JPH01232872A - Original reader - Google Patents

Abstract

PURPOSE:To obtain original read information without dimensional deformation even if the distance from a transparent board till the original is fluctuated by adjusting the scanning line pitch of a read head in response to the height up to the read face of the original. CONSTITUTION:A distance measuring instrument 10 moves in preceding over the read head 2 to measure the height of the original 100 up to the read face by a prescribed pitch respectively. An arithmetic circuit 11 obtains the length of the original read face for each pitch from the difference of the height up to the original read face at the preceding and succeeding measuring position and the measured pitch length. A control circuit 13 controls motors 6, 9 based on the length of the original read face and the pitch length to adjust the scanning line pitch of the read head 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a document reading device provided in a copying machine or the like.

A document reading device such as a distortion copying machine moves the reading head located under the transparent plate relative to the document placed on the transparent plate for reading the document in a state parallel to the transparent plate. The configuration is such that a document is read by a reading head. Characters read by such a manuscript reading device.

Manuscript information such as figures etc. 1. The scanned data is sent to a printing unit such as a copying machine and printed on recording paper.

For this reason, when the document on the transparent plate 1 is a thick book 100 as shown in FIG.
0 becomes a valley in the width direction, and as a result, in the printed recording paper, the manuscript information near the valley becomes more vertical than the original font, resulting in dimensional distortion.

The present invention has been made in view of the above circumstances, and provides a document reader that can read a document in a clean state without dimensional distortion even if the distance from the transparent plate to the document varies. The purpose is to provide equipment.

A document reading device according to the present invention for reading an original is configured to move a reading head located under a transparent plate relative to a document placed on a transparent plate for reading the document in a state parallel to the transparent plate. In a document reading device that reads a document with a reading head, a distance measurement method in which the reading head moves ahead of the reading head to the reading surface of the document and measures the height to the reading surface of the document at a constant measurement pitch. means, a calculation means for calculating the length of the original reading surface corresponding to the measured pitch from the measured pitch length and the difference in height to the original reading surface at successive measurement positions; The present invention is characterized by comprising a control means for adjusting the scanning line pitch of the reading head when reading the reading surface portion of the document based on the pitch length.

In the present invention, the distance measuring means moves ahead of the reading head to the surface of the document that is read by the reading head,
The height to the reading surface of the original is measured at every fixed pitch, and the calculation means calculates the length of the reading surface of the original for each pitch from the measured pitch length and the difference in height to the reading surface of the original at successive measurement positions. The control means adjusts the scanning line pitch of the reading head when reading the reading surface portion of the document based on the length of the document reading surface and the pitch length. The document can be read while the reading head is moved parallel to the reading surface of the document.

FIG. 1 is a block diagram showing a state in which the apparatus of the present invention is applied to a copying machine, and FIG. 2 is a plan view showing the vicinity of the movement area of the reading head. In the figure, reference numeral 1 denotes a transparent plate provided in the copying machine. A document 100 is placed on the transparent plate 1, and a reading head 2 is provided below the transparent plate 1. As shown in FIG. 2, the reading rod 2 is mounted on an endless belt 5 which is hooked onto pulleys 4 attached to both ends of a rotating shaft 3 provided on the left and right sides of the copying machine so as to rotate in the left and right direction. The reading head 2 is moved back and forth in the upper circumferential region of the endless belt 5 by a motor 6 provided on one rotating shaft 3, and is also moved parallel to the transparent plate 1. ing. The rotational speed of the motor 6 is adjusted by pulse number control by the control circuit 13.

The reading head 2 has a large number of image pickup elements along its length, and reads the entire surface of the original 100 by scanning in a main scanning direction in which the image pickup elements are lined up and in a sub-scanning direction perpendicular to which direction. Information such as characters and figures written on the original 100 is read by the reader 2, stored in the image memory 7, and output to the printing section of the copying machine.

Between the two endless belts 5, 5, another endless belt 8 driven by a motor 9 is provided in the same direction, and the motor 9, like the motor 6, has a pulse number controlled by a control circuit 13. The rotation speed is adjusted by Endless belt 8
The motor 9 operates independently of the reading head 2, and the distance measuring device 10 attached to the upper circumferential portion of the endless belt 8 is caused to repeatedly circulate in the upper circumferential region. Regarding the positional relationship between the distance measuring device 10 and the reading head 2,
The distance measuring device 10 and the reading head 2 are attached to each endless belt at positions such that the distance measuring device 10 is always located on the sub-scanning direction side relative to the reading head 2.

The driving control of the endless belt, which is attached to each of them, is designed, and the movement of the distance measuring device 10 in the sub-scanning direction is performed at a constant speed by a constant number of pulses from the control circuit 13. That's how it is.

The distance measuring device 10 has, for example, an autofocus function and measures distance optically, and is provided on the endless belt 8 with the measuring direction facing directly upward. Distance measuring device 1
0, the height to the original 100 is measured at a constant measurement pitch in the sub-scanning direction, and the measured height to the original 100 is input to the arithmetic circuit 11. The measurement pitch is wider than the sub-scanning line pitch of the reading head 2, and is determined such that, for example, a plurality of sub-scanning lines fall within the pitch.

The arithmetic circuit 11 calculates a value obtained by performing a computation described later based on the length of the measurement pitch (measurement pitch length) D that is inputted in advance and the input height to the original 100. /A converter 12 to control circuit 13 .

The control circuit 13 controls the two motors 6.9, and determines the position of the reading head 2 in the sub-scanning direction and the distance measuring device 10 based on the number of pulses output for driving the motors 6.9. Understand the location. Further, the position measured by the distance measuring device 10 and the reading position by the reading head 2 are made to correspond to each other based on the grasped positional relationship, and the D/A
While controlling the rotational speed of the motor 6 based on the signal inputted through the converter 12, reversal control is also performed for reciprocating movement of the rad 2 toward reading.

The operation of the apparatus of the present invention configured as described above will be explained using an example in which the document to be read is a book.

When the start key (not shown) is pressed to start reading the book 100, the distance measuring device 10 located on the sub-scanning direction side of the reader rad 2 first starts measuring the distance to the book 100. Subsequently, the reader 2 starts reading the book 100. Information on the book 100 begins to be detected along the sub-scanning direction by the reading head 2, and the information read by the reading head 2 is input into the image memory 7.

On the other hand, the measurement by the distance measuring device 10 is carried out at a (-) constant measurement pitch as described above.
．． It is constant and short at one end of the book 100, becomes longer as it gets closer to the center of the book 100, then becomes shorter as it gets farther away from the center, contrary to the above, and becomes constant and shorter as it approaches the other end.

For this reason, the distance measuring device 10 is equipped with an autofocus mechanism. This autofocus mechanism is as shown in Fig. 3(a) and Fig. 4(a).
A light-shielding film (not shown) provided on the front surface of the lens 14 through which light from 0 passes is directed to a light-receiving element array, e.g. The CCD array 15 is irradiated and the two lights A and B are CC
The separation distance is measured based on the position on the D array 15. Specifically, when the book 100 is in contact with the transparent plate 1, the lights A and B are CC
They overlap at the same point on the D array 15, as shown in FIG. 3(b), so that the peak of the electrical level of the two lights A and B output by the CCD array 15 is on one CCD.

Therefore, when the book 100 is away from the transparent plate 1, the CCD array 1 of the lights A and B is moved as shown in FIG. 4(a).
5 is in focus (so-called front bin state), and as shown in FIG. By using the fact that there is a certain relationship that the larger the separation distance from the transparent plate 1, the larger the size of the deviation, the size of the deviation can be calculated between the peaks of the electric level on the CCD array 15 or between the peaks of the electric level on the CCD array 15. The distance is measured by detecting the distance from the center of the array 15 to the peak of one of the electrical levels. Note that this distance measurement may be performed using other optical measurement methods instead of the autofocus mechanism.

In this way, the distance measurement values obtained by measuring the distance at each measurement pitch D are measured, for example, from one end of the book 100 to the middle as shown in FIG. . , 1. ..., 1. ,, l a, l
□l+Nn+2, then at one end of the book 100, the width of the read information of the reading head 2 at the measurement pitch D and the book 1
However, in the middle part of the book 100, the width of the information read by the reading head 2 is the same as the measurement pitch D between the n-th and n+1-th positions, for example, as shown in FIG. is shorter than the width dn of the information to be read. This is the cause of the dimensional distortion that has conventionally occurred.

By the way, since the distance measurement direction is constant, the dfi
is expressed by the following formula 1.

d, l# D2+(in+I An)2...(
1) This formula and the measurement pitch D are input and set in advance to the calculation circuit 11, and the calculation circuit 11 is input to the distance measuring device 10.
The above d7 is determined based on the separation distance between successive measurement positions measured by , the above equation 1, and the measurement pitch D. Next, the arithmetic circuit 11 calculates the measurement pitch D at the portion where the document is in contact with the transparent plate 1, which has been input and set in advance.
Based on the standard sub-scanning line @ (sub-scanning line density) β contained in The sub-scanning line density β' falling within d7 is determined.

β'=βxd, /p (2) The sub-scanning line density β' found will be larger than β if there is a difference between the two measured values at successive measurement positions, and 2
If the measured values are the same, it is the same as β.

Next, find the reciprocal number β〃(=1/β′) of β′, and use this as D
The signal is input to the control circuit 13 via the /A converter 12. This input signal is a signal related to the degree to which the interval between the sub-scanning lines of the reading head 2 is narrowed when β'>β. This is to make it equivalent to reading at the same sub-scanning line interval along the line. As a result, the control circuit 13 slows down the rotational speed of the motor 6 by the required amount, that is, the pitch of the sub-scanning lines is set when the reader rad 2 reads along the surface of the valley of the book 100. .

FIG. 7 shows the sub-scanning line density when the reading pitch in the sub-scanning direction is varied in this manner and printing is performed by a printing section (not shown) based on information read by the reading head 2. As can be understood from this figure, in Fig. 5, D
The number of sub-scanning lines in the section where ≠d7 increases, which causes D
The occurrence of dimensional distortion that would otherwise occur in the section where ≠d1 is prevented.

As described in detail above, in the case of the present invention, the distance measuring means moves ahead of the reading head to the reading surface of the original by the reading head, and maintains a constant height to the reading surface of the original. The calculation means calculates the length of the original reading surface for each pitch from the measured pitch length and the difference in height to the original reading surface at successive measurement positions, and the control means calculates the length of the original reading surface for each pitch. The scanning line pitch of the reading head when reading the reading surface of the document is adjusted based on the length of the reading surface and the pitch length, so that by adjusting the scanning line pitch, the appearance is upward and parallel to the reading surface of the document. It is possible to read the document while moving the reading head, and the excellent effect is that the read information of the document is in a clean state without dimensional distortion.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the implementation state when the device of the present invention is applied to a copying machine, Fig. 2 is a plan view showing the vicinity of the movement area of the reading head, and Fig. 3.4 shows the height to the document reading surface. Fig. 5 is an explanatory diagram of distance measurement contents, Fig. 6 is an explanatory diagram of calculating the length of the document reading surface, and Fig. 7 is a diagram showing the sub-scanning line density when printed. , FIG. 8 is an explanatory diagram of the problem in the case of the prior art. DESCRIPTION OF SYMBOLS 1...Transparent plate, 2...Reading head, 7...Image memory, 10...Distance measuring device, 11...Arithmetic circuit, 1
3...Control circuit. Patent applicant Murata Machinery Co., Ltd. Figure 3 (a) (b) Figure 4 (a) (b) Figure 5 Figure 6

Claims (1)

[Claims] (1) In a document reading device that moves a reading head under a transparent plate relative to a document placed on a transparent plate for reading the document in parallel with the transparent plate, and reads the document by the reading head, a distance measuring means that moves ahead of the reading head to the reading surface of the document by the reading head and measures the height to the reading surface of the document at a constant measurement pitch; a measurement pitch length; and successive measurements. a calculation means for calculating the length of the document reading surface corresponding to the measurement pitch from the difference in height to the document reading surface at the position; 1. A document reading device comprising: control means for adjusting a scanning line pitch of a reading head when reading a portion.