better than that of a Gaussian type.

[0005]

In order to solve the above problems, in the present invention, the number of original reading lenses is set to a minimum of three, the power of the lens arranged closest to the image side is set to "negative", and The negative power lens is arranged near the image plane. Set the number of lenses to "minimum 3
With “sheets”, various aberrations can be easily corrected, and high performance can be realized. That is, the original reading lens of the present invention is a "lens for reading an original image", and has a front group on the object side and a rear group on the image side. The “front group” includes two to four lenses including one or more positive lenses.
The “rear group” includes one negative lens. Therefore, the total number of components is 3 to 5. The back focus in the actual use state is 30% or less of the entire length of the lens,
The air gap between the front group and the rear group is 50% or more of the entire length of the lens. The front group can be composed of two lenses, can be composed of three lenses, and can be composed of four lenses.

The document reading lens according to the first aspect of the invention can be configured such that "all lenses are configured as spherical lenses". When all the lenses are constituted by spherical lenses in this manner, the production of each constituent lens is easy, and the original reading lens can be realized at low cost. Of course, in the original reading lens according to the first aspect, one or more lens surfaces may be aspherical. In this case, the aspherical surface can be used for the “rear group incident side surface (object side surface)” (claim 2) or can be used for the “rear group image side surface” (claim 3). That is, the rear group may have an aspherical object side surface and / or an image side surface. In the original reading lens according to any one of the first to third aspects, "the rear group may be a plastic lens" (claim 4). In the document reading lens according to the present invention, since the rear group is arranged near the image plane, the size of the rear group is larger than that of the front group. Therefore, by configuring such a large lens with plastic, the cost of the original reading lens can be further reduced.
If the rear group is made of a plastic lens, it is easy to form an aspherical surface when an aspherical surface is used for the object side surface and / or the image side surface.

[0007] The rear unit is arranged near the image plane.
Since the light receiving element array is arranged, the outer shape of the rear group does not have to be “rotationally symmetric with respect to the optical axis” (claim 5).
In this case, the outer shape of the rear group can be a "strip shape long in the main scanning direction" (claim 6). Here, the “main scanning direction” refers to the arrangement direction of the light receiving elements in the light receiving element array combined with the document reading lens. When the rear group is made of a plastic lens, a "positioning, holding, or fixing engagement portion" can be formed in a part of the rear group (claim 7). The engaging portion is a convex portion or a concave portion. In the original reading lens according to any one of the first to seventh aspects, the back focus in the actual use state can be set to "10% or less of the entire length of the lens" (claim 8). A shorter back focus is "advantageous in correcting aberrations". The “back focus is 30% of the entire lens length” of the original reading lens according to claim 1 is the upper limit of the back focus. However, if there is a large back focus within 30% of the entire lens length, for example, there is an advantage that an "adjustment mechanism for adjusting the position of the light receiving element array with respect to the rear group" can be arranged in the back focus. In the original reading lens according to claims 5 to 7, the outer shape of the rear group is not rotationally symmetric with respect to the optical axis, but the outer shape of both the front group and the rear group is rotationally symmetric with respect to the optical axis, and the original is scanned by the area sensor. Can be read simultaneously.

[0008] To achieve good performance in the document reading lens according to any one of the preceding claims 1-8, "front group of focal length is a focal length of f _F and the rear group: balance f _R" is Becomes important.

[0009] These focal length: f _F and f _R preferably has a magnitude of the absolute value of the same degree, both the ratio: ranges of f _R / f _F is -1.8 <f _R It is preferable that / f _F <−0.8.

An original reading lens unit according to the present invention holds the original reading lens according to any one of the first to eighth aspects described above, and each lens of the original reading lens, and integrates the entire original reading lens. And a holding means for changing the shape (claim 9). The “holding unit” may be formed by integrally forming a holding unit for holding each lens of the front group and a rear group mounting unit for mounting the rear group, or the front group of the document reading lens. It is also possible to provide a front group holding means for holding, a rear group holding means for holding the rear group, and a connecting means for integrating these holding means. In this case, the front group holding means can be "translatable in the optical axis direction and / or rotatable about the optical axis relative to the rear group holding means". If the front group can be translated and displaced in the optical axis direction, the focus can be adjusted by the displacement of the front group in the optical axis direction. When the front unit is rotatable around the optical axis, by rotating the front unit, the inclination of the image plane due to eccentricity or the like can be adjusted. The document reading lens unit according to the ninth aspect may have "one or more bending mirrors for bending the optical path" between the front group and the rear group of the document reading lens. By using one or more bending mirrors, the degree of freedom of the layout of the document reading lens is increased.

The document reading lens unit may have "shading means for correcting the brightness of the image on the image plane in the main scanning direction" between the front group and the rear group of the document reading lens. In this case, the shading means can be a "light shield plate having an opening of a predetermined shape". Further, by providing the bending mirror with a predetermined reflection surface shape, the bending mirror can also serve as “shading means for correcting the brightness of an image in the main scanning direction on the image plane”. Note that, in the case where the entire screen of the document is read at one time using the area sensor, the shading means can correct the brightness of the image on the area sensor.

The "document reading module" of the present invention is a module for reading a document image and converting it into an electric signal, and has a document reading lens and a light receiving element array.
The “document reading lens” is the document reading lens according to any one of the first to eighth aspects. "Light receiving element array"
An image of a document image formed by the document reading lens is sampled and subjected to photoelectric conversion. The document reading module according to the tenth aspect of the present invention can be configured as “a configuration in which the rear group of the document reading lens and the light receiving element array are integrated”. In the document reading module according to the eleventh aspect, when the “back focus in the actual use state” of the document reading lens is sufficiently short, the image side surface of the rear group can “also serve as a shield material of the package of the light receiving element array” ( Claim 12). In particular, when the back focus in the actual use state of the document reading lens is substantially 0, that is, when the image side of the rear group coincides with the image plane, "the light receiving element array is directly attached to the image side of the rear group. (Claim 13). In the case of the document reading module described in claim 13, the image side surface of the rear group of the document reading lens may be non-planar.

In the document reading module according to any one of claims 10 to 14, the document reading lens may be integrated by a holding unit, and the document reading lens and the holding unit may be combined by the document reading lens. It is possible to constitute a lens unit (claim 15).
The holding means may be “a holding unit for holding each lens of the front group and a rear group mounting unit for mounting the rear group integrally formed” (Claim 16). It has a front group holding means for holding a group, a rear group holding means for holding a rear group, and a connecting means for integrating these holding means "(claim 17), in the latter case. It is also possible to make the front group holding means relatively translatable and displaceable in the optical axis direction relative to the rear group holding means (claim 18). To be rotatable around the optical axis. "
9) In the document reading module according to claim 19, "the front group holding means can be translated and displaced in the optical axis direction relative to the rear group holding means" (claim 20).

The document reading module according to any one of claims 10 to 20 may have "a folding mirror for bending an optical path between a front group and a rear group of document reading lenses". And "shading means for correcting the brightness of the image in the main scanning direction on the image plane between the front group and the rear group of the original reading lens" can be provided (claim 22). The shading means of the document reading module according to the twenty-second aspect can be a "light-shielding plate having an opening having a predetermined shape" (claim 23), or a folding mirror as in the document reading module according to the twenty-first aspect. In this case, the reflecting surface of the folding mirror can be formed into a predetermined reflecting surface shape, and can also serve as a shading means for correcting the brightness of the image in the main scanning direction on the image surface. .

The document reading method according to the present invention includes the steps of "forming an image of a document image by a document reading lens on a light receiving element array,
A document reading method for scanning a document, reading a document image, and converting it into an electric signal, wherein the document reading lens is used as a document reading lens.
The document scanning lens according to any one of (1) to (5) is used. In the document reading method according to the twenty-fifth aspect, "the document reading lens is unitized as a document reading lens unit, and the unit reading document unit is used as the unitized document reading unit." Further, in the document reading method according to claim 25, the document reading module and the light receiving element array are used as a document reading module, and the document reading module according to any one of claims 10 to 24 is used as the document reading module. Use. "

The scanning of the original in the original reading method can be performed by "moving the original with respect to the original illuminating unit while illuminating the original with the original illuminating unit set at a fixed position". Fixing the part from the reading lens to the light receiving element array, illuminating the original in the main scanning direction by the illuminating means, guiding the light flux from the original part illuminated by the illuminating means to the original reading lens by a group of mirrors, Is displaced in the sub-scanning direction, and the one group of mirrors is displaced while maintaining the optical path length of the light guide from the illumination unit by the illumination lamp to the document reading lens. "

The document reading apparatus according to the present invention is configured such that "an image of a document image formed by a document reading lens is formed on a light receiving element array,
A document reading apparatus that reads a document image and converts it into an electric signal while scanning the document, comprising: a scanning unit, a light receiving element array, a document reading lens, a signal processing unit, and an image processing unit. ). "Scanning means" is means for scanning a document. The “light receiving element array” samples an image formed thereon and performs photoelectric conversion. The "document reading lens" converts the light flux from the scanned document
2. A lens which forms an image on a light receiving element array.
The original reading lens described in any one of (1) to (8) is used.
The "signal processing means" processes the output signal of the light receiving element array. The "image processing means" performs image processing on the signal that has been subjected to the signal processing.

In the document reading apparatus according to the twenty-sixth aspect, the document reading lens can be unitized as a document reading lens unit, and the document reading lens unit according to the ninth aspect can be used as a unitized document reading unit. (Claim 27) Alternatively, the document reading lens and the light receiving element array may be used as a document reading module, and the document reading module according to any one of claims 10 to 24 may be used as the document reading module. Claim 28). The document reading device according to claim 26, 27 or 28, wherein the scanning means for scanning the document comprises:
It can be constituted by contact glass, running means, and lighting means (claim 29). The “contact glass” is provided at a fixed position. The "traveling means" travels the document in contact with the surface of the contact glass. The “illuminating unit” illuminates the original on the contact glass in the main scanning direction.

The "scanning means for the manuscript" in the manuscript reading apparatus according to the twenty-sixth or twenty-seventh aspect can also be constituted by a manuscript glass, illumination means, a group of mirrors, and displacement means. (Claim 30).
The “document glass” is a glass plate for placing the document in a plane. The “illuminating unit” is a unit that illuminates the original placed on the original glass in the main scanning direction. "1
The group mirror "guides the light beam from the document portion illuminated by the illumination means to the document reading lens. "Displacement means"
Displaces the illuminating means in the sub-scanning direction (a direction orthogonal to the main scanning direction) and displaces the one group of mirrors while maintaining the optical path length of the light guide from the illuminating section by the illuminating means to the original reading lens. . The document reading apparatus according to any one of claims 26 to 30, wherein "the signal processing means and / or
Alternatively, the image processing means has a function of electrically adjusting the reading magnification. "

An image information processing apparatus according to the present invention comprises an image information reading apparatus comprising: a document reading apparatus for reading a document image and converting the signal into an electric signal; and an output unit for outputting signal information converted into an electric signal by the document reading apparatus. And a document reading device according to any one of claims 26 to 31 (claim 3).
2). The above-mentioned "output means" displays an image on a display medium (CRT, liquid crystal display, liquid crystal panel of a liquid crystal projector, etc.)
It can be a display device for displaying on top (claim 33) or a "writing device for writing image information on an electronic recording medium (magnetic tape, magnetic disk or various optical disks)" (claim). 34),
"It may be a transmission device (such as a facsimile transmission part) for transmitting image information in a wired or wireless communication form.
5), a printer device that prints image information on a sheet-like recording medium such as plain paper or an OHP sheet (such as a plastic sheet for an overhead projector) may be used (claim 36). The “printer device as an output unit” can be an ink jet printer or an “electrophotographic optical printer device”. The image information processing apparatus according to claim 32,
The output means may have two or more of the above. For example, if the above-described transmission device, writing device, printer device, or the like is provided as an output device, the image information processing device reads a document to form image information, and writes and records this on a magnetic disk or optical disk such as a floppy disk. Information processing with multiple functions, such as a function as a reading device, a facsimile function for transmitting image information of a read document by a transmission device, and a function as an image forming device for forming a read document on a sheet-shaped recording medium. Device.

[0021]

FIG. 1 shows an embodiment of a document reading lens according to the present invention. As shown in FIG. 1, the original reading lens has a front group GF on the object side (left side in the figure) and a rear group GR on the image side. The front group GF includes "one or more positive lenses. The rear group GR includes “1 lens”.
Of negative lenses. In this embodiment, the number of members of the front group is three, but the number of members of the front group can be two, as shown in an example described later.
4 can also be used. In FIG. 1, the distance: B is “the back focus (the distance between the image side surface of the rear group GR and the image surface IS) in the actual use state”, the distance: A is “the entire lens length”, and the distance: C is “the front group GF” Air gap between the rear group GR "
It is. The back focus B in the actual use state is “the total length of the lens: 30% or less of A”, and the air gap C is “the full length of the lens: 50% or more of A”. The symbol S in FIG. 1 indicates an aperture. The stop S is provided at an appropriate position of the front group GF by an appropriate method. Front group G
F mainly shares the imaging action, and the rear group GR plays a role as a so-called “field flattener”.

In order to ensure "sufficient imaging performance" for such a document reading lens, the front group GF needs to be composed of two or more lenses. If the front group is composed of one sheet, even if an aspherical surface is introduced into the lens surface, its aberration correction capability is limited, and it is used as a document reading lens for digital copiers and "multifunctional image information processing apparatuses". But not enough performance. In order for the rear group GR to fully fulfill the role of "field flatner",
The back focus B in the actual use state needs to be 30% or less of the total lens length A. In order to efficiently correct the “field curvature” of the front group GF with the rear group GR, it is necessary to increase the “off-axis principal ray height” in the rear group GR as much as possible. B is desirably short. Further, in order to reduce the size of the front group GR, the air gap C between the front group GF and the rear group GR needs to be 50% or more of the total lens length A. Air spacing: C
However, if it is smaller than 50% of the total lens length: A, the “front group GF becomes large” and the cost is increased.

By adopting the above configuration, the original reading lens of the present invention is disclosed in, for example, JP-A-2000-111.
A function equivalent to or greater than “a Gaussian original reading lens having a six-sheet configuration” as described in JP-A-794.
The performance can be realized with "smaller number of components" of 3 to 5, and cost reduction can be achieved.

Further, by forming the rear group GR as a plastic lens, the cost can be further reduced. In the document reading lens according to the present invention, the rear group GR is arranged near the image plane IS, so that the paraxial ray height in the rear group GR is reduced. For this reason, when the rear group GR is made of plastic, even if the "power fluctuation of the rear group GR due to a temperature change" becomes large, the "effect on aberration and back focus" of the power fluctuation is small. For this reason, the rear group GR of the original reading lens of the present invention is suitable for plasticization. In order to make the original reading lens of the present invention "larger in diameter and higher in performance", it is desirable that at least one surface of the rear group GR be aspherical.

Since the rear group GR is close to the image plane IS, and the light flux for each image height passes sufficiently separated, an aspherical surface is introduced into the rear group GR to "effectively correct off-axis aberrations". be able to. In particular, when the rear group GR is a "plastic molded product", an aspherical surface can be introduced relatively easily, and there is almost no increase in cost. The rear group GR can have a “shape that is not rotationally symmetric with respect to the optical axis” as necessary. One-dimensional light receiving element array (line sensor)
When used in combination with the above, the light beam effective range required for the rear group GR is “a belt-like shape that is long in the main scanning direction and short in the sub-scanning direction”. In such a case, the shape of the rear group GR is as shown in FIG.
Can be a "strip-shaped outer shape obtained by cutting off a part of a circle", or can have a "rectangular outer shape" as indicated by reference numeral GR 'in FIG. As described above, it is possible to make the rear groups GR and GR 'non-rotationally symmetrical outer shapes by using a glass lens as the rear group, but it can be more easily realized by making the rear group a molded plastic product.

In the case where the rear group is made of a molded plastic product, an engaging portion 41 for positioning and engaging portions 42 and 43 for holding or fixing may be provided as in the rear group GRa shown in FIG. Easy (can be formed integrally with the lens). 2 to 4, the left figures are perspective views, and the right figures are views seen from the optical axis direction. In the document reading lens described above, the front group GF and the rear group GR are held by holding means, and the whole is integrated into a "document reading lens". The holding means includes a holding unit that holds each lens of the front group,
An embodiment in which the rear group mounting portion to which the rear group is mounted is formed integrally will be described later. FIG. A group holding means, a rear group holding means for holding the rear group, and a connecting means for integrating the respective holding means. " In FIG. 5, the front lens barrel 50 is a “front group holding unit that holds the front group”. Rear group G
The rear group holding means 51 for holding Ra is substantially “rectangular flat plate”, and has seats 53 and 55 for forming positioning grooves at longitudinal ends, and holds the rear group GRa. Column-shaped engaging portions 57 and 59 for fixing are provided upright.

The rear group GRa is of the type shown in FIG. 4, and the positioning engagement portion 41 is moved in the longitudinal direction (main scanning method).
An engaging portion 42 (not shown) for holding and fixing and an engaging portion 43 are formed on both sides in the longitudinal direction. The rear group GRa is configured such that the engagement portion 41 is
The engaging portions 42 and 43 for holding and fixing are pressed by leaf springs 57 a and 59 a provided on the engaging portions 57 and 59, and are positioned in the groove between the rear group holding members 55. It is fixed to 51.

The front lens barrel 50 for holding the front lens group GF is formed in a rotationally symmetrical shape with respect to the optical axis, and is locked to the flat part of the holding means 51 by the connecting means 52. That is, the front-group barrel 50 is integrated with the rear-group holding means 51 by the connecting means 52, but the front-group barrel 50 is integrated with the rear-group holding means 51, It is rotatable with respect to the optical axis of the group GR, and is displaceable in the optical axis direction. When the original reading lens unit is configured as described above,
By rotating only the front group GR about the optical axis, the "tilt of the image plane caused by eccentricity of the lenses" can be adjusted, and the effect is obtained when used in combination with a one-dimensional light receiving element array (line sensor). large.

Further, "focus adjustment" can be performed by moving only the front group GF in the optical axis direction. In this case, by not moving the rear group, the "mounting structure" can be simplified as shown in the figure, especially when the rear group is not in a rotationally symmetric shape. As shown in FIG. 5, the rear group GRa is provided by the rear group holding means 51 having the seat portions 53 and 55.
(Thickness in the sub-scanning direction) can be set thin. In configuring the original reading lens unit,
Various forms of the holding means are possible. Also, when the document reading lens is integrated by the holding means, there is a degree of freedom in the form of the document reading lens held. For example,
In the embodiment of FIG. 6A, the front group GF and the rear group GR are arranged on the optical axis straight line and are integrated by an appropriate holding means 61. In the embodiment shown in FIG. 6B, the optical axis of the original reading lens is integrated by a suitable holding means 62 between the front group GF and the rear group GR with the optical path bent by the bending mirror M. Has been

By "bending the optical path" in this way,
The degree of freedom of layout in the document reading device increases.

The brightness of an image formed by an imaging lens generally follows a cosine fourth law, and decreases toward the periphery of the image. This is no exception in the document reading lens, and the brightness of the document image on the image plane where the light receiving means is located gradually decreases from the optical axis toward the periphery.
If the “document image having uneven brightness” is read as it is, “uneven density” appears in the reproduced image when the image is reproduced with the read image information. The density unevenness can be eliminated by electrically correcting the read image information, setting the illuminance distribution so that the illuminance of the original illuminating unit increases from the center to the peripheral portion, and setting the optical path of the image forming light flux. This can be achieved by providing so-called shading means in the inside, or by combining two or more of these methods. In the document reading lens according to the present invention, since the space between the front group and the rear group is widely open, shading means can be provided in this portion, and a space for providing shading means is provided in a space outside the document reading lens. Do not need. FIG. 7 shows an embodiment of a document reading lens unit having shading means 71 for correcting the brightness of an image in the main scanning direction on the image plane between a front group GF and a rear group GRa of the document reading lens. Is shown.

In this embodiment, the shading means 71 is a light-shielding plate (shading correction plate) having an opening of a predetermined shape (a shape in which a light beam portion with a small angle of view blocks light more). 51 fixedly provided. In FIG. 7, parts other than the shading correction plate 71 are the same as those in the embodiment of FIG. Further, when the optical path is bent by the bending mirror M between the front group GF and the rear group GR as in the document reading lens unit shown in FIG. And a reflection part MR,
By forming a non-reflecting portion NR around the reflecting portion MR, the shape of the reflecting portion MR, that is, the “reflecting surface shape” is set to a predetermined shape (such that a light flux portion having a smaller angle of view has a smaller reflecting area). The shading means for correcting the brightness of the image in the main scanning direction on the image plane can also be used.

FIG. 9 is an explanatory diagram showing one embodiment of the original reading module of the present invention. The document reading module 90 “reads a document image and converts it into an electric signal”
A document reading lens, and a light receiving element array SA that samples an image of a document image formed by the document reading lens and performs photoelectric conversion on the document reading lens. is there. The original reading lens is the original reading lens according to any one of claims 1 to 8 described above, and as shown in FIG.
And a rear group GR. As the light receiving element array SA, a known CCD, CMOS sensor, or the like can be used. These light-receiving element arrays SA are generally in a commercially available form, as shown in FIG.
And is sealed in a package PK by a shield glass SG which is a shielding material.

The light receiving element array SA is provided so that its light receiving surface coincides with the image plane position of the original reading lens. However, in the original reading lens of the present invention, the rear group is arranged at a position close to the image plane. As in the embodiment shown in FIG. 11, the rear group GR of the document reading lens in the document reading module and the light receiving element array SA can be integrated.

Various forms are possible for the integration of the light receiving element array and the rear group. In the embodiment shown in FIG. 11, the image side surface of the rear group GR is formed of a shielding material (shield glass) SG. This is an example in which the surface is bonded and integrated using a transparent adhesive 11A. When the “back focus in the actual use state” of the document reading lens is sufficiently short, as in the embodiment shown in FIG. 12, the image side surface of the rear group GR is replaced with the “shielding material of the package PK of the light receiving element array SA”. You can make it double. Further, when the “back focus in the actual use state” of the document reading lens is substantially 0, as in the embodiment shown in FIG.
The light receiving element array SA itself can be directly adhered to the image side surface of the rear group GR using the adhesive 11A. FIG.
In the embodiment shown in FIG. 13, the image side of the rear group of the document reading lens is “flat or substantially flat”. However, when the “light-receiving element array is directly adhered” to the image side of the rear group, FIG. As in the embodiment shown in FIG. 14, even when the image side surface of the rear group GR is “non-planar”, the rear group GR and the light receiving element array can be easily integrated. 13 and FIG.
The lower diagram in FIG. 7 shows the upper diagram as viewed from the main scanning direction (vertical direction in the upper diagram). In the embodiment shown in FIGS. 11 to 14, the structure of the light receiving element array is simplified, which is effective for cost reduction.

Of course, the original reading module of the present invention
A configuration in which the rear group of the document reading lens and the light receiving element array are not integrated by uniting is also possible. In particular, when the back focus is large to some extent, it is not necessary to combine the rear group and the light receiving element array. As described above, when the rear group of the document reading lens and the light receiving element array are not combined,
As in the embodiment shown in FIG. 15, "focus adjustment" can be performed by displacing the light receiving element array SA in the optical axis direction on the image side of the rear group GR of the original reading lens. If the focus adjustment is performed by the displacement of the light receiving element array SA, “the fluctuation in the performance of the reading lens due to the focus adjustment can be reduced as compared with the case where the focus adjustment is performed by displacing only the front group GF in the optical axis direction. There is an advantage. In particular, when the back focus is relatively large (10% or more of the entire length of the original reading lens), a displacement mechanism of the light receiving element array is provided in the space between the rear group GR of the original reading lens and the light receiving element array SA. It is possible to provide. In FIG. 15, reference numeral 91 denotes "appropriate integrating means" as in FIG.

In each document reading module described in the above embodiment, the method of "integrating the document reading lens and the light receiving element array as a module" is optional.
As in the embodiments described below, it is possible to “the entire document reading lens is integrated by the holding means, and the document reading lens and the holding means constitute a document reading lens unit”. In the embodiment shown in FIG. 16, the front group GF and the rear group G
Ra is held by the holding means 160 to constitute a document reading lens unit, and the light receiving element array SA is held by a dedicated holding member 170. The holding means 160 and the holding body 170 in the original reading lens unit are integrated with each other. In this case, the above-described “focusing by displacement of the light receiving element array” can be performed by displacing the holder 170 with respect to the holding unit 160 in the optical axis direction of the document reading lens. The holding means 160 is formed by integrally forming a holding portion for holding each lens of the front group GF and a rear group attaching portion to which the rear group GRa is attached. The holding means 160 is, specifically, shown in FIG.
The configuration is as shown in FIG.

Each lens of the front group is inserted and held in each lens receiving portion of the holding portion 161, and is held by an adhesive or the like.
Fixed to 1. Further, the rear group GRa is of the type described with reference to FIGS. 4 and 5, and the manner in which the holding means 160 is held by using a leaf spring as in the embodiment shown in FIG. Have gone. If the front group GF and the rear group GRa are held by the structure as shown in FIGS. 16 and 17, compared to the case where the front group GF is held by a separate lens barrel 50 shown in FIG. The number of parts can be greatly reduced, and the cost can be reduced. The holding unit 160 in the embodiment shown in FIGS. 16 and 17 includes a holding unit 161 for holding each lens of the front group GF, a rear group mounting unit to which the rear group GR can be mounted, as a holding unit for the original reading lens unit. Formed integrally with each other ". Of course, in the document reading module, when using a document reading lens unit in which a document reading lens is integrated by holding means, the form of the document reading lens unit may be as described above with reference to FIGS. Various forms are possible.

For example, as the holding means of the original reading lens unit which forms a part of the original reading module, for example, as shown in FIGS. 5 and 7, a front group for holding the front group GF of the original reading lens The holding means 50, the rear group holding means 51 for holding the rear group GRa, and the connecting means 52 for integrating the respective holding means may be provided. In this case, the front group holding means 50 is
It can be translationally displaceable in the direction of the optical axis relative to 1, or can be rotatable about the optical axis. FIG. 6B shows an original reading lens unit.
As in the embodiment shown in FIG.
Mirror M that bends the optical path between the mirror and the rear group GR
The front group GF and the rear group G of the original reading lens can be used as in the embodiment shown in FIG.
A shading unit 71 for correcting the brightness of the image in the main scanning direction on the image plane may be provided between the shading unit 71 and Ra. The shading means can be a “light shield plate having an opening of a predetermined shape” as in this case, or as described with reference to FIG. 8, “the folding mirror M has a predetermined reflection surface shape. And also serves as shading means for correcting the brightness of the image in the main scanning direction on the image plane. "

Referring to FIGS. 18 and 19, two embodiments of the document reading apparatus will be described. The document reading device is a document reading device that forms an image of a document image by a document reading lens ORL on a light receiving element array SA, reads the document image while scanning the document OR, and converts it into an electric signal. Scanning means for scanning and light receiving element array SA
A document reading lens ORL for forming a light beam from a scanned document portion on the light receiving element array, a signal processing means 185 for performing signal processing on an output signal of the light receiving element array SA, and Image processing means 186 for performing image processing. Then, the original reading lens O
As the RL, the original reading lens according to any one of claims 1 to 8 is used. A document reading apparatus according to an embodiment shown in FIG. 18 includes a contact glass 180 provided at a fixed position, a scanning means for scanning a document, a traveling means for traveling the document in contact with the surface of the contact glass, and a contact glass. Illumination means for illuminating the original document 180 over the main scanning direction.

The transport rollers 181 and 182 are driven by a motor (not shown) to rotate at a constant speed. The document OR from which a document image is to be read is transported in the direction of the arrow by the transport rollers 181 and 182 in contact with the upper surface of the contact glass 180, and runs on the contact glass 180 at a constant speed. The pressing plate indicated by reference numeral 180A prevents the document surface of the running document OR from floating from the upper surface of the contact glass 180. These transport rollers 18
1, 182, the pressing plate 181A, and a motor (not shown) constitute "traveling means". The illumination lamp indicated by the symbol LP is an “illumination unit”, and illuminates a document traveling on the contact glass 180 in the main scanning direction (a direction orthogonal to the drawing). That is, scanning of the document OR is performed by moving the document with respect to the document illuminating unit while illuminating the document OR with the document illuminating unit set at the fixed position (on the contact glass 180). In the document illuminating section, the light flux reflected on the document image surface is bent by the reflecting mirror 183 and guided to the document reading lens ORL, and a document image (reduced image) is formed on the light receiving element array SA. The light receiving element array SA repeatedly outputs the photoelectric conversion output regardless of the traveling of the document OR. This output is subjected to “signal processing such as A / D conversion” in the signal processing unit 186 and input to the image processing unit 186. Image processing means 1
Reference numeral 86 processes the input image information signal into a signal form suitable for output.

The image processing means can be realized as a computer or the like. Note that the reflecting mirror 183 may be omitted depending on the layout of the document reading device. Conversely, depending on the layout, two or more reflecting mirrors may be used to guide the light flux from the illumination unit to the document reading lens ORL. Is also good. In the document reading apparatus according to the embodiment shown in FIG. 19, the means for scanning the document includes a document glass 190 on which the document OR is fixed in a plane, and a document placed on the document glass 190 in the main scanning direction (perpendicular to the drawing). ), And a group of mirrors 191 and 192 for guiding a light beam from the document portion illuminated by the lighting device LP to a document reading lens.
193 and the illumination means LP in the sub-scanning direction (left-right direction in the figure)
And a group of mirrors 191, 192, 1
93 is provided with a displacing means for displacing 93 while maintaining the “light guide optical path length” from the illuminating section by the illuminating means LP to the original reading lens ORL.

The illumination means LP is an illumination lamp. When reading a document, the document OR is placed flat on the document glass 190 with the side having the document image to be read down. When reading is commanded in this state, the illumination lamp L
P emits light and illuminates the original OR long in the main scanning direction,
The document OR is moved to the right side of the figure at a constant speed: V, and the original OR is scanned by illumination. Original reading lens ORL to light receiving element array SA
Until fixed. Together with the movement of the illumination lamp LP, the mirror 191 is displaced rightward in the drawing at a constant speed: V. At the same time, the mirrors 192 and 193 are integrally displaced to the right in the figure at a constant speed: V / 2. The luminous flux from the document portion illuminated by the illumination lamp LP is sequentially reflected by mirrors 191, 192, and 193 and guided to the document reading lens ORL. At this time, the “optical path length of the light guide” from the document surface to the document reading lens ORL is unchanged. The document reading lens ORL forms a document image on the light receiving element array SA. Conventionally, this type of development reading has been used as a displacement means for displacing the illumination means lamp LP and a group of mirrors 191 to 193 while maintaining the "optical path length of the light guide from the illumination unit to the document reading lens ORL by the illumination lamp LP". Any suitable device known in connection with the device can be used.

The processes of reading and signal processing / image processing by the light receiving element array SA are the same as those in the embodiment shown in FIG. Therefore, according to the document reading apparatus according to the embodiment shown in FIGS.
The document reading method according to any one of claims 1 to 8, wherein the image of the document image by the RL is formed on the light receiving element array SA, the document OR is scanned, and the document image is read and converted into an electric signal. This is performed using a document reading lens. The document reading lens ORL in the document reading apparatuses of FIGS. 18 and 19 may be unitized as the document reading lens unit according to the ninth aspect, and further, the document reading lens ORL and the light receiving element array SA may be combined with each other. Claim 1
The document reading module according to any one of 0 to 24 may be modularized. In addition, the signal processing unit 185 and / or the image processing unit 186 can be configured to have “a function of electrically adjusting the reading magnification”. As described above, if the reading magnification is adjusted electrically, the adjustment does not have to be performed optically.
Since there is no need to consider the reading magnification at the time of focus adjustment, the adjustment mechanism and the adjustment process can be simplified.

FIG. 20 is an explanatory diagram showing one embodiment of the "image information processing apparatus" of the present invention. An image information processing apparatus according to the present invention includes: a document reading apparatus that reads a document image and converts the signal into an electric signal; and an output unit 187 that outputs signal information converted into an electric signal by the document reading apparatus. The document reading apparatus according to any one of claims 26 to 31 is used as the document reading apparatus. In the embodiment shown in FIG. "The embodiment shown in FIG. 19" is used as the reader. Of course, it is needless to say that "the embodiment shown in FIG. 18" may be used as the document reading apparatus.

As described above, as the output means 187, various means, for example, a "display device for displaying an image on a display medium", a "writing device for writing image information on an electronic recording medium", and the like. , A "transmission device for transmitting image information", a "printer device for printing and recording image information on a sheet-like recording medium", and the printer device may be an "inkjet printer" or an "electrophotographic optical printer device". And the like. The image information processing apparatus may have two or more of these various types as the output unit 187.

FIG. 21 shows an embodiment of the image information processing apparatus. This image information processing apparatus is of the "multi-function type" described above. First, a description will be given of the reading of a document. A document OR to be read is placed flat on a document glass 190, illuminated by an illumination lamp LP in a main scanning direction (a direction orthogonal to the drawing), and is illuminated in a sub-scanning direction (FIG. Is scanned to the right. The reflected light flux from the illuminated document part is
The light is guided to the document reading module 201 by a group of mirrors 191, 192, and 193, and is converted into a signal by the light receiving element array of the module 201. That is, a portion for reading a document has the same configuration as that of the document reading apparatus according to the embodiment shown in FIG. The signal output from the document reading module 201 is input to the controller 202. The controller 202 has various input / output units centered on a microcomputer controlled by a program, and has a signal processing unit and an image processing unit which form a part of the document reading apparatus. The controller 202 also controls each part of the device. The motor 210 is a driving source of each operation unit in the apparatus. As a part of a displacement unit in the document reading apparatus, a motor 210 drives a displacement mechanism (not shown) to drive mirrors 191 to 193 (described with reference to FIG. 19). ) Displacement is performed.

When reading the original, the controller 202
It also controls the blinking of the illumination lamp LP. This image information processing apparatus has a modem 20 as a transmission device as an output unit.
4. An electrophotographic optical printer is provided as the writing device 203 and the printer. If the user wants to transmit the “document image information” read by the above operation by facsimile, and instructs “facsimile transmission” from an operation panel (not shown), the controller 202 reads the image information input from the document reading module 201, Signal processing and image processing into a signal form suitable for transmission, and modem 2
04. If the user wants to write the read image information on the floppy disk FD or the optical disk CD, he or she instructs “write” on the operation panel and writes the floppy disk FP or the optical disk CD into the writing device 2.
Set to 03. The controller 202 converts the document image information into a signal form suitable for the set “electronic recording medium”, and writes the document image information on the set electronic recording medium (floppy disk FD or optical disk CD).

When printing an original image,
Select "Copy" on the operation panel. Then, the controller 202 executes copying of the document image as follows.
That is, the controller 202 performs a process of converting document image information into a signal form suitable for optical scanning by the optical scanning device 207, while rotating the photoconductive photoconductor 205 at a constant speed in the direction of the arrow, and Charging means 206 (a contact charging type using a charging roller is shown, but a corona discharge type may be used) to uniformly charge. Next, the controller 202 applies image information to the optical scanning device 207 to perform writing by optical scanning. The electrostatic latent image (negative latent image) thus formed is reversely developed by the developing device 208 and is visualized as a toner image. This toner image is
In the transfer section, transfer paper 209 (a contact type using a transfer roller is shown, but a type using a transfer charger or a type using an intermediate transfer medium such as an intermediate transfer belt) may be used. The image is transferred onto a sheet-like recording medium S such as a sheet or an OHP sheet.

The recording medium S has the toner image fixed by the fixing device 211 and is discharged outside the device. The photosensitive member 205 after the transfer of the toner image is
As a result, residual toner and paper dust are removed. In this image information processing apparatus, image information input from the outside via the modem 204 can be printed on the recording medium S, or can be written and recorded on a floppy disk or optical disk. And the information of the optical disk is read by the writing device 203 and the modem 204
Can be transmitted to the outside via a PC, or can be printed and recorded on the recording medium S.

[0051]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the original reading lens of the present invention will be described below. In each of the embodiments, the aberration is sufficiently corrected, and the performance is sufficient for use in reading an original of a digital copying machine or a multifunctional image information processing apparatus as described above.

The third, seventh, eighth, ninth and tenth embodiments are based on the assumption that they are used in combination with a light receiving element array having a shield glass SG (see FIG. 11). It is assumed that the package of the light receiving element array is directly sealed in the rear group (see FIG. 12). The meaning of the symbol in each embodiment is as follows. f: Focal length of the whole system m: Magnification F _m : Effective F number at magnification m (normal FNo. ×
(1 + m) × (entrance pupil diameter / exit pupil diameter)) Y: maximum object height R: radius of curvature D: surface interval N _d : refractive index (d line) ν _d : Abbe number K: aspherical conical constant A ₄ : Aspherical coefficient of 4th order A ₆ : Aspherical coefficient of 6th order A ₈ : Aspherical coefficient of 8th order A ₁₀ : Aspherical coefficient of 10th order The aspherical surface used here is the reciprocal of the paraxial radius of curvature (near Assuming that C is the axial curvature and H is the height from the optical axis, it is defined by the following known equation. ^{X = CH 2 / [1 +} √ {(1- (1 + K) C 2 H 2)}] + A 4 · H 4 + A 6 · H 6 + A 8 · H 8 + A 10 · H 10 Note that with the dimension of length The unit of the amount is “mm”.

Example 1 f = 41.08, m = 0.11102, F _m = 4.80, Y = 152.4 Surface number RDN _d ν _d Notes 01 ∞ 3.20 1.51680 64.20 Contact glass 02 ∞ 03 17.300 2.34 1.71300 53.94 First lens 04 62.620 1.80 05 -43.884 4.84 1.62004 36.30 Second lens 06 16.577 2.22 07 31.300 2.79 1.60311 60.69 Third lens 08 -25.973 39.91 09 -35.734 1.00 1.53046 55.84 Fourth lens 10 全長 Total lens length: 54.9 Back focus: 1.01 (1.8% of total lens length) The distance between the front group and the rear group: 39.91 (72.3% of the total lens length) f _F / f _R = −1.56 In the first embodiment, all the lens surfaces are spherical.
The upper diagram in FIG. 22 shows the lens configuration of Example 1, and the lower diagram shows the aberration diagram. C, e, and F in the aberration diagram represent the C line, e line, and F line, respectively, and the broken line in the spherical aberration diagram represents the “sine condition”. A broken line in astigmatism represents a meridional ray, and a solid line represents a sagittal ray. The same applies to the aberration diagrams of the following embodiments.

Example 2 f = 39.68, m = 0.11102, F _m = 4.35, Y = 152.4 Surface number RDN _d ν _d Notes 01 ∞ 3.20 1.51680 64.20 Contact glass 02 ∞ 03 18.136 2.54 1.77250 49.62 First lens 04 99.502 2.14 05 -43.344 4.40 1.72825 28.32 2nd lens 06 18.141 1.30 07 34.251 3.62 1.59551 39.22 3rd lens 08 -23.307 37.70 09 * -22.795 1.00 1.53046 55.84 4th lens 10 ∞ Aspheric surface: 9th surface K = 0.0, A ₄ = 6.16139 × 10 ^-5 , A ₆ = -2.39719 × 10 ^-7 , A ₈ = 6.82553 × 10 ^-10 , A ₁₀ = -6.07709 × 10 ^-13 Total lens length: 52.7 Back focus: 1.00 (1.9% of total lens length) distance between the group and the rear group: 37.70 in the upper diagram of (a lens 71.5% of the total length) f _F / f _R = -1.01 Figure 23 shows the lens arrangement of example 1, show aberrations in the figure below.

Example 3 f = 41.00, m = 0.11102, F _m = 4.40, Y = 152.4 Surface number RDN _d ν _d Notes 01 ∞ 3.20 1.51680 64.20 Contact glass 02 ∞ 03 19.958 2.24 1.74330 49.22 First lens 04 75.700 2.09 05 -32.834 4.95 1.68893 31.16 Second lens 06 22.884 1.52 07 49.445 3.19 1.80420 46.50 Third lens 08 -26.788 36.82 09 * -16.135 1.00 1.53046 55.84 Fourth lens 10 -36.377 11 ∞ 1.00 1.51680 64.20 Shield glass 12 ∞ Aspheric surface: Ninth Surface K = 0.0, A ₄ = 5.33596 × 10 ^-5 , A ₆ = -4.97559 × 10 ^-9 , A ₈ = -3.08944 × 10 ^-10 , A ₁₀ = 2.95608 × 10 ^-12 Lens length: 51.81 Back focus: 3.66 distance between front and rear groups (7.1% conversion lens length in air): 36.82 (71% of the total lens length) in the upper diagram of f _F / f _R = -1.36 24, the lens configuration of example 1 Is shown, and the aberration diagram is shown in the lower figure.

Example 4 f = 38.90, m = 0.11102, F _m = 4.50, Y = 152.4 Surface number RDN _d ν _d Remarks 01 ∞ 3.20 1.51680 64.20 Contact glass 02 ∞ 03 * 38.353 6.22 1.84666 23.78 First lens 04 * 24.257 4.50 05 69.817 3.28 1.48749 70.44 Second lens 06 -17.301 42.65 07 * -18.025 2.00 1.53046 55.84 Third lens 08 ∞ Aspheric surface: Third surface K = 0.0, A ₄ = -5.31404 × 10 ^-5 , A ₆ = -1.84115 × 10 ^-7 , A ₈ = -6.12936 × 10 ^-10 , A ₁₀ = 1.35889 × 10 ^-12 Aspheric surface: fourth surface K = 0.0, A ₄ = -4.32 140 × 10 ^-5 , A ₆ = -2.17569 × 10 ^-7 , A ₈ = 3.50371 × 10 ^-10 , A ₁₀ = 8.11068 × 10 ^-12 Aspheric surface: 7th surface K = 0.0, A ₄ = 6.36218 × 10 ^-5 , A ₆ = -2.74719 × 10 ^-7 , A ₈ = 1.09686 × 10 ^-9 , A ₁₀ = -1.03521 × 10 ^-12 Total lens length: 58.65 Back focus: 1.00 (1.7% of total lens length) Interval between front and rear groups: 42.65 (73% of total lens length) ) in the upper diagram of f _F / f _R = -0.818 Figure 25 shows the lens arrangement of example 1, the aberration diagrams in the figure below Show.

Example 5 f = 61.62, m = 0.18898, F _m = 4.80, Y = 152.4 Surface number RDN _d νd Remarks 01 ∞ 3.20 1.51680 64.20 Contact glass 02 ∞ 03 35.901 8.00 1.74330 49.22 First lens 04 76.694 2.43 05- 64.307 8.00 1.68893 31.16 Second lens 06 34.790 0.58 07 54.494 8.00 1.83400 37.34 Third lens 08 -319.753 0.10 09 109.219 8.00 1.48749 70.44 Fourth lens 10 * -45.001 70.04 11 * -38.671 2.58 1.53046 55.84 Fifth lens 12 ∞ Aspheric surface: 10th surface K = 0.0, A ₄ = 3.13841 × 10 ^-7 , A ₆ = -7.22203 × 10 ^-10 , A ₈ = -4.79523 × 10 ^-11 , A ₁₀ = 1.38768 × 10 ^-13 Aspheric surface: 11th surface K = 0.0, A ₄ = 9.80652 × 10 ^-6 , A ₆ = -1.78814 × 10 ^-8 , A ₈ = 2.17574 × 10 ^-11 , A ₁₀ = -9.08966 × 10 ^-15 Lens length: 107.73 Back focus: 1.00 ( lenses 0.9% of the total length) spacing between the front and rear groups: 70.04 (65% of the total lens length) in the upper diagram of f _F / f _R = -1.03 Figure 26 shows the lens arrangement of example 1, below Shows the aberration diagram

[0058] Example 6 f = 70.29, m = 0.23622 , F m = 6.22, Y = 152.4 Face Number RDN _d [nu _d Remarks 01 ∞ 3.20 1.51680 64.20 contact glass 02 ∞ 03 34.071 3.27 1.60311 60.69 first lens 04 321.127 5.26 05 -65.711 8.00 1.72342 37.99 2nd lens 06 38.825 2.45 07 71.413 8.00 1.69680 55.46 3rd lens 08 -46.983 89.00 09 * -42.383 4.29 1.53046 55.84 4th lens 10 ∞ Aspheric surface: 9th surface K = 0.0, A ₄ = 7.50222 × 10 ^-6 , A ₆ = -7.35149 × 10 ^-9 , A ₈ = 5.82164 × 10 ^-12 , A ₁₀ = -1.46608 × 10 ^-15 Total lens length: 120.27 Back focus: 1.01 (0.8% of total lens length) The distance between the group and the rear group: 89.00 (74% of the total lens length) f _F / f _R = −0.95 The upper diagram of FIG. 27 shows the lens configuration of Example 1, and the lower diagram shows an aberration diagram.

[0059] Example 7 f = 73.20, m = 0.23622 , F m = 6.01, Y = 152.4 Face Number RDN _d [nu _d Remarks 01 ∞ 3.20 1.51680 64.20 contact glass 02 ∞ 03 37.478 3.44 1.69680 55.46 first lens 04 197.210 7.91 05 -62.309 8.00 1.71736 29.50 Second lens 06 38.767 2.54 07 67.415 8.00 1.70154 41.15 Third lens 08 -46.115 83.36 09 * -62.269 2.00 1.53046 55.84 Fourth lens 10 * 277.552 11 ∞ 1.00 1.51680 64.20 Shield glass 12 ∞ Aspheric surface: Ninth Surface K = 0.0, A ₄ = -3.76635 × 10 ^-6 , A ₆ = 6.30996 × 10 ^-9 , A ₈ = -1.85384 × 10 ^-12 , A ₁₀ = -5.96053 × 10 ^-16 Aspheric surface: 10th surface K = 0.0, A ₄ = -4.68601 × 10 ^-6 , A ₆ = 1.26013 × 10 ^-9 , A ₈ = 3.19086 × 10 ^-12 , A ₁₀ = -1.87719 × 10 ^-15 Total lens length: 115.25 Back focus: 4.66 (air interval 4.0%) the front group and the rear group of the middle terms lens length: 83.36 (72% of the total lens length) in the upper diagram of f _F / f _R = -1.14 Figure 28 shows the lens arrangement of example 1 In the figure below Shows a diagram.

Example 8 f = 63.63, m = 0.18898, F _m = 5.01, Y = 152.4 Surface number RDN _d ν _d Remarks 01 ∞ 3.20 1.51680 64.20 Contact glass 02 ∞ 03 35.539 4.88 1.48749 70.44 First lens 04 212.293 9.32 05 -51.136 8.00 1.72825 28.32 2nd lens 06 516.722 2.35 07 * 310.769 8.00 1.69350 53.34 3rd lens 08 -42.331 67.10 09 * -51.910 2.00 1.53046 55.84 4th lens 10 * 106.745 11 ∞ 1.00 1.51680 64.20 Shield glass 12 ∞ Aspheric surface: No. 7 surfaces K = 0.0, A ₄ = -3.66708 × 10 ^-6 , A ₆ = -1.16532 × 10 ^-8 , A ₈ = 2.14790 × 10 ^-10 , A ₁₀ = -1.33775 × 10 ^-12 Aspheric surface: 9th surface K = 0.0, A ₄ = -1.46868 × 10 ^-5 , A ₆ = 4.32801 × 10 ^-8 , A ₈ = -5.35630 × 10 ^-11 , A ₁₀ = 2.59883 × 10 ^-14 Aspheric surface: 10th surface K = 0.0 , A ₄ = -1.60498 × 10 ^-5 , A ₆ = 3.08020 × 10 ^-8 , A ₈ = -2.84394 × 10 ^-11 , A ₁₀ = 1.00585 × 10 ^-14 Lens length: 101.65 Back focus: 4.66 (in air conversion) (4.6% of total lens length) Interval between front and rear groups: 67.10 ( 66%) shown above of f _F / f _R = -0.92 Figure 29 lens total length, shows the lens arrangement of Example 1, show aberrations in the figure below.

Example 9 f = 41.00, m = 0.11102, F _m = 4.40, Y = 152.4 Surface number RDN _d ν _d Notes 01 ∞ 3.20 1.51680 64.20 Contact glass 02 ∞ 03 17.338 2.37 1.77250 49.62 First lens 04 61.199 3.53 05 -32.820 1.14 1.80518 25.46 Second lens 06 20.606 1.38 07 47.180 5.58 1.83400 37.34 Third lens 08 -23.995 31.47 09 * -14.590 1.00 1.53046 55.84 Fourth lens 10 -26.330 11 ∞ 1.00 1.51680 64.20 Shield glass 12 ∞ Aspheric surface: Ninth Surface K = 0.0, A ₄ = 3.57449 × 10 ^-5 , A ₆ = 2.01006 × 10 ^-7 , A ₈ = -1.47522 × 10 ^-9 , A ₁₀ = 8.45052 × 10 ^-12 Lens length: 46.47 Back focus: 6.66 ( (Equivalent in air: 14.3% of total lens length) Distance between front and rear groups: 31.47 (68% of total lens length) f _F / f _R = -1.60 The upper diagram of FIG. 30 shows the lens configuration of the first embodiment. The figure below shows the aberration diagram.

Example 10 f = 42.25, m = 0.11102, F _m = 4.43, Y = 152.4 Surface number RDN _d ν _d Remarks 01 ∞ 3.20 1.51680 64.20 Contact glass 02 ∞ 03 18.725 2.15 1.79450 45.39 First lens 04 50.452 1.82 05 -35.539 5.54 1.72825 28.32 Second lens 06 20.467 1.57 07 33.614 2.92 1.83500 42.98 Third lens 08 -29.292 28.43 09 * -13.555 1.00 1.53046 55.84 Fourth lens 10 -22.209 11 ∞ 1.00 1.51680 64.20 Shield glass 12 ∞ Aspheric surface: Ninth Surface K = 0.0, A ₄ = 2.21483 × 10 ^-5 , A ₆ = 1.77589 × 10 ^-7 , A ₈ = -1.30330 × 10 ^-9 , A ₁₀ = 1.08288 × 10 ^-11 Total lens length: 43.43 Back focus: 10.66 ( interval 24.5%) front and rear groups conversion lens length in air: 28.43 (65% of the total lens length) in the upper diagram of f _F / f _R = -1.79 FIG 31, the lens configuration of example 1 The figure below shows the aberration diagram.

The original reading lenses of the first to tenth embodiments are lenses for reading an original image, and include a front unit GF on the object side and a rear unit GR on the image side. GF
Is composed of two to four lenses including one or more positive lenses, and the rear group GR is composed of one negative lens.
%, And the air gap between the front group and the rear group (C in FIG. 1) is 50% or more of the entire length of the lens (A in FIG. 1). . In the document reading lens of Example 4, the front group GF is configured by two lenses, and Examples 1, 2, 3, 6 to 10
The front group GF is composed of three lenses, and the original reading lens of the fifth embodiment is such that the front group GF is composed of four lenses. In the original reading lens of the first embodiment, all the lenses are spherical lenses, and in the original reading lenses of the second to tenth embodiments, one or more lens surfaces are aspherical. Is an aspherical surface (claim 2). In the document reading lenses of Examples 7 and 8, the image side surface of the rear group is aspherical.

In each of the original reading lenses of Examples 1 to 10, the rear group GF is a plastic lens (Claim 4). The original reading lenses of Examples 1 to 8 have a back focus in an actual use state. , Is 10% or less of the entire length of the lens (claim 8). Further, in the embodiment shown in FIGS. 2 to 4, the outer shape of the rear group GF (GFa) is not rotationally symmetric with respect to the optical axis (claim 5), and the rear group GF (GFa)
4 is a strip shape long in the main scanning direction, and FIG.
In the embodiment shown in (1), the rear group GFa is a plastic lens and has positioning, holding, or fixing engagement portions 41, 42, and 43 (claim 7). FIG.
The embodiment shown in FIG. 8 has a document reading lens and holding means for holding each lens of the document reading lens and integrating the whole document reading lens (claim 9). In the embodiment shown in FIG. 7, the holding means integrates the front group holding means 50 for holding the front group GF of the document reading lens, the rear group holding means 51 for holding the rear group GR, and these holding means. FIG. 6 includes a connecting unit 52, and the front group holding unit 50 is capable of translationally displacing in the optical axis direction and / or rotatable around the optical axis relative to the rear group holding unit 51.
The embodiment shown in FIG. 1 is an original reading lens unit having a bending mirror M for bending an optical path between a front group GF and a rear group GR of the original reading lens (claim 9).

In the embodiment shown in FIG. 7, a shading means 71 for correcting the brightness of an image in the main scanning direction on the image plane is provided between the front group GF and the rear group GR of the original reading lens. The shading means 71 is a light shielding plate having an opening having a predetermined shape. In the embodiment described with reference to FIG. 8, the bending mirror M has a predetermined reflecting surface shape MR, and also serves as a shading means for correcting the brightness of the image in the main scanning direction on the image plane. I have. Also, in the "document reading lens unit portion" of the embodiment shown in FIGS. 16 and 17, the holding means 160 has a holding portion 161 for holding each lens of the front group, and a rear group attaching portion for attaching the rear group GR. Are integrally formed. The document reading module according to the embodiment shown in FIG. 9, FIG. 11 to FIG. 17 is a document reading module for reading a document image and converting it into an electric signal.
F, GR) and a light receiving element array SA for sampling and photoelectrically converting an image of a document image formed by the document reading lens (Claim 10). In the embodiment shown in FIGS. The rear group GR of the document reading lens and the light receiving element array SA are integrated (claim 11).

In the embodiment shown in FIG. 12, the back focus in the actual use state of the original reading lens is sufficiently short, and the image side surface of the rear group GF also serves as the shield material of the package PK of the light receiving element array SA. (Claim 12),
In the embodiment shown in FIGS. 13 and 14, the “back focus in the actual use state is substantially 0” of the document reading lens, and the light receiving element array SA is directly attached to the image side surface of the rear group GR. Item 13), In the embodiment of FIG. 14, the image side surface of the rear group to which the light receiving element array SA is attached is non-planar (claim 14). In the embodiment of the document reading module shown in FIGS. 16 and 17, the entire document reading lens is integrated by the holding means 160, and the document reading lens and the holding means 160 constitute a document reading lens unit. The holding means 160 is formed by integrally forming a holding portion 161 for holding each lens of the front group and a rear group mounting portion to which the rear group GR is mounted.
6).

The holding means in the document reading module is
As shown in FIGS. 5 and 7, the front group GF of the original reading lens
, A rear group holding means 51 for holding the rear group GR, and a connecting means 52 for integrating these holding means.
7) In such a case, the front group holding means 50 can be translated and displaced in the optical axis direction relative to the rear group holding means 51 (claim 18), and can be rotated around the optical axis. It can also be possible (claims 19, 20). Also, in the document reading module, as shown in FIG. 6, a "bending mirror M for bending the optical path" can be provided between the front group GF and the rear group GR of the document reading lens.
1), as shown in FIGS. 7 and 8, between the front group GF and the rear group GR, there can be provided a shading means 71 for correcting the brightness of the image in the main scanning direction on the image plane ( (22) The shading means 71 can be a light shielding plate having a predetermined opening shape (claim 23), or as shown in FIG.
Can be used also as a shading means for correcting the brightness of the image in the main scanning direction on the image plane (claim 24).

The document reading apparatus according to the embodiment shown in FIGS. 18 and 19 forms an image of a document image on the light receiving element array SA by the document reading lens ORL, and scans the document OR while scanning the document OR. A document reading device for reading and converting the document into an electrical signal, comprising: scanning means for scanning the document; a light receiving element array; a document reading lens for forming a light beam from the scanned document portion on the light receiving element array; A signal processing unit 185 for performing signal processing on an output signal of the element array;
9. An image processing means 186 for performing image processing on a signal subjected to signal processing, and as an original reading lens.
The original reading lens according to any one of (1) to (3) is used. The original reading lens can be unitized as an original reading lens unit according to claim 9 (claim 27), and the original reading lens and the light receiving element array can be arranged as any one of claims 10 to 24. The module can be modularized as the document reading module described in (2).
8).

In the embodiment shown in FIG. 18, the scanning means for scanning the original OR includes a contact glass 180 provided at a fixed position and traveling means 181 and 182 for traveling the original in contact with the surface of the contact glass. Illuminating means LP for illuminating the original on the contact glass in the main scanning direction (claim 29). In the embodiment shown in FIG. 19, the means for scanning the original OR places the original OR in a plane. Document glass 190 to be illuminated and illumination means LP for illuminating the document placed on the document glass in the main scanning direction.
And a group of mirrors 191 to 19 for guiding a light beam from a document portion illuminated by the illuminating means to a document reading lens.
3, while displacing the illumination means LP in the sub-scanning direction,
Displacement means for displacing the group of mirrors 191 to 193 while maintaining the optical path length of the light guide from the illumination unit by the illumination means to the original reading lens ORL is provided. In the embodiment shown in FIGS. 18 and 19, the signal processing means 18
The fifth and / or image processing means 186 has a function of electrically adjusting the reading magnification.

Therefore, according to the image reading apparatus shown in FIGS. 18 and 19, the image of the original image by the original reading lens ORL is formed on the light receiving element array SA, and the original OR is scanned. A document reading method for reading a document image and converting it into an electric signal, wherein the document reading lens is used as a document reading lens.
An original reading method using the original reading lens according to any one of (1) to (8) is performed, and the original reading lens ORL is used.
The document reading lens unit according to claim 9 can be used as a unit, and the document reading lens ORL and the light receiving element array SA can be modularized as the document reading module according to any one of claims 10 to 24. Can be used. In the embodiment of FIG. 18, a document reading method is implemented in which the document OR is scanned by moving the document OR with respect to the document illuminating unit while illuminating the document with the document illuminating unit set at a fixed position. In the embodiment shown in FIG. 19, the original reading lens ORL is connected to the light receiving element array S
A is fixed, the original OR is illuminated in the main scanning direction by the illumination means LP, and a light beam from the original portion illuminated by the illumination means LP is guided to the original reading lens ORL by a group of mirrors 191 to 193. The original is scanned by displacing the illumination unit LP in the sub-scanning direction and displacing the group of mirrors 191 to 193 while maintaining the optical path length of the light guide from the illumination unit by the illumination unit to the original reading lens ORL. A document reading method is performed.

An image information processing apparatus according to the embodiment shown in FIG. 20 reads an original image and converts it into an electric signal, and outputs signal information converted into an electric signal by the original reading apparatus. 27. An image information processing apparatus having an output means 187 as a document reading apparatus.
The document reading device according to any one of (1) to (31) is used. The output means 186 may be a display device for displaying an image on a display medium (claim 33) or a writing device for writing image information on an electronic recording medium (claim 34). Transmission device (Claim 35), a printer device for printing image information on a sheet-shaped recording medium (Claim 36), and the printer device may be an ink jet printer. Alternatively, it may be an electrophotographic optical printer device. And FIG.
An image information processing apparatus according to an embodiment of the present invention includes an output unit configured to output an image according to any one of claims 33 to 36 as an output unit.
It has the above.

[0072]

As described above, according to the present invention, a novel document reading lens, a document reading lens unit,
A document reading module, a document reading method, a document reading device, and an image information processing device can be realized. As described above, the original reading lens of the present invention can be constituted by a smaller number of lenses than the Gaussian type, and can realize performance equal to or higher than that of a Gaussian original reading lens and at a low cost. Further, the original reading lens unit of the present invention can be integrated with the original reading lens having the above-mentioned good performance, and the original reading module of the present invention is compact with the original reading lens and the light receiving element array of the present invention as a module. And can be easily handled and incorporated. The document reading method and apparatus of the present invention can read a document image with good performance by using the document reading lens of the present invention, and the image information processing apparatus of the present invention using such a document reading apparatus is By reading the document image satisfactorily, good writing and good image formation can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a document reading lens of the present invention.

FIG. 2 is a diagram for explaining an example of the shape of a rear group of a document reading lens.

FIG. 3 is a view for explaining another example of the shape of the rear group of the document reading lens.

FIG. 4 is a diagram for explaining another example of the shape of the rear group of the document reading lens.

FIG. 5 is a view for explaining an original reading lens unit, one embodiment;

FIG. 6 is a view for explaining another embodiment of the original reading lens unit.

FIG. 7 is a diagram for explaining another embodiment of the original reading lens unit.

FIG. 8 is a diagram for explaining a folding mirror that also serves as shading means.

FIG. 9 is a diagram for explaining a document reading module.

FIG. 10 is a diagram for explaining a package of the light receiving element array.

FIG. 11 is a diagram showing only a characteristic portion of the first embodiment of the document reading module.

FIG. 12 is a diagram showing another embodiment of the document reading module, showing only the characteristic portions.

FIG. 13 is a diagram showing another embodiment of the document reading module, showing only characteristic portions.

FIG. 14 is a diagram showing another embodiment of the document reading module, showing only characteristic portions.

FIG. 15 is a diagram showing another embodiment of the document reading module, showing only the characteristic portions.

FIG. 16 is a diagram showing another embodiment of the document reading module, showing only characteristic portions.

FIG. 17 is a perspective view of the embodiment of FIG. 18;

FIG. 18 is a diagram for describing one embodiment of a document reading device.

FIG. 19 is a view for explaining another embodiment of the document reading apparatus.

FIG. 20 is a diagram for describing one embodiment of an image information processing apparatus.

FIG. 21 is a diagram for describing an embodiment of an image information processing apparatus having a plurality of types of output units.

FIG. 22 is a diagram illustrating a lens configuration and aberrations according to the first embodiment.

FIG. 23 is a diagram illustrating a lens configuration and aberrations according to the second embodiment.

FIG. 24 is a diagram illustrating a lens configuration and aberrations according to a third embodiment.

FIG. 25 is a diagram illustrating a lens configuration and aberrations according to a fourth embodiment.

FIG. 26 is a diagram illustrating a lens configuration and aberrations according to a fifth embodiment.

FIG. 27 is a diagram illustrating a lens configuration and aberrations according to a sixth embodiment.

FIG. 28 is a diagram illustrating a lens configuration and aberrations according to a seventh embodiment.

FIG. 29 is a diagram illustrating a lens configuration and aberrations according to an eighth embodiment.

FIG. 30 is a diagram illustrating a lens configuration and aberrations according to a ninth embodiment.

FIG. 31 is a diagram illustrating a lens configuration and aberrations according to a tenth embodiment.

[Explanation of symbols]

 GF Front group GR Rear group IS Image plane B Back focus

Continued on the front page (72) Inventor Akihisa Itahashi 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H087 KA08 KA18 LA01 MA06 NA09 PA03 PA04 PA05 PA17 PB03 PB04 PB05 QA02 QA05 QA06 QA07 QA12 QA17 QA21 QA22 QA25 QA26 QA37 QA38 QA41 QA45 QA46 RA05 RA12 RA13 RA32 RA42 RA44 UA01 2H108 AA05 CA01 CB01 GA04 GA09 GA20 5C051 AA01 BA01 DA03 DB01 DB22 DB24 DC07 FA01

Claims (36)

[Claims] 1. A lens for reading a document image, comprising a front group on the object side and a rear group on the image side, wherein the front group includes one or more positive lenses. The rear group is composed of one negative lens, the back focus in actual use is 30% or less of the entire lens length, and the air gap between the front group and the rear group is An original reading lens, wherein the original reading lens is 50% or more of the entire length of the lens. 2. The original reading lens according to claim 1, wherein an incident side surface of the rear group is aspheric. 3. The original reading lens according to claim 1, wherein the image side surface of the rear group is an aspherical surface. 4. The original reading lens according to claim 1, wherein the rear group is a plastic lens. 5. The original reading lens according to claim 1, wherein an outer shape of the rear group is not rotationally symmetric with respect to an optical axis. 6. The original reading lens according to claim 5, wherein the outer shape of the rear group is a rectangular shape long in the main scanning direction. 7. The original reading lens according to claim 5, wherein the rear group is a plastic lens, and has a positioning, holding, or fixing engagement portion. 8. The original reading lens according to claim 1, wherein a back focus in an actual use state is 10% or less of a total length of the lens. 9. An original reading lens, and holding means for holding each lens of the original reading lens and integrating the entire original reading lens, wherein the original reading lens is any one of claims 1 to 8. A document reading lens unit, wherein the document reading lens unit is the document reading lens described in (1). 10. A document reading module for reading a document image and converting it into an electric signal, comprising: a document reading lens; and a light receiving element array for sampling an image of the document image formed by the document reading lens and performing photoelectric conversion. A document reading module, comprising: the document reading lens according to claim 1, wherein the document reading lens is the document reading lens according to claim 1. 11. The original reading module according to claim 10, wherein a rear group of the original reading lens and a light receiving element array are integrated. 12. The document reading module according to claim 11, wherein the back focus of the document reading lens in an actual use state is sufficiently short, and the image side surface of the rear group also serves as a shield material of a package of the light receiving element array. An original reading module, comprising: 13. The document reading module according to claim 11, wherein the back focus of the document reading lens in actual use is substantially 0, and the light receiving element array is directly adhered to the image side surface of the rear group. An original reading module, comprising: 14. The document reading module according to claim 13, wherein the image side surface of the rear group of the document reading lens is non-planar. 15. The original reading module according to claim 10, wherein the entire original reading lens is integrated by a holding means,
A document reading module, wherein the document reading lens and the holding means constitute a document reading lens unit according to claim 9. 16. A document reading module according to claim 15, wherein said holding means is formed integrally with a holding portion for holding each lens of the front group and a rear group mounting portion for mounting the rear group. An original reading module, comprising: 17. A document reading module according to claim 15, wherein said holding means comprises a front group holding means for holding a front group of the document reading lens, a rear group holding means for holding a rear group, and each of said holding means. An original reading module, comprising: connecting means for integrating. 18. The document reading module according to claim 17, wherein the front group holding means is capable of being translated and displaced in the optical axis direction relative to the rear group holding means. 19. The document reading module according to claim 17, wherein the front group holding means is rotatable around the optical axis relative to the rear group holding means. 20. The original reading module according to claim 19, wherein the front group holding means is capable of being translated and displaced in the optical axis direction relative to the rear group holding means. 21. The original reading module according to claim 10, further comprising a bending mirror for bending an optical path between a front group and a rear group of the original reading lens. module. 22. The document reading module according to claim 10, wherein the brightness of the image in the main scanning direction on the image plane is corrected between a front group and a rear group of the document reading lens. A document reading module having shading means for reading. 23. The document reading module according to claim 22, wherein the shading means is a light shielding plate having an opening having a predetermined shape. 24. The original reading module according to claim 21, wherein the folding mirror has a predetermined reflecting surface shape and also serves as a shading means for correcting the brightness of the image in the main scanning direction on the image plane. A document reading module. 25. A document reading method for forming an image of a document image on a light receiving element array by a document reading lens, scanning the document, reading the document image and converting it into an electric signal, wherein the document reading lens is used. A document reading method using the document reading lens according to any one of 1 to 8. 26. A document reading apparatus which forms an image of a document image on a light receiving element array by a document reading lens, reads the document image and converts it into an electric signal while scanning the document, and scans the document. Means, a light receiving element array, a document reading lens for forming a light beam from a scanned document portion on the light receiving element array, signal processing means for performing signal processing on an output signal of the light receiving element array, and signal processing 9. An original reading apparatus, comprising: an image processing unit for performing image processing on a signal obtained by using the original reading lens according to any one of claims 1 to 8 as the original reading lens. 27. A document reading apparatus according to claim 26, wherein the document reading lens is unitized as a document reading lens unit, and the unitized document reading unit is the document reading lens unit according to claim 9. An original reading device. 28. The original reading apparatus according to claim 26, wherein the original reading lens and the light receiving element array are an original reading module, and the original reading module is used as the original reading module.
A document reading apparatus using the document reading module according to any one of the items 1 to 24. 29. The original reading apparatus according to claim 26, wherein the scanning means for scanning the original includes a contact glass provided at a fixed position, and a traveling mechanism for traveling the original in contact with a surface of the contact glass. And an illuminating means for illuminating the original on the contact glass in the main scanning direction. 30. An original reading apparatus according to claim 26, wherein the means for scanning the original includes: an original glass for placing the original in a plane; and a document placed on the original glass in the main scanning direction. Illuminating means for illuminating; a group of mirrors for guiding a light beam from a document portion illuminated by the illuminating means to a document reading lens; and displacing the illuminating means in the sub-scanning direction;
A document reading device, comprising: a displacement unit for displacing a group of mirrors while maintaining an optical path length of light guided from the illumination unit by the illumination unit to the document reading lens. 31. The document reading apparatus according to claim 26, wherein the signal processing means and / or the image processing means has a function of electrically adjusting a reading magnification. Document reading device. 32. An image information processing apparatus comprising: a document reading device for reading a document image and converting the signal into an electric signal; and output means for outputting signal information converted into an electric signal by the document reading device. An image information processing apparatus using the document reading apparatus according to any one of claims 26 to 31 as a reading apparatus. 33. The image information processing apparatus according to claim 32, further comprising a display device for displaying an image on a display medium, as the output unit. 34. The image information processing apparatus according to claim 32, further comprising a writing device for writing image information to an electronic recording medium as the output means. 35. An image information processing apparatus according to claim 32, further comprising a transmission device for transmitting image information as output means. 36. An image information processing apparatus according to any one of claims 32 to 35, further comprising, as output means, a printer device for printing and recording the image information on a sheet-shaped recording medium. Processing equipment.