JPH03195173A - Picture reader - Google Patents

Abstract

PURPOSE:To obtain a portable and compact picture reader, which size namely thickness is reduced, by arranging an image formation lens system including a condenser lens, which guides picture information form an original to the picture reader, out of a picture reading area in a sub scanning direction. CONSTITUTION:A means 2 to converge light in the area in the main scanning direction of the original surface, optical means 50 to return a picture information beam from the original surface in the sub scanning direction, optical sub scanning means 40, and image forming means 60 to form the image of the picture information beam out of the picture read area and to transform the beam to picture information are provided. In such a way, the image formation lens system 60 including a condenser lens 64 to guide the picture information from the original, which is loaded on an original platen, to a picture reader 70 is arranged out of the picture read area in the sub scanning direction. Thus, while reducing the size namely thickness of the reader, the portable and compact picture reader can be obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention is directed to inputting image information into an image forming apparatus such as a laser printer, or an image processing apparatus connected to a computer, etc. The present invention relates to an image reading device, and particularly relates to a fixed-document type image reading device that reads and reads images with a fixed document.

(Prior Art) Generally, image reading devices that input image information to an image processing device connected to a computer or the like are broadly classified into a moving original type and a fixed original type.

In a document moving type image reading device, a document is usually read using, for example, a CCD dense line sensor. In this case, the documents that can be read are limited to those in sheet form. On the other hand, in a fixed document type image reading device, a transparent document table made of glass or plastic is used, so the document may be a three-dimensional object. Image information on the surface of the document placed on the document table is imaged onto a reading device such as a CCD sensor by an imaging lens system with a deep depth of focus.

In the above-described fixed document image reading device, since the overall size of the device is large, two folding mirrors are used in the imaging lens system to reduce the installation area of the device. However, in this type of document fixed type image reading device, an imaging lens system including two folding mirrors and a condensing lens is placed below the document table, so the size of the device in the height direction is large. becomes larger.

(Problems to be Solved by the Invention) In the above-mentioned fixed-document type image reading device, the imaging lens system including two folding mirrors and a condensing lens is placed below the document mounting table, so the height of the image reading device is high. Size in horizontal direction (
There is a problem that the thickness of the device becomes large (thick).

SUMMARY OF THE INVENTION An object of the present invention is to dispose an imaging lens system outside the image reading area in the sub-scanning direction in a document fixed type image reading apparatus, thereby reducing the size, that is, the thickness of the apparatus.

[Structure of the Invention] (Means for Solving the Problems) The present invention has been made based on the above-mentioned problems, and includes a means for focusing light on an area in the main scanning direction of the document surface, and a means for focusing light on an area of the document surface in the main scanning direction. folding optical means for folding back the information beam in the sub-scanning direction; optical sub-scanning means for optically sub-scanning the image of the document by moving the folding optical means within the image reading area along the sub-scanning direction; An image reading device is provided, comprising: an image forming means for forming an image of the image information light beam directed in the sub-scanning direction outside the image reading area and converting it into image information. Further, a means for focusing light on a region of the document surface in the main scanning direction, a folding optical means for folding the image information beam from the document surface in the sub-scanning direction, and a folding optical means for folding the image information beam from the document surface in the sub-scanning direction; optical sub-scanning means for optically sub-scanning an image of a document by moving within a reading area; and an optical sub-scanning means for optically sub-scanning an image of a document by moving within a reading area; An image reading device is provided, comprising: a reflecting means that reflects in a direction intersecting a surface containing the image; and an imaging means that forms an image of the image information beam from the reflecting means and converts it into image information. .

(Function) According to the present invention, image information from a document placed on a document table is guided to an image reading device (an imaging lens system including a condensing lens is disposed outside an image reading area in the sub-scanning direction). Therefore, an image reading device is provided in which the size or thickness of the device is reduced.

In addition, since the imaging lens system including the condenser lens that guides image information from the document to the image reading device is arranged in a direction intersecting the sub-scanning plane and the main scanning plane outside the image reading area in the sub-scanning direction, the device An image reading device is provided in which the size or thickness of the image reading device is further reduced.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross section of an image reading device that is an embodiment of the present invention. The image reading device 2 includes a reading window 1B whose bottom surface is placed on a document, and a reading window 10 that is arranged opposite to the reading window 16 and has a lighting window 14 that takes in light from the outside. ing. This housing 1
0 includes a first carriage 40 that scans an original at a predetermined speed, and a second carriage 5 that guides the light from the carriage 40 to the image reading unit 70 by total reflection twice.
0, and a carriage support mechanism 20.degree. 22, detailed in FIG. 5, which supports the first and second carriages so as to be movable independently of each other. Also, /X Uzing lO
is the fifth carriage driving the first and second carriages 40.50.
The drive mechanism detailed in the figure is also provided therein.

The housing 10 further includes an imaging unit 60 that forms an image of image information from a document, an image reading unit 70 that reads the image information formed by the imaging unit 60, and a signal from the image reading unit 70. A convex portion I2 (formed, for example, in the shape of a handle) that accommodates a signal processing unit that processes and outputs the
At one end of the spectrum. Further, on the side of the convex portion 12 facing the lighting window 14, a reflective surface m made of metal oil or a mirror is formed so as not to reduce the amount of light incident on the lighting window 14.

Next, each unit forming an image forming apparatus according to an embodiment of the present invention will be described in detail.

As shown in FIG. 1, an image reading device 2 including a housing 10 having a lighting window 14 and a reading window 16 is placed such that the reading window 16 is in close contact with the surface of a document G that supplies information to be read. Ru. This lighting window 14 and reading window 16
is a transparent plate made of polycarbonate or acrylonitrile, for example, and when pressed from the outside, the inside of the transparent plate is pressed to avoid contact with the first and second carrier Fujis due to deflection caused by force. Below, metal wires parallel to the main reading direction and having a diameter of 22n are embedded at 11 intervals.

The first carriage 40 housed in the housing IO is supported at both ends by carriage support members 20 so as to be movable in the sub-scanning direction, and is scanned at a predetermined speed in the sub-scanning direction by a drive mechanism to be described later. This carriage 4
0 includes a Fresnel lens 42 disposed near the lighting window 14 and substantially parallel to the lighting window 14, a first mirror 44 for guiding part of the reflected light from the document to a corner cube prism that is an optical path folding device, It also includes a connecting member that receives a drive from a drive member (not shown). The Fresnel lens 42 and the first mirror 44 that guide a part of the reflected light from the document surface to the corner cube prism 52 are
Carriage 4 at a predetermined position in the main scanning direction and sub-scanning direction.
Fixed to 0.

Further, the second carriage 50, which is similarly housed in the housing 1O, includes a corner cube prism 52 that guides the reflected light from the document to the image information reading section by total reflection twice.
, and a connecting member (not shown) for following the movement of the first carriage at approximately 1/2 the speed.

The corner cube prism 52 is fixed to the carriage 50 perpendicularly and parallel to the main scanning direction and the sub-scanning direction.

The carriage support member 20.22, which is shown in detail in FIG.
Between the lighting window 14 and the reading window 16 (i.e., the image reading device 2
It is arranged so as to support the first and second carry Fujis from below, or to sandwich the first and second carry Fujis from above and below, without vibrating (in the vertical direction).

The imaging unit 60 includes a second mirror 62 which bends the light guided from the second carrier Fuji 50 and guides it to an imaging lens 64, an imaging lens 64 which is a lens uni-soto in which a plurality of lenses are combined, and this lens. A third mirror 66 is provided to bend the light from the imaging lens 64 and guide it to the image reading section 70.

The lens 64 is disposed outside the sub-scanning area and has a relatively zero front focal length for the purpose of reducing the thickness of the 7% Uzing lO (that is, reducing the size in the height direction). ing. The imaging lens 64 forms an image of the reflected light from the document guided through the first mirror, the corner cube prism, and the second mirror on the reading surface 72 of the image reading section.

The image reading unit 70 includes a reading surface or CCD sensor 72 for reading formed light beams or image information, an electrical equipment board 74 on which the CCD sensor 72, a signal processing circuit 76, etc. are arranged, and a signal sensor arranged on the electrical equipment board 74. Processing section 76
and an output section 78. Light, which is image information from the document G, is converted into an electrical signal by the reading surface 72, subjected to predetermined processing by the signal processing section 76, and sent from the output section 78 to an external output device or external storage device (not shown).

Table 1 shows data on the imaging optical system related to the imaging lens 64 and CCD sensor 72 incorporated in the imaging section 60 and reading section 70.

Table 1 Data list of imaging optical system Next, the process by which image information on the document surface is guided to the image reading section will be explained. The light from the outside that enters through the lighting window 14 is
The light is focused by the Fresnel lens 42 onto the document surface of the document G held by the reading window 16 .

In this embodiment, the Fresnel lens 42 condenses the light to five times the brightness. The surface of the document G is illuminated by this focused light, and reflected light is generated in an unspecified direction. A part of the reflected light from the original G is reflected by a first mirror 44 fixed to a first carriage 40 and is incident on the first surface of a corner cube prism 52 fixed to a second carriage 50. . This light is reflected at right angles from the first surface of the prism 52 and is incident on the second surface.

The light incident on the second surface is reflected again at right angles and guided to the second mirror 62 at the imaging section 6°. That is, the direction of the light reflected from the original document is changed by 180' by total reflection in two areas at the corner cube prism 52. The light guided to the second mirror 62 is reflected upward at a substantially right angle, enters the imaging lens 64, and is converted into convergent light. The imaging lens 64 is disposed outside the region where the first carriage 40 is scanned, that is, the sub-scanning region including the optical path of the light reflected from the prism 52 in the housing 10 . Further, this lens 64 has a relatively long front focal length for the purpose of reducing the thickness of the housing 10. The light that has passed through this lens 64 is guided to the third mirror 6B, is reflected again at a substantially right angle, and is imaged onto the reading surface 72 of the image reading section 70. This reading surface 72 is, for example, a CCD.
The image reading sensor generates an image signal according to image information of a document. This image signal is processed by an image processing circuit, which will be described later, and is input to the image forming apparatus and used for image reproduction.

As mentioned above, the image of the document G is read in the main reading direction (
For example, in the direction of the short side of the original), the reflected light from the original surface is CC
The image is formed on the D sensor 72 in the scanning direction (i.e., the sub-scanning direction,
For example, in the longitudinal direction of the document, the first and second carriages are scanned at a predetermined speed in the sub-scanning direction.
All the image information in a document having a size such as 85 is read. The driving of the first and second carriages in the sub-scanning direction will be described in detail in FIG.

FIG. 2 shows details of the Fresnel lens used in the apparatus shown in FIG. This Fresnel lens 42
is a plate-like lens that focuses light from the outside of the lighting window 14 onto the surface of the document G, and when parallel light rays are incident, the light is focused on a single focusing point S. In this embodiment, since the light from the outside is white natural light including a lot of scattered light, the condensing point S is formed in the shape of a band with a width of 2 to 3 mm. To outline the Fresnel lens 42, the thickness t is approximately 1■-1
Distance to focal point S #1 (different from actual focal length) h
P is approximately 20 mm, the width is approximately 20 mm, and the length direction (not shown), that is, the depth (at least larger than the short side direction of A4 m) is 220 av. The convergence point S of light from the outside by this lens is set at a position above the document surface G by a distance d to prevent an extreme decrease in light intensity even when the document is three-dimensional. In the example, it is set to approximately 2■.

In addition, as the distance from the condensing point S increases, the curvature of the sawtooth lens surface becomes smaller (i.e., from the side end g of the Fresnel lens at a predetermined distance Mf from the condensing point S in Fig. 2). It is set so that an angle α is given to the length gl, an angle β is given to the length gl, an angle γ is given to the length g, and an angle δ is given to the length g4. The curvature of the lens surface is changed for each pitch p. This pitch p may be constant or may vary individually, and in this embodiment, an example in which the lenses are carved at a constant pitch is shown.

FIG. 3 shows the positional relationship between the first mirror 42 and the original G. As shown in FIG. The first mirror 42 is arranged at an angle θ slightly smaller than approximately 45° with respect to the original G so that the reading position of the original does not fall into the shadow of the mirror 42 when the original G is exposed to light from outside the lighting window 14. It is located. This angle θ
If is too small, the reading aperture in the sub-scanning direction will be larger than the reading pitch, resulting in inaccurate reading, so it is preferably arranged at an angle within the range of 40' to 30'.

Table 2 shows the distance Lh from the original G to the first mirror 42 as 15.
The distance χ between the first mirror 42 and the reading position on the document and the incremental error δ of the reading aperture in the case of a dragon are shown. In this case, α is an angle indicating the amount of increase in the distance χ with respect to the distance RI. Further, the incremental error δ of the reading aperture is δ, -1(y/Y)-1) where the original reading aperture is Y1 and the aperture including the increase due to tilting of the first mirror is y. Indicated by xloo.

Table 2 Tilt angle and reading error of first mirror FIG. 4 shows details of the corner cube prism incorporated in the image reading device shown in FIG. 1.

As shown in FIG. 1, in one embodiment of the present invention, in order to reduce the thickness of the housing IO, the housing IO is disposed outside the sub-scanning area and has a relatively long front focal length. A lens 64 is provided. That is, in the second carriage having a right-angle mirror in which two mirrors are normally arranged at right angles, the interval between the two mirrors can be reduced. This makes it possible to arrange the corner cube prism 52 in place of the right-angle mirror.

Here, the image reading line of the CCD sensor 72 incorporated in the image reading unit 70, that is, the deviation of the optical axis limited by the sensor pixel size of the CCD sensor 72 will be considered. The image reading by the CCD sensor 72 is performed using the width orthogonal to the main scanning line of the first mirror 44, that is, the sub-scanning line, because the line width of the main scanning line on the document surface of the document G corresponding to the aperture is as narrow as several tens of meters. The directional width is reduced. This allows the first carriage 40 to be made lighter and smaller. On the other hand, the precision of the optical axis of the reflecting mirror that forms the optical path that guides image information to the CCD sensor 72 (especially
The perpendicularity of a right-angle mirror, in which two mirrors are arranged at right angles, is important. For example, in a right-angle mirror conventionally used in the second carriage, in which two mirrors are arranged at right angles, the optical axis that forms an image on the sensor pixel of the CCD sensor 72 may be distorted due to lack of angular precision (squareness of the right-angle mirror). In order to suppress the deviation γ of the optical axis, which is an indicator of deviation from the first mirror 44, to ±0.5■ or less, the second carriage 5 shown in FIG.
The maximum value of the moving distance g of 0 (in this example, at least 1/2 of the length larger than the long side direction of A4 paper) approximately 160 mm
On the other hand, the deviation angle φ of the optical axis is approximately ±0° to 18°.

If this angle is replaced with the permissible width of the right angle mirror, it becomes 90''±0.09°.

The corner cube prism 52 described above has a diameter of approximately 1.4
The first reflective surface 53 is made of a material having a refractive index of 14 or more.
and the second reflective surface 54 are formed at right angles, and the − side is approximately the number I.
It is a triangular prism-shaped refracting body having a cross-sectional shape of a right isosceles triangle. This first surface 53 and second surface 54
The perpendicularity of is formed fairly accurately and can be manufactured with tolerances of generally less than 5-2-(min). Preferably,
The corner cube prism 52 is formed of a material with a large Abbe number (approximately 60 or more) so that light rays incident from the periphery, that is, light rays incident at an angle to the optical axis, will not be split. In addition, the corner cube prism 52 has a light exit surface 52a shown in FIG. 4 made of a material with a transmittance of 96% or more, and a reflectance of 99% at the first and second reflecting surfaces 53 and 54. Since this is ensured, the total efficiency is 0.992 The total efficiency in the mirror is: 922→0.85 The reflection efficiency is improved.

The light incident on the first surface 53 of the corner cube prism 52 is bent by exactly 90'' and guided to the second reflective surface 54.
The light is bent, the direction of incidence on the first surface 53 is changed by 180° (that is, it is retroreflected), and the light is guided to the imaging means 60 .

According to the embodiment of the present invention, since the corner cube prism 52 is used as a part of the folding mirror of the second carriage that guides the reflected light from the original to the reading section, the two mirrors that were conventionally used are arranged at right angles. Problems regarding the required squareness tolerance of the arranged right-angle mirrors are easily resolved. That is, even if the conner cube prism 52 is disposed at a slight inclination with respect to the optical axis, as is well known, the direction of the incident light beam and the outgoing light beam can be changed accurately by 180'. 50, no adjustment is required to maintain squareness.

In addition, the corner cube prism 52 does not require the above-mentioned Cf force/reflection to maintain the perpendicularity, but instead of the conventional right-angle mirror (1. There is also no need to make adjustments regarding variations in parallelism.

FIG. 5 schematically shows a driving device in the sub-scanning direction of the image reading apparatus shown in FIG.

The housing IO includes a support member 20 that movably supports the first carriage 40, a support member 22 that movably supports the second carriage 50, and the respective carriages 40 and 5.
A driving member, ie, a timing belt 24, is provided for driving the timing belt 24. Further, this housing 1O includes a drive pulley 28 that drives a timing belt, a first and second carriage 4, and a drive pulley 28 that drives a timing belt.
switch 30.32.34 detecting operation of 0.50;
It includes a roller 36 that supports the timing belt, a spring 38 that applies a predetermined tension to the timing belt, and a drive motor (not shown). On the other hand, the first carriage 40 is a connecting member 2 used for connecting with the timing belt 24.
5, the second carriage 50 is driven by the timing belt 24 at a moving speed 1/2 that of the first carriage 40. It is equipped with 27.

The carriage 40 having the Fresnel lens 42 and the first mirror 44 is moved by the first support member 20, and the second carriage 5° having the corner cube prism 52 is moved by the second support member 22, respectively, to a predetermined height. It is supported by the scanning I'I■ function. The timing belt 24 has one end fixed to the housing 100 at a predetermined position. The direction of the timing belt 24 is reversed via the pulley 26 of the second carriage 50, and at the same time, the timing belt 24 is converted to the same height as the connecting portion of the first carriage 40. The first carriage 40 is attached to the connecting member 25 of the heald 24 whose height has been changed to the connecting part with the first carriage 40.
directly fixed in place via the The belt 24 is again changed in height and direction via the drive pulley 28, and is guided below the fixed position where one end of the belt 24 is fixed. Belt 28 whose direction is reversed at drive pulley 28
is further transformed in height and direction via rollers 36,
It is guided to a pulley 27 of the second carriage 50, which is located close to the pulley 26 of the second carriage 50. The belt 24 guided to the pulley 27 is further changed in height and direction, and the belt 24
It is connected to a spring 38 which applies a predetermined tension to.

The first carriage 40 is directly connected to the timing belt 24 and has a drive pulley 2 that transmits the drive from the drive motor.
8 at a predetermined speed V.

Further, the second carriage 50 follows the movement of the first carriage 40, as is clear from FIG. Belt 2 from being folded back
It moves in section B by 1/2 distance with respect to the moving speed of 4. That is, the ratio of the moving speeds of the first carriage 4° and the moving speed of the second carriage 50 is 2:1. Furthermore, since the switches 30, 32, and 34 are arranged at the home position, reading start position, and reverse position of the first carriage 40, respectively, the movements of the first and second carriages 40, 50 are detected. .

FIG. 6 schematically shows the operation panel of the image reading device shown in FIG. The housing 10 includes an optical imaging section 6
An operation panel 4 is provided near or on the convex portion 12 that accommodates 0.0. The operation panel 4 has a red LED 6 and a start button 8, and when the start button 8 is pressed to start image reading, the reading operation is started. The red LED 6 lights up during the reading operation, and blinks when a reading error occurs. For the LED 6, for example, a two-color display type LED capable of emitting red and green light is used, and various application examples are recognized, such as a green light being lit in a readable state and a red light being lit during a reading operation. Needless to say.

FIG. 7 schematically shows electric circuits such as a signal processing circuit of the image reading device shown in FIG. 1 and a control circuit that controls the entire device. An electric circuit 76 such as a signal processing circuit and a control circuit for controlling the entire device is connected to an image reading surface, that is, a CCD sensor 72 housed in a convex portion of the housing 10 shown in FIG. It is integrally formed with the printed circuit board 74 to be placed. This electric circuit 76 is
A processing circuit, that is, a CPU 80, and a ROM 81 that stores fixed data such as a control program for the entire device. RAM 82 for storing temporary information such as image information, and human output ports 83 and 84 for receiving and passing signals to control each operation of the device.
It is equipped with electric parts such as 85, 86, 87 and a secondary battery 88. The CPU 80 is used for overall control of the device and signal processing. The ROM 81 is a read-only memory that stores a control program for operating the CPU 80 or fixed data necessary for processing image information. RAM
82 is used as a line memory for temporarily storing image data or as a working buffer memory for the CPU 80. The input/output port 83 controls the reception and transfer of data to and from the operation panel 4. The human output boat 84 includes a motor driver 8 that controls a motor that drives the sub-scanning direction.
A signal from the CPU 80 is supplied to the CPU 9. Person output port 8
5 is a switch 30 for detecting the home position of the first carriage 40, and a switch 32 for detecting the reading start position.
and a signal from the switch 34 that detects the reverse position.
Transfer to U80. The human output port 86 transfers the CCD sensor control signal from the CPU 80 to the CCD sensor driver circuit 90 to drive the CCD sensor 72.

The output signal from the CCD sensor 72 is amplified to a predetermined gain by the amplifier circuit 91, and converted into a white or black signal with a certain level as the boundary by the binarization circuit 92, and is converted into a white or black signal by the binarization circuit 92.
The data is stored in the line memory of the RAM 82 via the 0 bus 93. After the output signal from the CCD 72 is subjected to the above processing, it is transferred to an external storage device or an external output device (not shown) via the ink face 94. The input/output port 87 monitors the voltage of the secondary battery 88 when an auxiliary unit such as a card connector is connected, and determines whether it is necessary to charge the secondary battery 88.

Another embodiment of the invention is shown in FIG. FIG. 8 schematically shows a document-mounting type image reading device that includes a light source device for reading a document. In this embodiment, the first carriage 40 collects a lamp 46, a focusing mirror 47, and the light beam from the lamp 46 instead of the Fresnel lens 42, which is an external light focusing device of the image reading device 2 shown in FIG. It is equipped with reflective plates 48 and 49 that emit light. Further, an elastic body M1, for example, a document presser 99 made of urethane or rubber, is attached to the housing to keep the document G placed in the lighting window 14 with the document surface facing downward (the surface of the polycarbonate transparent member) in close contact with the polycarbonate transparent member. It is located at lO.

In this apparatus as well, the image information of the document G is read in the same manner as in the image reading apparatus of the embodiment of the present invention shown in FIGS. 1 to 7 described above.

(Effects) As explained above, according to the present invention, the imaging lens system including the condenser lens that guides image information from a document to the image reading device is disposed outside the image reading area in the sub-scanning direction. The size or thickness of the image reading device is significantly reduced, providing a portable and compact image reading device. Furthermore, transportation efficiency or storage efficiency is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an image reading device which is an embodiment of the present invention, and FIG. 2 is a sectional view of a Fresnel lens used in the image reading device which is an embodiment of the invention shown in FIG. 3 are schematic diagrams showing the positional relationship between the first mirror and the document G, and FIG. 4 is a diagram showing the corner cube prism incorporated in the image reading device shown in FIG. 1, which is an embodiment of the present invention. A characteristic diagram, FIG. 5 is a schematic diagram showing a driving method in the sub-scanning direction of the image reading device which is an embodiment of the present invention shown in FIG. 1, and FIG. Schematic diagram of an operation panel of an image reading device according to an embodiment of the present invention, No. 7
The figure is a block diagram schematically showing electric circuits such as a signal processing circuit and a control circuit for controlling the entire apparatus of the image reading device which is an embodiment of the present invention shown in FIG. 1, and FIG. FIG. 2 is a sectional view showing an image reading device according to another embodiment of the present invention. 2... Image reading device, 10... Housing, 14...
... Lighting window, 16... Reading window, 40... First carriage, 42... Fresnel lens, 44... First mirror, 50... Second carriage, 52... Corner cube prism , 60... Imaging unit, 62... Second mirror, 64... Imaging lens, 66... Third mirror, 7
0... Image reading unit, 72... CCD sensor,
80...CPU card connector RAM cart' etc.

Claims (2)

[Claims] (1) means for focusing light on a region of the document surface in the main scanning direction; a folding optical means for folding the image information beam from the document surface in the sub-scanning direction; an optical sub-scanning means for optically sub-scanning an image of a document by moving within an image reading area; and an optical sub-scanning means for optically sub-scanning an image of a document by moving within an image reading area; An image reading device comprising an image forming means for converting. (2) means for focusing light on a region of the document surface in the main scanning direction; a folding optical means for folding the image information beam from the document surface in the sub-scanning direction; an optical sub-scanning means for optically sub-scanning an image of a document by moving within an image reading area; and an optical sub-scanning means for optically sub-scanning an image of a document by moving within an image reading area; 1. An image reading device comprising: a reflecting means that reflects the light beam in a direction intersecting a surface including the reflecting means; and an imaging means that forms an image of the image information beam from the reflecting means and converts it into image information.