JP2006270822A - Image scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image scanner capable of adjusting equally scanning magnifying powers of images on front and rear faces of a manuscript, even when the scanning magnifying powers have become different between positions of scanning the images on the front and rear faces of the manuscript due to variations in the environmental condition, the type of manuscripts, a past record of reading-in manuscripts (a conveyance affector) or the like. <P>SOLUTION: Information on the conveyance affector is obtained. The reading-in cycle of the manuscript by CCDs 9, 9' provided in first and second image reading sections X1, X2 to read-in both surfaces of the manuscript is set depending on the information obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that reads both front and back sides of a document, and in particular, the reading cycle by an optical sensor (CCD) of an image reading unit for each of the front and back sides is determined according to environmental conditions, document types, document reading results, and the like. The present invention relates to an image reading apparatus having a function to be set accordingly.

In recent years, as disclosed in, for example, Patent Document 1, Patent Document 2, and the like, an image reading apparatus capable of reading image information on both sides of a document being conveyed has been used. FIG. 1 shows a schematic configuration diagram of a double-sided image reading apparatus in a conventional example. Hereinafter, a schematic configuration of a double-sided image reading apparatus according to a conventional example will be described with reference to FIG.
A conventional scanner B (image reading apparatus) shown in FIG. 1 includes an ADF apparatus α1 and a surface optical part α2. The ADF device α1 includes a document tray 1 and a paper discharge tray 2, and a predetermined transport path 3 is formed from the document tray 1 toward the paper discharge tray 2. Transport rollers (an example of transport means) 4 are provided at a plurality of positions along the transport path 3. The document to be read is transported along the transport path 3 by the rotation of the transport roller 4.

A first image reading unit X1 that reads an image on the surface (one surface) of the document is formed in the surface optical unit α2. The first image reading unit X1 reads the image when the document conveyed along the conveyance path 3 passes a predetermined first reading position 5.
The first image reading unit X1 includes an exposure device 6, a light guide mirror 7, a lens 8, a CCD 9, and the like. When the original passes through the first reading position 5, image reading light is emitted from the exposure device 6 toward the original. The image reading light is reflected by the original and guided to the lens 8 by the light guide mirror 7. The image reading light is imaged on the CCD 9 by the lens 8. The image reading light is converted into an electrical signal by the CCD 9 and input to an image processing control unit Y1 (see FIG. 4) described later. As a result, the image information on the surface of the original is read by the first image reading unit X1.

On the other hand, the ADF apparatus α1 is provided with a second image reading unit X2 that reads an image on the back side (the other side) of the document. The second image reading unit X2 is configured so that the original conveyed along the conveyance path 3 passes the second reading position 10 positioned downstream in the document conveying direction from the first reading position 5. The image on the back side of the document is read. Similarly to the first image reading unit X1, the second image reading unit X2 includes an exposure device 6 ′, a light guide mirror 7 ′, a lens 8 ′, a CCD 9 ′, and the like.
On the CCD 9 ′, image reading light irradiated on the back surface of the original is imaged. Further, the image reading light is converted into an electric signal by the CCD 9 ′ and input to the image processing control unit Y1. Thereby, the image information on the back side of the original is read by the second image reading unit X2. In the transport path 3, a downwardly convex bent portion β1 and an upwardly convex bent portion β2 are formed between the first reading position 5 and the second reading position 10.
Note that the first reading position 5 and the second reading position 10 cannot be provided at the same position in the transport path 3. This is because when the same position is provided, when reading an image on one side of the document, the image reading light enters the image reading unit that reads the other side, and an accurate image reading light is generated. This is because it cannot be obtained.

Incidentally, as shown in FIG. 1, the transport roller 4 (an example of a transport unit) is positioned upstream in the transport direction from the first reading position 5 and in the transport direction from the second reading position 10. Are arranged at a plurality of positions including downstream positions. The transport roller 4 sequentially transports the document along the transport path 3. The rotation speed of each of the plurality of transport rollers 4 during transport of the document is controlled based on the transport speed of the document set by the image processing control unit Y1. Specifically, the transport speed of the transport roller 4 positioned on the downstream side in the transport direction is set to be larger, thereby preventing slack during transport of the original.
Accordingly, the passing speed when the original passes through the first reading position 5 and the passing speed when the original passes through the second reading position 10 are the same as the passing speed when passing through the second reading position 10. Will be bigger.

In addition, each of the image reading cycles (reading speeds) of the CCD 9 of the first image reading unit X1 and the CCD 9 ′ of the second image reading unit X2 has the original reading position 5 set. It is set according to the passing speed when passing and the passing speed when passing through the second reading position 10. For example, when the ratio of the passing speed when passing through the first reading position 5 and the passing speed when passing through the second reading position 10 is 1: 1.05, the reading cycle of the CCD 9 The reciprocal of the ratio to the reading cycle of the CCD 9 ′ is also set to 1: 1.05.
As described above, the reading period of each of the CCD 9 and CCD 9 ′ is set according to the passing speed at each reading position. Specifically, the ratio between the reading cycle of the CCD 9 and the reading cycle of the CCD 9 ′ is set to match the ratio of the passing speed with respect to the first reading position 5 and the passing speed with respect to the second reading position 10. . As a result, it is possible to make the reading magnifications of the images on the front and back sides of the document the same, and it is possible to prevent any one of the images from being stored in a stretched state with respect to the other image.
JP 2000-184134 A JP 2003-264671 A

However, each of the transport rollers 4 may change in diameter based on environmental conditions such as temperature and humidity. Therefore, the passing speed when the document passes through the first reading position 5 and the second reading position 10 for both the front and back surfaces changes with environmental conditions such as temperature and humidity, and the passing speed ratio also changes accordingly. . As a result, there is a problem in that the reading magnification for reading the front side of the document and the reading magnification for reading the back side of the document are shifted, and one image is read in a stretched state with respect to the other image.
The same applies to changes in the type of document. That is, it is considered that the degree of deformation of the transport roller 4 when contacting the respective transport rollers 4 is different between the case where the original is plain paper and the case where the original is thick paper. The ratio of the passing speed when passing through the first reading position 5 and the second reading position 10 also changes. In addition to this, when the type of the original changes, the expansion rate during the conveyance of the original also changes, so that the reading magnification also changes.
Further, this is considered to be the same for the document reading results (for example, the number of continuous readings).
Accordingly, the present invention has been made in view of the above circumstances, and its object is to read a reading position and a back surface for reading the surface of the document due to changes in environmental conditions, document types, document reading results, and the like. It is an object of the present invention to provide an image reading apparatus capable of adjusting the reading magnifications of the images on the front and back sides of the document to be the same even when the reading magnification with respect to the reading position for reading is shifted.

In order to achieve the above object, the present invention provides a first image reading unit that reads one image of a document conveyed along a predetermined conveyance path, and the other surface of the document on the downstream side in the conveyance direction of the document. A second image reading unit that reads the first image, and conveying means disposed at a plurality of positions including an upstream side in the conveying direction from the first image reading unit and a downstream side in the conveying direction from the second image reading unit. And the first image reading unit and the second image reading unit based on the acquired transport influence factor information, a function of acquiring transport influence factor information such as environmental conditions, document types, document reading results, and the like. And an image reading apparatus having a function of setting a reading period in the document conveyance direction by one or both of the units.
According to the present invention, the ratio of the passing speed of the document with respect to the first image reading unit and the passing speed with respect to the second image reading unit changes with respect to the environmental condition, the type of document, the reading result of the document, and the like. Or, even when the reading magnification between the front and back sides is shifted, such as when the document expands or contracts, depending on the conveyance influencing factor information, one or both of the first image reading unit and the second image reading unit A reading cycle in the transport direction is set, and this allows the reading magnification on both the front and back surfaces to be kept the same.

The environmental condition is a concept including temperature, humidity and the like. That is, due to these factors, for example, a part or all of the conveying means may be expanded, and accordingly, the document passing speed with respect to the first image reading unit and the passage with respect to the second image reading unit may be considered. The ratio with the speed changes, and the reading magnification shifts on both sides.
The types of originals include original thickness (normal thickness paper, thick paper, thin paper, etc.), original size (A4, B5, etc.), original material (plain paper, OHP paper, etc.), etc. It is a concept. This also changes the passage speed and the elongation rate of the original, and causes a deviation in the ratio of the reading magnification to the front and back surfaces.
Further, the document reading results are a concept including the number of documents read, reading time, and the like after reading is started. For example, it is considered that the temperature of the conveying means is changed and thermal expansion occurs even in accordance with the number of read documents.
Therefore, by setting the reading cycle of the original according to the above conditions, it is possible to maintain the same reading magnification on both the front and back sides.
Further, when the conveyance state changes in multiple stages, it is conceivable to set the reading cycle of each of the first image reading unit and the second image reading unit step by step for each of the multiple stages. According to this, even in the read image read by each of the first image reading unit and the second image reading unit, with the same reading magnification by the first image reading unit and the second image reading unit. The reading magnification can be made uniform, and the image quality is further increased.

  According to the present invention, the reading magnification of the first image reading unit that reads one side (for example, the front side) of the original and the other side of the original due to changes in environmental conditions, the type of original, the actual reading results of the original, and the like. Even when there is a deviation in the reading magnification of the second image reading unit that reads the side (for example, the back side), depending on the change, one or both of the first image reading unit and the second image reading unit Since the reading cycle is set, it is possible to adjust the reading magnification of the images on the front and back sides of the document to be the same.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a schematic configuration diagram of a printer according to an embodiment of the present invention, FIG. 2 is a conceptual diagram for explaining a method of adjusting a reading cycle by a CCD, and FIG. 3 is a diagram of a conveyance roller and first and second reading positions. FIG. 4 is a block diagram of a main part of the printer according to the embodiment of the present invention, and FIG. 5 is a process procedure for setting a reading cycle for each image reading unit by the printer according to the embodiment of the present invention. FIG. 6 is a block diagram of the main part of the printer according to the second embodiment of the present invention, FIG. 7 is a graph showing speed changes in a plurality of stages during document conveyance, and FIG. 8 is a third embodiment of the present invention. It is a block diagram of the principal part of the printer which concerns on the Example.

(1) Features of the scanner according to the embodiment of the present invention.
A scanner A (image reading apparatus) according to an embodiment of the present invention shown in FIG. 1 has two characteristic functions as follows.
That is, the first function is a function of measuring (acquiring one example) an environmental condition (an example of conveying influence factor information) in the vicinity of each of the plurality of conveying rollers 4 on the conveying path 3. Here, the environmental conditions are a temperature condition and a humidity condition, and each temperature sensor 11a, 11b, 11c, each humidity sensor 12a, 12b, 12c shown in FIG. 3 (an example of conveyance influence factor information acquisition means). Is measured (an example of acquisition).
The second function is that the environmental conditions (an example of transport influence factor information) acquired by the temperature sensors 11a, 11b, 11c and the humidity sensors 12a, 12b, 12c (an example of transport influence factor information acquisition means). Based on the above, each of the CCD 9 included in the first image reading unit X1 that reads an image on the front surface (an example of one side) of the document, and the CCD 9 ′ included in the second image reading unit X2 that reads an image on the back side (an example of the other side), This is a function for setting a reading cycle in the document transport direction. The second function is executed by an image processing control unit Y1 (an example of a reading cycle setting unit) shown in FIG. 4 as described later.
With these functions, the diameter of each of the transport rollers 4 changes based on changes in temperature conditions and humidity conditions, and the first reading position 5 where the original is read by the first image reading unit X1 and the second image. Even when the passing speed with respect to one or both of the second reading positions 10 read by the reading unit X2 is changed, the reading period is set (specifically, the setting is changed) for each of the CCD 9 and the CCD 9 ′. The reading magnification (on the front side of the original) by the image reading unit X1 and the reading magnification (by the back side of the original) by the second image reading unit X2 are kept the same.

(2) Regarding a method for adjusting the reading cycle of the CCD.
As shown in FIG. 2, the basic clock for reading an image for one pixel (time required for reading one pixel) as a reading cycle (for one line of pixels in the main scanning direction) by the CCD A time required for multiplying the number of pixels for one line in the main scanning direction (hereinafter referred to as a basic time) is required.
However, normally, the basic time is rarely used directly as a reading cycle, and the basic time obtained by adding a grace period called a dummy is set as the reading cycle. The dummy is a time during which image reading is not actually performed. By adjusting the length of the dummy, it is possible to make only the reading cycle variable without affecting the resolution of image reading.

(3) The positional relationship between the conveyance path 3, the conveyance roller 4, and the first and second reading positions of the scanner according to the embodiment of the present invention.
FIG. 3 is a schematic diagram showing a relationship between a document conveyance path, a conveyance roller, and a reading position provided in the scanner according to the embodiment of the present invention. The conveyance rollers 4a to 4c are related to conveyance of the original when the original passes through the first reading position 5 and the second reading position 10 among the plurality of conveyance rollers 4 shown in FIG. is there. Further, the conveying roller 4 arranged on the most upstream side in the conveying direction of the document along the conveying path 3 is arranged on the most downstream side like the conveying roller 4a, and the conveying roller 4 arranged on the middle stream like the conveying roller 4b. This is called the conveyance roller 4c.
Hereinafter, the first reading position 5 is provided between the arrangement position of the conveyance roller 4a and the arrangement position of the conveyance roller 4b, and the arrangement position of the conveyance roller 4b and the arrangement of the conveyance roller 4c. A case where the second reading position 10 is provided between the positions will be described.

When the document reaches the first reading position 5, the document is transported only by the transport roller 4 a, and when the document finishes passing through the first reading position 5, the document is transported by the transport roller 4 a. It is conveyed by the roller 4b and the conveyance roller 4c. Further, when the original reaches the second reading position 10, the original is conveyed by the conveying roller 4 a and the conveying roller 4 b, and when the original finishes passing through the second reading position 10, the original Is transported only by the transport roller 4c.
In this case, the average passing speed when the original passes through the first reading position 5 and the second reading position 10 depends on the transport speed (the product of the rotational speed and the diameter) of each of the transport rollers 4a to 4c. . Hereinafter, the average passing speed when the original passes through the first reading position 5 is referred to as V1, and the average passing speed when the original passes through the second reading position 10 is referred to as V2. Further, when the diameter of each of the transport rollers 4a to 4c is changed, an influence coefficient for V1 and V2 is defined as wij (i = a, b, c, j = 1, 2).
Further, the temperature sensors 11a to 11c and the humidity sensors 12a to 12c are provided in the vicinity of the transport rollers 4a to 4c so that the temperature and humidity around the transport rollers 4a to 4b can be controlled. It is measured. As will be described later, these measurement results are input to the image processing control unit Y1, and are used to set the reading period of the CCD 9 and the CCD 9 ′.

FIG. 4 is a block diagram showing the configuration of the main part of the scanner according to the embodiment of the present invention. The main part of the scanner A will be described below with reference to FIG. The scanner A performs various processes on the images read by the first image reading unit X1 and the second image reading unit X2 and stores them, and also performs an overall control of the scanner A. Y1 is included.
The image processing control unit Y1 stores the acquired image, the CPU 401 that is a calculation unit, the ROM 402 that stores a predetermined control program for controlling the scanner A, the RAM 403 that is a non-volatile memory and the work area of the CPU 401, and the like. An image memory 404 and the like are included.

Each of the first image reading unit X1 and the second image reading unit X2 is connected to the image processing control unit Y1, thereby being read by each of the first image reading unit X1 and the second image reading unit X2. The image is input to the image processing control unit Y1. Further, the reading cycle of the CCD 9 included in the first image reading unit X1 and the reading cycle of the CCD 9 ′ included in the second image reading unit X2 are controlled by the image processing control unit Y1.
The image processing control unit Y1 is connected to a conveyance motor 405 that is a driving source of each of the conveyance rollers 4a to 4c. The image processing control unit Y1 controls the driving of the transport motor 405 based on a predetermined rotational speed setting value, thereby driving the transport rollers 4a to 4c.
Further, an operation unit 406 is provided on the outer surface of the scanner A for a user to input an operation, and is connected to the image processing control unit Y1. The user can make an image reading request of the document to the scanner A by an operation input from the operation unit 406.
The image processing control unit Y1 is connected to each of the temperature sensors 11a to 11c and the humidity sensors 12a to 12c, and detection results from these sensors are input to the image processing control unit Y1. .

(4) Regarding the reading cycle setting procedure.
FIG. 5 is a flowchart showing a procedure of processing in which the image processing control unit Y1 of the scanner A according to the embodiment of the present invention sets a reading cycle for each of the CCD 9 and the CCD 9 ′. Hereinafter, the processing procedure for setting the reading cycle by the image processing control unit Y1 will be described in detail with reference to the flowchart of FIG. 5, S1, S2,... Represent processing numbers. Each time an image reading request is made from the operation unit 406 (see FIG. 4), the processing starts from step S1.
In step S1, the image processing control unit Y1 inputs detected values of the temperature and humidity around the transport rollers 4a to 4c detected by the temperature sensors 11a to 11c and the humidity sensors 12a to 12c, respectively.
In the process of step S2 following step S1, the CPU 401 uses the detected values of the temperature and humidity input in step S1 to cause the original to move to the first reading position via the degree of expansion of each of the transport rollers 4a to 4c. 5, The average passing speed when passing through each of the second reading positions 10 is calculated.

但し，αは温度変化に対する前記搬送ローラ４ａ〜４ｃの径の変化率，βは湿度に対する径の変化率であり，既知の値である。Ｖ10，Ｖ20は温度，湿度がそれぞれＴi0，Ｍi0の場合における前記原稿が前記第１読取位置５，前記第２読取位置１０を通過するときの平均の通過速度であり，これらの数値は予め実験等から求めることが可能である。 That is, assuming that the detected temperature value input in step S1 is Ti (i = a, b, c) and the detected humidity value is Mi (i = a, b, c), the following (1), (2 ), Average passage speeds V1 and V2 when the original passes through the first reading position 5 and the second reading position 10 are calculated.

However, (alpha) is a change rate of the diameter of the said conveyance rollers 4a-4c with respect to a temperature change, (beta) is a change rate of the diameter with respect to humidity, and is a known value. V10 and V20 are average passing speeds when the original passes through the first reading position 5 and the second reading position 10 when the temperature and humidity are Ti0 and Mi0, respectively. It is possible to obtain from

In step S3 following step S2, the CCD 9 of the first image reading unit X1 and the second image reading unit X2 have the image processing control unit Y1 according to V1 and V2 calculated in step S2. The reading cycle of each CCD 9 ′ is set.
For example, the relationship between the calculated V1 (V2) and the reciprocal of the reading cycle (that is, the reading frequency) is linear, and the proportionality constant is stored in the ROM 402. The proportional constant is read from the RAM 403 by the CPU 401, and the reading period of each of the CCD 9 and the CCD 9 ′ is calculated from the V1 (V2) read in step S2 while referring to the proportional constant. And set.
The reading cycle of the CCD 9 of the first image reading unit X1 is fixed, and the ratio of the reciprocal of the reading cycle of the CCD 9 to the reciprocal of the reading cycle of the CCD 9 ′ (having the second image reading unit X2). However, when the reading cycle of the CCD 9 ′ is set so as to coincide with the ratio between the V1 and the V2, or when only the reading cycle of the CCD 9 is set with the reading cycle of the CCD 9 ′ fixed. It is done.
As described above, the temperature condition and the humidity condition which change each time depending on the outside air temperature, the heat source in the apparatus, and the like are measured, and the diameter change of the transport rollers 4a to 4c based on the temperature condition, that is, the original is the first reading position 5 and the first. 2 Changes in average passing speeds V1 and V2 when passing through the reading position 10 are calculated, and the reading periods of the CCD 9 and the CCD 9 ′ are set accordingly, so that the first image reading unit X1 ( The reading magnification (on the front side of the document) and the reading magnification (on the back side of the document) by the second image reading unit X2 are kept the same.

(5) About the first embodiment.
In the above-described embodiment, the reading cycle of each of the CCD 9 included in the first image reading unit X1 and the CCD 9 ′ included in the second image reading unit X2 is set based on the detected environmental conditions such as temperature conditions and humidity conditions. Although examples have been disclosed, the present invention is not limited thereto.
Depending on the type of the document from which image information is to be read (an example of conveyance influencing factor information), the average passing speed when the document passes through each of the first reading position 5 and the second reading position 10, and the conveyance of the document The degree of elongation in the direction changes, and the appropriate reading cycle changes. Therefore, it is conceivable to set the reading cycle of each of the CCD 9 included in the first image reading unit X1 and the CCD 9 ′ included in the second image reading unit X2 in accordance with the setting of the material type of these documents. The image reading apparatus according to the first embodiment of the present invention having such a function will be described below.
An operation panel (not shown) provided on the outer surface of the image reading apparatus is connected to the image processing control unit Y1 (see FIG. 4). In addition, through operation input using the operation panel (an example of a conveyance influence factor information acquisition unit), information on the thickness of the original (information about normal thickness paper, thin paper, thick paper, etc.), the size of the original (Information such as A4, B5...) And information on the original material (information such as plain paper, OHP paper...) Can be set. After the information is set, when the image reading request for the original is made by the user's operation input, each of the set information is input to the image processing control unit Y1.

In the ROM 402 of the image processing control unit Y1, detailed setting information should be set for each of the CCD 9 of the first image reading unit X1 and the CCD 9 'of the second image reading unit X2. The correspondence relationship with the reading cycle is stored.
That is, when all of the information on the thickness of the original, the information on the size of the original, and the information on the material of the original are determined, the information is converted into reading cycles for the CCD 9 and the CCD 9 ′ (for example, When the thickness is normal, the size is A4, and the paper is OHP paper, the reading cycle for each of the CCD 9 and the CCD 9 ′ is 1 / (14.05 × 10 ^ 6) S, 1 / (14.00). × 10 ^ 6) Table information for S) is stored in the ROM 402, and the CPU 401 uses such table information from each of the inputted information to the CCD 9 and the CCD 9 ′. The reading cycle is calculated.
Note that such table information is obtained by conducting an experiment to measure the document passage speed and the document expansion / contraction rate in advance while actually changing various conditions such as the thickness, size, and material type of the document. It is considered that this is obtained by calculating an optimum reading cycle for the passing speed and the expansion / contraction rate obtained based on the result of such an experiment.
As described above, the original that can change every time an image is read due to changes in the thickness of the original, the size of the original, the material of the original (that is, the type of the original), and the like. Even if the average passing speed at the time of passing through each of the second reading positions 10 and the degree of extension in the document transport direction are changed, the CCD 9 and the CCD 9 according to the information measured in advance through experiments or the like. Since the reading cycle of each CCD 9 'is set, the reading magnification (on the front side of the original) by the first image reading unit X1 and the reading magnification (by the back side of the original) by the second image reading unit X2 are set. Keep the same.

(6) Regarding the second embodiment.
Similarly, the following printer according to the second embodiment in which the reading cycle of each of the CCD 9 and the CCD 9 ′ is set in accordance with the reading result of the original (an example of conveyance influence factor information) is also conceivable.
The document reading results are, for example, the number of sheets read when the document is continuously read, or the continuous reading time when the document is continuously read. When these factors change, the internal temperature of the image reading apparatus gradually changes with repeated reading operations, and the diameters of the transport rollers 4a to 4c (see FIG. 3) also change. As a result, the passing speed when the original passes the first reading position 5 and the second reading position 10 changes. Therefore, the image reading apparatus according to the second embodiment of the present invention, based on such reading results of the original, the CCD 9 included in the first image reading unit X1 and the CCD 9 ′ included in the second image reading unit X2. Each has a function of setting a reading cycle for each image information reading operation.

That is, as shown in FIG. 6, the image processing control unit Y2 of the printer counts the number of documents read continuously (that is, acquires document reading performance information) counter 407 (conveying influence). An example of factor information acquisition means). The CPU 401 sets a reading cycle for each of the CCD 9 and the CCD 9 ′ in accordance with the count number by the counter 407.
Therefore, the ROM 402 stores in advance the correspondence between the specific count number and the set value of the reading period for each of the CCD 9 and the CCD 9 ′. The correspondence obtained as described below is used. That is, the average passage speeds V1 and V2 when the document passes the first reading position 5 and the second reading position 10 for each count number are obtained in advance by experiments or the like. Also, an appropriate reading cycle for V1 and V2 is calculated (the reading cycle is determined so that the passing speed and the reciprocal of the reading cycle are proportional). The correspondence is obtained by associating the calculation result with the count number.

Similarly, it is conceivable to change the setting of the reading cycle of each of the CCD 9 and the CCD 9 ′ according to the reading time of the original. In that case, a timer for measuring the reading time is used in place of the counter 407 for counting the number of read documents. Further, the correspondence between the measurement time by the timer and the reading period of each of the CCD 9 and the CCD 9 ′ is stored in the ROM 402, and the CCD 9 and the CCD 9 ′ are referred to with reference to the measurement time of the timer for each image reading operation. What is necessary is just to set each reading period.
As described above, the reading magnification (on the surface of the original) by the first image reading unit X1 and the second image reading unit X2 (the original document) according to the reading results of the original document (an example of conveyance influence factor information). The reading magnification (on the back side) is kept the same.
If the techniques disclosed in the above embodiment, the first and second embodiments are used in combination, a plurality of the CCD 9, The reading cycle of each CCD 9 ′ is set.

(7) About the third embodiment.
In the above-described embodiment, the first and second examples, the example in which the average reading cycle by each of the CCD 9 and the CCD 9 ′ is set uniformly is disclosed, but the present invention is not limited to this. That is, the original is accelerated in a plurality of stages when being conveyed on the conveyance path 3 (see FIG. 3), and similarly when passing through each of the first reading position 5 and the second reading position 10. Accelerated. Therefore, based on such a plurality of stages of speed changes, the reading cycles by the CCD 9 of the first image reading unit X1 and the CCD 9 'of the second image reading unit X2 are determined during conveyance of the document. It may be set in a plurality of stages.
Hereinafter, it is assumed that the positional relationship among the first reading position 5, the second reading position 10, and the transport rollers 4a to 4c is as shown in FIG. Further, when the document reaches the first reading position 5, it is transported only to the transport roller 4 a, and when it passes through the first reading position 5, it is transported only by the transport roller 4 b. To do. Further, when the document reaches the second reading position 10, it is conveyed only to the conveying roller 4b, and when it passes through the second reading position 10, it is conveyed only by the conveying roller 4c. To do.
In this case, the document passes through the first reading position 5 while being accelerated in three stages. That is, the original is transferred in the order of the first stage conveyed by the conveying roller 4a only, the second stage conveyed by the conveying roller 4a and the conveying roller 4b, and the third stage conveyed by the conveying roller 4b. The first reading position 5 is passed while accelerating. The passage speed similarly changes when the original passes the second reading position 10.
Such a three-stage speed change is obtained as a graph as shown in FIG. 7 in which the passing speed changes stepwise with respect to the conveyance of the original. By predicting and calculating the passage speed of the original document at each stage, the reading cycle of each of the first image reading section X1 and the second image reading section X2 is set according to the passage speed that changes stepwise. It is possible to set stepwise and keep the reading magnification uniform even in the read image for each of the front and back sides.

但し，Ｖa0は，前記搬送ローラ４ａの周辺の温度，湿度がそれぞれＴa0，Ｍa0の場合において，前記原稿が前記搬送ローラ４ａのみに搬送される場合の前記原稿の通過速度である。Ｖa0，Ｖb0も同様の意味を持つ。ωは前記画像処理制御部Ｙ１により設定されている，前記搬送ローラ４ａ〜４ｃを駆動する搬送モータ４０５の駆動速度（即ち，回転速度）である。
また，上述のように前記ＣＰＵ４０１により算出されたＶａ〜Ｖｃに基づいて，以下の式（６）〜（１１）により通過速度Ｖ11，Ｖ12，Ｖ13，Ｖ21，Ｖ22，Ｖ31を算出する。
Ｖ11＝Ｖａ …（６）
Ｖ12＝（Ｖａ＋Ｖｂ）／２ …（７）
Ｖ13＝Ｖｂ …（８）
Ｖ21＝Ｖｂ …（９）
Ｖ22＝（Ｖｂ＋Ｖｃ）／２ …（１０）
Ｖ31＝Ｖｃ …（１１）
更に，前記ＣＰＵ４０１は，これらの通過速度Ｖ11，Ｖ12，Ｖ13，Ｖ21，Ｖ22，Ｖ31に対する適切な前記ＣＣＤ９，前記ＣＣＤ９’の読取周期を算出する。このような読取周期の算出は，上述した実施形態と同様，算出された通過速度と読取周期の逆数（つまり，読み取り周波数）との関係を線型としておき，ＲＯＭ４０２に記憶された比例定数を参照して読取周期を算出する。
また，このように算出された読取周期各々を，前記原稿が前記第１読取位置５を通過するときの各段階，また，前記原稿が前記第２読取位置１０を通過するときの各段階に対応付け，対応表としてＲＡＭ４０３に記憶する。 FIG. 8 is a block diagram showing the configuration of the main part of the scanner according to the third embodiment of the present invention in which a plurality of reading cycles are set as described above. Hereinafter, an example of setting a plurality of reading cycles will be described in detail with reference to FIG.
Hereinafter, a case where the reading cycle is set with respect to environmental conditions such as temperature and humidity as in the scanner A according to the embodiment of the present invention will be described. It should be noted that the speed of the first stage when the document passes the first reading position 5 (in a state where the original is transported only to the transport roller 4a) is V11, and the speed of the second stage (the transport roller 4a and the previous transport). The speed (in the state of being conveyed to the roller 4b) is referred to as V12, and the speed in the third stage (in the state of being conveyed only to the conveying roller 4b) is referred to as V13. Similarly, V21 (= V13) is the speed of the first stage when the original passes the second reading position 10 (in the state where the original is transported only to the transport roller 4b), and the second stage (the transport). The speed (in the state of being conveyed to the roller 4b and the conveying roller 4c) is referred to as V22, and the speed in the third stage (in the state of being conveyed only to the conveying roller 4c) is referred to as V23.
As in step S1 shown in the flowchart of FIG. 5, the image processing control unit Y1 is measured by the temperature sensors 11a to 11c and the humidity sensors 12a to 12c (see FIG. 3) in the vicinity of the transport rollers 4a to 4c. Enter the detected temperature and humidity values. Further, using the following formulas (3) to (5), the original is conveyed by the conveying rollers 4a to 4c alone from the detected values of temperature and humidity through the degree of expansion of the conveying rollers 4a to 4c. The passing speeds Va, Vb, Vc at the time are calculated.

However, Va0 is the passage speed of the original when the original is conveyed only to the conveying roller 4a when the temperature and humidity around the conveying roller 4a are Ta0 and Ma0, respectively. Va0 and Vb0 have the same meaning. ω is a driving speed (that is, rotational speed) of the transport motor 405 that drives the transport rollers 4a to 4c, which is set by the image processing control unit Y1.
Further, based on Va to Vc calculated by the CPU 401 as described above, passage speeds V11, V12, V13, V21, V22, and V31 are calculated by the following equations (6) to (11).
V11 = Va (6)
V12 = (Va + Vb) / 2 (7)
V13 = Vb (8)
V21 = Vb (9)
V22 = (Vb + Vc) / 2 (10)
V31 = Vc (11)
Further, the CPU 401 calculates the reading cycle of the CCD 9 and the CCD 9 ′ appropriate for these passing speeds V11, V12, V13, V21, V22, and V31. In the calculation of the reading cycle, the relationship between the calculated passing speed and the reciprocal of the reading cycle (that is, the reading frequency) is linear, and the proportional constant stored in the ROM 402 is referred to, as in the above-described embodiment. To calculate the reading cycle.
Further, each reading cycle calculated in this way corresponds to each stage when the original passes through the first reading position 5 and each stage when the original passes through the second reading position 10. And stored in the RAM 403 as a correspondence table.

As shown in FIG. 8, the image processing control unit Y1 of the scanner according to the third embodiment of the present invention is in contact with each of the transport rollers 4a to 4c when the document is transported along the transport path 3. (In other words, whether the first reading position 5 or the second reading position 10 is being passed, and which is the first to third stages), that is, a state detection for detecting a speed change in a plurality of stages. Part 408. The state detection unit 408 (an example of a speed change detection unit) includes, for example, a document detection sensor provided in the vicinity of each of the transport rollers 4a to 4c.
During the conveyance of the original, the CPU 401 (an example of a part of the reading cycle setting unit) determines that the original moves the first reading position 5 based on the detection result by the state detection unit 408 (speed change detection unit). It is sequentially determined whether the first stage, the second stage, the third stage when passing, or the first stage, the second stage, and the third stage when passing through the second reading position 10. Further, each time a change of state is detected, the correspondence table (correspondence table between each stage and the reading cycle) stored in the RAM 403 is referred to, and the reading of each of the CCD 9 and CCD 9 ′ is performed according to the change of state. The cycle is switched to a plurality of stages with values stored in sequence.
As described above, the reading magnifications of the first image reading unit X1 and the second image reading unit X2 are made the same, and the readings read by the first image reading unit X1 and the second image reading unit X2 are performed. The reading magnification can be made uniform even in the image, and the image quality is further improved.

1 is a schematic configuration diagram of an image reading apparatus according to an embodiment of the present invention. The conceptual diagram explaining the adjustment method of the reading period by CCD. FIG. 6 is a schematic diagram illustrating a positional relationship between a conveyance roller and first and second reading positions. 1 is a block diagram of a main part of an image reading apparatus according to an embodiment of the present invention. 6 is a flowchart illustrating a processing procedure in which the image reading apparatus according to the embodiment of the present invention sets a reading cycle for each image reading unit. FIG. 5 is a block diagram of a main part of a printer according to a second embodiment of the present invention. 6 is a graph showing speed changes in a plurality of stages during document conveyance. FIG. 9 is a block diagram of the main part of a printer according to a third embodiment of the present invention.

Explanation of symbols

A ... Scanner (image reading apparatus) according to an embodiment of the present invention
B ... Scanner α1 according to the conventional example ... ADF device α2 ... Surface optical parts β1, β2 ... Bending part X1 ... First image reading part X2 ... Second image reading part Y1, Y2 ... Image processing control part 3 ... Conveyance path 4a -4c ... Conveying roller 5 ... First reading position 10 ... Second reading position 401 ... CPU
402 ... ROM
403 ... RAM
404 ... Image memory 405 ... Conveyance motor 406 ... Operation unit 407 ... Counter 408 ... State detection unit

Claims (5)

First image reading means for reading an image from one side of a document being conveyed along a predetermined conveyance path, and second for reading an image from the other surface of the document being conveyed on the downstream side in the document conveyance direction Image reading means;
Arranged at a plurality of positions including at least a position upstream of the first image reading means in the document transport direction and a position downstream of the second image reading means in the document transport direction in the transport path. A plurality of conveying means for sequentially conveying the document;
An image reading apparatus comprising:
A transport influencing factor information acquisition means for acquiring transport influencing factor information including one or more of an environmental condition, a document type, and a document reading record;
A reading period setting unit configured to set a reading period in the document conveying direction by the first image reading unit and / or the second image reading unit based on the conveyance affecting factor information acquired by the conveying influence factor information acquiring unit; ,
An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein the environmental condition includes a temperature condition and a humidity condition.   The image reading apparatus according to claim 1, wherein the type of the original includes a thickness of the original and a size of the original.   The image reading apparatus according to claim 1, wherein the reading result of the original includes the number of read originals and the reading time of the original. A speed change detecting means for detecting a speed change in a plurality of stages during conveyance of the original;
The reading cycle setting unit sets a reading cycle in the document conveyance direction by the first image reading unit and / or the second image reading unit for each of the plurality of stages at which a speed change is detected by the speed change detecting unit. The image reading apparatus according to claim 1, wherein the image reading apparatus is one.

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