JP2006044101A - Image forming apparatus and method for detecting right/left end position of image forming medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can correctly detect right/left end positions of an image forming medium by a reflection type optical image sensor even for the image forming medium with an image of a fringe, background or the like formed thereon, or the image forming medium of a material susceptible to offset, and to provide a method for detecting right/left end positions of an image forming medium. <P>SOLUTION: The medium 17 transferred by a belt platen advances from a tip 17a in a transfer direction Y. A detection output by a left side image sensor 28h (right side is omitted from the illustration) is A/D converted to be an A/D value and is transmitted to a medium right left end position detecting part 7. The medium right/left end position detecting part 7 compares the A/D value with a threshold (a) sequentially from a detecting element of the outmost side to a detecting element of the inner side, and determines a detected element position which first outputs the A/D value of not larger than the threshold (a) as the left (or right) end position of the medium 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus and an image processing method that always detect the right and left end positions of an image forming medium correctly.

  2. Description of the Related Art Conventionally, in an image forming apparatus, when an image forming medium is fed from an image forming medium supply unit such as a cassette or a tray to the image forming unit by, for example, a conveying belt, the fed image forming medium is conveyed in the conveying direction (sub-scanning direction). ) May be displaced in a direction orthogonal to the main scanning direction (main scanning direction). Then, an image shifted in the main scanning direction is formed on the image forming medium.

Therefore, a sensor composed of, for example, an image sensor or a line sensor for detecting the left and right end portions of the image forming medium is provided on the upstream side in the transport direction from the image forming unit, and a position shift in the main scanning direction is detected, and the detection result Based on the above, a method for correcting the writing position of image data on the image forming medium has been proposed. (For example, refer to Patent Document 1.)
In general, when the left and right end positions of an image forming medium conveyed from the image forming medium supply unit to the image forming unit are detected by a light receiving element such as an image sensor or a line sensor, the image forming medium and the image forming medium are The end position of the image forming medium is determined based on the level difference of the reflected light from the supporting member (for example, the conveyor belt). Therefore, when a reflection type light receiving element is used, the difference in output level of the light receiving element due to the reflected light is further increased by making the conveyor belt black when the image forming medium is white. be able to.
Japanese Patent Laying-Open No. 2003-223088 ([Summary], FIG. 1)

  However, when an image such as a border pattern or a background pattern is formed on the image forming medium, the output level of the light receiving element changes depending on the image or the like, and the change point is mistaken for the edge of the image forming medium. May be recognized.

  Further, in the case of forming the second side image after the first side in the double-sided image formation, if the image forming medium on which the image formation on the first side can be seen through is made of a material that tends to show through, the show-through The same erroneous detection may occur even when the first surface image is formed.

  Then, the image mask position for the image data to be formed on the image forming medium is set based on the erroneous detection, and the image data is sequentially read out based on the set image mask position and transmitted to the image forming unit. Then, image formation is executed. For this reason, there arises a problem that an image is not formed at a correct position on the image forming medium. And the solution about such a malfunction is not disclosed by patent document 1. FIG.

  In view of the above-described conventional situation, the object of the present invention is to accurately position the left and right end portions of an image forming medium even when an image or the like is formed on the image forming medium or when the image forming medium is a material that tends to show through. It is an object to provide an image forming apparatus capable of detecting and a method for detecting positions of left and right end portions of an image forming medium.

  First, an image forming apparatus according to a first aspect of the present invention is provided with a transport mechanism that transports an image forming medium supplied from a supply unit to an image forming unit, and an upstream side in the transport direction of the image forming unit. A position information detection unit that detects position information of at least one end position candidate in the left-right direction of the image forming medium by reflected light in a direction orthogonal to the conveyance direction of the image forming medium, and a position information detection unit that detects the position information A left / right position detection unit for detecting left / right end position information of the image forming medium from the at least one position information, and left / right end position information of the image forming medium detected by the left / right position detection unit. An image forming range generating unit that generates image forming range information for the image forming medium based on the image forming range information generated by the image forming range generating unit. Configured to perform image formation based.

  The left and right position detection unit, for example, sees the position information from the outer side of the left and right side edges of the image forming medium to the inner side, and detects the first position information as the left and right edge position information of the image forming medium. Configured to do.

  The image forming apparatus further includes, for example, a memory that stores the position information detected by the position detection unit in order. In this case, for example, the left and right position detection unit sequentially reads the position information stored in the memory from the inside of the left and right side edges of the image forming medium in the outward direction, and obtains the last position information. You may comprise so that it may detect as the right-and-left edge part position information of the said image forming medium.

  Next, an image forming medium left and right end position detecting method according to a second aspect of the invention includes a conveying mechanism that conveys an image forming medium supplied from a supply unit to the image forming unit, and an upstream side in the conveying direction from the image forming unit. A position information detection unit that detects position information of at least one end position candidate in the left-right direction of the image forming medium by reflected light in a direction perpendicular to the conveying direction of the image forming medium being conveyed; A left and right position detection unit that detects left and right end position information of the image forming medium from at least one or more of the position information detected by the position information detection unit, and the left and right position detection unit includes the position information When the information is viewed inward from the outside of the left and right side edges of the image forming medium, the first position information is detected as left and right edge position information of the image forming medium.

  According to the present invention, the change of the output data detected by the light receiving element of the image sensor is sequentially confirmed from the outer side to the inner side of the image forming medium, and the position where the level of the output data changes first on the left and right sides is determined at the left and right ends of the medium. Since the position data is used, the positions of the left and right edges of the image forming medium are accurately detected even when an image such as a border decoration or background is formed on the image forming medium, or even when the image forming medium is a material that tends to show through. be able to.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, for the sake of simplicity, “printing” is used synonymously with “image formation”, and “image forming medium” may be simply referred to as “medium”. Further, “paper” is used synonymously with “image forming medium” or “medium”. Also, the medium conveyance direction is defined as the Y direction or the sub-scanning direction, and the direction orthogonal to the conveyance direction is defined as the X-axis direction or the main scanning direction.

FIG. 1 is a configuration block diagram of an image forming apparatus equipped with a medium left and right edge detection system according to a first embodiment of the present invention.
As shown in FIG. 1, the medium left and right edge detection system 1 includes a control unit 2, a transport mechanism unit 3, and an image formation range generation unit 4. The control unit 2 includes a formation control unit 5, a storage unit 6, and a medium left and right end position detection unit 7. In addition to image data input from the image data memory 8, the control unit 2 includes a medium front end detection unit. 9 and a medium edge detection result from the medium left and right edge reader 11. Further, an ink head unit 13 is connected to the control unit 2 via a head driving unit 12.

  The transport mechanism 7 includes a transport distance detection unit 14. Although not shown, the transport mechanism 7 includes a platen belt mechanism that serves as both a medium transport and a platen during image formation, and is supplied from a medium supply unit (not shown) under the control of the control unit 2 by the platen belt mechanism. Transport the media. In addition, an encoder or the like is attached to the drive unit of the platen belt mechanism, for example, and the transport distance detection unit 14 of the transport mechanism 7 detects the number of rotation pulses of the encoder, and the detected number of encoder rotation pulses is stored in the medium. It outputs to the control part 2 as information of a conveyance amount (movement amount).

  The medium front end detection unit 9 is configured by, for example, a transmissive or reflective optical sensor, a capacitive sensor, or the like. The medium leading edge detection unit 9 is provided downstream of the medium supply unit in the medium conveyance direction, detects the leading edge of the medium supplied to the conveyance mechanism 7, and outputs the detection information to the control unit 2.

  Further, the medium left and right edge reading unit 11 is constituted by, for example, a line sensor or an image sensor provided with a CCD (charge coupled device) as a detection element in an array shape. The medium left and right edge reading unit 11 is provided on the downstream side in the medium conveyance direction with respect to the medium leading edge detection unit 9 and on the upstream side in the medium conveyance direction with respect to the image forming unit on which the ink head unit 13 is disposed. An end in the width direction (that is, the main scanning direction) is detected, and the detection information is output to the control unit 2. The detection information of the medium left and right edge reading unit 11 input to the control unit 2 is held in the storage unit 6.

  The medium left and right edge position detection unit 7 of the control unit 2 uses the medium edge reading information obtained by the medium left and right edge reading unit 11 to detect the exact left and right edges of the medium based on a predetermined procedure. This will be described in detail later.

  The image forming range generation unit 4 includes a parameter memory 15 and a nozzle address extraction unit 16. The parameter memory 15 stores mechanical correction values of the respective parts of the image forming apparatus, that is, manufacturing errors of each component such as a dimensional error in the finished product, assembly errors of components generated in the manufacture of the apparatus, that is, machine differences that are different for each apparatus. On the other hand, ink liquid reference ejection timing information of each ink head of the ink head unit 13 when the medium is transported is stored in advance. This ink liquid reference ejection timing information is the number of encoder rotation pulses from the transport distance detection unit 14 that uses the medium leading edge detection signal from the medium leading edge detection unit 9 as a trigger.

  The image forming range generation unit 4 extracts the shape of the medium, that is, the non-image forming position based on the detection information of the left and right ends of the medium held in the storage unit 6 of the control unit 2. Based on this extraction result, the nozzle address extraction unit 16 extracts the nozzle address (nozzle number) of the ink ejection nozzle that is not used for image formation for each ink head of the ink head unit 13, that is, does not eject ink droplets. Thereby, the image forming range on the medium is defined.

  The image forming range generation unit 4 sets the ink liquid jetting timing in the parameter memory 15 together with the information on the generated image forming range on the medium (nozzle address information of the ink ejecting nozzle that does not eject ink droplets). By reading the timing information, the timing is switched and notified to the control unit 2.

  The control unit 2 controls the entire system and controls the image formation range on the medium by the formation control unit 5 according to the image formation range determined by the nozzle address extracted by the nozzle address extraction unit 16. The ink head unit 13 is driven via the head driving unit 12.

  Although not particularly shown, the ink head unit 13 is a line head configured by arranging a plurality of ink heads in the main scanning direction of the medium so that part of the end portions overlap so that the ink ejection position is not interrupted. As a whole, the number of ink ejection nozzles corresponding to the nozzle address (= nozzle number) is provided, and ink droplets are selected from the ink ejection nozzles selected under the drive control from the formation control unit 5 of the control unit 2. To form an image.

  FIG. 2 is a diagram illustrating an arrangement example of components constituting the medium transport mechanism unit 3 and the medium left and right end detection system. In the example shown in this figure, for convenience of explanation, only one ink head portion 13 is shown, but the present invention is not limited to this.

  Normally, assuming that a single color image is formed by a single ink head unit, at least three subtractive color primary colors, cyan, magenta, and yellow, are ejected to form a color image. Three ink head portions are required. Furthermore, if the ink head unit is for ejecting black ink dedicated to the dark part of the image or characters, or is configured to use inks such as light magenta and light cyan of intermediate colors to obtain high gradation, the ink head part is There are 6 in total.

  As shown in FIG. 2, in the arrangement example of the constituent elements of this example, first, from the left side of the figure, a medium supply cassette 18 that accommodates a large number of media 17 and the media 17 from the medium supply cassette 18 one by one in order. The supply roller 19 to be taken out, temporarily stops rotation and temporarily stops and bends the advance of the medium 17 fed from the supply roller 19 to correct the inclination of the medium 17 and wait for the feeding timing. A stop standby roller pair 21 that feeds the medium 17 to the transport mechanism unit 3 according to the feeding timing, and a transport mechanism unit 3 that takes over the transport of the medium 17 fed from the stop standby roller pair 21 are arranged.

  The transport mechanism unit 3 includes a driving roller 22 and a driven roller 23, a platen belt 24 formed of an endless belt that is stretched flatly between the driving roller 22 and the driven roller 23, and a rotation shaft of the driving roller 22. And an encoder sensor 26 for detecting a rotation pulse of the encoder 25. The encoder 25 and the encoder sensor 26 constitute the conveyance distance detection unit 14 of the conveyance mechanism unit 3 shown in FIG.

  In FIG. 2, a medium front end detection unit that detects the leading edge 17 a and the trailing edge 17 b of the medium 17 immediately after passing through the standby roller pair 21 is located above the most upstream side in the medium transport direction of the transport mechanism unit 3. 9, an edge sensor 27 is provided. The edge sensor 27 is an optical transmission type sensor in this example. Thereby, the edge sensor 27 detects light shielding by the medium 17.

  Between the edge sensor 27 and the ink head unit 13 disposed on the downstream side in the medium conveyance direction, the left and right ends of the medium that detect the end of the medium 17 in the width direction (left and right direction, main scanning direction). An image sensor 28 serving as the reading unit 11 and an illumination unit 29 that illuminates the lower part of the image sensor 28, that is, the detected part are arranged.

  The image sensor 28 is provided to detect a so-called edge based on a difference in contrast between the medium 17 and the platen belt 24. For this reason, for example, if the medium 17 is white, the platen belt 24 is preferably a dark color such as black, that is, a color in which a difference in contrast tends to occur with respect to the color of the medium 17.

The illumination unit 29 is an illumination device in which a large number of LEDs (light emitting diodes) are arranged in an array, for example.
FIG. 3 is a plan view showing the positional relationship between the medium 17 and the image sensor 28 (28h, 28m) on the platen belt 24 described above. In the figure, the same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG. 2 in other components. Further, the illustration of the edge sensor 27 and the illumination unit 29 arranged in the vicinity of the image sensor 28 is omitted.

  As shown in FIG. 3, the image sensor 28 includes two image sensors, a left image sensor 28 h and a right image sensor 28 m, arranged in series in the main scanning direction of the medium 17. Each of the left image sensor 28h and the right image sensor 28m includes 2001 detection elements (CCD elements) having addresses from 0 to 2000 from the left end to the right end in the drawing. In other words, the image sensor 28 includes a total of 4002 detection elements.

  FIG. 4 is a plan view showing a part of the surface of the platen belt 24 described above in the transport mechanism unit 3. As shown in the figure, a large number of holes 31 are formed on the surface of the platen plate 7. Further, in the transport mechanism unit 3 of this example, although not shown in FIG. 2, a suction fan is disposed inside the loop shape of the platen belt 24, and on the platen belt 24 through the holes 31. The medium 17 is sucked and the medium 17 is sucked and fixed on the platen belt 24. Therefore, on the platen belt 24, the medium 17 is not moved or displaced.

Next, detection of the left and right end position of the medium 17 by the medium left and right end position detecting unit 7 will be described.
FIG. 5A is a diagram illustrating a state in which the position of the vicinity of the left end portion of the medium 17 is being detected by the left image sensor 28h described above. FIGS. 5B and 5C are diagrams illustrating the position detection described above. It is a figure which shows the example of the detected value of the position of the left end part vicinity of the medium 17 converted from the analog electric signal into the digital electric signal as a result. The detection of the vicinity of the right end portion position of the medium 17 by the right image sensor 28m can be easily explained by inverting the left and right of the same figure (a), (b), (c).

  5B and 5C, the horizontal axis indicates the 2001 detection element positions of the left image sensor 28h, and the vertical axis indicates the digitized output value of each detection element. In this example, an output value higher than a preset threshold value a is an output value for medium non-detection, and an output value lower than the threshold value a is an output value for medium detection. Note that the threshold determination method may be a predetermined fixed value or a known method such as averaging the maximum value and the minimum value of A / D conversion data.

  FIG. 5B shows the detected value near the left end when the medium 17 is a plain white sheet. In this example, the digital output value of the detection element at the position n1 is equal to or less than the threshold value a, and the digital outputs of the detection elements at positions inside it are all equal to or less than the threshold value a. That is, the output value of the entire left image sensor 28h indicates one edge at the position n1.

  On the other hand, FIG. 7C shows a material in which the image formation on the first surface is easy to show through when the medium 17 is formed with some image such as a border pattern or a background pattern, or in double-sided image formation. The detected value near the left end in the case of In this example, in the output value of the entire left image sensor 28h, three edges appear at positions n1, n2, and n3 as edges that are equal to or less than the threshold value a. That is, there are three candidate data indicating the edge position of the medium. Actually, the edge of the position n1 is the position of the side edge portion of the medium 17, and the edges of the position n2 and the position n3 are edges obtained by reading a border pattern, a background pattern, or an image formation of the show-through first surface. Such a detection state causes the above-described misrecognition of the left and right end positions of the medium.

In the present invention, the right and left end positions of the medium 17 are accurately detected by the same detection method in both cases of FIGS. 5B and 5C.
FIG. 6 is a flowchart that will be described with reference to FIGS. 1 to 3 and 5 again even when an image or the like is formed on the image forming medium as described above, or even when the image forming medium is a material that easily shows through. It is.

  Hereinafter, referring again to FIGS. 1 to 3 and 5, based on the flowchart shown in FIG. 6, processing and image data for accurately detecting the right and left end positions of the medium 17 in the image forming apparatus configured as described above. The flow of image formation by the will be described.

  First, the image forming apparatus of this example in which the components constituting the medium left and right edge detection system 1 shown in FIG. 1 are arranged and mounted as shown in FIG. When the material, the number of sheets, the print mode, and other designations of 17) are input from the operation panel (not shown) as a key input or a signal from a host device (not shown) connected, the control unit 2 executes printing (image formation). To start.

  The supply roller 19 takes out one uppermost medium 17 accommodated in the medium supply cassette 18 every rotation and feeds it to the stop standby roller pair 21. The stopping standby roller pair 21 temporarily stops rotation to temporarily stop the progress of the medium 17, corrects the skew of the medium 17 in the main scanning direction, waits for the conveyance timing, and when the image formation timing comes, the conveyance mechanism unit 3. The conveyance of the medium 17 is started.

  Therefore, the edge edge 17 a of the medium 17 is detected by the edge sensor 27. When the detection signal (trigger signal) of the edge sensor 27 is received by the control unit 2, the control unit 2 turns on the illumination unit 29 in order to detect the left and right edge positions of the medium by the image sensor 28 (step S61). ).

In this example, as described above, the lighting unit 29 is turned on only when necessary, thereby preventing unnecessary lighting of the lighting unit 29, thereby extending the life of the lighting unit 29.
Subsequently, the control unit 2 sets a threshold value in the medium left and right end position detection unit 7 (step S62). As a result, the threshold value a shown in FIGS. 5B and 5C is set in the medium left and right edge position detection unit 7.

  Following the above, the medium 17 is transferred to the platen belt 24, and the medium 17 passes under the image sensor 28. At this time, the image sensor 28 reads the reflected light from the medium 17 or the platen belt 24 by a total of 4002 detection elements and outputs it as an analog electric signal (step S63).

  This analog electrical signal is converted into A by a not-shown A / D (analog / digital) converter connected between the medium left and right edge reading unit 11 (image sensor 28 (28h, 28m)) and the control unit 2. / D converted and input to the controller 2 as a digital electrical signal (step S64).

  The medium edge position detection by the medium left and right edge position detection unit 7 based on a detection output value (hereinafter referred to as A / D value) converted into a digital signal from the analog output value by the image sensor 28 input to the control unit 2. Is started (step S65).

  First, the medium left and right edge position detection unit 7 compares whether or not the A / D value is larger than the threshold value a, one by one from the detection element at the outer position of the medium 17 to the detection element at the inner position (step). S66).

  In this process, in the case of the output from the left image sensor 28h, the A / D value is compared with the threshold value a from the detection element at the address “0” to the detection element at the address “2000”. In the case of the right image sensor 28m, the A / D value is compared with the threshold value a from the detection element at the address “2000” to the detection element at the address “0”.

  When the A / D value is larger than the threshold value a (YES in S66), the comparison between the A / D value of the detection element at the next address and the threshold value a is similarly performed in the process of step S66. repeat.

  When there is an A / D value that is equal to or smaller than the threshold value a (NO in S66), the medium left and right end position detection unit 7 detects the position corresponding to the address of the detection element that outputs the A / D value. Is the detected value of the left (or right) end position of the medium 17, and this detected value (position data of the medium end position) is synchronized with the detection signal of the encoder pulse of the transport distance detecting unit 14. The data is sequentially stored in the storage unit 6 (step S67).

  Thus, in the medium left and right edge detection system of this example, the A / D value of the detection element and the threshold value a are compared from the outermost side to the inner side of each detection element of the image sensor 28 (28h, 28m). First, the detection element position that outputs the A / D value that is equal to or less than the threshold value a is detected as the medium edge position. By suspending the detection processing for the same line at the time of detection, extra processing can be omitted.

  As a result, as a matter of course in the case of FIG. 5 (b), even when a detection output value as shown in FIG. Can be detected.

  Thereafter, immediately before the leading edge 17a of the medium 17 reaches below the ink head unit 13, the control unit 2 sets a position data group indicating the left and right end positions of the medium 17 stored in the storage unit 6 as a nozzle address. It transmits to the extraction part 16. The nozzle address extraction unit 16 reads each ink liquid ejection timing in the ink head unit 13 from the parameter memory 15 and adds it to the above position data group as image formation range information, and controls the information on the image formation range. Send to part 2.

  In the control unit 2, information on the image formation range input from the nozzle address extraction unit 16 is transferred to the formation control unit 5. At this time, the image data stored in the image data memory 8 of the image forming apparatus is read by the control unit 2 to the formation control unit 5.

  In the image formation based on the image data, the formation control unit 5 performs ink from the ink ejection nozzle of the nozzle address corresponding to each nozzle address of the ink head unit 13 that falls outside the image formation range based on information on the image formation range. Processing that does not eject liquid (also referred to as image mask setting processing or white data processing) is performed.

  After this processing, the formation control unit 5 drives and controls the ink head unit 13 via the head driving unit 12. As a result, ink droplets based on the information on the image forming range are ejected from the ink head unit 13, and an image in which the image forming range is accurately recognized is formed on the medium 17.

  In the first embodiment, the positions of the left and right end portions of the medium 17 are detected using only the information acquired by the image sensor 28 (28h, 28m). The left and right end positions of 17 can be detected.

  In this case, for example, the right and left ends of the medium 17 conveyed by the platen belt 24 based on the position information of a sheet guide (not shown) of the medium supply cassette 18 shown in FIG. The part position is calculated.

  Then, the information acquired by the image sensor 28 (28h, 28m) is A / D converted, and one or a plurality of media left and right edge position candidates are calculated based on the data after A / D conversion and the threshold value. When calculating, the medium end position detection processing may be performed from the outside to the inside of the medium 17 as in the first embodiment, or conversely, the medium end position from the inside to the outside of the medium. The detection process may be performed.

  Then, the difference between the right and left edge position of the medium and the right and left edge position of the medium should be taken, and the candidate of the right and left edge position of the medium having the smallest difference is set as the normal right and left edge position. If the difference between the right and left edge position of the medium and the right and left edge position of the medium should not be within the predetermined range, the right and left edge position of the medium should be the normal medium right and left edge position. Alternatively, processing such as stopping the image forming process as a medium left and right edge position detection error may be performed.

  Although several embodiments have been specifically described above with reference to the drawings, the present invention is not limited to the above-described embodiments, and all the embodiments performed without departing from the scope of the present invention. Includes form.

1 is a configuration block diagram of an image forming apparatus equipped with a medium left and right edge detection system according to a first embodiment of the present invention. It is a figure which shows the example of arrangement | positioning of the component which comprises a medium conveyance mechanism and a medium right-and-left edge part detection system. It is a top view which shows the arrangement | positioning relationship between the medium and image sensor on a platen belt. It is a top view which cuts out and shows a part of surface of the platen belt of a conveyance mechanism. (a) is a diagram showing a state in which a position near the left end position of the medium is being detected by the left image sensor, and (b) and (c) are diagrams showing examples of detected values as position detection results. 10 is a flowchart for explaining processing for accurately detecting the left and right end positions of an image forming medium even when an image or the like is formed on the image forming medium or when the image forming medium is a material that tends to show through.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Medium left-right edge detection system 2 Control part 3 Conveyance mechanism part 4 Image formation range production | generation part 5 Formation control part 6 Storage part 7 Medium left-right edge part position detection part 8 Image data memory 9 Medium front-end | tip detection part (photo sensor)
11 Media left and right edge reading unit (image sensor)
DESCRIPTION OF SYMBOLS 12 Head drive part 13 Ink head part 14 Conveyance distance detection part 15 Parameter memory 16 Nozzle address extraction part 17 Medium 17a Front end edge 17b Rear end edge 18 Medium supply cassette 19 Supply roller 21 Stopping standby roller pair 22 Drive roller 23 Driven roller 24 Platen belt 25 Encoder 26 Encoder sensor 27 Edge sensor 28 (28h, 28m) Image sensor 29 Illuminating section 31 Hole

Claims (5)

A transport mechanism for transporting the image forming medium supplied from the supply unit to the image forming unit;
At least one or more end position candidates in the left-right direction of the image forming medium are provided on the upstream side of the image forming unit in the transport direction and reflected light in a direction orthogonal to the transport direction of the image forming medium being transported A position information detector for detecting position information;
A left and right position detection unit that detects left and right end position information of the image forming medium from at least one of the position information detected by the position information detection unit;
An image forming range generating unit that generates image forming range information for the image forming medium based on left and right end position information of the image forming medium detected by the left and right position detecting unit;
With
The image forming unit executes image formation based on the image forming range information generated by the image forming range generating unit;
An image forming apparatus.   The left and right position detection unit detects the position information as the left and right end part position information of the image forming medium when the position information is viewed from the outside of the left and right side end parts of the image forming medium to the inside direction; The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 1, further comprising a memory for storing the position information detected by the position detection unit in order.   The left and right position detection unit sequentially reads the position information stored in the memory from the inner side to the outer side of each of the left and right side edges of the image forming medium, and each of the last position information of the image forming medium. The image forming apparatus according to claim 3, wherein the image forming apparatus is detected as left and right end position information. A transport mechanism for transporting the image forming medium supplied from the supply unit to the image forming unit;
At least one or more end position candidates in the left-right direction of the image forming medium are provided on the upstream side of the image forming unit in the transport direction and reflected light in a direction orthogonal to the transport direction of the image forming medium being transported A position information detector for detecting position information;
A left and right position detection unit that detects left and right end position information of the image forming medium from at least one of the position information detected by the position information detection unit;
With
The left and right position detection unit detects the position information as the left and right end part position information of the image forming medium when the position information is viewed from the outside of the left and right side end parts of the image forming medium to the inside direction; A method for detecting the left and right end positions of an image forming medium.

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