JP2003005304A - Regular size sheet holder and image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regular size sheet holder capable of easily positioning several kinds of regular size original sheets on the platen surface of an original platen in an image reader where an original reading area is limited to a part of the original platen. SOLUTION: One film holder 50 is made usable at least in two ways by arranging 1st positioning parts 58 and 62 and 2nd positioning parts 52 and 68 coming into contact with an original guide 16 in diagonal positions on a sheet-like member, and positioning transparent original sheets having mutually different shapes by taking respective positioning parts as a reference. That is, as for the 1st positioning parts 58 and 62 and the 2nd positioning parts 52 and 68, opening parts 54 and 64 positioned in a reading area 19 when the positioning parts are brought into contact with the original guide 16 and a holding part for holding a strip film or a mount film in the opening parts 54 and 64 are arranged, and the shape of the opening part 54 is made to differ from that of the opening part 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed sheet holder for holding a fixed original sheet in a reading area and an image reading apparatus.

[0002]

2. Description of the Related Art Conventionally, there is known an image reading apparatus such as an image scanner, a copying machine or a facsimile machine, which has a function of reading a transparent original recorded on a photographic film or the like. Flatbed image scanner, etc.
In an image reading apparatus (hereinafter, referred to as a flat bed type image reading apparatus) in which a manuscript sheet is placed on a manuscript table, the manuscript table is considerably larger than the size of the transparent manuscript sheet on which the transmissive manuscript such as photographic film is recorded. Since it is wide, it is possible to place a plurality of transparent original sheets on the original table and read a plurality of transparent originals at one time. In a flat bed type image reading apparatus, a so-called film holder for holding a transparent original sheet is generally used when positioning a standard transparent original sheet such as a photographic film on the platen surface of the original table. FIG. 2A shows a conventional film holder 90. The openings 92 are formed in four rows and each row holds one 35 mm strip film. The opening 92 is divided into two rows by a partition 93. The opening 91 is formed to detect white reference data for shading correction.

[0003]

In the flat bed type image reading apparatus, the reading area is almost the entire area of the original table for the reflective original, while the irradiation area of the light source is limited for the transparent original. It is known that the manuscript table is limited to a part. In the film holder used in such a flat bed type image reading device, the film holder is adjusted to fit the width of the reading area.
Like the film holder 94 shown in (B), the number of transparent original sheets to be held is generally small, and the number of types of transparent originals to be held is one per film holder.
Limited to types.

Therefore, when trying to read many kinds of transparent original sheets with a flat bed type image reading apparatus in which the reading area of the transparent original is limited to a part of the original table, a transparent original sheet which can be mounted on one film holder is used. Since there is only one type, the film holder must be frequently replaced, and the attachment and detachment of the original and the standard sheet holder are complicated.

The present invention provides a standard sheet holder capable of easily positioning a plurality of types of standard document sheets on the platen of the document table in an image reading apparatus in which the document reading area is limited to a part of the document table. With the goal.
SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading device capable of easily positioning a plurality of types of standard document sheets on the platen surface of a document table.

[0006]

According to the first aspect of the present invention, the positioning portions that come into contact with the first guide portion and the second guide portion, which are generally L-shaped, are arranged diagonally to the plate member. However, by adopting a configuration in which originals having different shapes are positioned on the basis of the respective positioning portions, one fixed sheet holder can be used in at least two ways. That is, the first positioning portion and the second positioning portion are provided diagonally of the plate-shaped member, and for each positioning portion, when the positioning portion is in contact with the first guide portion and the second guide portion An opening portion and a holding portion for holding a standard transparent original sheet are provided in the opening portion, and the shapes of the respective opening portions are different from each other. According to the first aspect of the invention, the first holding portion holds the original sheet in the first opening, and the first positioning portion is brought into contact with the first guide portion and the second guide portion to read the original, and Since the second holding portion holds the original sheet in the second opening portion and the second positioning portion is brought into contact with the first guide portion and the second guide portion to read the original, there are two ways to use the document sheet. A standard document sheet can be easily positioned on the platen surface of the document table.

According to the invention of claim 2, a document table,
A first guide portion and a second guide portion arranged in a substantially L-shape around the document table, a transparent document light source for illuminating a part of the reading area on the plate surface of the document table, and the transparent document document An image pickup unit that outputs an image signal according to the shade of a transmitted light image of a document image illuminated on a light source, and a plate-shaped standard sheet holder mounted on the plate surface of the document table are provided. According to the invention of claim 2, in the standard sheet holder, the first positioning portion capable of contacting the first guide portion and the second guide portion, and the first positioning portion includes the first guide portion and the first guide portion. A first opening located in the reading area when in contact with the two guides, and a first holding part provided around the first opening and holding a standard document sheet in the first opening, A second positioning portion that is formed diagonally to the first positioning portion and is capable of contacting the first guide portion and the second guide portion, and the two positioning portions are the first guide portion and the second guide portion. A second opening which is located in the reading area and has a different shape from the first opening when abutting, and a fixed transparent original sheet provided around the second opening is held in the second opening. Since it has a second holding part to
Multiple types of standard document sheets can be easily positioned on the platen surface of the document table.

According to the invention of claim 3, the image pickup section is
The standard sheet holder has a linear sensor and a sub-scanning driving unit that moves the main scanning line in a direction perpendicular to the main scanning line.
A notch or opening lined up in the sub-scanning direction with the first opening,
It has a notch or an opening aligned with the second opening in the sub-scanning direction. According to the invention of claim 3, by forming these notches or openings, it is possible to secure an optical path for detecting the shading of the optical system.

According to a fourth aspect of the present invention, the linear sensor has a lens for forming a transmitted light image on a main scanning line of an original image illuminated by the transparent original light source, and the reading area is main-scanned. Since it is the whole or a part of the locus in the center of the line, the distortion of the transmitted light image can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plurality of embodiments showing the embodiments of the present invention will be described below with reference to the drawings. 3 and 4
1 shows an image scanner 10 as an image reading device according to an embodiment of the present invention.

The image scanner 10 is a so-called flat bed type in which a manuscript stand 14 is provided on the upper surface of a substantially box-shaped housing 12, and an image pickup device 20 and an optical system 30 for forming a manuscript image on the image pickup device 20. A processing unit 100 that processes an output signal of the image sensor 20, and a drive unit 4 that drives the image sensor 20.
0 and a control unit 110. The image pickup unit described in the claims is composed of an image pickup device 20, a processing unit 100, a control unit 110, and the like.

The original table 14 is formed of a transparent plate such as a glass plate, and an original sheet is placed on the surface of the original plate. Platen 14
As shown in FIG. 3, a white reference 28 having a high-reflectance uniform reflection surface is provided on the edge portion of the. As shown in FIG. 1, FIG. 3, FIG. 5 and FIG.
A document guide 16 for positioning the reflection document sheet is provided on the board surface of No. 4. The document guide 16 has a square or L-shape and has at least two guide portions 17 that are orthogonal to each other.

As shown in FIG. 5, the case 12 is provided with a transparent original document unit 38. The transparent manuscript unit 38 has a light source 37 for a transparent manuscript, is mounted above the manuscript table 14 when reading a transparent manuscript, and is removed when reading a reflective manuscript. The transparent original light source 37 in this embodiment is a surface light source composed of a tube illumination such as a fluorescent lamp (not shown) and a reflection plate and a diffusion plate (not shown). Light from the tube illumination is placed on the original table 14 by the diffusion plate. The transparent original reading area 19 is irradiated with a substantially uniform surface. The transmitted light image of the transparent original on the original table 14 illuminated by the transparent original light source 37 is formed on the light receiving portion of the image pickup device 20 by the optical system 30. As a light source for the transparent original, a fluorescent lamp that moves in the sub-scanning direction along with the main scanning line may be used.

The transparent original reading area 19 is shown in FIGS.
Further, as shown in FIG. 6, it is desirable to make it a part of the center locus of the main scanning line. Since the condenser lens 36, which will be described later, has a small optical image distortion in the vicinity of the optical axis and a large optical image distortion in the peripheral portion, the transparent original reading area 19 is limited to the central portion of the original table 14 in the main scanning direction. This is because the distortion of the transmitted light image formed on the linear sensor 20 can be reduced. Further, since the irradiation range can be reduced, the transparent original light source 37 can be made small and simple.

The film holder 50 as a fixed sheet holder described in the claims is placed on the platen surface of the document table 14 as shown in FIG. 1 or 6. The film holder 50 is a thin plate member made of plastic or the like and has a plurality of openings formed therein.

The contour of the film holder 50 is generally rectangular and point-symmetrical. The size of the contour of the film holder 50 is such that the transparent original reading area 1 is defined from two sides of the guide portion 17 on the reading origin side (the upper right side in FIG. 1) of the original guide 16.
It is a size that covers up to 9. The first positioning portion described in the claims has an end face 58 on the short side and an end face 6 on the long side.
2 and the second positioning portion has an end surface 68 located opposite the end surface 58 and an end surface 5 located opposite the end surface 62.
It consists of 2. That is, the first positioning portions 58 and 62
And the second positioning portions 68 and 52 each have an L-shape and are formed at diagonal positions. Triangular marks 60 and 70 are formed at corners of the first positioning portions 58 and 62 and the second positioning portions 68 and 52, respectively. These marks 60, 70 guide the user how to position the film holder 50 by making them correspond to the marks 18 formed on the document guide 16.

As shown in FIG. 1, the film holder 50 has a notch 56 at a position which becomes the reading area 19 when the first positioning portions 58 and 62 come into contact with the two guide portions 17 on the reading origin side of the document guide 16. And a first opening 54.

The outline of the first opening 54 is a rectangle having a size that surrounds the exposure range of 4 to 6 frames of the 35 mm strip film. The longitudinal axis of the first opening 54 is parallel to the sub-scanning direction axis (vertical axis in FIG. 1). As shown in FIGS. 1 and 7, a concave portion 55 as a first holding portion and a generally U-shaped groove 53 are formed around the first opening 54. The 35 mm strip film straddles the first opening 54 and is stretched over the recess 55. Both long sides of the 35 mm strip film are locked in the groove 53.

As shown in FIG. 1, the notch 56 has a reading area 1 when the first positioning portions 58 and 62 come into contact with the two guide portions 17 on the reading origin side of the document guide 16.
9 at the position occupying a part of 9 on the sub-scanning direction axis.
4 and 4 are arranged side by side, and the document table 14 is formed so as to directly illuminate the transparent document light source 37 in a part of the reading area 19. The width of the notch 56 in the sub-scanning direction (left-right direction in FIG. 1) is wider than the width of the first opening 54 in the sub-scanning direction. Hereinafter, the area of the reading area 19 which is always directly illuminated by the transparent original light source 37 is referred to as a shading detection area.

As shown in FIG. 6, the film holder 50 has a notch 66 at a position which becomes the reading area 19 when the second positioning portions 68 and 52 come into contact with the two guide portions 17 on the reading origin side of the document guide 16. And four second openings 6
Have 4.

The second opening 64 is a square having a size into which the frame portion of the 35 mm mount film fits. The four second openings 64 are aligned parallel to the longitudinal axis of the first opening 54. The square-shaped end surface forming the second opening 64 corresponds to the second holding portion described in the claims. A semicircular recess 63 is formed in a part of the peripheral edge of the second opening 64. The concave portion 63 makes it easy to hook a fingertip on the frame portion of the mount film.

As shown in FIG. 6, the notch 66 has a reading area 1 when the second positioning portions 68 and 52 come into contact with the two guide portions 17 on the reading origin side of the document guide 16.
The second opening 6 on the axis in the sub-scanning direction at a position occupying a part of 9
4 is formed side by side with 4 to secure a shading detection area when the mount film is read. still,
In this embodiment, the shading area is cut out 56, 66.
However, it may be secured by a square opening.

Although a linear sensor is used for the image pickup device 20 shown in FIGS. 3 and 4, a contact type two-dimensional sensor may be used. The linear sensor 20 is mounted on the carriage 24 in a posture in which a plurality of photoelectric conversion elements are arranged substantially linearly in a direction perpendicular to the moving direction of the carriage 24. A photodiode or the like is used as the photoelectric conversion element. The arrangement direction of the photoelectric conversion elements of the linear sensor 20 defines the main scanning direction,
The movement direction of the carriage 24 is the sub-scanning direction. The linear sensor 20 stores electric charges obtained by photoelectrically converting light in a predetermined wavelength region such as visible light, infrared light, and ultraviolet light for a certain period of time, and outputs an electric signal corresponding to the amount of received light to a CCD (Charge Cou
pled device), a device that outputs using a MOS transistor switch, etc. is used. In this embodiment, a lens reduction type linear image sensor is used as the linear sensor 20, but a contact type linear image sensor may be used.

The color output method is an on-chip method, and a color filter array is formed on the light-receiving portion on-chip, one line for each RGB, or three lines for each RGB.
A linear sensor 20 composed of 6 lines is used. Any of the dichroic mirror system, the light source switching system, and the filter switching system may be adopted as the color output system. Further, the present invention can naturally be applied to a monochrome output image reading device.

An optical system 30 for forming an original image on the image pickup device 20 is composed of a reflective original light source 22, a transparent original light source 37, a mirror 34, a condenser lens 36 and the like. As shown by the broken line in FIG. 1, the transmitted light image of the transparent original sheet A on the original table 14 illuminated by the transparent original light source 37 is formed on the light receiving portion of the linear sensor 20 by the mirror 34 and the condenser lens 36. It The mirror 34 is for increasing the optical path length from the document to the linear sensor 20.

Driving unit 40 for driving the linear sensor 20
Is mainly composed of an electronically operated main scanning drive section 102 and a mechanically operated sub-scan drive section 26.

The main scanning drive unit 102 includes a linear sensor 20.
Is an electronic circuit that generates a drive pulse such as a shift pulse and a transfer pulse required to drive the, and outputs the drive pulse to the linear sensor 20. The main scanning drive unit 102 is composed of, for example, a synchronization signal generator, a driving timing generator, and the like.

The sub-scanning drive unit 26 for moving the main scanning line in the sub-scanning direction is provided with a carriage 24, a belt locked by the carriage 24, a stepping motor for rotating the belt, for example, which is easily controlled. Carriage 24
Is slidably locked to a shaft or the like and is reciprocally movable in a direction parallel to the plate surface of the document table 14 (direction a in FIG. 3). The carriage 24 conveys the linear sensor 20 and the reflective original light source 22 in parallel to the surface of the original table 14 by driving the belt, for example.

As shown in FIG. 4, the processing section 100 includes a main scanning drive section 102, an analog signal processing circuit 104, and an A / D.
It is composed of a converter 106 and a digital signal processing unit 108. In this embodiment, the main scanning drive unit 102, the analog signal processing circuit 104, and the A / D of the processing unit 100.
The converter 106 is mounted on the carriage 24, and the digital signal processing unit 108 is fixed to the housing 12. The connection between the circuit mounted on the carriage 24 and the circuit fixed to the housing 12 is realized by a flexible flat cable (FFC) not shown.

The analog signal processing circuit 104 performs analog signal processing such as amplification and noise reduction processing on the analog electric signal output from the linear sensor 20, and the processed signal is sent to the A / D converter 106. Output. A / D
The converter 106 converts the analog electric signal output from the analog signal processing circuit 104 into a digital image signal, and outputs the image signal to the digital signal processing unit 108.

The digital signal processing unit 108 performs various processes on the image signal output from the A / D converter 106, and outputs image data to be transferred to the image processing device 150 connected to the image scanner 10. It is a thing.
Specifically, the digital signal processing unit 108 has a shading correction unit 120, a gamma correction unit 122, and a defective pixel correction unit 124. The various processes performed by the digital signal processing unit 108 can be replaced with processes by a computer program executed by the control unit 110 or the image processing apparatus 150.

The shading correction section 120 varies the sensitivity of each pixel of the linear sensor 20 or each block consisting of several pixels, the irradiation light amount distribution of the reflection original light source 22 or the transmission original light source 37 in the main scanning direction, and the light collection. Shading caused by the optical characteristics of the lens 36 and the like is corrected. Shading correction when reading transparent originals is
Before the reading of the original, the light emitted from the light source for transparent original 37 passes through the shading area and is incident on the linear sensor 20 without passing through the transparent original sheet. This is performed in combination with black reference data stored in advance in a memory (for example, ROM 134 described later).

The gamma correction unit 122 includes the image processing device 15
The gamma correction of the image signal is performed according to the gamma characteristic of 0. The defective pixel correction unit 124 generates a defective pixel signal by interpolating a signal of an adjacent pixel by a pixel interpolation method.

The control unit 110 includes a CPU 130 and a RAM 13
2. A microcomputer having a ROM 134. The control unit 110 controls the movement of the carriage 24 (that is, the driving of the sub-scanning drive unit 26) by executing the computer program recorded in the ROM 134, and the light source 2
The overall control of the image scanner 10 is performed, such as blinking of 2 and 37, control of light amount, operation control of each element of the processing unit 100, and the like.

The control section 110 is connectable to an image processing apparatus 150 such as a personal computer via an interface 140 provided on the housing 12.
The control unit 110 has the image processing device 150 connected to it.
Based on the read command signal from the computer, one of the computer programs stored in the ROM 134 for reading the original is executed.

The configuration of the image scanner 10 has been described above. The usage and operation of the image scanner 10 will be described below. In the following description, it is assumed that the image scanner 10 is connected to the image processing device 150.

The film holder 50 is used when reading a transparent original recorded on a transparent original sheet such as a negative film or a positive film. Film holder 50 is 35m
An m-strip film (hereinafter referred to as a negative film) and a 35 mm mount film (hereinafter referred to as a positive film) can be held and positioned on the platen surface of the document table 14.

(Positioning of negative film) First opening 5
The exposed portion of the negative film is positioned in the first opening 54 by locking the end portion in the groove 53 formed in the peripheral edge of the No. 4 film. Figure 1
As shown in, the first positioning portions 58 and 62 are brought into contact with the guide portions 17 on the two sides of the original guide 16 on the reading origin side, and the first opening 54 is positioned in the transparent original reading area 19. As a result, the exposed portion of the negative film is positioned in the transparent original reading area 19.

(Positioning of the positive film) As shown in FIG. 6, the second positioning portions 68 and 52 are brought into contact with the guide portions 17 on the two sides of the original guide 16 on the reading origin side and the four second opening portions 64. Is positioned in the transparent document reading area 19. When the positive film is fitted into each of the second openings 64, the frame portion of the positive film is held by the plate surface of the document table 14 and the inner wall surface of the second opening 64, whereby the exposed portion of the positive film is the transparent original reading area. Positioned at 19.

The user of the image scanner 10 positions the transparent original sheet on the platen surface of the original table 14 as described above, and then specifies the reading range and the reading resolution of the original by the input operation to the image processing apparatus 150. Command 10 to read the document. In response to the command, the image scanner 10 operates as follows. (1) The transparent original light source 37 is turned on to illuminate the shading area on the platen of the original table 14 to acquire white reference data. (2) The transparent original light source 37 is turned on, and the transmitted light image of the negative film or the positive film is formed on the light receiving portion of the linear sensor 20 by the optical system 30. (3) The main scanning drive unit 102 inputs a drive pulse such as a shift pulse to the linear sensor 20 in a predetermined sequence. As a result, the linear sensor 20 accumulates an amount of electric charge (signal electric charge) that correlates with the density of the transmitted light image, and the accumulated electric charge is processed by the CCD or the like as an electric signal into the processing unit 1.
00 (analog signal processing circuit 104). (4) The electric signal output from the linear sensor 20 is processed by the processing unit 100, and the image data output as a result is transferred to the image processing apparatus 150. (5) While moving the carriage 24 at a constant speed, (2) to (4) are repeatedly executed for each main scanning line in the transparent original reading area 19. As a result, the image data representing the optical density information of the transparent original image recorded on the negative film or the positive film is transferred to the image processing device 150.

According to the image scanner 10 according to the embodiment of the present invention, one film holder can be used in two ways, and it is not necessary to use the film holder separately for the negative film and the positive film. Therefore, the image scanner 10 can reduce the complexity of exchanging the film holder. That is, according to the image scanner 10, a plurality of types of standard document sheets can be easily positioned on the surface of the document table. Further, according to the image scanner 10, since the reading area 19 of the transparent original is limited to the center locus of the main scanning line, the condenser lens 3
The image distortion at the peripheral portion of 6 does not affect the reading resolution of the transparent original. Further, the light source 37 for transparent original can be made small and simple. In addition, 2 of the film holder 50
Since the film holder 50 is positioned on the document table 14 by bringing the side and the two sides of the document guide 16 into contact with each other, the film can be positioned at an accurate position.

Although one embodiment of the present invention has been described in detail above, this is merely an example, and the present invention should not be construed as being limited by the description of such an embodiment. For example, in the above embodiment, the film holder 50
The two positioning parts are formed diagonally on one side so that one film holder 50 can be used in two ways. However, a film holder having a substantially square contour has four positioning parts at each corner part. It may be formed so that one film holder can be used in four ways.

[Brief description of drawings]

FIG. 1 is a plan view showing a film holder of an image scanner according to an embodiment of the present invention.

FIG. 2 is a plan view showing a conventional example of a film holder.

FIG. 3 is a schematic diagram showing an image scanner according to an embodiment of the present invention.

FIG. 4 is a block diagram illustrating an image scanner according to an exemplary embodiment of the present invention.

FIG. 5 is a perspective view showing an image scanner according to an embodiment of the present invention.

FIG. 6 is a plan view showing a film holder of the image scanner according to the embodiment of the present invention.

7 is a sectional view taken along line VII-VII of FIG.

[Explanation of symbols]

10 image scanner 12 cases 14 Platen 16 Document guide 17 Guide 18 mark 19 Transparent original reading area 20 Linear sensor (image sensor) 22 Light source for reflective originals 24 carriage 28 White standard 30 Optical system 34 Mirror 36 Condensing lens 37 Light source for transparent original 38 Transparent manuscript unit 40 Drive 50 film holder 53 groove 54 First opening 64 Second opening 100 processing unit 110 control unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/00 108 H04N 1/00 108F 5C072 1/10 1/10 1/107 F term (reference) 2H012 BA02 BA08 BA11 2H076 AA06 AA58 BA03 BA05 BB06 2H109 AA02 AA15 AA23 AB44 AB48 DA19 5B047 AA05 AB04 BA02 BB03 BC05 BC09 BC11 BC15 BC16 BC20 5C062 AB03 AB36 AD06 AE03 BA02 5A07 DA03 RA06 DA02 DA04 DA04 DA02 DA04 DA02 DA04

Claims (4)

[Claims] 1. An image of a document recorded on a document sheet which is positioned and mounted on a platen surface of a document table by a first guide portion and a second guide portion which are arranged in a generally L-shape is formed on an image sensor. A fixed sheet holder that holds a fixed original sheet in a reading area of an image reading device that outputs an image signal according to the density of an original image, and includes a plate-shaped member placed on the plate surface of the original table. The plate-shaped member includes a first positioning portion that can abut the first guide portion and the second guide portion, and the first positioning portion abuts the first guide portion and the second guide portion. When the first opening is located in the reading area, a first holding unit that is provided around the first opening and holds a standard document sheet in the first opening, and a diagonal of the first positioning unit. Formed on the first guide portion and the A second positioning part capable of contacting the second guide part, and the first opening part located in the reading area when the second positioning part contacts the first guide part and the second guide part. A fixed sheet holder, comprising: a second opening having a different shape; and a second holding portion which is provided around the second opening and holds a fixed transparent original sheet in the second opening. . 2. A document table, a first guide section and a second guide section which are arranged in a substantially L shape around the document table, and a transparent plate which irradiates a part of the reading area on the plate surface of the document table. An original light source, an image pickup unit that outputs an image signal according to the density of a transmitted light image of an original image irradiated on the transparent original light source, and a plate-shaped standard sheet holder mounted on the plate surface of the original table. And a fixed sheet holder, a first positioning portion capable of contacting the first guide portion and the second guide portion, the first positioning portion to the first guide portion and the second guide portion. A first opening portion located in the reading area when abutting, a first holding portion which is provided around the first opening portion and holds a standard document sheet in the first opening portion, and the first positioning Formed on the diagonal of the first part and the first guide part and the first part. A second positioning part capable of contacting the second guide part, and a shape different from the first opening part positioned in the reading area when the second positioning part contacts the first guide part and the second guide part. An image reading apparatus comprising: a second opening portion having a second opening portion; and a second holding portion that is provided around the second opening portion and holds a standard transparent original sheet in the second opening portion. 3. The image pickup unit includes a linear sensor and a sub-scanning drive unit that moves a main scanning line in a direction perpendicular to the main scanning line, and the fixed sheet holder has the first opening portion. The image reading apparatus according to claim 2, further comprising a notch or an opening lined up in the sub-scanning direction, and a notch or an opening lined up in the sub-scanning direction with the second opening. 4. The image pickup unit has a lens for forming a transmitted light image on a main scanning line of an original image illuminated by the light source for the transparent original on the linear sensor, and the reading area is a main scanning line. The image reading apparatus according to claim 3, wherein the central locus is the whole or a part of the central locus.