JP2007150570A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection precision and a detection speed while reducing erroneous detection in original-manuscript size detection by executing emission control of a lamp at periodic intervals while focusing attention on an unlit time of the lamp. <P>SOLUTION: An original-manuscript reader has the lamp 2 for emitting light to an original manuscript set at an original-manuscript reading position, a CCD 9 for acquiring image data of the original manuscript while scanning the original manuscript with the lamp 2, an IPU 105 for detecting a main scanning size from the image data obtained by the CCD 9, and a CPU 101 for controlling emission timing of the lamp 2 at periodic intervals independently of timing for acquiring the image data by the CCD 9. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus in an image forming apparatus such as a digital copying machine or a multifunction machine.

  In a conventional document reading apparatus, an infrared sensor is used as a method for detecting a document size at the time of reading a book. However, in recent years, a method for detecting a document size using a line sensor for reading a document is used without using an infrared sensor. It is getting to be. When detecting the document size, not only the main scanning size but also the size in the sub-scanning direction is required. However, when the document size detection in the sub-scanning direction is performed, it is necessary to pre-scan the document surface. Since this will affect the scanning speed, etc., the document size detection in the sub-scanning direction is actually performed by the infrared sensor as in the past, and only the main scanning direction detection uses the read data from the line sensor. (For example, see Patent Documents 1, 2, and 3).

  Japanese Patent Application Laid-Open No. 2004-228561 is a method for determining the document size in the main scanning direction assuming that the inside of the document is white and the outside of the document is black when the pressure plate is opened. Patent Document 2 is the same as Patent Document 1 in determining the document size in the main scanning direction, assuming that the inside of the document is white and the outside of the document is black when the pressure plate is opened. It is characterized in that the data is taken under the condition of 2 when the light is turned off and the influence of ambient light is removed. Patent Document 3 is the same as Patent Document 1 in determining the document size in the main scanning direction, assuming that the inside of the document is white and the outside of the document is black when the pressure plate is opened, but at a plurality of points in the main scanning direction. The main scanning document size is detected using the read data of the line sensor. In Patent Documents 1 and 2, there is no description that it is friendly to the user's eyes.

  By the way, the lamp used as the document irradiating means has a non-lighting time until lighting is started after energization called dark start at the time of lighting, and there is a time from the start of lighting to the stabilization of the light quantity. .

JP-A-10-257255 JP 2000-138798 A JP 2003-198809 A

  However, the conventional techniques as described above have the following problems. Although Patent Documents 1 and 2 are effective in increasing the accuracy of document size detection from two or more types of read data, the time until the pressure plate is closed cannot be shortened. In Patent Document 3, the time until the pressure plate is closed may be short, but it does not mention whether the lamp is lit or not, and since it is simply averaged in the sub-scanning, the lamp on / The possibility of malfunctioning increases due to the off state.

  In general, when reading a document, the reading is often started after the dark guidance time and the light amount stabilization time have elapsed. However, in the document size detection, the detectable time is limited depending on the state of the pressure plate. For this reason, depending on the characteristics of the lamp, it may be impossible to wait for the light amount stabilization time including the dark start time to elapse.

  The present invention has been made in view of the above, and pays attention to the lamp non-lighting time, and controls the document irradiating means at periodic intervals, thereby reducing false detection and detection accuracy in document size detection. And it aims at improving the detection speed.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is directed to a document irradiating unit for irradiating light to a document set at a document reading position, and scanning the document by the document irradiating unit. An image reading unit that acquires image data of the original and a detection unit that detects a main scanning size from the image data acquired by the image reading unit, the image reading unit Irradiation timing control means for controlling the irradiation timing of the document irradiating means at periodic intervals irrespective of the timing of acquiring the image data is provided.

  According to the first aspect of the present invention, by providing the irradiation timing control means of the document irradiation means at the time of image reading, image data for size detection from the start of lamp irradiation at the time of document size detection or image reading. It is possible to shorten the time until the start of acquisition.

  According to a second aspect of the present invention, in the first aspect, the irradiation timing control unit includes a holding unit that holds a result of whether pre-irradiation has been executed at periodic intervals, and determines the main scanning size of the document. When executing the above, the timing of starting the acquisition of the image data after irradiating the document is controlled depending on whether or not the pre-irradiation has been executed in the holding means.

  According to the second aspect of the present invention, the irradiation timing control means is used, and as much as possible of the document irradiation means at the time of image reading from the start of lamp irradiation at the time of document size detection to the start of image data acquisition for size detection. By providing the irradiation timing control means, it is possible to shorten the time from the start of lamp irradiation at the time of document size detection or image reading to the start of image data acquisition for size detection, The time required for the size detection process can be reduced. Further, by executing the pre-irradiation, the amount of light emitted from the document irradiating means is stabilized in a short time, so that an effect of improving the document size detection accuracy and reducing false detection can be expected.

  According to a third aspect of the present invention, in the first or second aspect, the irradiation timing control means prohibits execution of the preliminary irradiation according to a predetermined condition.

  According to the third aspect of the present invention, the irradiation timing control means executes the start of document irradiation under conditions (periodic intervals) other than the operation of the user of the image reading apparatus. There is a possibility that a disadvantage may be caused by performing the irradiation in advance. Therefore, it is possible to solve the above problem by providing a means for prohibiting the pre-irradiation so that the pre-irradiation is not selectively executed according to the conditions.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the measurement device includes a measurement unit that measures a time interval at which the document irradiation is started, and the irradiation timing control unit executes irradiation timing control according to the measurement result of the measurement unit. It is characterized by doing.

  According to the fourth aspect of the present invention, the image forming apparatus may use the number of times of image reading, the power-on time, etc. to determine the periodic interval. By measuring the interval and executing the pre-irradiation timing control, it is possible to shorten the light amount stabilization time of the document irradiating means without depending on the usage status of the apparatus.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the time measurement stop means for stopping the measurement of the irradiation start time interval by the measurement means, and the time for restarting the measurement of the irradiation start time interval by the measurement means. And a measurement resumption means.

  According to the fifth aspect of the present invention, the irradiation timing control means is a means that operates asynchronously with document size detection and document reading. Therefore, there is a concern that a malfunction may be caused such as the document irradiating device is turned off when the periodical interval is reached during the document size detection and the pre-irradiation operation is performed. Therefore, by providing a means for stopping the measurement of the time interval and a means for re-measuring (restarting) the time interval, for example, the time interval is prohibited during other processing (using the document irradiating means). By controlling to resume, it is possible to control the pre-irradiation timing exclusively and safely from other processes.

  The invention according to claim 6 is characterized in that, in claim 4, there is provided setting means for arbitrarily setting the measurement of the irradiation start time interval.

  According to the sixth aspect of the present invention, there is a difference (variation) in characteristics between the document irradiating means connected to the image reading apparatus. Therefore, it is possible to efficiently control the irradiation timing by providing means that can arbitrarily set the period of time measurement.

  According to a seventh aspect of the present invention, in the third aspect of the present invention, the condition for prohibiting the execution of the pre-irradiation is when the platen is open or when the original irradiation is started to acquire image data. It is characterized by that.

  According to the seventh aspect of the present invention, the irradiation light from the document irradiating unit is incident on the user of the image reading apparatus by first prohibiting the pre-irradiation when the pressure plate is open. Can be prevented, and irradiation timing control can be performed without causing discomfort to the user. Further, by prohibiting the pre-irradiation while the document irradiation is already being performed, it is possible to control the irradiation timing exclusively and safely from other processes.

  Since the image reading apparatus according to the present invention is provided with the irradiation timing control means of the document irradiating means at the time of image reading, an image for size detection from the start of lamp irradiation at the time of document size detection or image reading. There is an effect that the time until the start of data acquisition can be shortened.

  The image reading apparatus according to the present invention (claim 2) uses the irradiation timing control means, and irradiates the document at the time of image reading from the start of lamp irradiation at the time of document size detection to the start of acquisition of image data for size detection as much as possible By providing the irradiation timing control means, it is possible to reduce the time during which it is possible to reduce the time from the start of lamp irradiation at the time of document size detection or image reading to the start of image data acquisition for size detection. As a result, the time required for the size detection process can be shortened. Further, by executing the pre-irradiation, the amount of light emitted from the document irradiating means is stabilized in a short time, so that the effect of improving the document size detection accuracy and reducing the false detection can be expected.

  In the image reading apparatus according to the present invention (claim 3), the irradiation timing control means executes the start of document irradiation under conditions (periodic intervals) other than the operation of the user of the image reading apparatus. May cause disadvantages due to careless irradiation. Therefore, there is an effect that the above problem can be solved by providing means for prohibiting the pre-irradiation so that the pre-irradiation is not selectively executed according to the conditions.

  In the image reading apparatus according to the present invention (claim 4), in the image forming apparatus, the number of times of image reading, the power-on time, and the like may be used for the periodic interval determination. By measuring the time interval and executing the irradiation timing control, it is possible to shorten the light amount stabilization time of the document irradiating means without depending on the usage status of the apparatus.

  In the image reading apparatus according to the present invention (claim 5), the irradiation timing control means is a means that operates asynchronously with document size detection and document reading. Therefore, there is a concern that a malfunction may be caused such as the document irradiating device is turned off when the periodical interval is reached during the document size detection and the pre-irradiation operation is performed. Therefore, by providing means for stopping the measurement of the time interval and means for re-measuring (restarting) the time interval, for example, the time interval is prohibited during other processing (using the document irradiating means), and after the processing is completed. By controlling to resume, the irradiation timing can be controlled exclusively and safely from other processes.

  In the image reading apparatus according to the present invention (Claim 6), there is a difference (variation) in characteristics between the document irradiating means connected to the image reading apparatus. Therefore, there is an effect that the irradiation timing can be controlled efficiently by providing means capable of arbitrarily setting the period of time measurement.

  In the image reading apparatus according to the present invention (first aspect), the irradiation light of the document irradiating means is incident on the user by prohibiting the pre-irradiation when the pressure plate is open. It is possible to prevent this, and it is possible to control the irradiation timing without causing discomfort to the user. Further, by prohibiting the pre-irradiation while the document irradiation is already being performed, there is an effect that the irradiation timing can be controlled exclusively and safely from other processes.

  Exemplary embodiments of an image reading apparatus according to the present invention are explained in detail below with reference to the accompanying drawings.

(Embodiment)
In the present invention, when the platen or ADF (automatic document feeder) is opened and a book document or sheet document is set on the contact glass and read, the main scanning size determination of the document and image data reading are not involved. By providing a function to control the start / end of irradiation of the document irradiation means at periodic intervals, the time from the start of lamp irradiation at the time of document size detection or image reading to the start of image acquisition for size detection can be shortened Is possible. This will be specifically described below.

  FIG. 1 is a block diagram showing a main configuration of an image reading apparatus according to an embodiment of the present invention. In this figure, reference numeral 1 is a contact glass on which a book document is set, reference numeral 2 is a lamp for irradiating light toward the contact glass 1, reference numeral 9 is a CCD (line sensor) for reading an optical image, and reference numeral 13 is a carriage. A home position sensor for detecting a predetermined position, reference numeral 20 is a reflective infrared sensor, and a size sensor for detecting a plurality of sizes in the sub-scanning direction. Reference numeral 21 is an opening / closing of a pressure plate or ADF (automatic document feeder, not shown). Reference numeral 101 denotes a CPU for controlling the entire image reading apparatus, reference numeral 102 denotes a lamp control unit for controlling the lighting of the lamp 2, reference numeral 103 denotes a carriage driving unit, and reference numeral 105 denotes image processing of the read image data. IPU (image processing unit) that performs the operation, 110 is a predetermined setting by the user In addition, an operation unit for displaying the device status, a CPU 111 for controlling the operation unit 110, a display unit 112 for displaying a setting state, an operation state, and the like of the device are provided. A timer for measuring a periodic time interval for controlling the start / end of pre-irradiation, reference numeral 114 is a start key pressed at the start of reading, and reference numeral 115 is whether pre-irradiation was executed at periodic intervals. It is a memory as a holding means for storing the result. The CPU 101 has a function of an irradiation timing control unit described later. Details of these will be described below.

  FIG. 2 is a cross-sectional view showing a schematic configuration of the image reading apparatus in FIG. This image reading apparatus irradiates a document 10 placed on a contact glass 1 forming a document surface with light from a lamp 2 and reflects light reflected by a first mirror 3, a second mirror 4, and a third mirror 5. The light is collected by the lens 8 and imaged on the CCD 9. While the lamp 2 and the first mirror 3 travel a distance L, the second mirror 4 and the third mirror 5 travel a distance L / 2. This keeps the optical path length of the optical system constant and scans the entire document.

  FIG. 3 is a perspective view showing a mechanical configuration of the image reading apparatus in FIG. The first carriage 6 including the lamp 2 and the first mirror 3 is attached to the drive wire 11, and the second carriage 7 including the second mirror 4 and the third mirror 5 is wound around the pulley 12. The drive wire 11 is wound around the wire pulley 15 connected to the drive shaft 14, and the drive of the motor 18 is transmitted by the timing pulley 16 and the timing belt 17. A position where a certain distance is returned after one end of the first carriage 6 crosses the home position sensor 13 is defined as a home position.

  FIG. 4 is a block diagram showing the overall configuration of a digital copying machine (multifunction machine) equipped with the image reading apparatus. When an original is set on the scanner 120 and the start key 114 (see FIG. 1) is pressed, the original is read by the scanner 120, a series of image processing is performed in the IPU 105, image data is output to the printer 130, and paper is discharged. Is called. Necessary parameters in the scanner 120, the IPU 105, and the printer 130 are held in the RAM 104 of the CPU 101, and the CPU 101 sets each device. Further, mode information necessary for parameter setting is configured to be specified by the user using the operation unit 110, and information is exchanged by communication between the CPU 111 and the CPU 101 in the operation unit 110. .

  FIG. 5 is a block diagram showing a configuration within IPU 105 in FIG. Although desired image processing is performed on the original reading data received from the scanner 120, when the original size detection operation is performed, the image data is stored in a multi-line memory 503 connected to the image processing module 501. A memory controller 502 that controls the multi-line memory 503 is also provided, and the CPU 101 can read / write data in the multi-line memory 503.

  Next, the size detection operation in the image reading apparatus configured as described above will be described with reference to the flowchart shown in FIG. The control of the size detection operation is executed by the CPU 101 via the IPU 105. First, it is determined from the output signal of the pressure plate opening / closing sensor 21 whether or not the pressure plate or ADF is opened (step S1). If it is determined that the pressure plate has been released, the information of the size sensor 20 is monitored (step S2), and it is determined whether or not the document state has changed based on the information of the size sensor 20 (step S3). If it is determined that the document state has changed, settings for document reading timing, settings necessary for shading (optical distortion) correction, and the like are executed (step S4).

  That is, it is detected that a carriage (hereinafter, simply referred to as a carriage because only the first carriage 6 moves) is placed at the document size detection position and the pressure plate is closed, or the user detects the document. When the reading is started, the document size detection operation is started. The opening / closing of the pressure plate is detected by ON / OFF of the pressure plate opening / closing sensor 21. When document size detection is started, first, preparations necessary for document size detection are made. Further, the setting of the document reading timing for detecting the document size as shown in FIGS. 7 and 8 and the preparation setting necessary for the shading correction are executed as necessary.

  When the preparation is completed as described above, the irradiation of the document is started for reading the document (step S5). Subsequently, the original is read (step S6), the irradiation of the original is terminated (step S7), and the read original image data is taken out (step S8). Subsequently, the image data is analyzed (step S9), and it is determined whether or not the document size is successfully detected (step S10). If the document size is successful, the document size is determined (step S11).

  In steps S2 to S5, the processing is sequentially performed. However, there is no particular order, and parallel processing can be performed.

  That is, when the preparation for size detection and the processing for starting the document irradiation are completed, the document is read. A write signal for a document size is generated, image data is read within the valid period of the write signal, and the process is terminated. At this time, reading may be performed while moving the carriage and scanning the document, or reading may be performed while the carriage is stopped at the document size detection position to acquire read image data of two or more lines. When reading is performed while moving the carriage and scanning the document, it is possible to read images at different positions on the document, which may cause erroneous detection of the document size depending on the contents of the image data on the document. In addition to preventing this, the carriage is moved to the original document reading (main scanning) position in parallel with the reading, so that the time until the start of the main scanning after the document detection can be shortened. On the other hand, if reading is performed while the carriage is stopped at the document size detection position, it is possible to clearly detect the influence of external light on the document table and the change in the lighting state of the document irradiation lamp from the contents of the image data. (The detection is not impossible even when the carriage is moved). When the reading of the original is completed, the irradiation of the original is terminated.

  However, in the case where the main scan is started immediately after the document reading for size detection is completed, the document irradiation lamp may be left on without performing the document irradiation process. FIG. 6 does not describe a process for determining whether to execute the main scan. In addition, the document irradiation process can be performed in parallel without any definition of the order of the image data extraction process described below. When the document reading process is completed, the read document image data is taken out in order to analyze the document size. In this embodiment, the read document image data is extracted by reading the data stored in the multi-line memory 503 from the CPU 101 shown in FIG. The extracted image data is analyzed, and the document size is determined. Details of the analysis will be described later. If the document size is successfully determined, the document size is determined.

  Specifically, the determination of the document size is to store the document size information in the program execution RAM 104 connected to the CPU 101 in FIG. 5, and thereafter, the determined document size information is read as necessary. Use. After the document size is determined, the document size detection operation is completed. If the determination of the document size fails, the document size detection operation is completed without determining the document size. Examples of document size determination failure include a black document, the influence of external light on the document table, and the illumination state of the illumination lamp (reading with the lamp 2 turned on but the light quantity is not stable) For example, the size of the document cannot be determined from the read data. The basic sequence of the document size detection operation in the present invention is as described above.

  Next, the above-described analysis of document image data (determination of document size) will be described in detail. FIG. 9 shows an example of the memory controller 502. The line sensor (CCD9) reading receives the XLSYNC signal as a reference for one line, the PCLK as the pixel clock, and the XFSYNC signal indicating the line sensor reading start trigger from the image processing module 501, and write reset (XWRST) to the multi-line memory 503 ) Signal and a write enable (XWE) signal. At the same time, the CPU 101 receives four parameters of the main scan start, main scan width, sub-scan start, and sub-scan width indicating the memory write area from the CPU 101, and determines the write position of the memory (RAM 104) from two reference signals: XFSYNC and XLSYNC. .

  FIG. 7 shows the timing in the sub-scanning direction, and FIG. 8 shows the timing in the main scanning direction. By having the above configuration as the memory controller 502, data of a plurality of patches in a two-dimensional direction as shown in FIG. 10 can be simultaneously written in the memory (RAM 104). The shaded area indicates the memory write area. Although the main scanning direction and the sub-scanning direction are used as parameters and timing, the sub-scanning direction in the present invention indicates not only the sub-scanning direction with respect to document reading but also the passage of time. The horizontal axis t in FIG. 10 is an example showing the passage of time, and shows the position of the reading patch at T1 and T2.

  Next, an example of extracting image data will be described with reference to the flowchart shown in FIG. Here, the patch data shown in FIG. 10 is read from the plurality of line memories 503 one by one to the RAM 104 of the CPU 101, and an average value of one patch is obtained and binarized, thereby performing monochrome determination of the patch. In FIG. 11, the monochrome determination flow starts, and first, the number of pixels in one patch is set (step S21). Thereafter, reading is performed in units of one pixel from the plurality of line memories 503, and the set N pixels are added (steps S22 and S23). Thereafter, it is determined whether or not the number of added pixels is equal to or greater than the set number of pixels (step S24). If the added pixel number is not greater than the set pixel number, one more pixel is read (step S29).

  On the other hand, if it is determined that the number of pixels added in step S24 is equal to or greater than the set number of pixels, an average value in the patch is obtained (step S25), and the patch is binarized (step S26). From the result, the white and black pixels of the patch are determined (steps S27 and S28).

  In the above, the flow for obtaining the average value is the total average after the total addition of N pixels. For example, the addition in only the main scanning direction is performed to obtain the average in one line, and then the addition and averaging of the next line are repeated. Even in the final determination method, there is no influence on the realization of the present invention.

Next, an embodiment of the present invention will be described with reference to FIG. The basic algorithm for document size detection utilizes the fact that when the platen is open, the white background portion of the document and the non-document portion outside the document are black with no reflected light. That is, in FIG. 12, it is determined that there is an original when it is brighter than TH, and that there is no original when it is darker than TH. However, as shown in FIG. 12, in the case of a document having a dark background density, even if the inside of the document is read, TH is not exceeded and it is erroneously determined that there is no document. In order to prevent this, the patches read at times T1 and T2 are set as PAT1 and PAT2 as described above, and a difference value between PAT1 and PAT2 is obtained. Like to do. In addition to the start / width in the main scanning direction and the start / width in the sub-scanning direction as parameter settings from the CPU 101 in FIG. 9, a ΔD setting is added.

  Next, an example of analyzing the above-described image data will be described according to the flowchart shown in FIG. As shown in FIG. 10, L (n) IN and L (n) JUDGE are used as reading patches. N of L (n) indicates the number of times of reading since the reading of the line sensor (CCD 9) is started (indicating the passage of time), IN and JUDGE indicate the position in the main scanning direction, and IN is the detection target The main scanning position where all the originals enter the original is shown, and JUDGE indicates the main scanning position where the inside / outside of the original is switched by the original.

  In FIG. 13, first, the maximum number of detections N is set (step S31), and n = 1 is set as an initial value (step S32). Subsequently, it is determined whether or not n exceeds the maximum number of detections N (step S33). If it exceeds N, it is determined that no detection is possible (step S41), and the detection flow is exited. On the other hand, if n does not exceed the maximum number of detections N in step S33, it is determined whether L (n) IN (see FIG. 10) is white (step S34). Here, if L (n) IN is not white, the detection count n is incremented by 1, and the process returns to step S32 (step S40).

  If it is determined in step S34 that L (n) IN is white, the nth L (n) JUDGE (see FIG. 10) is set as a detection candidate (step S35), and the detection count n is increased by one (step S36). , L (n) JUDGE is determined to be black (step S37). Here, if L (n) JUDGE is black, L (n) JUDGE is determined (step S38). On the other hand, if L (n) JUDGE is not black, the detection count is returned by one (step S39). ).

  Thus, the following determination is repeatedly performed until n = N. It is determined whether Ln (IN) is white. If the original is also black, it is determined that the lamp is off, n = n + 1 is set, and the process returns to step S32. When Ln (IN) is white, the determination result of L (n) JUDGE is set as a detection candidate, and the process proceeds to the next step. The detection result candidate n is incremented by 1, and the next reading result is determined. It is determined whether L (n) JUDGE is black. If it is white, there is a high possibility that the pressure plate has been closed. Therefore, the determination is not made here, and the result of the previous detection candidate is used as it is. If it is black, it is considered that the lamp is more stable than the previous time, so this determination result is used.

  The above is the basic sequence and algorithm related to size detection in the embodiment of the present invention.

  Next, an example of irradiation timing control that is a feature of the present invention will be described.

  FIG. 14 is a flowchart showing the processing operation of the irradiation timing control according to the embodiment of the present invention. This control is centrally executed by the CPU 101. When this pre-irradiation timing control flow is started, it is first determined whether or not a period interval for executing pre-irradiation has been reached (step S51). Here, when it is determined that the period interval for executing the pre-irradiation has been reached, the process proceeds to the pre-irradiation start in step S52. On the other hand, if the period interval has not been reached, this determination process is repeated. In step S52, a light source such as a lamp which is a document irradiating unit is turned on. Thereafter, the passage of time necessary for preliminary irradiation is waited (step S53). In step S53, after the pre-irradiation time has elapsed, the process proceeds to step S54 and the pre-irradiation ends. The completion of the pre-irradiation is performed with the light source such as a lamp serving as a document irradiating unit being turned off, and when the turning off is completed, the process proceeds to step S55. In step S55, it is determined whether to complete the pre-irradiation timing control. An example of the condition for determining whether or not to complete is that pre-irradiation is not necessary (including when it is impossible) because the power of the image reading apparatus is turned off. If it is determined in step S55 that the pre-irradiation timing control is to be completed, this flow ends. On the other hand, if it is determined that the process is not completed, the process proceeds to step S51 to repeatedly execute the process.

  By providing the irradiation timing control means of the document irradiation means at the time of image reading, it is possible to shorten the time from the start of lamp irradiation at the time of document size detection or image reading to the start of image data acquisition for size detection. Become.

  FIG. 15 is a flowchart showing a result storing operation in the irradiation timing control according to the embodiment of the present invention. This control is centrally executed by the CPU 101. When this operation is started, it is first determined whether or not the pre-irradiation period interval has been reached (step S61). Here, when it is determined that the pre-irradiation period interval has been reached, it is further determined whether or not the pre-irradiation can be executed (step S62). If it is determined that the pre-irradiation cannot be executed, the pre-irradiation result is stored (step S63), and the process proceeds to step S68. On the other hand, if it is determined in step S62 that the pre-irradiation can be executed, the pre-irradiation is started (step S64), and the pre-irradiation result is stored (step S65). Thereafter, the process waits until the pre-irradiation ends (step S66), ends the pre-irradiation (step S67), and further determines whether or not the pre-irradiation timing control is completed (step S68). Here, if it is determined that the pre-irradiation timing control is completed, this flow is stopped, and if it is not completed, the process returns to step S61 to execute the subsequent processing.

  As described above, when it is determined in step S61 that the period interval for executing the pre-irradiation has been reached, the process proceeds to step S62. In step S62, it is determined whether pre-irradiation can be executed. The determination of whether or not the pre-irradiation can be performed may not be possible because the power of the image reading apparatus is turned off as described above. In step S62, when it is determined that the pre-irradiation can be executed, the process proceeds to step S54, and after the light source such as a lamp as the document irradiating means is turned on, the result of the pre-irradiation is stored. If it is determined in step S62 that the pre-irradiation cannot be executed, the result of the pre-irradiation not being executed is stored.

  Next, with reference to a flowchart shown in FIG. 16, an operation of irradiating a document when a document size is detected will be described. This control is a detailed operation of step S52 in FIG. When this operation is started, document irradiation is first started, and a light source such as a lamp as document irradiating means is turned on (step S71), and the stored pre-irradiation result is read (step S72). Subsequently, the read pre-irradiation result is determined (step S73). Here, if the pre-irradiation result is “execution”, the irradiation light amount stabilization time at the time of executing pre-irradiation is set as a waiting time for light amount stabilization (step S74). On the other hand, when it is determined in step S73 that the pre-irradiation result is “unexecuted”, the irradiation light amount stabilization time when the pre-irradiation is executed is set as a waiting time for light amount stabilization (step S75). That word, the time until the irradiation light quantity is stabilized is waited (step S76). Then, after this set time has elapsed, the flow is terminated.

  As described above, the irradiation light amount stabilization time when executing the pre-irradiation has a shorter waiting time for stabilizing the light amount than that when the pre-irradiation is not executed. As a result, it is possible to shorten the document size detection processing time.

  By using irradiation timing control means, from the start of lamp irradiation at the time of document size detection to the start of acquisition of image data for size detection, by providing irradiation timing control means of the document irradiation means in the image reading apparatus, the document The time required for size detection processing can be reduced by shortening the time from the start of lamp irradiation at the time of size detection or image reading to the start of image data acquisition for size detection. Become. Further, by executing the pre-irradiation, the amount of light emitted from the document irradiating means is stabilized in a short time, so that an effect of improving the document size detection accuracy and reducing false detection can be expected.

  Next, FIG. 17 shows an example of an operation screen of the operation unit 110 for operating the image reading apparatus as an example of a means for prohibiting execution of pre-irradiation. Here, setting is performed by inputting a numerical value indicating whether or not to prohibit the operation screen, and the processing in FIG. 18 is executed based on the set value.

  FIG. 18 is a flowchart illustrating an example of irradiation timing control based on an input on the operation screen. This operation is centrally executed by the CPU 101. First, it is determined whether or not the pre-irradiation period interval has been reached (step S81). If the pre-irradiation period interval has been reached, it is determined whether or not pre-irradiation is prohibited from the input on the operation screen (step S81). S82). It is determined whether the pre-irradiation is prohibited (step S83). If the pre-irradiation is not prohibited, the pre-irradiation is started (step S84). On the other hand, if pre-irradiation is prohibited, the process proceeds to step S86. After step S84, the process waits until the pre-irradiation ends (step S85), and the pre-irradiation ends (step S86). Subsequently, it is determined whether or not the pre-irradiation timing control is to be completed (step S87). If it is completed, this flow is ended. If not, the process returns to step S81 to execute the subsequent control.

  Thus, when it is determined in step S81 that the period interval for executing the pre-irradiation has been reached, the process proceeds to step S82. In step S82, it is determined whether pre-irradiation is prohibited. The determination that the pre-irradiation can be performed is performed by reading the value set in FIG. After reading the set value, the process proceeds to step S83. If it is determined in step S83 that pre-irradiation is not prohibited, the process proceeds to step S84 to turn on a light source such as a lamp that is a document irradiating unit. On the other hand, if it is determined in step S83 that the pre-irradiation is prohibited, the process proceeds to step S87.

  Since the irradiation timing control means starts the document irradiation under conditions (periodic intervals) other than the operation of the user of the image reading apparatus, there is a disadvantage that the irradiation is performed carelessly depending on the usage conditions. May occur. Therefore, the above problem can be solved by providing means for prohibiting the pre-irradiation so that the pre-irradiation is not selectively executed according to the conditions.

  Next, an example of measuring time intervals will be described. FIG. 19 is a flowchart showing an operation of pre-irradiation cycle time measurement. This operation is realized by using a timer 113 or the like connected inside the CPU 101 or as a peripheral circuit. When the pre-irradiation cycle time measurement is started, first, a start process including execution of timer reset for cycle time measurement is performed (step S91). When the measurement is started, the passage of the cycle time is waited (step S92), and it is determined whether or not the pre-irradiation cycle interval has been reached (step S93). Here, if the time measurement result has reached the cycle time interval, the related processing means is notified that the cycle time has been reached (step S94). Subsequently, it is determined whether or not to continue the time measurement (step S95). As an example of the determination condition of whether or not to complete, the time measurement is not continued because the pre-irradiation is unnecessary (including the case where it is impossible) because the power of the image reading apparatus is turned off. There are cases. If it is determined in step S95 that the time measurement is completed, this flow ends. On the other hand, if it is determined to continue, the process proceeds to step S91 to repeat the process.

  In the image forming apparatus, the number of times of image reading, the power-on time, and the like may be used for the periodic interval determination. In the present invention, the timing of the pre-irradiation is measured by measuring the time interval for starting the document irradiation. By doing so, the light quantity stabilization time of the document irradiating means can be shortened without depending on the usage status of the apparatus.

  Next, an example in which the measurement of the time interval is stopped and an example in which the time interval is remeasured (restarted) will be described. The means for stopping the measurement of the cycle time interval determines whether or not there is a measurement stop request in each of steps S91 to S94 in FIG. 19, and if there is a stop request, interrupts the processing of each step. To complete the cycle time measurement flow. Further, the remeasurement is performed by restarting the operation of FIG.

  The irradiation timing control means operates asynchronously with document size detection and document reading. Therefore, there is a concern that a malfunction may be caused such as the document irradiating device is turned off when the periodical interval is reached during the document size detection and the pre-irradiation operation is performed. Therefore, by providing means for stopping the measurement of the time interval and means for re-measuring (restarting) the time interval, for example, the time interval is prohibited during other processing (using the document irradiating means), and after the processing is completed. By controlling to resume, it is possible to control the pre-irradiation timing exclusively and safely from other processes.

  Next, an example in which the measurement time interval can be arbitrarily set will be described. FIG. 20 shows an example of an operation screen of the operation unit 110 for operating the image reading apparatus as an example of setting means for the periodic time interval to be measured. Setting is performed by inputting a numerical value of time on this operation screen, and processing for waiting for the elapse of the periodic time in FIG. 19 (step S92, step S93) is executed based on the set value.

  There is a characteristic difference (variation) in the document irradiating means connected to the image reading apparatus. Therefore, it is possible to efficiently control the pre-irradiation timing by providing means that can arbitrarily set the time measurement period.

  Next, the pre-irradiation is prohibited from being executed when the pressure plate (means for shielding the original irradiation surface) is open (not in a shielding state) or when the original is already started for image data acquisition. An example will be described. The determination of this condition is performed in the flow of step S82 and step S83 shown in FIG. Whether the pressure plate is open can be determined by reading the output signal of the above-described opening / closing detection sensor 21 and determining whether document irradiation has started by reading the lighting control signal from the CPU 191. In step S83, prohibition is determined based on the result of each signal.

  In this way, by first prohibiting pre-irradiation when the platen is open. For the user of the image reading apparatus, it is possible to prevent the irradiation light of the document irradiating means from entering the user, and it is possible to control the pre-irradiation timing without causing discomfort to the user. Further, by prohibiting the pre-irradiation while the document irradiation is already being executed, the pre-irradiation timing can be controlled exclusively and safely from other processes.

  As described above, the image reading apparatus according to the present invention is useful for an image forming apparatus such as a digital copying machine, a scanner, and the like. In particular, an irradiation timing control unit for a document irradiation unit (lamp) at the time of image reading is provided, It is suitable for an apparatus that shortens the time from the start of lamp irradiation at the time of document size detection or image reading to the start of acquisition of image data for size detection, and a system using the same.

1 is a block diagram illustrating a configuration of main parts of an image reading apparatus according to an embodiment of the present invention. It is sectional drawing which shows schematic structure of the image reading apparatus in FIG. FIG. 3 is a perspective view showing a mechanical configuration of the image reading apparatus in FIG. 2. 1 is a block diagram showing an overall configuration of a digital copying machine (multifunction machine) equipped with an image reading device. It is a block diagram which shows the structure in IPU in FIG. 6 is a flowchart showing a document size detection operation according to the embodiment of the present invention. 6 is a timing chart showing timing in the sub-scanning direction in document size detection according to the embodiment of the present invention. 6 is a timing chart showing timing in the main scanning direction in document size detection according to the embodiment of the present invention. It is a block diagram which shows the input / output signal of the memory controller concerning embodiment of this invention. It is explanatory drawing which shows the monochrome determination process of the patch in the document size detection concerning embodiment of this invention. It is a flowchart which shows the extraction example of the image data concerning embodiment of this invention. It is explanatory drawing which shows the processing operation of step S26 in FIG. It is a flowchart which shows the analysis process of the image data concerning embodiment of this invention. It is a flowchart which shows the processing operation of the irradiation timing control concerning embodiment of this invention. It is a flowchart which shows the processing operation | movement which preserve | saves the result of the preliminary irradiation in the irradiation timing control concerning embodiment of this invention. It is a flowchart which shows the setting operation | movement of the irradiation light quantity stabilization time at the time of prior irradiation execution / non-execution in the irradiation timing control concerning embodiment of this invention. It is explanatory drawing which shows the setting screen of irradiation control concerning embodiment of this invention. It is a flowchart which shows the process operation | movement of prohibition / execution of irradiation control concerning embodiment of this invention. It is a flowchart which shows the processing operation of the period time measurement of the prior irradiation control concerning embodiment of this invention. It is explanatory drawing which shows the setting screen of the prior irradiation cycle time concerning embodiment of this invention.

Explanation of symbols

2 Lamp 6 First Carriage 13 Home Position Sensor 20 Size Sensor 21 Pressure Plate Open / Close Sensor 101 CPU
102 Lamp control unit 103 Carriage drive unit 104 RAM
105 IPU
110 Operation unit 111 CPU
112 Display unit 113 Timer 114 Start key 115 Memory

Claims (7)

Document irradiating means for irradiating a document set at a document reading position, image reading means for scanning the document with the document irradiating means to acquire image data of the document, and acquired by the image reading means Detecting means for detecting the main scanning size from the image data,
An image reading apparatus comprising irradiation timing control means for controlling the irradiation timing of the document irradiation means at periodic intervals irrespective of the timing at which the image data is acquired by the image reading means. The irradiation timing control means includes holding means for holding a result of whether pre-irradiation has been executed at periodic intervals,
2. The timing for starting acquisition of image data after irradiating a document is controlled depending on whether or not pre-irradiation has been performed in the holding unit when determining the main scanning size of the document. The image reading apparatus described in 1.   The image reading apparatus according to claim 1, wherein the irradiation timing control unit prohibits execution of the preliminary irradiation according to a predetermined condition. A measuring means for measuring the time interval of the start of document irradiation,
The image reading apparatus according to claim 1, wherein the irradiation timing control unit performs pre-irradiation timing control according to a measurement result of the measurement unit. A time measurement stop means for stopping the measurement of the time interval of the start of irradiation by the measurement means;
Time measurement restarting means for restarting the measurement of the time interval of irradiation start by the measuring means;
The image reading apparatus according to claim 4, further comprising:   The image reading apparatus according to claim 4, further comprising a setting unit that arbitrarily sets measurement of the time interval at which the irradiation starts.   The image reading apparatus according to claim 3, wherein the condition for prohibiting the execution of the pre-irradiation is a state in which the pressure plate is open or when document irradiation is started to acquire image data.

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