JPH0568906B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a document reading device for reading document images using, for example, a digitally controlled copying machine or a facsimile transmitter.

[Conventional technology]

Conventionally, it has been known that a document reading device uses an optical system to sequentially project a document image onto the photosensitive surface of the reading elements while moving an array of reading elements arranged in one dimension and having a scanning function. There is. That is, main scanning is performed by the scanning function of the reading element, and sub-scanning is performed by the movement of the reading element.
To move the reading element array, loop wires are connected to both sides of a moving table on which the reading element array is attached, and the loop wires are suspended around a pulley to drive the pulley.

However, if the wires on both sides expand and contract at different amounts, or if the diameters of the pulleys, gears, and other drive systems on both sides are out of alignment, or if the amount of eccentricity is different, the reading element array will tilt. .
As a result, there is an inconvenience that the image is read as a distorted image.

[Problem that the invention seeks to solve]

The present invention aims to eliminate the above-mentioned drawbacks of conventional devices and provide a document reading device that can perform accurate reading.

[Means for solving problems]

In order to solve the above problems, the present invention provides a moving member equipped with a reading element array that is arranged in a one-dimensional direction and performs main scanning in that direction; a guide member that guides the movement of the movable member in the sub-scanning direction; and a document reading device that projects a document image onto the reading element array using an optical system to read the document; a fixed first sliding member that is slidably supported from one of the one-dimensional directions; and a second sliding member that is slidably and elastically supported from the other one-dimensional direction. , the joining position of the first sliding member and the guide member is located at a position corresponding to a reference position for changing the projection magnification of the optical system.

[Effect]

Since such a means is adopted, the reading element moves in the sub-scanning direction without being displaced at least at a position corresponding to the reference line for changing the projection magnification of the optical system.

〔Example〕

FIG. 1 is a longitudinal cross-sectional view of an embodiment of a document reading apparatus to which the present invention is applied, and FIG. 2 is a cross-sectional view thereof. In these figures, the book original O to be read is
is placed on the document table glass plate 1 along the alignment guide 4. The document illumination lamp 2 equipped with a reflective shade 3 illuminates the image surface of the document O, and the reflected light is imaged on the light-receiving surface of the reading element array 6 by a lens array 5, which is an imaging optical system. . The reflective shade 3, document illumination lamp 2, lens array 5, and reading element array 6 are each attached to a moving table 8.

As shown in FIG. 3, the lens array 5 is made up of short-focus, small-diameter imaging lenses, such as self-occurring lenses (trade name), arranged in the X direction. The lens array 5 is fitted into a notch in the movable table 8 and is pressed and fixed by an elastic member 9 such as a partially bent plate spring or rubber, so that it can absorb deformation even if it expands or contracts due to heat generation from the lamp 2, etc. It is set as. Further, the reading element array 6 has a base 6a connected to an elastic member 1 such as a plate spring.
It is installed while being held down by 0. End A of the reading element array 6 (see FIG. 2) is the main scanning start end,
The moving line of this end A in the Y direction becomes a reference line in the main scanning direction.

As shown in FIG. 4, sliding members 12a, 12b and 12 whose lower sides are sliding surfaces are provided on the lower surface of the movable table 8.
c and 12d are mounted on guide rails 13a and 13b, respectively, which are fixed to the main body of the apparatus. In addition, a sliding member 15 that corresponds to the side surface of the guide rail 13a is fixedly installed on the movable table 8 with a mounting plate 16, and the guide rail 15 faces the sliding member 15.
A sliding member 17 that sandwiches 3a is attached with a mounting member 18 made of an elastic body. The contact point B between the guide rail 13a and the sliding member 15 is located directly below the end A of the reading element array 6 (see FIG. 2).
Therefore, the movement guide line of the reading element array 6 and the reference line in the main scanning direction coincide when viewed from the optical system 5 side. FIG. 5 is a side view of the vicinity of the reading element array 6.
The contact point B between the guide rail 13a and the sliding member 15 is also located directly below the reference C of the reading element array 6 in the sub-scanning direction.

Note that a leaf spring, a rubber plate, or the like is used as the elastic mounting member 18. Sliding members 12a, 12b, 12c, 1
2d, 15, 17 are ultra high molecular weight polyethylene, etc.
Abrasion resistant, low friction materials are used. In addition, sliding members 12a, 12b, 12c, 12d, 15,
17 have the same shape, and as shown in FIG.
is fitted into the oblong hole 21 of the moving table 8 to prevent rotation. A spring ring 23 fits into the cylindrical projection 22 passing through the oblong hole 21 to prevent it from coming off.

As shown in FIG.
and 25b, respectively, with fasteners 26a and 26b. Each wire 25a and 25b is connected to a drive pulley 28a and 28b and a driven pulley 29a and 2, respectively.
It is being hung on 9b. Drive pulleys 28a, 28
The drive shaft 30 to which the motor b is attached is connected to a motor 33 (see FIGS. 1 and 2) by a belt 32. The driven pulleys 29a and 29b are connected to the main chassis of the device by springs 35a and 35b, and the wires 25a and 25b maintain appropriate tension. The driving pulleys 28a and 28b and the driven pulleys 29a and 29b are arranged below the stoppers 26a and 26b, and the moving platform 8 is connected to the guide rail 13.
It is pressed against the a and 13b sides.

FIG. 8 is a diagram showing the state of electrical wiring that transmits electrical signals from the reading element array 6 to the wiring board 38. The flexible wiring 36 is held down by plates 37a, 3
7b so as not to apply stress to the electrical contacts of the reading element array 6.

With the above configuration, when the motor 33 rotates, the moving base 8
moves in the direction of arrow Y along guide rails 13a and 13b. That is, sub-scanning is performed by the original illumination lamp 2, the imaging lens array 5, and the reading element array 6. At this time, since the guide rail 13 is sandwiched between the sliding members 15 and 16, it does not swing in the direction of the arrow X, that is, in the main scanning direction.
FIG. 9 shows a state in which the movable table 8 is tilted due to the difference in the amount of extension of the wires 25a and 25b. It is tilted around the contact point B between the guide rail 13 and the sliding member 15. α is its inclination angle. D and E indicate both left and right ends of the reading element array 6, respectively. Since BD<BE, the difference in reading width between point D and point E is _1D < _1E . Since the alignment guide 4 on the original glass table 1 is provided on the point D side, when changing the magnification based on the guide 4, the deviation of the magnification change reference is reduced, and the magnification error in the main scanning direction is also reduced.

In the embodiment described above, the movement guide reference (contact B) in the sub-scanning direction is placed closer to the document positioning guide 4 side, but the image center Oc of the document O as shown in FIG.
An apparatus that changes the magnification based on the image is constructed so that the movement guide reference G is directly below the image center Oc, as shown in FIG. Sliding member 15' and guide rail 13
The distance m from the contact point G of c to the image center Oc is within ±1/4 l, where l is the length of the reading element array 6 in the main scanning direction. By arranging the magnification reference and the movement guide reference at corresponding positions in this way, the magnification error in the main scanning direction can also be reduced.

〔Effect of the invention〕

As explained above, the document reading device of the present invention has the following features:
Since the reading element moves in the sub-scanning direction without misalignment at least at the position corresponding to the reference line that changes the projection magnification of the optical system, magnification errors in the main-scanning direction can be minimized, resulting in extremely accurate reading. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of a document reading device to which the present invention is applied, FIG. 2 is a cross-sectional view thereof, and FIGS.
FIG. 9 is a diagram for explaining details of the main part, and FIGS. 10 and 11 are diagrams for explaining another embodiment. 0 is a document, 2 is a document illumination lamp, 5 is an imaging lens eye, 6 is a reading element array, 8 is a moving table, 1
2a, 12b, 12c, 12d, 15, 17 are sliding members, 13a, 31b are guide rails, 25a,
25b is a wire, A is a scanning reference position, B is a moving direction reference, X is a main scanning direction, and Y is a sub-scanning direction.

Claims (1)

[Scope of Claims] 1. A movable member mounted with a reading element array arranged in a one-dimensional direction and performing main scanning in that direction, and a movable member supporting at least both ends of the movable member and supporting a sub-scanning direction perpendicular to the one-dimensional direction. a guide member that guides the movement of the movable member, and reads the document by projecting a document image onto the reading element array using an optical system, wherein the movable member moves the guide member in the one-dimensional direction. a fixed first member slidably supported from one side of the
and a second sliding member that is slidably and elastically supported from the other side in the one-dimensional direction, and the joining position of the first sliding member and the guide member is in the optical system. A document reading device characterized in that it is located at a position corresponding to a reference position for changing projection magnification.