JP3912376B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus having a double-sided document reading function and a continuous reading function.

2. Description of the Related Art Conventionally, as an image reading apparatus, an apparatus having a double-sided document reading function and a continuous reading function for a plurality of documents is known. In such an image reading apparatus, for example, an ADF apparatus (automatic document feeder) is provided, and a plurality of documents set on the ADF apparatus can be continuously conveyed and read. Further, for example, by providing two image sensors for the front side and the back side, the front side and the back side of the document conveyed by the ADF apparatus can be read almost simultaneously by the front side and back side image sensors.
When reading one side of a document with the image reading apparatus, only one side of the document is read using only the front surface image sensor.

  Japanese Patent Application Laid-Open No. 2004-151858 discloses a technique for switching between double-sided printing and single-sided printing on a copy sheet based on a first read image of a document in a copying machine. Also, if it is determined that the first sheet is a document sheet printed on both sides, only the printed side of the subsequent document sheets is sequentially copied on both sides of the copy sheet, while one sheet A technique is disclosed in which, when it is determined that the eye is a document sheet on which only one side is printed, only the printed side of the subsequent document sheets is sequentially copied onto the surface of the copy sheet.

Japanese Patent Laid-Open No. 7-23156

  However, the conventional image reading apparatus has a problem that reading cannot be performed correctly when a document is set in the ADF apparatus with the reading surface facing in the reverse direction. In addition, when single-sided reading of a plurality of documents is continuously performed, there is a problem that reading fails for the amount of reading. In this case, it would be convenient for the user if one-sided reading can be executed correctly without being aware of the orientation of the original.

In the technique disclosed in Patent Document 1, even when a document bundle composed of a plurality of documents includes a double-sided printed document, a single-sided printed document, and a double-sided blank document. Although we are trying to provide a compatible copier, the following problems can be considered.
In general, the document bundle is mostly a double-sided document bundle printed on both sides or a single-sided document bundle printed on one side, and it is considered that problems due to mixing hardly occur. For this reason, it is only necessary to prevent problems due to an error between a double-sided original and a single-sided original, and in particular, a reading failure due to an error in setting the original in single-sided reading.

In the copying machine disclosed in Patent Document 1, blank sheets are detected on both the front and back sides of a document by a CCD for detecting blank sheets while being conveyed by the ADF apparatus prior to reading image data for printing. Therefore, the apparatus configuration is complicated and expensive.
Furthermore, since the blank sheet detection CCD performs blank sheet determination on both sides of each sheet, the time required for reading is longer than in the case of normal continuous reading.

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
That is, in claim 1,
An image reading apparatus having a double-sided reading function and a continuous reading function for a sheet-like document,
In the single-sided scanning mode that performs single-sided scanning of a document,
Of the plurality of sheet originals, double-side reading is performed on the first sheet original, and both sides of the original are effective as reading targets based on the image information on both sides of the first sheet original. An effective image detection unit for determining whether the image is an effective image plane ;
Control that controls to notify the user by text display or voice that the both sides of the document are valid image planes when the valid image detection unit determines that both sides of the document are valid image planes Means,
The effective image surface when only one surface is determined to be the effective image surface by the effective image detection unit, or the reading surface set by the input operation of the operation unit after the notification is made, the second and subsequent sheets Setting means for setting as a reading surface for single-sided reading of the sheet-like document;
Is provided.

The effective image detection unit according to claim 2, wherein the number of pixels in which the gradation of each color falls within a predetermined range among the pixels constituting the image information is determined based on the images on both sides of the first sheet-like document. The effective image plane is determined by comparison with information.

According to a third aspect of the present invention, the effective image detection unit determines an effective image plane based on an encoding amount of image information on both sides of the first sheet-like document.

In claim 4,
The control means includes
If it is determined by the effective image detection unit that both sides of the document are valid image surfaces and the notification is made and the document reading surface is not set by the input operation of the operation unit, the document confirmation is performed. Is controlled so as to notify the user of a message prompting the user by text display or voice .

As effects of the present invention, the following effects can be obtained.
That is, according to the image reading apparatus as set forth in claims 1 and 4 , in the case of single-sided reading, reading can be performed correctly regardless of whether the sheet-like document is set face-up or face-down. Further, the user can perform single-sided reading without being conscious of the orientation in which the sheet-like document is set. Further, the reading speed of the second and subsequent sheet originals is not impaired. Further, it is not necessary to provide a blank sheet detecting CCD separately from the reading CCD in the image reading apparatus, and the apparatus does not become expensive.

  According to the image reading apparatus as set forth in claim 2, the surface with the larger amount of writing and the darker portion of the writing is set as the reading surface in the single-sided reading. Therefore, an effective image to be read can be correctly read even with a small amount of writing, a pattern, a sheet-like original of color paper with a light color, and the like.

  According to the image reading apparatus as set forth in claim 3, the surface on which the complex image is drawn is set as the reading surface in the single-side reading. Therefore, an effective image to be read can be correctly read even with a small amount of writing, a pattern, or a sheet-like original on color paper.

Next, the best mode for carrying out the invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing an embodiment of a control configuration of a multifunction machine to which the image reading apparatus of the present invention is applied, FIG. 2 is a diagram showing a reading control procedure of the image reading apparatus, and FIG. FIG. 4 is a diagram showing a procedure of a single-sided reading automatic discrimination mode, FIG. 4 is a diagram showing a double-sided scanner, FIG. 5 is a diagram showing a control configuration of a multifunction machine to which an image reading device of another embodiment is applied, and FIG. It is a figure which shows the procedure of the single-sided reading mode of a reader.

  First, a schematic configuration of a multifunction machine to which the image reading apparatus of the present invention is applied will be described with reference to FIG. The multifunction machine has a facsimile function and a copy function. The multi-function peripheral includes MPU (Micro Processing Unit) 11, ROM 12, RAM 13, image memory 14, printer controller 15, liquid crystal driver 17, codec (encoder / decoder) 19, modem 20, NCU (control unit). Network control unit) 21, key operation unit 23, LAN interface 25, double-sided scanner 30, and effective image detection unit 34, and these units are communicably connected via the bus 10.

  The MPU 11 is a control unit that controls each unit of the multifunction peripheral based on an input operation or the like to the key operation unit 23. The ROM 12 stores a control program for controlling the multifunction machine. The RAM 13 temporarily stores various information such as the control state of the multifunction machine. The image memory 14 temporarily stores image data such as a document image read by the duplex scanner 30 and a received image received via the modem 20.

A printer 16 that is an image recording unit is connected to the printer control unit 15. The printer control unit 15 controls the printer 16 in response to an instruction from the MPU 11. The printer 16 is configured by, for example, an electrophotographic system, and records (prints) a document image output from the double-sided scanner 30 and a received image received via the modem 20 on a recording sheet.
A liquid crystal display device 18 as a display unit is connected to the liquid crystal driver 17. Upon receiving an instruction from the MPU 11, the liquid crystal driver 17 displays various information (character messages) such as the operation state of the multifunction peripheral on the liquid crystal display device 18, and displays an operation procedure when using the copy function or the facsimile function. Or

  On the other hand, the codec 19 functions as an encoder, and encodes (encodes) an original image read by the double-sided scanner 30 by, for example, the MH, MR, or MMR system in order to transmit the image via the bus 10. On the other hand, it functions as a decoder and decodes (decodes) encoded image data. The modem 20 modulates transmission / reception data and demodulates reception data based on a facsimile transmission control procedure according to ITU (International Telecommunication Union) recommendation. The NCU 21 performs connection control with a communication line (telephone line), and detects transmission and reception of a dial signal corresponding to the telephone number (including the facsimile number) of the other party. Further, the multifunction device can be connected to an external personal computer (PC) 27, a server 28, and the like through a LAN (Local Area Network) 26 by a LAN interface 25.

  In the key operation unit 23, as an input means for operating the multifunction device, a ten-key for inputting the number of copies and a destination telephone number, a one-touch key for registering a facsimile destination telephone number, copying or facsimile transmission, etc. Various operation keys such as a start key for starting the operation are provided. Input operations of these operation keys are transmitted to the MPU 11, and the multifunction peripheral is controlled based on the input operations. The key operation unit 23 is provided with a reading mode switching key 24 for switching the reading mode of the double-sided scanner 30.

  The double-sided scanner 30 as an image reading unit optically scans (scans) a sheet-like document (hereinafter simply referred to as “document”) such as a document or a drawing, and measures the intensity of the reflected light. This is subjected to AD conversion (analog-digital conversion) to output image information which is image data.

  In the present embodiment, the double-sided scanner 30 has a double-sided reading function for originals and a continuous reading function for a plurality of originals. The double-sided scanner 30 is provided with an ADF device (automatic document feeder) 31, by which the double-sided scanner 30 continuously reads a plurality of documents set on the ADF device 31. Making it possible.

  As shown in FIG. 4, the double-sided scanner 30 includes a front side reading sensor 32 and a back side reading sensor 33 that are image sensors (for example, a CCD or a contact image sensor). The front side reading sensor 32 and the back side reading sensor 33 are fixedly provided at predetermined positions on both sides of the document conveying path 37 from the supply tray 35 to the discharge tray 36 of the ADF device 31. By these front surface reading sensor 32 and back surface reading sensor 33, it is possible to read the front surface and the back surface of the document conveyed on the document conveyance path 37 by the ADF device 31 substantially simultaneously.

  As described above, the double-sided scanner 30 is configured so as to perform double-sided reading in a so-called one pass while performing only one original conveyance on the original conveyance path 37. That is, the document is not configured to be switched back and read one side at a time. Image information on the front and back sides of the document read by the duplex scanner 30 is stored in the image memory 14 as storage means. A monochrome scanner having a monochrome reading function can also be used, and a color scanner having a monochrome reading function and a color reading function can also be used.

  In the present embodiment, the double-sided scanner 30 is provided with three types of reading modes. A “single-sided scanning mode” for performing single-sided reading of a document, a “double-sided scanning mode” for performing double-sided scanning of a document, and a “double-sided scanning” described later that automatically reads the document and automatically reads the document. / Single-sided reading automatic discrimination mode (hereinafter simply referred to as “automatic discrimination mode”) ”. These three types of reading modes can be selectively switched by operating a reading mode switching key 24 provided in the key operation unit 23. Thereby, the user can arbitrarily select the reading mode of the double-sided scanner 30 from the double-sided reading mode, the single-sided reading mode, and the automatic determination mode. If the user does not switch the reading mode of the double-sided scanner 30, the reading mode is set to the single-sided reading mode.

  An effective image detection unit 34 is connected to the duplex scanner 30. The effective image detection unit 34 is provided to detect the presence of an effective image for each of the front and back sides of the document read by the double-sided scanner 30, and reads one side based on image information on both sides of the document. It functions as a determination means for determining an effective image plane as a target. The effective image surface means a document surface having a document image to be read. For example, when there is a small amount of writing or a pattern on one side of a document, there is a case where it is desired to process a blank page ignoring the document image on such a surface. The front and back surfaces of the document are determined by the orientation of the document when the document is set on the duplex scanner 30 (for example, the lower surface of the set document is the front surface in FIG. 4).

  The effective image detection unit 34 calculates the number of effective images in one page of the image information of the document read by the double-sided scanner 30 (the number of black pixels in the case of monochrome reading, the number of colored pixels in the case of color reading), The calculated effective pixel number is compared with a preset threshold value, and if the result of this comparison is that the effective pixel number is less than or equal to the threshold value, the document read at this time is not an effective image surface but a blank page. Conversely, if the number of effective pixels exceeds the threshold value, it is determined that the original read at this time is an effective image plane. As described above, the effective image detection unit 34 determines whether each of the front and back surfaces of the document is an effective image surface based on the number of effective pixels in one page of the image information of the document read by the double-sided scanner 30. Detected.

Here, the number of effective pixels means that the gradation (256 gradations, etc.) of each color (RGB, monochrome, etc.) is a predetermined range (256 gradations are the darkest gradations) among the pixels constituting the image information. The number of pixels of 10 gradations or more).
For example, in the case of a color image of 256 gradations for each color of RGB, the R color (red) is 10 gradations or more, the G color (green) is 10 gradations or more, or the B color (blue) is the 10th floor. Pixels that are greater than or equal to the key are determined as effective pixels. In other words, a pixel in which the R color is 9 gradations or less, the G color is 9 gradations or less, and the B color is 9 gradations or less is defined as an invalid pixel. In the case of a monochrome image of black and white (monochrome), the first gradation white pixel is an invalid pixel, and the second gradation black pixel is an effective pixel.
Note that the total number of pixels of the read image changes depending on the size of the document. For example, the total number of pixels of the read image of A4 is larger than the total number of pixels of the read image of B5. Is set.

  According to such an effective image detecting unit 34, depending on the setting of the threshold value, not only a complete blank sheet but also a small amount of writing or a pattern can be determined as a blank page. That is, the surface with the larger amount of writing and the portion with the darker writing color is set as the reading surface in the single-sided reading. Therefore, an effective image to be read can be correctly read even with a small amount of writing, a pattern, an original of color paper with a light color, and the like.

The effective image detection process as described above may be executed in accordance with an effective image detection program stored in the ROM 12. Further, the effective image detection process may be performed on the image information of the document stored in the image memory 14.
Further, the effective image plane may be detected by calculating the encoding amount (data amount of the encoded data) after compressing the image information of the document read by the duplex scanner 30. In this case, when the encoding amount of the image information of the document is equal to or less than the threshold, it is determined that the image is not an effective image surface, and conversely, when it exceeds the threshold, it is determined that the image is an effective image surface. . Thereby, a surface on which a large amount of encoding, for example, a complex image is drawn, is set as a reading surface in single-sided reading. Therefore, an effective image to be read can be correctly read even with a small amount of encoding, for example, a slight writing or pattern, a color paper document, or the like.

  Next, reading control of the duplex scanner 30 of the multifunction machine will be described with reference to the flowchart of FIG. FIG. 2 shows the reading control of the double-sided scanner 30 when the multifunction machine functions as a copier. Specifically, a plurality of originals set on the ADF device 31 are read by the double-sided scanner 30. The reading control of the double-sided scanner 30 when copying on recording paper is shown.

First, a plurality of originals are set in the ADF device 31 of the double-sided scanner 30, and copy conditions such as the number of copies and the reading mode of the double-sided scanner 30 are input by the key operation unit 23 (step S 1), and the start key is operated. It is determined whether or not it has been done (step S2). When the start key is operated, the MPU 11 starts reading control of the double-sided scanner 30. As described above, when the reading mode switching operation of the double-sided scanner 30 is not particularly performed, the reading mode is set to the single-sided reading mode.
Next, the MPU 11 determines whether the reading mode of the double-sided scanner 30 is set to the single-sided reading mode, the double-sided reading mode, or the automatic determination mode (step S3).

  If it is determined in step S3 that the double-sided reading mode is set, the MPU 11 reads both the front and back sides of the document with the double-sided scanner 30 (step S4). At this time, image information of the original (both sides) read by the double-sided scanner 30 is accumulated in the image memory 14. Thereafter, the process proceeds to step S19, where the printer 16 executes the printing process of the image information of the document read by the double-sided scanner 30.

  If it is determined in step S3 that the automatic discrimination mode is set, the MPU 11 performs automatic discrimination reading of the original with the double-sided scanner 30 (step S5). At this time, image information of the document read by the double-sided scanner 30 is accumulated in the image memory 14. Thereafter, the process proceeds to step S19, where the printer 16 executes the printing process of the image information of the document read by the double-sided scanner 30.

Here, the automatic discrimination mode of the double-sided scanner 30 will be described with reference to FIG.
In the automatic discrimination reading, first, the MPU 11 executes double-sided reading of the first original with the double-sided scanner 30 (step S21). At this time, the first document is transported by the ADF device 31, the front surface of the document is read by the front surface reading sensor 32, and the back surface of the document is read by the back surface reading sensor 33. Then, the effective image detection unit 34 determines the effective image surface for both sides of the first document read by the double-sided scanner 30, in other words, determines the blank page (step S22).

  As a result, the effective image detecting unit 34 determines whether or not a blank page exists on at least one side of the first document (step S23), and a blank page exists on one side of both of the first document. If not, the MPU 11 automatically sets the reading mode of the duplex scanner 30 to the duplex reading mode (step S24). Thereafter, the process proceeds to step S30, and the MPU 11 reads the second and subsequent originals in the reading mode automatically set in the double-sided scanner 30 (in this case, the double-sided reading mode).

  On the other hand, if there is a blank page on at least one side of the first document in step S23, in the next step S25, the effective image detection unit 34 determines whether both front and back sides of the first document are blank pages. Determine whether. When the front and back sides of the first document are blank pages, the MPU 11 executes a third error process (step S26). Here, the third error process is a process of notifying the user that both surfaces of the first document are blank pages and ending the reading control in the automatic determination mode. The notification to the user is, for example, a text message such as “The first sheet is blank on both sides. Please set the document again and press the start key.” It is done by doing. Moreover, you may make it output as a voice message. After this error processing, the MPU 11 ends the reading control of the double-sided scanner 30 (FIG. 2).

  If it is determined in step S25 that the front and back sides of the first document are not blank pages, then the effective image detection unit 34 determines whether the front surface is a blank page (step S27). When the front surface of the first document is a blank page, the MPU 11 sets the reading mode of the double-sided scanner 30 to the back side of the document, that is, a surface different from the surface determined to have a blank page as the reading surface. The single-sided reading mode is automatically set (step S28). Thereafter, the process proceeds to step S30, and the MPU 11 reads the second and subsequent originals in the reading mode automatically set in the double-sided scanner 30 (in this case, the single-sided reading mode with the back side and the reading side of the original). Execute.

  On the other hand, if it is determined in step S25 that the surface of the first document is not a blank page, the MPU 11 sets the reading mode of the double-sided scanner 30 to the surface of the document, that is, the surface that is determined to have a blank page. A single-sided reading mode in which a different surface is the reading surface is automatically set (step S29). Thereafter, the process proceeds to step S30, and the MPU 11 reads the second and subsequent originals in the reading mode automatically set in the double-sided scanner 30 (in this case, the single-sided reading mode using the front side and the reading side of the original). Execute.

  In the determination in step S3 described above (FIG. 2), when the single-sided reading mode is set, reading control is performed as in steps S6 to S18 below. In step S <b> 6, the MPU 11 performs double-sided reading of the first original with the double-sided scanner 30. At this time, the first document is transported by the ADF device 31, the front surface of the document is read by the front surface reading sensor 32, and the back surface of the document is read by the back surface reading sensor 33. Then, the effective image detection unit 34 determines the effective image surface for both sides of the first document read by the double-sided scanner 30, in other words, determines the blank page (step S7).

  As a result, the effective image detection unit 34 determines whether or not a blank page exists on at least one side of the first document (step S8). When there is no blank page on at least one side of the first document. In other words, when it is determined that both surfaces are valid image surfaces, the MPU 11 executes a first error process (step S9). Here, the first error processing is to notify the user that both sides of the first document are valid image planes, and when one-sided reading is continued, either one of the front side and the back side is set as the reading side. This is a process for causing the user to select the above. For example, “Notice that you have single-sided scanning, but there are valid images on both front and back sides. If you want to continue scanning one-sided, enter which side you want to scan. This is performed by displaying a character message such as “Please display” on the liquid crystal display device 18. Moreover, you may make it output as a voice message. As a result, the key operation unit 23 is input to set a reading surface for single-sided reading.

  In the next step S10, the MPU 11 determines whether or not the front surface is selected as the reading surface. In the next step S11, the MPU 11 determines whether or not the back surface is selected as the reading surface. As a result, when the surface is selected as the reading surface, the process proceeds to step S17. If the back side is selected as the reading surface, the process proceeds to step S16. However, if neither the front side nor the back side is selected as the reading side, the MPU 11 reads characters such as “Please check the original, set the original again, and press the start key”. After outputting the message to the liquid crystal display device 18 (step S12), the reading control of the double-sided scanner 30 is terminated. Note that it may be output as a voice message.

  On the other hand, in step S8, if there is a blank page on at least one side of the first document, that is, if at least one side is not an effective image surface, in the next step S13, the effective image detection unit 34 sets 1 It is determined whether both front and back sides of the first document are blank pages. If the front and back surfaces of the first document are blank pages, that is, if both surfaces are not valid image surfaces, the MPU 11 executes the second error process (step S14). Here, the second error process is a process of notifying the user that there is no valid image on both sides of the first document and ending the reading control in the single-sided reading mode. The notification to the user is, for example, a text message such as “The first sheet is blank on both sides. Please set the document again and press the start key.” It is done by doing. Moreover, you may make it output as a voice message. After this error processing, the MPU 11 ends the reading control of the double-sided scanner 30.

If it is determined in step S13 that the front and back surfaces of the first document are not blank pages, that is, if one side is an effective image surface, then the effective image detection unit 34 determines whether the surface is a blank page. Is determined (step S15). When the front surface of the first document is a blank page, that is, when the back surface is an effective image surface, the MPU 11 scans the back surface of the document determined to be an effective image surface by the double-sided scanner 30. The reading surface is automatically set (step S16). In this manner, the MPU 11 functions as a setting unit that sets the reading surface of the second and subsequent originals. Specifically, such a reading surface setting process is executed according to a reading surface setting program stored in the ROM 12.
At this time, image information of the first original (back side) read by the double-sided scanner 30 is accumulated in the image memory 14. Thereafter, the process proceeds to step S18, and the MPU 11 performs single-sided reading of the second and subsequent documents on the reading surface automatically set in the double-sided scanner 30 (in this case, the back surface of the document). At this time, image information of the second and subsequent originals (back side) read by the double-sided scanner 30 is accumulated in the image memory 14. Thereafter, the process proceeds to step S19, where the printer 16 executes the printing process of the image information of the document read by the double-sided scanner 30. At this time, for the second and subsequent originals, all of the image information of the read original may be printed on one or both sides of the recording paper regardless of the presence of blank pages, or the second original For the subsequent originals, the effective image detection unit 34 detects the presence of a blank page, and the image information of the detected blank page is not accumulated in the image memory 14 but skipped and printed on one or both sides of the recording paper. It may be.

On the other hand, if it is determined in step S15 that the surface of the first document is not a blank page, that is, if the surface is an effective image surface, the MPU 11 determines that the double-sided scanner 30 is an effective image surface. The surface of the original document is automatically set as the reading surface (step S17). In this manner, the MPU 11 functions as a setting unit that sets the reading surface of the second and subsequent originals. As described above, such a reading surface setting process is executed in accordance with a reading surface setting program stored in the ROM 12.
At this time, image information of the first original (front side) read by the double-sided scanner 30 is accumulated in the image memory 14. Thereafter, the process proceeds to step S18, and the MPU 11 performs single-sided reading of the second and subsequent originals on the reading surface automatically set in the double-sided scanner 30 (in this case, the surface of the original). At this time, image information of the second and subsequent originals (front side) read by the double-sided scanner 30 is accumulated in the image memory 14. Thereafter, the process proceeds to step S19, where the printer 16 executes the printing process of the image information of the document read by the double-sided scanner 30. At this time, for the second and subsequent originals, all the image information of the read original may be printed on one or both sides of the recording paper regardless of the presence of blank pages. For the subsequent originals, the effective image detection unit 34 detects the presence of a blank page, and the image information of the detected blank page is not accumulated in the image memory 14 but skipped and printed on one or both sides of the recording paper. It may be.

  As described above, the second and subsequent originals are read based on the read image of the first original, regardless of whether the original is set face-up / backward by reading control in the single-sided reading mode of the double-sided scanner 30. Can be automatically set, and one-sided reading can be performed correctly. In addition, the user can perform single-sided reading without being aware of the direction in which the document is set. The reading speed of the second and subsequent originals is not impaired. In addition, the double-sided scanner 30 does not need to be provided with a CCD for detecting blank paper separately from the reading surface reading sensor 32 and the back surface reading sensor 33, and the apparatus is not expensive.

In the above-described reading control in the single-sided reading mode by the double-sided scanner 30, the reading side for single-sided reading is set by performing the determination of the effective image surface by the effective image detecting unit 34, that is, the blank page determination. For example, the reading control without blank page determination may be performed. For example, the reading surface for single-sided reading may be set by determining the effective image surface by the effective image detection unit 134 (FIG. 5) described below.
This reading control will be described with reference to FIGS. The multifunction device shown in FIG. 5 has substantially the same configuration as the multifunction device shown in FIG. 1 except that the effective image detection unit 34 in FIG. 1 becomes an effective image detection unit 134 in FIG. It is a point. The effective image detection unit 134 is provided to detect which side of the document read by the double-sided scanner 30 is the effective image surface, and based on the image information on both sides of the document, Functions as a judging means for judging that the image surface is an effective image plane.

  Unlike the above-described effective image detection unit 34, the effective image detection unit 134 does not determine whether each of the front and back surfaces is a blank page. That is, the number of effective pixels is not compared with the threshold value. Then, instead of determining whether the page is a blank page, the following effective image plane determination is performed. The effective image plane determination performed by the effective image detecting unit 134 is performed by determining the number of effective images in one page of image information (the number of black pixels in the case of monochrome reading, In the case of color reading, the number of colored pixels) is calculated and the number of effective pixels on the front surface is compared with the number of effective pixels on the back surface, and the surface with the larger effective pixel number is determined as the effective image surface. In other words, the effective image surface means the surface having the larger number of effective pixels among the front surface and the back surface. As described above, the effective image detection unit 134 determines which of the front and back surfaces of the document is the effective image surface based on the number of effective pixels in one page of the image information of the document read by the double-sided scanner 30. It is detected. The number of effective pixels has the same meaning as described above, and is the number of pixels in which the gradation of each color (RGB, monochrome, etc.) is in a predetermined range among the pixels constituting the image information. According to such an effective image detection unit 134, a surface having a larger amount of writing or a portion having a darker writing color is set as a reading surface in single-sided reading. Therefore, an effective image to be read can be correctly read even with a small amount of writing, a pattern, an original of color paper with a light color, and the like.

The effective image detection process as described above may be executed in accordance with an effective image detection program stored in the ROM 12. Further, the effective image detection process may be performed on the image information of the document stored in the image memory 14.
Further, the effective image plane may be detected by calculating the encoding amount (data amount of the encoded data) after compressing the image information of the document read by the duplex scanner 30. In this case, it is determined that the surface with the larger encoding amount of the image information of the document is the effective image surface. Thereby, a surface on which a large amount of encoding, for example, a complex image is drawn, is set as a reading surface in single-sided reading. Therefore, an effective image to be read can be correctly read even with a small amount of encoding, for example, a slight writing or pattern, a color paper document, or the like.

  FIG. 6 shows reading control in the single-sided reading mode when the effective image plane is determined by the effective image detecting unit 134, and only the portion corresponding to step S6 to step S18 in the flowchart of FIG. 2 is shown. . With reference to FIG. 6, the reading control in the single-sided reading mode when the effective image detection unit 134 determines the effective image surface will be described.

  In the reading control in the single-sided reading mode, first, the MPU 11 performs double-sided reading of the first original with the double-sided scanner 30 (step S101). At this time, the first document is transported by the ADF device 31, the front surface of the document is read by the front surface reading sensor 32, and the back surface of the document is read by the back surface reading sensor 33. Then, the effective image detection unit 134 determines the effective image plane for both sides of the first document read by the duplex scanner 30 (step S102).

  As a result, the effective image detection unit 134 compares the number of effective pixels on the front side of the first document with the number of effective pixels on the back side to determine whether the number of effective pixels on the front side is larger than the number of effective pixels on the back side. Determination is made (step S103), and if the number of effective pixels on the front surface is not larger, it is determined that the back surface is an effective image surface, and the process proceeds to step S104. Conversely, if the number of effective pixels on the surface is larger, it is determined that the surface is an effective image surface, and the process proceeds to step S105.

In step S <b> 104, the MPU 11 automatically sets the back side of the document that is determined to be an effective image surface as the reading surface in the double-sided scanner 30. The MPU 11 functions as setting means for setting the reading surface of the second and subsequent originals. Specifically, such a reading surface setting process is executed according to a reading surface setting program stored in the ROM 12.
At this time, image information of the first original (back side) read by the double-sided scanner 30 is accumulated in the image memory 14. Thereafter, the process proceeds to step S106, and the MPU 11 performs single-sided reading of the second and subsequent documents on the reading surface automatically set in the double-sided scanner 30 (in this case, the back surface of the document). At this time, image information of the second and subsequent originals (back side) read by the double-sided scanner 30 is accumulated in the image memory 14.

In step S105, the MPU 11 automatically sets, as the reading surface, the surface of the document that is determined to be an effective image surface in the double-sided scanner 30. The MPU 11 functions as setting means for setting the reading surface of the second and subsequent originals. Specifically, such a reading surface setting process is executed according to a reading surface setting program stored in the ROM 12.
At this time, image information of the first original (front side) read by the double-sided scanner 30 is accumulated in the image memory 14. Thereafter, the process proceeds to step S106, and the MPU 11 performs single-sided reading of the second and subsequent documents on the reading surface (in this case, the surface of the document) automatically set by the double-sided scanner 30. At this time, image information of the second and subsequent originals (front side) read by the double-sided scanner 30 is accumulated in the image memory 14.

1 is a diagram illustrating an example of a control configuration of a multifunction machine to which an image reading apparatus of the present invention is applied. FIG. 5 is a diagram illustrating a reading control procedure of the image reading apparatus. The figure which shows the procedure of the double-sided reading / single-sided reading automatic discrimination mode of an image reading apparatus. The figure which shows a double-sided scanner. The figure which shows the control structure of the multifunctional machine to which the image reading apparatus of another Example is applied. The figure which shows the procedure of the single-sided reading mode of the image reading apparatus of another Example.

Explanation of symbols

11 MPU
DESCRIPTION OF SYMBOLS 30 Double-sided scanner 31 ADF apparatus 32 Front surface reading sensor 33 Back surface reading sensor 34 Effective image detection part

Claims (4)

An image reading apparatus having a double-sided reading function and a continuous reading function for a sheet-like document,
In the single-sided scanning mode that performs single-sided scanning of a document,
Of the plurality of sheet originals, double-side reading is performed on the first sheet original, and both sides of the original are effective as reading targets based on the image information on both sides of the first sheet original. An effective image detection unit for determining whether the image is an effective image plane ;
Control that controls to notify the user by text display or voice that the both sides of the document are valid image planes when the valid image detection unit determines that both sides of the document are valid image planes Means,
The effective image surface when only one surface is determined to be the effective image surface by the effective image detection unit, or the reading surface set by the input operation of the operation unit after the notification is made, the second and subsequent sheets Setting means for setting as a reading surface for single-sided reading of the sheet-like document;
An image reading apparatus comprising: The effective image detection unit compares the number of pixels in which the gradation of each color falls within a predetermined range among the pixels constituting the image information with the image information on both sides of the first sheet-like document, The image reading apparatus according to claim 1, wherein an effective image plane is determined. The image reading apparatus according to claim 1, wherein the effective image detection unit determines an effective image surface based on a coding amount of image information on both sides of the first sheet-like document. The control means includes
If it is determined by the effective image detection unit that both sides of the document are valid image surfaces and the notification is made and the document reading surface is not set by the input operation of the operation unit, the document confirmation is performed. Control to notify the user with a text display or voice message to prompt
The image reading apparatus according to claim 1, 2, or 3.

Images