JPH0546374Y2 - - Google Patents

Description

[Detailed description of the invention] A. Purpose of the invention (1) Industrial application field The present invention relates to an image scanner, and more particularly to a serial type image scanner equipped with a correction plate for performing Schieden ink correction on the scanning path of the scanner. Regarding.

(2) Prior Art In general, a serial image scanner includes a carriage that is reciprocated along the surface of a platen, a light source that illuminates the document supported by the carriage, and a light source that directs reflected light from the document in a predetermined direction. The amount of reflected light from the original is detected by an imaging optical system that guides the image, and an image sensor that detects the amount of light guided by this imaging optical system, and the density of the image on the original is determined based on the amount of detected reflected light. It's reading.

However, since there are variations in the characteristics of the plurality of light-receiving elements that make up the image sensor and the imaging optical system that guides the reflected light to them, it is difficult for the light-receiving elements to receive reflected light from pixels of the same density on the document. Consequently, a difference occurs in the detected value of the amount of received light. Also,
The illumination light source usually has an elongated shape and is arranged in parallel with the plurality of light receiving elements arranged in a row, so that the pixels illuminated at the center of the light source and the pixels illuminated at both ends There is a difference in the amount of illumination light, and even if the density of those pixels is the same, there is a difference in the amount of reflected light from those pixels. Furthermore, the temperature of the illumination light source generally increases as time passes after it is turned on, and the brightness increases accordingly, so the amount of illumination light that illuminates the original changes over time, and the same density on the original changes. The amount of reflected light from a pixel tends to increase as time passes after the illumination light source is turned on.

As mentioned above, there is a difference between the actual density of the pixels on the original and the detected density signal (original reading signal) due to the amount of illumination light that illuminates the pixels on the original, the characteristics of the imaging optical system, the image sensor, etc. Distortion has occurred. In order to correct this distortion, Schieden ink correction has been conventionally performed.

In the Schieden ink correction, a correction plate whose surface is uniformly colored is disposed on one side of the platen so as to be located substantially on the same plane as the original, and this correction plate is scanned prior to scanning the original. The correction data is obtained by In other words, by scanning the correction plate with the illumination light source turned off and on, the dark output and bright output are detected from the amount of reflected light in each state, and the actual output is calculated based on the dark output and bright output. The density signal obtained by scanning the original is corrected to accurately read the density of pixels on the original.

(3) Problems to be solved by the invention However, as shown in Fig. 4, although the surface of the document A placed along the platen P to be read and scanned is curved outward in a convex manner, Since the scanning surface of the correction plate F' used in conventional serial image scanners was formed into a flat surface, the light receiving conditions for the illumination light from the illumination light source L of the image sensor were the original A and the correction plate. F′ did not match, and accurate correction could not be performed.

That is, since the document A is generally conveyed to the surface of the platen P after being changed direction by the paper feed roller 01, the guide member 02, etc., the portion of the document A facing the image sensor, that is, the portion to be read. is curved so that the downward slope becomes larger as it goes to the bottom, and for this reason,
Since the amount of light reflected from the lower end of the document A is directed downward than the image sensor, the amount of reflected light is reduced compared to the bottom end of the correction plate F'. For this reason, the correction plate F' was unable to properly monitor the amount of reflected light from the original A, which hindered accurate Schade ink correction.

The present invention has been developed in view of the above-mentioned circumstances, and an object of the present invention is to provide a serial type image scanner that can accurately perform Schieden ink correction by improving the shape of the correction plate.

B. Structure of the invention (1) Means for solving the problem In order to solve the above problem, the serial image scanner of the present invention is arranged along the surface of a platen extending in the main scanning direction. a carriage drive device that reciprocates a carriage along a main scanning direction in order to read and scan an original; a paper drive device for feeding paper; a correction plate disposed substantially on the same plane as the surface of the portion of the document to be read and scanned and whose surface is uniformly colored; and a correction plate supported by the carriage and the light source. Or an illumination original for illuminating a correction plate, an imaging optical system that guides the original illuminated by this illumination light source and reflected light from the correction plate in a predetermined direction, and an original guided by this imaging optical system. A serial image scanner comprising: an image sensor that detects the amount of light reflected from the correction plate; characterized in that the surface of the correction plate is curved to have substantially the same curved surface as the surface of the document along the platen. shall be.

(2) Effects According to the present invention having the above-described configuration, since the amount of light reflected by the correction plate is detected under the same conditions as the amount of light reflected from the actual document, it is possible to obtain suitable correction data. It becomes possible.

(3) Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a serial type image scanner printer as an embodiment of the present invention, in which a carriage drive device _D1 is reciprocated by a step motor _M1 for driving a carriage and a step motor _M1 for driving the carriage. It is composed of an endless carriage drive belt 1 and the like. A synthetic resin carriage B whose lower surface is fixed to the carriage drive belt 1 and guided along a guide bar 2 extending in the main scanning direction X includes a print head support member B ₁ and an image sensor support member B. ₂
and is reciprocated along the surface of a platen P disposed along the main scanning direction X.

Recording paper such as thermal transfer paper or original A is main-scanned by a paper drive device D 2 consisting of a paper-feeding step motor M ₂ , a paper-feeding roller 3 rotationally driven by the paper-feeding step motor M ₂ , and a guide member (not shown). It is conveyed to the surface of a platen P arranged along the direction X.
The recording paper, original A, etc. are then fed by a paper drive device D ₂ at a predetermined pitch in the sub-scanning direction Y each time the carriage B is moved along one scanning line of the recording paper, original A, etc. be done. At this time, the recording paper or document A inserted downward from the back side of the platen P is bent upward and guided to the front surface of the platen P, so that the surface to be read and scanned becomes a curved surface convex to the outside. Become.

As is clear from FIG. 2, which is an enlarged view of a portion of FIG. 1, a correction plate F whose surface to be read and scanned is uniformly colored white is fixed to the left end side of the platen P. The surface of the correction plate F that is read and scanned is formed into a curved surface that is substantially the same as the outwardly convex curved surface of the recording paper, original document A, etc. Therefore, as shown in FIG. 4, the surface of this correction plate F substantially coincides with the surface of the recording paper, document A, etc.

A thermal transfer type print head 4 is supported on the print head support member _B1 of the carriage B, and an ink ribbon cassette 5 is configured to be detachably mounted on the upper surface of the print head support member _B1 . ing.

As shown in FIG. 3, the image sensor support member _B2 of the carriage B has an optical system support part _B21 disposed in the front part (the part facing the platen) of the print head support member _B1 , and the The sensor substrate support part _B22 is disposed on one side of the print head support member _B1 in the main scanning direction X. Rollers R ₁ and R ₂ are arranged on both sides of the optical system support part B ₂₁ , and the roller R ₂ and the other roller R ₃ are as follows.
They are arranged on both sides of the print head 4.

The optical system support part B ₂₁ is provided along the main scanning direction X in a narrow area between the ink ribbon cassette 5 and the platen P, and includes:
An imaging optical system K having a mirror 6 and a rod lens array 7 and a light source L are arranged along the main scanning direction X.

The image sensor G is supported by the sensor substrate support part B ₂₂ , and the image sensor G is
_A plurality of light-receiving elements 9, 9, . ), external connection wiring 11, etc. The light receiving elements 9, 9, . . . are arranged so as to receive, via the imaging optical system K, reflected light from the original A or the correction plate F illuminated by the light source L.

The print head 4 is then driven by a print head drive circuit 11 of a control unit U connected via a suitable connection cable. Further, the detection signal detected by the image sensor G is inputted to the shading ink correction circuit 12 of the control unit U via a suitable connection cable.

The control unit U is composed of the print head drive circuit 11, shaded ink correction circuit 12, microcomputer 13, etc.
3 is comprised of a central processing unit CPU, random access memory RAM, read-only memory ROM, input/output interface 10, and the like.

The control unit U also includes an output signal Ih of a home position sensor S _H that detects that the carriage B is in the home position, and an output signal of a paper detection sensor S _P that detects the presence or absence of the document A.
_IP etc. are input.

The control unit U also outputs a drive signal Om ₁ for the carriage drive step motor M ₁ , a drive signal Om ₂ for the paper feed step motor M ₂ , and a drive signal O _in for the image sensor on the carriage B.
etc. is output.

The amount of movement of the carriage B and the amount of paper feed of the document A from the positions of the home position sensor S _H and paper detection sensor S _P are determined by the drive of the step motor M ₁ for driving the carriage and the step motor M ₂ for driving the paper. In other words, the number of input pulses to each step motor M ₁ and M ₂ is counted by the microcomputer 13 to be detected.

Next, the operation of the embodiment of the present invention having the above-described configuration will be explained.

Paper feed step motor _M2 operates and documents A
When B is moved to the initial reading position, the carriage drive step motor _M1 is activated and the carriage B is moved to the scanning start point (left side in the main scanning direction X). Next, the carriage B driven by the carriage drive step motor _M1 starts moving in the main scanning direction X, and first the correction plate F is scanned.
At this time, the light source L is turned off, and a small amount of reflected light from the correction plate F passes through the mirror 6 and rod lens ray 7 of the imaging optical system K to the image sensor G.
, and the dark output of the correction plate F is detected here. Next, the light source L is turned on, and the reflected light from the correction plate F is transmitted to the light receiving element 9,
9, . . . , and the bright output of the correction plate F is detected here. When the scanning of the correction plate F is completed, the carriage B is further moved in the main scanning direction X by the carriage drive step motor _M1 , and scanning of the original A is started. The reflected light passes through the imaging optical system K to the light receiving elements 9, 9,...
, and the density signal of the pixel of original A is detected.

In the above reading scanning process, since the surfaces of the correction plate F and the original A are curved in approximately the same shape, the illumination light from the light source L is reflected under the same conditions, and the resulting dark output and brightness of the correction plate F are The output will be appropriate.

When one line of scanning is completed in this way,
The paper feed step motor _M2 is driven to move the document A one pitch in the sub-scanning direction Y, and the carriage drive step motor _M1 is driven to return the carriage B to the scanning start position to move the document A one pitch in the sub-scanning direction Y. Scanning begins.

The above-mentioned scanning of the correction plate F may be performed for each line, or may be performed once per several lines or per page. Then, the density signal obtained by scanning the original A is corrected based on the latest correction data obtained by scanning the correction plate F, and the density of pixels on the original is accurately read. Can be done.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, and can be applied to various small designs without departing from the present invention described in the claims of the utility model registration. It is possible to make changes.

For example, the dark output detected when the light source L is turned off is
Since it is not affected by variations in the light amount of the light source L or the shape of the correction plate F, the dark output can be replaced with a constant reference value. In addition, the present invention has the print head 4.
It is also possible to apply the present invention not only to a serial type image scanner installed in parallel with the print head 4 but also to a single serial type image scanner unrelated to the print head 4. Furthermore, the color of the correction plate F may be another color instead of white,
For example, it is possible to use the same color as the background color of document A.

C. Effect of the invention According to the above-mentioned serial image scanner of the present invention, when scanning the correction plate to obtain correction data, the surface shape of the correction plate is curved to be approximately the same as the surface shape of the original. This allows both to have the same reflection characteristics. Therefore,
By correcting the image signal using the correction data obtained by scanning the correction plate, it becomes possible to accurately read the density of pixels on the document.

[Brief explanation of the drawing]

1 is an overall perspective view of a serial type image scanner according to an embodiment of the present invention, FIG. 2 is an enlarged view of a portion of FIG. 1, and FIG. 3 is an enlarged perspective view of an image sensor portion of the same embodiment. FIG. 4 is a diagram showing the shape of a conventional correction plate. A...Original, B...Carriage, _D1 ...Carriage drive device, _D2 ...Paper drive device, F...
Correction plate, G... Image sensor, K... Imaging optical system, L... Light source for illumination, P... Platen, X...
Main scanning direction, Y...sub scanning direction.

Claims (1)

[Claims for Utility Model Registration] A carriage that drives a carriage B back and forth along the main scanning direction a drive device D ₁ ; a paper drive device D ₂ that feeds the document A at a predetermined pitch in the sub-scanning direction Y each time the carriage B moves along one scanning line of the document A; a correction plate F disposed on substantially the same plane as the surface of the portion to be read and scanned and whose surface is uniformly colored; and the carriage B.
an illumination light source L for illuminating the original A or the correction plate F, and an imaging device for guiding reflected light from the original A and the correction plate F illuminated by the illumination light source L in a predetermined direction; Optical system K
and an image sensor G that detects the amount of light reflected from the original A guided by the imaging optical system K and the correction plate F; A serial type image scanner characterized in that the image scanner is curved to have substantially the same curved surface as the surface of a document A along the .