JP2013093693A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus for selecting and performing an appropriate original size detection processing in accordance with a situation of disturbance light without performing manual setting.SOLUTION: A control section 8 sets a period for driving a light source 25 by a driving circuit 26 so that a fluctuation frequency of the light source 25 is the farthest from that of the disturbance light on the basis of the fluctuation frequency of the disturbance light, which is detected by an original sensor 34. When a light volume of the disturbance light is determined to be smaller than a threshold which is previously set, a first original size determination processing for determining an original size is instructed to a size determination section 12. When the light volume of the disturbance light is determined to be the previously set threshold or more, a second original size determination processing for determining the original size on the basis of the fluctuation frequency is instructed.

Description

  The present invention relates to an image forming apparatus including a document reading device that reads a document placed on a platen glass, and more particularly to an image forming device having a document size determination function.

  2. Description of the Related Art Conventionally, an electronic copying machine, a facsimile, and the like are known as an image forming apparatus provided with a document reading device that reads a document such as a photograph or a document on a platen glass. In such an image forming apparatus, there is known an apparatus that first determines a document size of a document placed on a platen glass, and controls reading, selection of a sheet to be printed, and the like based on the determined document size. .

  As a document size detection method, it has been proposed to use image data read by a scanner that reads a document (see, for example, Patent Documents 1 and 2). In Patent Document 1, the disturbance light distribution from the platen glass before the document is placed when the upper cover is opened is taken in, and the document is read by the scanner when the upper cover is closed, and from the read image data. The document size is detected by subtracting the disturbance light distribution. In Patent Document 2, the fluctuation frequency of the light source is set to be different from the fluctuation frequency of the disturbance light, the original is read by the scanner at the timing when the upper cover is closed, and the original size is determined from the read image data by the difference in the fluctuation period. Detected.

JP 9-135330 A JP 2006-197268 A

  However, in the prior art of Patent Document 1, it is necessary to unconditionally take in the disturbance light distribution every time the upper cover is opened and closed, and to perform an image processing operation to subtract the disturbance light distribution from the read image data. There has been a problem that the manuscript size detection operation becomes complicated. Further, in the prior art of Patent Document 2, it is necessary to manually set the fluctuation frequency of the light source at the time of factory shipment, by an end user, or a service person. However, the fluctuation frequency of disturbance light is diversified with the spread of LED lighting. Therefore, it is difficult to easily grasp the fluctuation frequency of disturbance light, and it is difficult to cope with manual setting.

  In view of the above problems, an object of the present invention is to solve the problems of the prior art, and to select and execute an appropriate document size detection operation according to the situation of ambient light without performing manual setting. An object is to provide an image forming apparatus.

An image forming apparatus of the present invention is an image forming apparatus that reads a document placed on a platen glass using a light source that blinks at a predetermined cycle and determines a document size, and drives the light source at a plurality of cycles. Driving light source, disturbance light detecting means for detecting disturbance light, and a period of driving the light source by the driving means based on the fluctuation frequency of the disturbance light detected by the disturbance light detecting means. A light source drive period setting means for setting the fluctuation frequency to be the farthest from the fluctuation frequency of the disturbance light, a light quantity determination means for determining the quantity of the disturbance light detected by the disturbance light detection means, A first document size determination that determines the document size based on the light amount when the light amount determination unit determines that the amount of the disturbance light is smaller than a preset threshold value. When the light amount determination means determines that the amount of the disturbance light is equal to or greater than a preset threshold value, a second document size determination process for determining the document size based on the variation frequency is performed. It is characterized in that it comprises a document size determination means for performing.
Furthermore, the image forming apparatus of the present invention further includes a document feeding unit that sequentially feeds the documents placed on the document placing unit one by one, and the disturbance light detecting unit is placed on the document placing unit. An original sensor that detects the presence or absence of the placed original may be used.
Furthermore, in the image forming apparatus of the present invention, the driving unit drives the light source in either a first cycle or a second cycle, and the light source driving cycle setting unit is detected by the disturbance light detection unit. Based on the fluctuation frequency of disturbance light, the period of driving the light source by the driving means is set such that the fluctuation frequency of the light source is further away from the fluctuation frequency of the disturbance light. You may make it set to either of 2 periods.

  According to the present invention, the period of driving the light source by the driving unit is set so that the fluctuation frequency of the light source is farthest from the fluctuation frequency of the disturbance light, and the amount of disturbance light is less than a preset threshold value. If it is determined to be small, a first document size determination process for determining the document size based on the light amount is performed, and the light amount determination unit determines that the amount of disturbance light is greater than or equal to a preset threshold value. In this case, the second document size determination process for determining the document size based on the fluctuation frequency is performed, so that an appropriate document size detection can be performed according to the ambient light without manual setting. There is an effect that an operation can be selected and executed.

1 is a schematic cross-sectional view showing an internal configuration of an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of the image forming apparatus illustrated in FIG. 1. 5 is a flowchart for explaining a light source drive cycle determination operation in the embodiment of the image forming apparatus according to the present invention. 5 is a flowchart for explaining a document size determination operation in the embodiment of the image forming apparatus according to the present invention.

Next, embodiments of the present invention will be specifically described with reference to the drawings.
An image forming apparatus 1 according to the present embodiment is a copying machine. Referring to FIG. 1, a document reading unit 2, a document feeding unit 3, a body unit 4, a stack tray 5, and an operation unit 6 are provided. I have. The document reading unit 2 is disposed on the top of the main body unit 4, and the document feeding unit 3 is disposed on the top of the document reading unit 2. The stack tray 5 is disposed on the recording paper discharge port 41 side of the main body unit 4, and the operation unit 6 is disposed on the front side of the image forming apparatus 1. The document feeding unit 3 is configured to be retractable, and the upper surface of the document reading unit 2 can be opened by opening the document feeding unit 3 upward.

  The operation unit 6 is provided with a liquid crystal display unit 61 and operation buttons 62. The user operates the operation unit 6 to input instructions, thereby making various settings for the image forming apparatus 1 and executing various functions such as image formation. The liquid crystal display unit 61 displays the state of the image forming apparatus 1, displays the image forming status and the number of copies, and can be used as a touch panel to perform various settings such as functions such as double-sided printing and black / white reversal, magnification setting, and density setting It has become. The operation button 62 includes a start button for instructing the user to start image formation, a stop / clear button used for stopping image formation, and various settings of the image forming apparatus 1 used for default settings. A reset button, a numeric keypad and the like are provided.

The document reading unit 2 includes a scanner 21, a platen glass 22, a document reading slit 23, and an open / close sensor 24. The scanner 21 includes a light source 25 using an LED (Light Emitting Diode), a CCD (Charge Coupled Device) sensor as a light receiving unit, and the like, and is configured to be movable in the document conveyance direction by the document feeding unit 3. Lighting of the light source 25 is controlled by the drive circuit 26. The drive circuit 26 blinks the light source 25 at a predetermined cycle, for example, turns on the light source 25 by PWM control. In the drive circuit 26, the cycle of blinking the light source 25 can be set to one of two types of the first cycle T ₁ (s) and the second cycle T ₂ (s). Accordingly, the fluctuation frequency of the light source 25 is either the first fluctuation frequency 1 / T ₁ or the second fluctuation frequency 1 / T ₂ . The platen glass 22 is a document table which is made of a transparent member such as glass and is disposed on the upper surface of the document reading unit 2. The document feeder 3 functions as an upper cover that opens and closes the upper surface of the platen glass 22. By opening the document feeder 3 upward, the upper surface of the platen glass 22 is opened, and a document can be set on the platen glass 22. Become. The document reading slit 23 has a slit formed in a direction perpendicular to the document transport direction by the document feeder 3. The open / close sensor 24 is an upper cover open / close detection unit that detects opening / closing of the document feeding unit 3, and shifts from an open state in which the document feeding unit 3 is opened to a closed state in which the document feeding unit 3 is closed. In the process, the timing before the document feeder 3 is completely closed is detected.

  The document feeding unit 3 includes a document placing unit 31, a document discharge unit 32, a document transport mechanism 33, and a document sensor 34. The originals placed on the original placement unit 31 are sequentially fed out one by one by the original conveyance mechanism 33, conveyed to a position facing the original reading slit 23, and then discharged to the original discharge unit 32. The document sensor 34 has an opening on the document placement surface of the document placement unit 31, and is an optical device such as a photosensor that detects the presence or absence of the document placed on the document placement unit 31 based on the presence or absence of disturbance light. Sensor.

  When reading of the document is instructed by the operation button 62 of the operation unit 6 in a state where the document sensor 34 does not detect the document, the document placed on the platen glass 22 is read. When reading a document placed on the platen glass 22, the scanner 21 is moved to a position facing the platen glass 22 and reads the document while scanning the document placed on the platen glass 22 to obtain image data. The acquired image data is output to the main unit 4.

  When a document reading is instructed by the operation button 62 of the operation unit 6 with the document sensor 34 being detected, the document fed by the document feeding unit 3 is read. When reading the document conveyed by the document feeding unit 3, the scanner 21 is moved to a position facing the document reading slit 23, and the document feeding operation by the document feeding unit 3 is performed via the document reading slit 23. The document is read synchronously to acquire image data, and the acquired image data is output to the main unit 4.

  The main body unit 4 includes the recording unit 7, and includes a paper feeding unit 42, a paper conveyance path 43, a conveyance roller 44, and a discharge roller 45. The paper feed unit 42 includes a plurality of paper feed cassettes 42a1 to 42an and paper feed rollers 42b1 to 42bn that feed recording sheets from the paper feed cassettes 42a1 to 42an one by one to the paper transport path 43. The paper feed rollers 42b1 to 42bn, the transport roller 44, and the discharge roller 45 function as a transport unit, and the recording paper is transported. The recording paper fed to the paper transport path 43 by the paper feed rollers 42 b 1 to 42 bn is transported to the recording unit 7 by the transport roller 44. Then, the recording paper on which recording is performed by the recording unit 7 is discharged to the stack tray 5 by the discharge roller 45.

  The recording unit 7 includes a photosensitive drum 71, an exposure unit 72, an image forming unit 73, a transfer unit 74, and a fixing unit 75. The exposure unit 72 is an optical unit including a laser device, a mirror, and the like, and outputs a laser beam based on image data to expose the photosensitive drum 71 to form an electrostatic latent image on the surface of the photosensitive drum 71. To do. The image forming unit 73 is a developing unit that develops the electrostatic latent image formed on the photosensitive drum 71 using toner, and forms a toner image based on the electrostatic latent image on the photosensitive drum 71. The transfer unit 74 transfers the toner image formed on the photosensitive drum 71 by the image forming unit 44 to a recording sheet. The fixing unit 75 heats the recording paper on which the toner image is transferred by the transfer unit 74 to fix the toner image on the recording paper.

  FIG. 2 is a block diagram illustrating a schematic configuration of the image forming apparatus 1. The document reading unit 2, the document feeding unit 3, the transport unit (feed rollers 42 b 1 to 42 bn, the transport roller 44, the discharge roller 45), the operation unit 6, and the recording unit 7 are connected to the control unit 8. The operation is controlled by 8. The control unit 8 is connected to an image processing unit 9, a storage unit 10, an ambient light determination unit 11, and a size determination unit 12.

  The control unit 8 is an information processing unit such as a microcomputer including a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM stores a control program for controlling the operation of the image forming apparatus 1. The control unit 8 reads out a control program stored in the ROM and develops the control program in the RAM, thereby controlling the entire apparatus according to predetermined instruction information input from the operation unit 6.

  The image processing unit 9 is means for performing predetermined image processing on the image data. For example, image improvement processing such as enlargement / reduction processing, gradation adjustment, and density adjustment is performed.

  The storage unit 10 is a storage unit such as a semiconductor memory or an HDD (Hard Disk Drive). The storage unit 10 stores image data acquired by reading a document by the document reading unit 2, and stores various management information. Yes.

The disturbance light determination unit 11 is a disturbance light determination unit that determines the amount and fluctuation frequency of disturbance light received by the document sensor 34. The output from the document sensor 34 is at a level corresponding to the amount of disturbance light received, and changes according to the blinking (fluctuating frequency) of the disturbance. Therefore, the disturbance light determination unit 11 determines the amount of disturbance light based on the output from the document sensor 34, compares and determines the amount of disturbance light and a preset threshold value, and compares the determination result with the control unit 8. Output to. The disturbance light determination unit 11 detects the fluctuation frequency of the disturbance light based on the output from the document sensor 34, and the fluctuation frequency of the disturbance light is the current fluctuation frequency (1 / T ₁ or ₁ / T ₂ ) of the light source 25. The similarity determination result is output to the control unit 8.

  The size determination unit 12 analyzes the output from the document reading unit 2 (scanner 21) based on the amount of light (input level), and thereby the first document size determination process for determining the document size and the document reading unit 2 ( By analyzing the output from the scanner 21) based on the fluctuation frequency, one of the second document size determination processing for determining the document size is performed to determine the document size, and the determined document size is determined. Output to the control unit 8.

Next, the light source drive cycle determination operation in the image forming apparatus 1 of the present embodiment will be described in detail with reference to FIG.
Referring to FIG. 3, the control unit 8 instructs the disturbance light determination unit 11 to perform a variation frequency determination process for determining the variation frequency of the disturbance light at a predetermined timing. The disturbance light determination unit 11 instructed to perform the variation frequency determination process first determines whether disturbance light is received by the document sensor 34 based on the output from the document sensor 34 (step A1), and the disturbance light. Is not received, the control unit 8 is notified that execution is impossible, and the variation frequency determination process is terminated.

When disturbance light is received in step A1, the disturbance light determination unit 11 detects the fluctuation frequency of disturbance light based on the output from the document sensor 34 (step A2), and detects the fluctuation frequency of the detected disturbance light. Is similar to the current fluctuation frequency (1 / T ₁ or ₁ / T ₂ ) of the light source 25 (step A3). The similarity determination result is output to the control unit 8. In the similarity determination in step A3, it is determined which of the fluctuation frequencies 1 / T ₁ and 1 / T ₂ of the light source 25 is close to the fluctuation frequency of the detected disturbance light, and the fluctuation of the detected disturbance light is determined. When the frequency is a value close to the current fluctuation frequency (1 / T ₁ or ₁ / T ₂ ) of the light source 25, it is determined that they are similar.

If it is determined in step A3 that the images are similar, the control unit 8 instructs the drive circuit 26 of the document reading unit 2 to change the cycle for driving the light source 25, and ends the light source drive cycle determination operation. Thereby, the drive circuit 26 drives the light source 25 at the changed cycle until at least the next light source drive cycle determination operation is performed. For example, when the light source 25 is driven in the first period T ₁ (s) and the fluctuation frequency of the light source 25 is the first fluctuation frequency 1 / T ₁ , if it is determined that the light source 25 is similar in step A3, the light source 25 Is set to the second period T ₂ (s), and the fluctuation frequency of the light source 25 is changed to the second fluctuation frequency 1 / T ₂ . If it is determined in step A3 that they are not similar, the control unit 8 ends the light source drive cycle determination operation without changing the cycle for driving the light source 25.

  The timing for performing the light source drive cycle determination operation in steps A1 to A4 is arbitrary, but the fluctuation frequency of the light source 25 is further away from the fluctuation frequency of the disturbance light before reading the document placed on the platen glass 22. Therefore, the period for driving the light source 25 needs to be set so that the first time is desirably set when the image forming apparatus 1 is installed (at the time of initial setting or the like). Since the image forming apparatus 1 is basically used indoors, the fluctuation frequency of the disturbance light is in accordance with the illumination, and the fluctuation frequency of the disturbance light does not change unless the illumination of the place where it is installed is changed. . Therefore, the second and subsequent times can be performed at relatively long time intervals such as every other day or when the power is turned on.

In the present embodiment, the period for driving the light source 25 is two types of the first period T ₁ (s) and the second period T ₂ (s), but the first period T ₁ (s) and the second period It is desirable that the two periods T ₂ (s) are far apart. For example, the first period T ₁ (s) and the second period T ₂ (s) are set to have different numbers of digits. Furthermore, the period for driving the light source 25 may be set to three or more, and the period for driving the light source 25 may be set so that the fluctuation frequency of the light source 25 is farthest from the fluctuation frequency of the disturbance light.

  Next, the document size determination operation in the image forming apparatus 1 of the present embodiment will be described in detail with reference to FIG.

  Referring to FIG. 4, when the open / close sensor 24 detects a shift from the open state in which the document feeding unit 3 is opened to the closed state in which the document feeding unit 3 is closed (step B <b> 1), the control unit 8. Instructs the document reading unit 2 to read the platen glass 22, and instructs the disturbance light determination unit 11 to perform a light amount determination process for determining the fluctuation frequency of the disturbance light. The document reading unit 2 instructed to read drives the light source 25 at a cycle set by the drive circuit 26 and moves the scanner 21 to read the platen glass 22 (step B2).

  Next, the disturbance light determination unit 11 instructed to perform the light amount determination process first determines whether disturbance light is received by the document sensor 34 based on the output from the document sensor 34 (step B3). When disturbance light is not received in step B3, the disturbance light determination unit 11 notifies the control unit 8 of detection of the document, and the control unit 8 ends the document size determination operation.

  When disturbance light is received in step B3, the disturbance light determination unit 11 further determines the amount of disturbance light based on the output from the document sensor 34, and determines the amount of disturbance light and a preset threshold value. Is compared (step B4), and the comparison determination result is output to the control unit 8.

  When it is determined in step B4 that the amount of disturbance light is smaller than a preset threshold value, the control unit 8 instructs the size determination unit 12 to perform a first document size determination process based on the light amount, and the size determination unit. 12 executes a first document size determination process for determining the document size by analyzing the output from the document reading unit 2 (scanner 21) based on the light amount (input level) (step B5).

  If it is determined in step B4 that the amount of disturbance light is greater than or equal to a preset threshold value, the control unit 8 instructs the size determination unit 12 to perform a second document size determination process based on the variation frequency, and determines the size. The unit 12 analyzes the output from the document reading unit 2 (scanner 21) based on the fluctuation frequency, thereby executing a second document size determination process for determining the document size (step B6). In the second document size determination process, in the output from the document reading unit 2 (scanner 21), a document ant is detected at the same place as the fluctuation frequency of the light source 25, and the place different from the fluctuation frequency of the light source 25 is a document. The original size is determined as a pear. Thus, by canceling the frequency other than the fluctuation frequency of the light source 25 from the output from the document reading unit 2 (scanner 21), the document size can be accurately determined even when disturbance light is present.

  The document size determined in step B5 or step B6 is output to the control unit 8, and reading control, selection of paper to be printed, and the like are performed based on the determined document size.

  In the present embodiment, as the disturbance light detecting means for detecting the disturbance light, the document sensor 34 for detecting the presence / absence of the document placed on the document placement portion 31 is used, but a dedicated sensor for detecting the disturbance light is used. An optical sensor may be provided. The dedicated optical sensor is desirably disposed around the platen glass 22 or on the upper cover, and is desirably disposed at a location where disturbance of incident light is not prevented by the user.

  As described above, in the present embodiment, based on the fluctuation frequency of disturbance light detected by the document sensor 34, the control unit 8 sets the cycle of driving the light source 25 by the drive circuit 26 and sets the light source 25 to the fluctuation frequency. Is set so as to be farthest from the fluctuation frequency of disturbance light, and when the size determination unit 12 determines that the amount of disturbance light is smaller than a preset threshold value, A first document size determination process for determining the document size is instructed, and when it is determined that the amount of disturbance light is greater than or equal to a preset threshold, the document size is determined based on the variation frequency. The second document size determination process is instructed. As a result, an appropriate document size detection operation can be selected and executed according to the situation of disturbance light without performing manual setting. For example, when the amount of disturbance light is small, or when the fluctuation frequency of disturbance light is clearly different from that of the light source 25, there is no need to perform special processing, reducing unnecessary power consumption and improving processing speed. realizable.

  Further, in the image forming apparatus of the present invention, the document sensor 34 that detects disturbance light is an optical sensor that detects the presence or absence of a document placed on the document placement unit 31 of the document feeding unit 3. Thus, the cost can be reduced by using the existing sensor.

Further, in the image forming apparatus of the present invention, the driving circuit 26, the light source 25 is driven in either the first period T ₁ or second period T _2, the control unit 8 drives the light source 25 by the driving circuit 26 The period is configured to set the light source 25 to either the first period T ₁ or the second period T ₂ so that the fluctuation frequency is further away from the fluctuation frequency of the disturbance light. Thus, the operation | movement which sets the drive period of the light source 25 can be simplified by selecting the period which drives the light source 25 from two types.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a suitable number, position, shape, and the like in practicing the present invention. In each figure, the same numerals are given to the same component.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Original reading part 3 Original feeding part 4 Main body part 5 Stack tray 6 Operation part 7 Recording part 8 Control part 9 Image processing part 10 Memory | storage part 11 Disturbance light determination part 12 Size determination part 21 Scanner 22 Platen glass 23 Document reading slit 24 Open / close sensor 25 Light source 26 Drive circuit 31 Document placement unit 32 Document discharge unit 33 Document transport mechanism 34 Document sensor 41 Discharge port 42 Paper feed unit 42a1-42an Paper feed cassette 42b1-42bn Paper feed roller 43 Paper transport path 44 Conveying roller 45 Ejecting roller 61 Liquid crystal display unit 62 Operation button 71 Photosensitive drum 72 Exposure unit 73 Image forming unit 74 Transfer unit 75 Fixing unit

Claims (3)

An image forming apparatus that reads a document placed on a platen glass using a light source that blinks at a predetermined cycle and determines a document size,
Driving means for driving the light source at a plurality of cycles;
Disturbance light detecting means for detecting disturbance light,
Based on the fluctuation frequency of the disturbance light detected by the disturbance light detection means, the period of driving the light source by the driving means is set so that the fluctuation frequency of the light source is farthest from the fluctuation frequency of the disturbance light. A light source drive cycle setting means for setting
A light amount determination means for determining the amount of the disturbance light detected by the disturbance light detection means;
When it is determined by the light amount determination means that the amount of disturbance light is smaller than a preset threshold value, a first document size determination process is performed to determine the document size based on the light amount, and the light amount determination A document size determination unit that performs a second document size determination process for determining a document size based on the fluctuating frequency when it is determined by the means that the amount of disturbance light is equal to or greater than a preset threshold value. An image forming apparatus characterized by comprising. A document feeding unit that sequentially feeds the documents placed on the document placing unit one by one;
The image forming apparatus according to claim 1, wherein the disturbance light detection unit is a document sensor that detects the presence or absence of the document placed on the document placement unit. The driving means drives the light source in either the first period or the second period,
The light source drive period setting means sets the period of driving the light source by the drive means based on the fluctuation frequency of the disturbance light detected by the disturbance light detection means, and the fluctuation frequency of the light source changes the fluctuation of the disturbance light. 3. The image forming apparatus according to claim 1, wherein the first period or the second period is set so as to be farther from the frequency. 4.

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