JP2003348297A - Contact type image sensor and image reader - Google Patents

Contact type image sensor and image reader

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Publication number
JP2003348297A
JP2003348297A JP2002153876A JP2002153876A JP2003348297A JP 2003348297 A JP2003348297 A JP 2003348297A JP 2002153876 A JP2002153876 A JP 2002153876A JP 2002153876 A JP2002153876 A JP 2002153876A JP 2003348297 A JP2003348297 A JP 2003348297A
Authority
JP
Japan
Prior art keywords
image sensor
invisible light
rod lens
formed
cut layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
JP2002153876A
Other languages
Japanese (ja)
Inventor
Kenji Hiromatsu
憲司 広松
Original Assignee
Canon Inc
キヤノン株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Canon Inc, キヤノン株式会社 filed Critical Canon Inc
Priority to JP2002153876A priority Critical patent/JP2003348297A/en
Publication of JP2003348297A publication Critical patent/JP2003348297A/en
Withdrawn legal-status Critical Current

Links

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image sensor using a fluorescent lamp for image read ing whose infrared radiation during lighting is small for realizing an image reader of a good quality. <P>SOLUTION: In the image reader or the contact type image sensor comprising a fluorescent lamp for illuminating an original, a photoelectric conversion element for reading the original irradiated by the fluorescent lamp and a rod lens array image-forming the information of the original on the photoelectric conversion element, an invisible light cutting layer is formed on the end face of the rod lens array. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a contact type image sensor using a rod lens as an imaging element and an image reading apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, the following fluorescent lamps have been used as a light source for illuminating a document in an image reading apparatus. That is, an elongated light-tight hermetically sealed tube enclosing a discharge medium (e.g., a rare gas such as xenon) that radiates ultraviolet rays at the time of internal discharge, and a pair of opposing members arranged so as to generate a discharge upon contact with the tube. Fluorescent lamps are used. Here, at least one of the discharge electrodes is constituted by an external electrode.

[0003] A fluorescent substance is applied to the airtight tube, and converts the emitted ultraviolet light into visible light. In this fluorescent lamp, the phosphor is removed in the longitudinal direction of the tube,
An aperture for document illumination is formed. Further, in order to insulate a high voltage for discharge, a film or a tube-shaped insulating film is formed on the outer periphery of the tube so as to cover the external electrode.

[0004]

In recent years, it has been proposed to use a contact image sensor (hereinafter abbreviated as CIS) as an image reading device of a copying machine. This is cheaper in construction than a reading system using a reduction lens, and
This is because the image quality is sufficient even with a relatively dark light source because the sensitivity is about twice to ten times higher. For example, in the case of reading about 30 sheets / minute, in the case of a combination of a reduction optical system and a CCD image sensor, an original surface illuminance of about 40,000 lux is required, but in a CIS using a rod lens array, about 4000 lux is sufficient. It is.

However, the illuminance of the lamp is 4000lux.
40,000 l using a relatively dark lamp
With a lamp such as ux or 80,000 lux, the relative emission amount of near-infrared light, which was relatively small, is increased. FIG. 8 is a diagram for explaining the emission spectrum of a 4000 lux relatively low-luminance Xe lamp, and FIG.
It is a figure explaining the light emission spectrum of a 0000lux high intensity Xe lamp. 400-700
The emission spectrum in the visible light region of nm is almost the same, but 800 to 10% for the green peak around 550 nm.
Looking at the relative light emission amount in the near-infrared region of 00 nm, the 4000 lux lamp is 40000 l
It turns out that it is about three times larger than the ux lamp.

FIG. 101 is a diagram showing RGB spectral sensitivity characteristics of a general CCD image sensor. When a primary color RGB filter is formed with a dye or a pigment on a CCD or the like of an image reading sensor, as shown in FIG. 10, the CCD image sensor is not limited to an RGB region of 400 to 700 nm but also a near infrared region of 800 to 1000 nm. Also has sensitivity. Sensitivity to these near-infrared regions is essentially unnecessary, and efforts have been made to eliminate near-infrared sensitivities for RGB primary color filters of dyes and pigments, but such characteristics have not been realized yet. ing.

Accordingly, the CCD image sensor reads the near-infrared spectrum emitted from the fluorescent lamp, and as a result, RGB colors are mixed to lower the color discrimination accuracy, or the infrared spectral reflectance is high. When reading, for example, a special color ink using a color material, there is a problem that the reading is performed brighter than necessary. Since this adverse effect is more remarkable as the near-infrared region is relatively large, a problem arises when a relatively low illuminance lamp of about 4000 lux described with reference to FIG. 8 is used.

In order to solve this problem, conventionally, in a contact type image sensor, a method has been proposed in which an independent glass plate 307 provided with an optical multi-coating such as an infrared cut glass is inserted into an optical path as shown in FIG. Have been.
However, if an attempt was made to cover the 297 mm long side of the A4 size, it would be very expensive, such as several thousand yen, and could not be used for an inexpensive contact image sensor.

Of course, if an expensive rod lens array having a long optical path length is used, it is possible to insert an independent part. However, a recent cost-oriented rod lens array has a focus from the lens end face to the original. Distance is 6mm
Considering that the thickness of the platen glass is about 4 mm, the thickness of the infrared cut glass should be at least about 1.5 mm, considering breakage and manufacturability. It was virtually difficult to insert.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a contact-type image sensor according to claim 1 comprises an illumination lamp for illuminating a document;
A photoelectric conversion element for reading the document illuminated by the illumination lamp; and a rod lens having an invisible light cut layer formed on an end face thereof and forming an image of the information of the document on the photoelectric conversion element. .

[0011]

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

FIG. 1 is a diagram illustrating an image reading apparatus according to an embodiment of the present invention.

This image reading apparatus uses a platen glass 205
The information of the original 204-1 placed on the original or the original 204-2 conveyed on the flow reading glass 208 using the automatic original feeder 203 is transmitted to the contact type image sensor 30.
Read by 0. When reading the document 204-1 placed on the platen glass 205, the sub-scanning of the document 204-1 is performed by moving the contact image sensor 300 in the direction of the arrow by driving the sub-scanning motor. It is configured as follows. The image processing unit 150 generates a digital image based on an image signal output from the contact image sensor 300. The white level of the image signal is adjusted by reading the reference white plate 206.

FIG. 2 shows the contact type image sensor 300.
FIG. The fluorescent lamps 301a and 301b illuminate the original. Further, the information of the original is imaged on the reading element 305 by the rod lens array 302 which is an equal-magnification imaging element. Here, in the present embodiment, an infrared cut layer 306 is formed on the lower end surface of the rod lens array 302. Details will be described later. Further, the reading element 305 is mounted on the substrate 304 and is formed integrally with the resin casing 303.

FIG. 3 is a diagram for explaining the rod lens array 302. The rod lens array 302 has a refractive index distribution type cylindrical lens (rod lens) that acts as a lens for light traveling in the axial direction of the cylinder by continuously changing the refractive index along the radial direction of the cylinder. Many are arranged in an array in the main scanning longitudinal direction.

FIG. 4 is a sectional view of the fluorescent lamps 301a and 301b, and FIG. 5 is a view showing the longitudinal direction. As shown in FIG. 4 or FIG. 5, this fluorescent lamp comprises a light-transmitting glass tube 101 and a phosphor 10 coated on the inside of the glass tube.
2. A pair of discharge electrodes 103A and 103B arranged so as to contact the glass tube 101 and generate a discharge.
(Here, an example is shown in which both 103A and 103B are external electrodes, but at least one of them is an external electrode.) The discharge electrodes 103A and 103A
Transparent insulating film 104 formed so as to cover 103B
Consists of

The light transmitting glass tube 101 has a diameter of 4 m.
m, length 300 mm, and both ends are hermetically sealed by an airtight member (not shown). A rare gas (discharge medium) containing at least xenon gas is sealed in the glass tube 101, and a voltage of about 1.5 KV with respect to GND supplied from an inverter (not shown) is supplied between the external electrodes 103A and 103B. As a result, a discharge occurs, and ultraviolet rays are generated by the ionized rare gas atoms.

The generated ultraviolet light excites the phosphor 102 and is converted into visible light according to the order of the excitation energy.
The phosphor 102 has a high luminous efficiency with respect to ultraviolet light generated by xenon, and uses a plurality of types of phosphors in order to uniformly generate visible light of 400 to 700 nm. Further, since the fluorescent lamp is used as a light source for reading an image, an aperture is formed so that high luminance can be obtained in a direction of irradiating a document. Since the external electrodes generate a high voltage, the external electrodes are insulated by a transparent insulating film 104.

In this embodiment, as described above, by forming an infrared cut layer made of an infrared cut material that cuts near infrared light, which is invisible light, on the end face of the rod lens array, a very inexpensive structure can be used for 800 to 800 mm. This is to reduce the amount of 1000 nm infrared light to about 1/10 to 1/20.

FIG. 6 is a view for explaining an example of the spectral transmittance characteristics of the infrared ray cut material used in the present invention. FIG.
As can be seen from FIG.
It cuts off near-infrared light of 1000 nm,
It has high light transmittance in the visible light region of up to 700 nm, and has ideal characteristics that do not have large absorption characteristics at a specific wavelength in the visible region.

FIG. 7 is a view for explaining the spectrum of the light transmitted through the rod lens array provided with such an infrared cut layer, out of the emission spectrum of the image reading fluorescent lamp. The emission spectrum originally shown in FIG. 8 is thus improved by the effect of the infrared cut layer described with reference to FIG. That is, the emission spectrum in the visible light region hardly changes, and 800
The peak in the near infrared region of 領域 1000 nm can be relatively reduced to about 1/10 to 1/20 of the state in FIG.

In this embodiment, the infrared cut layer 306 is formed on the lower end surface of the rod lens array 302, that is, on the end surface of the rod lens array 302 facing the reading element 305. By forming in this position, it is possible to prevent the near infrared ray absorption characteristics from being reduced due to adhesion of dirt, dirt, and the like, as compared with the case where the rod is formed above the rod lens array 302.

The infrared cut layer 306 is made of a polymer resin in which an infrared absorbing dye is dispersed by using a rod lens array 302.
Or a polymer film in which an infrared absorbing dye is dispersed may be attached to the rod lens array 302. Further, an optical infrared cut multi-coating layer may be formed by depositing and coating a substance that absorbs or cuts infrared rays on the end surface of the rod lens array 302.

With the above arrangement, the image quality when reading a color image can be greatly improved with an inexpensive arrangement. In the present embodiment, an example has been described in which infrared light is cut off as invisible light. However, the present invention is not limited to this, and it may be configured to cut off ultraviolet light. Further, in the present embodiment, the description has been given of a rare gas fluorescent tube such as a xenon lamp. However, if a fluorescent tube is used, the same effect can be obtained with a mercury fluorescent tube such as a hot cathode tube or an example cathode tube. Nor.

[0025]

As described above, according to the present invention,
With a very inexpensive configuration, the amount of invisible light emitted from the illumination lamp can be significantly reduced. In addition, the image quality when reading a color image can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an image reading apparatus of the same magnification image forming type according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a contact image sensor according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a rod lens array.

FIG. 4 is a cross-sectional view of the fluorescent lamp according to the embodiment of the present invention.

FIG. 5 is a view of the fluorescent lamp according to the embodiment of the present invention when viewed in the longitudinal direction.

FIG. 6 is a diagram of a spectral transmittance of an infrared cut layer.

FIG. 7 is a diagram of an emission spectrum obtained by combining a low-luminance xenon lamp and an infrared cut layer.

FIG. 8 is a diagram of an emission spectrum of a low-brightness xenon lamp.

FIG. 9 is a diagram of an emission spectrum of a high-brightness xenon lamp.

FIG. 10 is a spectral sensitivity characteristic diagram of a reading element.

FIG. 11 is a diagram illustrating an embodiment of insertion of a conventional infrared cut glass.

[Explanation of symbols]

301a, 301b fluorescent lamp 302 rod lens array 305 read element 306 infrared cut layer

   ────────────────────────────────────────────────── ─── Continuation of front page    F-term (reference) 2H109 AA02 AA15 AA23 AA75 AA94                       AB33                 5C024 AX02 CX03 CY48 EX01 EX24                       EX42                 5C051 AA01 BA04 DB01 DB22 DC04                       DC07                 5C072 AA01 CA04 DA02 DA09 DA25                       EA05 EA07

Claims (8)

    [Claims]
  1. An illumination lamp for illuminating a document, a photoelectric conversion element for reading the document illuminated by the illumination lamp, and an invisible light cut layer formed on an end face, for connecting information of the document to the photoelectric conversion element. And a rod lens for imaging.
  2. 2. The lighting lamp according to claim 1, wherein the lamp comprises an airtight tube filled with a discharge medium that emits ultraviolet rays at the time of discharge and coated with a phosphor, and a discharge electrode for contacting the tube to generate a discharge. The contact type image sensor according to claim 1, wherein the contact type image sensor is a fluorescent lamp comprising:
  3. 3. The contact-type image sensor according to claim 1, wherein the invisible light cut layer is formed by coating an end surface of the rod lens with an invisible light absorbing material. .
  4. 4. The contact type image sensor according to claim 1, wherein the invisible light cut layer is formed by coating an end surface of the rod lens with an invisible light absorbing material. .
  5. 5. The contact type image sensor according to claim 4, wherein the invisible light cut layer is formed by dispersing the invisible light absorbing dye in a polymer resin.
  6. 6. The contact-type image sensor according to claim 1, wherein the invisible light cut layer is formed by dispersing an invisible light absorbing dye in a polymer film.
  7. 7. The close contact type according to claim 1, wherein the invisible light cut layer is formed on an end face of the rod lens array on a side facing the photoelectric conversion element. Image sensor.
  8. 8. A contact image sensor according to claim 1, further comprising: a sub-scanning unit for displacing a relative position between the original and the contact image sensor. An image reading apparatus characterized by the above-mentioned.
JP2002153876A 2002-05-28 2002-05-28 Contact type image sensor and image reader Withdrawn JP2003348297A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002153876A JP2003348297A (en) 2002-05-28 2002-05-28 Contact type image sensor and image reader

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002153876A JP2003348297A (en) 2002-05-28 2002-05-28 Contact type image sensor and image reader

Publications (1)

Publication Number Publication Date
JP2003348297A true JP2003348297A (en) 2003-12-05

Family

ID=29770804

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002153876A Withdrawn JP2003348297A (en) 2002-05-28 2002-05-28 Contact type image sensor and image reader

Country Status (1)

Country Link
JP (1) JP2003348297A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006227384A (en) * 2005-02-18 2006-08-31 Ricoh Co Ltd Image scanner, image forming apparatus and image reading method
US7411733B2 (en) 2005-10-17 2008-08-12 Funai Electric Co., Ltd. Compound-eye imaging device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006227384A (en) * 2005-02-18 2006-08-31 Ricoh Co Ltd Image scanner, image forming apparatus and image reading method
JP4669713B2 (en) * 2005-02-18 2011-04-13 株式会社リコー Image reading apparatus and image forming apparatus
US7411733B2 (en) 2005-10-17 2008-08-12 Funai Electric Co., Ltd. Compound-eye imaging device

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A300 Withdrawal of application because of no request for examination

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Effective date: 20050802