JPH0832756A - Image reader - Google Patents

Abstract

PURPOSE:To prevent a member, which possibly resonates, from resonating irrelevantly to a moving speed for an image read and to obtain data of image information of high picture quality by attaching and detaching a resonance preventive member to the member according to the moving speed. CONSTITUTION:The resonance preventive member 30 of the image reader 10D stands by in a corner in a housing 18 outside the normal movement range of a carriage 28 for reading a document mounted on a platen 16, and the shaft of a solenoid 32 stays in a lock hole formed in a plate 34 on which the member 30 is mounted. The member 30 consists of a permanent magnet and the carriage 28 advances in a direction B to make a scan; and the member 30 and a magnet piece 29 comes into contact with each other and the carriage 28 moves in a direction C. Consequently, the member 20 moves together with the carriage 28 and the weight of the carriage 28 increases, thereby reading the image by using a document feeder 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for photoelectrically reading an image recorded on a document by moving a document or a scanning optical member.

[0002]

2. Description of the Related Art In recent years, as an image reading device used in a copying machine or the like, a digital image reading device which photoelectrically reads image information by using an image sensor has become widespread. Below, a schematic configuration of various image reading apparatuses using an image sensor will be described.

FIG. 1 is a schematic sectional view of the image sensor fixing type reduction optical system type image reading apparatus. A document feeding device 12 is provided above the image reading device 10A. When a document 14 is set on the document feeding device 12 and a start button (not shown) is pressed, the set document 14 is indicated by an arrow A. One by one is conveyed along.

A platen 1 is provided below the document feeder 12.
6, that is, a document placing table made of glass is provided. Further, inside the housing 18 of the image reading apparatus 10, a carriage 20 and a carriage 22 in which a scanning optical system is incorporated.
Are provided so as to be movable in the directions of arrows B and C. Further, a light receiving unit 24 incorporating a light receiving optical system is fixed to the housing 18.

When the image recorded on the original is read by using the original feeding device 12, the carriages 20 and 22 are in the state of being moved to the positions shown in the figure, and the lamp 201 incorporated in the carriage 20 moves in the direction of arrow A. The original 14 being conveyed is irradiated with light, the light carrying the image information recorded on the original 14 is reflected from the original 14, and the reflected light is reflected by the mirror 202, and further the carriage 22.
Reflected by the two mirrors 221 and 222 incorporated in
The light enters the image sensor 243 fixed to the housing 18 via the fixing member 242 via the imaging lens 241 incorporated in the light receiving unit 24. This image sensor 243 is a one-dimensional image sensor in which a large number of optical sensors are arranged in a direction perpendicular to the paper surface of FIG. 1, and at one time, the original 14 being conveyed in the direction of arrow A is placed on the image sensor 243. The image on one line in the direction perpendicular to the paper surface of FIG. 1 is reduced by the imaging lens 241 to be imaged. When the document feeder 12 is used,
The image recorded on the original 14 is photoelectrically read.

The image reading device 10 is a document feeding device 1.
Place the original on the platen 16 without using 2,
An image can also be read from a document placed on the platen 16. In this case, the original does not move this time, the carriage 20 moves in the direction of the arrow B to the position shown by the broken line in the figure, and the carriage 22 also moves in the direction of the arrow B accordingly, so that the original is scanned and the original is scanned. The image recorded in is read.

At this time, in order to keep the optical path length between the original and the image sensor 243 constant, the carriage 22 moves at a speed half the speed of the carriage 20. FIG. 2 is a schematic configuration diagram of an image sensor moving type contact image reading apparatus. The same components as those of the image reading apparatus shown in FIG. 1 are designated by the same reference numerals as those shown in FIG.
Only the differences will be described.

Inside the housing 18 of the image reading apparatus 10B shown in FIG. 2, a lamp 261 for irradiating a document, an image forming lens 262, and an image sensor 2 fixed to a substrate 263 are provided.
A carriage 26 in which 64 is incorporated is provided so as to be movable in the directions of arrows B and C. The original is illuminated by the lamp 261 and the image information of the original due to the reflected light is imaged on the image sensor 264 via the imaging lens 262. The image sensor 263 is an image sensor having a size larger than that of the image sensor 243 shown in FIG. 1, and the image forming lens 262 forms an image having substantially the same size as the image recorded on the original on the image sensor 264. To be done.

In the image reading apparatus 10B shown in FIG. 2, as in the case of the image reading apparatus 10A shown in FIG. 1, the original document is fed by the original feeding device 12 to read the image recorded on the original document. Alternatively, the document can be placed on the platen 16 and the carriage 26 can be moved to read the image recorded on the document. FIG.
FIG. 1 is a schematic configuration diagram of an image sensor moving type reduction optical system type image reading apparatus. The same components as those of the image reading apparatus shown in FIGS. 1 and 2 are designated by the same reference numerals as those of FIGS. 1 and 2, and only different points will be described.

Inside the housing 18 of the image reading apparatus 10C shown in FIG. 3, a carriage 28 having a structure different from that of the carriage 26 shown in FIG. 2 is provided, and the carriage 28 irradiates a document. Lamp 281, two reflection mirrors 282, 283, imaging lens 284, substrate 285.
The image sensor 286 fixed to the above is incorporated. The original is illuminated by the lamp 281 and the image recorded on the original is reduced and imaged on the image sensor 286 via the two reflection mirrors 282 and 283 and the imaging lens 284. Also in the image reading apparatus 10C shown in FIG. 3, the image reading can be performed both by using the document feeding device 12 and by placing the document on the platen 16.

Copiers, which combine an image reading apparatus of various configurations as exemplified above and an electrophotographic image recording apparatus, are often used. However, these copiers usually use a reduced copy of an image. , Is configured so that enlarged copy can be performed. When reducing or enlarging an image (hereinafter referred to as "when reducing / enlarging / magnifying an image"), it is assumed that all the image reduction / enlargement processing is performed by processing image data obtained by reading with an image sensor. Since, for example, expensive parts such as a memory for storing the image data of one document are required, the arrangement direction of a large number of optical sensors forming the image sensor (main scanning direction; in FIG. 1, FIG. 2 and FIG. 3). The image is reduced and enlarged by processing the image data only in the direction (perpendicular to the paper surface), and in the direction (sub-scanning direction; directions of arrows B and C in FIGS. 1, 2 and 3) orthogonal to the array direction. Is the conveyance speed of the original document when the original document feeder 12 is used, and the carriages 20, 22, 2 when the original document is placed on the platen 16.
This is often done by changing the moving speed of 6, 28.

When reading an image, it is required to read a beautiful image that is as close as possible to the original image recorded on the original.
The carriage 20, 22, 26, 28, a component (for example, a mirror, etc.) incorporated in the carriage 20, 22, 26, 28, or a carriage moving mechanism for moving the carriage vibrates, or a document is conveyed. There is a problem that the document feeding mechanism section (for example, the document feeding roller) vibrates, and the vibration hinders reading of a high quality image. Vibration of the drive unit caused by changing the carriage moving speed or the document feeding speed and driving the carriage or the original at that speed, especially when the image is scaled up and down,
If the resonance of the carriage moving mechanism section, the carriage, the document feeding mechanism section, or their natural components coincides with each other to cause resonance, the image quality of the read image is significantly deteriorated.

Conventionally, as a countermeasure against this problem, the gear ratio of the drive unit is appropriately selected, or the weight of a member that is likely to cause vibration is appropriately adjusted, and the expansion / contraction change that can be set by the image reading apparatus is performed. In the drive corresponding to double, the natural frequency is adjusted to the frequency at which resonance does not occur.
It is also necessary to pay attention to the harmonics of N times the natural frequency, and the frequency of the vibration of the driving unit and the N times the natural frequency of the member generated by the drive corresponding to the scaling of the image reading apparatus. Even if it is unavoidable to match the harmonics, some efforts have been made to match the harmonics with the harmonics having a relatively small amplitude.

Further, Japanese Patent Laid-Open No. 64-81467 proposes that the apparent weight of the carriage is made different from the weight of the carriage itself by pressing the carriage in a certain direction by a magnetic absorption force. However, this is also one of the measures to make the natural frequency of the member that causes the vibration different from the frequency of the vibration caused by driving the carriage or the document.

[0015]

In recent years, the range of magnifications for reduction / magnification scaling has been greatly expanded to, for example, 25% to 1200% in copying machines, and the magnification is also 0.1%.
It is becoming possible to make fine adjustments in small steps such as steps. However, if such a wide range and reduction / magnification of fine steps are possible, it is impossible to adjust the natural frequency of the member that easily causes vibration, which affects the image quality of the read image, and the natural frequency cannot be adjusted anywhere. Inevitably, there is a problem that resonance occurs when reading an image at some magnification.

In view of the above circumstances, the present invention provides an image reading apparatus capable of preventing the vibration of a member regardless of the magnification of expansion / contraction magnification and thus obtaining a high-quality read image regardless of the magnification. The purpose is to

[0017]

In the image reading apparatus of the present invention which achieves the above object, at least one of a document and a scanning optical member is relatively moved so that the moving speed can be set and recorded on the document. In an image reading device that photoelectrically scans the scanned image by optically scanning the scanned image, a resonance prevention member that is detachably fixed to the movable member or the movable unit for the scanning, and a moving speed Accordingly, there is provided an attachment / detachment control means for fixing the resonance preventing member to the movable member or the movable unit or for making the resonance preventing member stand by at a predetermined position separated from the movable member or the movable unit. .

Here, the above-mentioned "movable member or movable unit" is not particularly limited as long as it is for optically scanning an original, and for example, when scanning is performed by conveying the original, A unit that constitutes a document feeding mechanism, for example, a unit in which components such as a document feeding roller or a plurality of components that configure the document feeding mechanism are combined, or when a document is placed on a platen and a scanning optical member is moved to perform scanning. Is a general term for optical members such as mirrors, a carriage in which a plurality of optical members are incorporated, members forming a carriage moving mechanism for moving the carriage, and the like.

The resonance preventing member is preferably fixed by magnetic force so as to be in close contact with the movable member or the movable unit.

[0020]

According to the image reading apparatus of the present invention, the resonance preventing member is fixed to the movable member (for example, the mirror) or the movable unit such as the carriage, or the resonance is prevented according to the moving speed of the original for scanning or the scanning optical member. Since the member is detached from the movable member or the movable unit and made to stand by, the resonance preventing member is fixed to the movable member or the movable unit when the moving speed at which the movable member or the movable unit is likely to resonate is set. As a result, the weight of the movable member or the movable unit changes, and resonance is avoided.
Further, at least when the moving speed at which resonance occurs in a state where the resonance preventing member is fixed to the movable member or the movable unit is set, the resonance preventing member is removed from the movable member or the movable unit and is placed at a predetermined position. It is placed in a waiting state. Thereby, the resonance of the movable member or the movable unit is avoided regardless of the magnification of the expansion / contraction variable magnification, and a high-quality read image can always be obtained.

[0021]

Embodiments of the present invention will be described below. 4 to 6 are schematic configuration diagrams showing an embodiment in which the present invention is applied to the image sensor moving type reduction optical system type image reading apparatus shown in FIG. 3, and FIG. 7 is a perspective view of a main part thereof. FIG.
Only differences from the image reading device shown in FIG.

The image reading apparatus 10D of this embodiment is provided with a resonance preventing member 30 which is detachably attached to the carriage 28. The resonance preventing member 30 stands by at a corner inside the housing 18, which is out of the normal movement range of the carriage 28 for reading a document placed on the platen 16,
In the standby state, the shaft of the solenoid 32 has entered the lock hole 34a provided in the mounting plate 34 on which the resonance preventing member 30 is mounted. A free rotation roller 36 is attached to the mounting plate 34, and the free rotation roller 36 rides on a rail 38 (see FIG. 7).

The resonance preventing member 30 is composed of a permanent magnet, while the carriage 28 is provided with a magnetic piece 29. Here, if a magnification with which the carriage 28 may resonate is set, the carriage 28 goes beyond the normal moving range for scanning in the direction of arrow B shown in FIG. 4 and resonates as shown in FIG. Preventing member 30 and magnetic piece 29
Contact and the shaft 32a of the solenoid 32 is locked in the lock hole 34a.
The carriage 28 moves in the direction of arrow C shown in FIG. Then, the resonance prevention member 30 moves along with the carriage 28 on the rail 38 while being magnetically fixed to the magnetic piece 29 while being guided by the guide rod 40. As a result, the weight of the carriage 28 is increased and the carriage 28 does not resonate and the document feeder 1
The image is read by conveying the document using the document No. 2, or the document placed on the platen 16 is read by moving the carriage 28. When the reading of the document is completed, the carriage 28 again moves in the direction of arrow B (see FIG. 4) beyond the normal movement range for scanning, and in that state, the shaft 32a of the solenoid 32 is inserted into the lock hole 34a. The carriage 28 moves in the direction of arrow C (see FIG. 6). At this time, the resonance prevention member 30 has the solenoid 32.
Since the shaft 32a of 4 is inserted into the lock hole 34a, it stays in that position, and only the carriage 28 moves in the direction of arrow C.

In this way, depending on whether or not the moving speed (magnification of the image) at which the carriage 8 is likely to resonate is set,
The resonance preventing member 30 is fixed to the carriage 28, or the resonance preventing member 30 is detached from the carriage 28 and kept waiting at a predetermined position. Therefore, regardless of the setting of the moving speed (magnification of the image), it is always high. Image data carrying image information of image quality can be obtained.

In the above embodiment, when a predetermined moving speed (magnification) is designated, the original is fed by the original feeding device 12 to read the image or the original placed on the platen 16 is read. Although the resonance preventing member 30 is fixed to the carriage 28 regardless of whether the carriage 28 is read, the carriage 28 may resonate only when reading a document placed on the platen 16, that is, when reading while moving the carriage 28. At this time, the resonance preventing member 30 is fixed to the carriage 28 only in the reading mode in which the original placed on the platen 16 is read according to the set magnification (moving speed) and the reading mode. Good.

FIG. 8 is a perspective view of the main part of another embodiment of the image reading apparatus of the present invention. Only differences from the above-described embodiment will be described. In this embodiment, the carriage 2
The magnetic piece 42 is fixed to the mirror 40 incorporated into the mirror 8, and the resonance preventing member 44 is formed in a triangular shape so as to be attached to and detached from the mirror 40.

As shown in this embodiment, the carriage 28
If the vibration of the component forming the carriage 28 is not a problem, but the resonance preventing member may be attached to or detached from the component. FIG. 9 is a perspective view of the main part of another embodiment of the image reading apparatus of the present invention, and FIG.
FIG. 10 is a sectional view taken along line XX of FIG. 9.

The resonance preventing member 50 in this embodiment is
Similar to the resonance prevention member 30 shown in FIG. 7, it is composed of a permanent magnet, but is fixed to the carriage 28 without relying solely on magnetic force, and a lock mechanism 52 for fixing the resonance prevention member 50 to the carriage 28 is provided. Has been. As shown in FIG. 10, the central portion of the lock mechanism 52 is rotatably supported by the arrow D.
A key member 53 biased in the direction
The carriage 28 has a key groove 54 that engages with the key member 53.
Is provided. When the shaft 32a of the solenoid 32 is inserted into the lock hole 34a, the tip of the shaft 32a pushes the key member 53 to rotate the key member 53 in the arrow E direction,
The engagement between the key member 53 and the key groove 54 is released, and the carriage 28 freely moves away from the resonance preventing member 50. Further, when the shaft 32a of the solenoid 32 is pulled out from the lock hole 34a while the carriage 28 is in contact with the resonance preventing member 50, the key member 53 is biased in the direction of arrow D, so that the key member 53 forms the key groove 54. The carriage 28 and the anti-resonance member 50 are brought into engagement with each other to move integrally.

As shown in this embodiment, the resonance preventing member may be fixed to the member for preventing the resonance which may cause resonance by a force other than the magnetic force and a force other than the magnetic force, or may be fixed without using the magnetic force. Good. However, for the purpose of preventing resonance, it is preferable to fix them integrally.
Although each of the above-described embodiments is an example of preventing the vibration of the carriage or the components incorporated in the carriage, the present invention is applied only when preventing the vibration of the carriage or the components incorporated in the carriage. The present invention can be widely applied to a movable member or a movable unit that may cause resonance depending on the moving speed.

[0030]

As described above, according to the image reading apparatus of the present invention, the resonance preventing member is attached to and detached from the member that may cause resonance in accordance with the moving speed for image reading. Prevents resonance of the member regardless of speed,
Image data bearing high-quality image information can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of the image sensor fixing type reduction optical system type image reading apparatus.

FIG. 2 is a schematic configuration diagram of an image sensor moving type contact image reading apparatus.

FIG. 3 is a schematic configuration diagram of an image sensor moving type reduction optical system type image reading apparatus.

FIG. 4 is a schematic configuration diagram of an embodiment of an image reading apparatus of the present invention.

FIG. 5 is a schematic configuration diagram of an embodiment of an image reading apparatus of the present invention.

FIG. 6 is a schematic configuration diagram of an embodiment of an image reading apparatus of the present invention.

FIG. 7 is a perspective view of a main part of the embodiment shown in FIGS.

FIG. 8 is a perspective view of a main part of another embodiment of the image reading apparatus of the present invention.

FIG. 9 is a perspective view of a main part of another embodiment of the image reading apparatus of the present invention.

10 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

 10D image reading device 12 document feeder 16 platen 18 housing 30, 44, 50 resonance prevention member 52 lock mechanism

Claims (1)

[Claims] 1. An image recorded on the document is optically scanned by relatively moving at least one of the document and the scanning optical member so that the moving speed can be freely set. In an image reading apparatus that reads the image, a resonance prevention member detachably fixed to the movable member or the movable unit for scanning, and the resonance prevention member fixed to the movable member or the movable unit according to the moving speed. Or an attachment / detachment control means for making the resonance prevention member stand by at a predetermined position separated from the movable member or the movable unit.