JP2007065421A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform high quality image formation even when an image has many horizontal lines. <P>SOLUTION: Horizontal lines and vertical lines in original document image information 21 stored in an image storage means 22 are compared with each other by a line detection and discrimination means 23, and image forming operation is executed by using converted image information resulting from rotating the original document image information 21 by about 90° by an image conversion means 24 in the case that it is detected that the number of horizontal lines is larger, whereby an image is so formed that the quantity of vertical lines is always larger than the quantity of horizontal lines in an output image. Thus even the image having many horizontal lines is obtained with a high quality by satisfactorily suppressing occurrence of conventional fixing explosion, trailing phenomenon, or shadow. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus configured to output an image to a recording medium based on document image information stored in an image information storage unit.

  In general, in various image forming apparatuses such as an electrophotographic copying machine and a printer, document image information stored in an image information storage unit is sent to an image recording unit and sent from a sheet feeding unit by a sheet feeding control unit. The recording medium is sent to the image recording means, and an image based on the original image information is output to the recording medium.

  However, in such a general image forming apparatus, due to the mechanical structure of the apparatus, when a straight line such as a ruled line is formed, the direction perpendicular to the rotation axis of the photosensitive drum, which is the sub-scanning direction, is used. There may be a difference in the output image between the “vertical line” extending in the horizontal direction and the “horizontal line” extending in the direction parallel to the rotational axis of the photosensitive drum, which is the main scanning direction (for example, Patent Document 1). That is, in the case of the “horizontal line”, since the image is formed in a direction substantially orthogonal to the rotation direction of the photosensitive drum, the rear end side in the line width direction that is the rotation direction of the photosensitive drum is likely to be affected. As a result, a defective image such as a “tail image” in which toner is scattered on the rear end side in the line width direction may be invited.

  In addition, even when passing through the transfer device, the toner on the photosensitive drum floats and scatters on the recording medium when the recording medium is exposed to the transfer discharge charge before it contacts the transfer roller, and the scattered toner May adhere to the rear end side in the line width direction of the “horizontal line”, resulting in an image like a “shadow”.

  Furthermore, in an image in which a plurality of “horizontal lines” are continuous, the water vapor existing between the toner bands on the recording medium forming the respective “horizontal lines” is recorded. When the medium passes through the fixing device, the medium expands, and the expansion of the water vapor may cause a so-called “fixing explosion or tailing phenomenon” in which the toner band is scattered downstream. Thus, an image with many “horizontal lines” is a hindrance in improving image quality.

JP 2002-103679 A

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of forming a high-quality image even for a biased image having many “horizontal lines”.

  In order to achieve the above object, in an image forming apparatus according to a first aspect of the present invention, an image information storage unit for storing document image information and a recording medium based on the document image information stored in the image information storage unit are provided. An image recording means for outputting an image; and a plurality of recording medium stacking sections for holding the recording medium in different states rotated approximately 90 degrees in length and breadth, from any of the recording medium stacking sections to the image recording means In an image forming apparatus comprising a sheet feeding unit that feeds a recording medium and a sheet feeding control unit that controls a feeding operation of the recording medium in the sheet feeding unit, the document image information stored in the image information storage unit is vertically and horizontally An image converting means for generating converted image information in a state rotated approximately 90 degrees, and a horizontal direction extending in the main scanning direction in the original document image information stored in the image information storing means. Is compared with the amount of vertical lines extending in the sub-scanning direction, and the image information having the larger amount of vertical lines is selected from the original image information and the converted image information, and the image recording means is selected. A line detection determination unit for sending out, and the line detection determination unit selects a recording medium stacking unit that holds a recording medium corresponding to the selected image information and causes the paper supply control unit to perform a paper supply operation. It is configured as follows.

  According to the image forming apparatus of the first aspect having such a configuration, the line detection determination unit detects that the “horizontal line” in the original document image information stored in the image recording unit is larger than the “vertical line”. Then, the converted image information obtained by rotating the original document image information vertically and horizontally by approximately 90 degrees in the image converting means is sent from the line detection determining means to the image recording means, and a recording medium corresponding to the converted image information is loaded. The sheet feeding operation from the recording medium stacking unit is performed by the sheet feeding control unit, and the image recording unit performs the image forming operation so that the amount of “vertical line” is always larger than the amount of “horizontal line”. It has come to be.

  More preferably, as in the image forming apparatus according to claim 2, when the line detection determination unit in claim 1 detects that the environmental condition is high humidity by the humidity detection unit, the supply of claim 1 The line detection discriminating means according to claim 1 is configured to execute a paper control operation or as claimed in claim 3 based on the value of the image density detected by the image density detecting means. The configuration is such that execution / non-execution of the paper feed control operation according to item 1 is determined.

Furthermore, in the image forming apparatus according to a fourth aspect, the paper feed control unit according to the first aspect can select a user to adopt the converted image information when the converted image information is adopted by the line detection determination unit. It is comprised so that.
According to the image forming apparatus of the fourth aspect having such a configuration, whether or not to adopt the converted image information rotated by approximately 90 degrees is determined by the user's intention.

Further, the image forming apparatus according to claim 5 is provided with a paper discharge control means for aligning the direction of the recording medium to be discharged when the converted image information is adopted by the line detection determining means according to claim 1. ing.
According to the image forming apparatus according to claim 5 having such a configuration, the orientation of the finally ejected recording medium is aligned even when the converted image information rotated approximately 90 degrees is employed. To be made.

According to a sixth aspect of the present invention, there is provided a display unit for displaying that the converted image information is adopted when the converted image information is adopted by the line detection determining means in the first aspect. .
According to the image forming apparatus of the sixth aspect having such a configuration, the state of image formation using the converted image information rotated by approximately 90 degrees is immediately confirmed by the user.

  As described above, in the image forming apparatus according to the first aspect of the present invention, the “horizontal line” and the “vertical line” in the original document image information stored in the image recording unit are compared by the line detection determination unit. In the case where it is detected that there are more “horizontal lines” than “”, the final image is formed by using the converted image information obtained by rotating the original document image information vertically and horizontally by approximately 90 degrees by the image conversion means. Since the image is formed so that the amount of “vertical lines” in the output image is always larger than the amount of “horizontal lines”, even an image with many “horizontal lines” The occurrence of the “fixing explosion or tailing phenomenon” and “shadow” can be suppressed satisfactorily to obtain a high quality image, and the reliability of the image forming apparatus can be improved.

  At this time, the image forming apparatus according to claim 2 performs the sheet feeding control operation according to claim 1 when the humidity detecting means detects that the environment is a high humidity environment in which “fixing explosion or tailing phenomenon” is likely to occur. By performing the setting so that the recording medium is not sent in the vertical direction as much as possible, an efficient image forming operation can be maintained without causing unnecessary throughput reduction.

  The image forming apparatus according to claim 3 performs the sheet feeding control operation according to claim 1 when the image density detecting unit detects that the image is a high density image in which “fixing explosion or tailing phenomenon” is likely to occur. By performing the setting so that the recording medium is not sent in the vertical direction as much as possible, an efficient image forming operation can be maintained without causing unnecessary throughput reduction.

  Further, according to a fourth aspect of the present invention, the paper feed control means in the first aspect enables the user to select the adoption of the converted image information when the converted image information is adopted by the line detection determining means. Accordingly, whether or not to adopt the converted image information rotated by approximately 90 degrees is determined by the user's intention, in addition to the above-described effects, the usability of the image forming apparatus by the user Can be further improved.

  Furthermore, the image forming apparatus according to claim 5 is provided with a paper discharge control means for aligning the direction of the recording medium to be discharged when the converted image information is adopted by the line detection determination means in claim 1. Therefore, even if the converted image information rotated by approximately 90 degrees is employed, the configuration is such that the orientation of the finally ejected recording medium is aligned. In addition to the effect, the usability of the image forming apparatus by the user can be further improved.

  On the other hand, the image forming apparatus according to claim 6 is provided with a display unit for displaying that the converted image information is adopted when the converted image information is adopted by the line detection determining means in claim 1. Thus, the image forming state using the converted image information rotated by approximately 90 degrees is configured to be immediately confirmed by the user. In addition to the above-described effects, the user can use the image forming apparatus. Can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Prior to that, the overall structure of the image forming apparatus will be outlined using a laser printer as an example.

  In the laser printer 10 shown in FIG. 1, for example, document image information sent from an external computer is processed as light modulation information 11a by a laser emission writing unit 11 via a video controller (not shown). The image is formed in a spot shape on a photosensitive drum 121 as an image carrier provided in the cartridge 12, and the light spot is reciprocated in the axial direction (main scanning direction) of the photosensitive drum 121 to thereby perform the photosensitive operation. An electrostatic latent image corresponding to the formed image is formed on the drum 121. Then, an unfixed toner image is formed by supplying developer (toner) to the electrostatic latent image on the photosensitive drum 121 from a developing device 122 that is also integrally provided in the process cartridge 12. It has become so.

  On the other hand, on the lower side of the apparatus, paper feed cassettes 13 and 14 as two-stage recording medium stacking sections are arranged to constitute paper feed means. In each of these paper feed cassettes 13 and 14, recording papers (recording media) P1 and P2 of the same size are stored in a stacked state in different states rotated vertically and horizontally by approximately 90 degrees. Then, the recording paper P in either one of the two paper feeding cassettes 13 and 14 is pulled out by the paper feeding rollers 13a and 14a, and the above-mentioned photosensitive drum 121 is taken while being appropriately timed by the registration roller 15. It is sent to the transfer area facing.

  Further, a transfer roller 16 as a contact transfer member is in contact with and disposed in the transfer area of the photosensitive drum 121 so as to be in contact with the surface of the photosensitive drum 121. A transfer bias is applied to the transfer roller 16, and the unfixed toner image on the photosensitive drum 121 is electrostatically transferred onto the recording paper P by the transfer bias. Further, the toner remaining on the photosensitive drum 121 after the transfer is scraped off by the sliding contact force of the cleaning roller 123 disposed so as to come into pressure contact with the surface of the photosensitive drum 121.

  Furthermore, the recording paper P carrying the unfixed toner by the transfer operation described above is conveyed toward the fixing device 17 disposed adjacent to the process cartridge 12. The fixing device 17 is provided with a fixing roller 17a and a pressure roller 17b as heaters, and unfixed toner on the recording paper P is removed by the heat fixing operation of the fixing roller 17a and the pressure roller 17b. As a result of heating and melting, the toner image is fixed and fixed on the recording paper P. The recording paper P on which the toner image is fixed by such a heat fixing operation is discharged onto a paper discharge tray 18 at the top of the apparatus.

  Further, in such a laser printer 10, as shown in FIG. 2, at least one page of the document image information 21 sent from the above-described external computer or the like is stored in an image information storage means (memory). ) The document image information 21 once stored in the image information storage unit 22 and then stored in the image information storage unit 22 is sent to the line detection determination unit 23 and the image conversion unit 24, respectively.

  Of these, the image conversion means 24 generates and stores converted image information in different states obtained by rotating the original document image information 21 in the vertical and horizontal directions by approximately 90 degrees, and any one of the document image information 21 and the converted image information is stored. Is sent to the image forming means 26, an image forming operation is performed on the recording paper P fed by the paper feed control means 25 from either one of the above-described paper feed cassettes 13 and 14, and then discharged. The paper is discharged to an appropriate part by the paper control means 27.

  The processing operation when the document image information 21 is sent to the image forming means 26 will be described next. As shown in FIG. 3, the document image information 21 once stored in the image information storage means (memory) 22 (ST1) is sent to the above-described line detection determination means 23, and the line detection determination means 23 The amount (number) of “horizontal lines” extending in the axial direction of the photosensitive drum 121 in the main scanning direction and the photosensitiveness in the sub-scanning direction based on the image dot data for one page in the document image information 21. The amount (number) of “vertical lines” extending in the direction orthogonal to the axial direction of the drum 121 is compared (ST2).

  For example, with respect to the “horizontal line” as shown in FIG. 4A, the predetermined number of thresholds (threshold A) is exceeded in the image for one page recognized by the line detection discriminating means 23. When several dots are continuously formed on the same horizontal line along the main scanning direction (axial direction of the photosensitive drum 121), it is determined as “horizontal line”. Further, regarding the “vertical line” as shown in FIG. 4B, the number of dots on the same horizontal line is less than the reference number (threshold A) in the case of the above-mentioned “horizontal line” and is shorter. When the horizontal line is continuously formed at the same position over the number of lines larger than a predetermined reference number (threshold B), it is determined as “vertical line”.

  The vertical / horizontal comparison result in the line detection / discriminating means 23 is obtained as a result of the paper feed control means for controlling the paper feed operations of the two-stage paper feed cassettes 13 and 14 as the recording medium stacking section of the paper feed means as described above. 25 (see FIG. 2) and also sent to the image recording means 26 for executing image formation. Then, based on the comparison result in the line detection determination means 23, image information to be output and a recording medium are selected.

  That is, when it is determined by the above-described line detection determination means 23 that the amount (number) of “vertical lines” is large in the original document image information 21, the original document image information 21 is selected as it is. To the image recording means 26. At the same time, of the two-stage paper feed cassettes 13 and 14 described above, the one holding the recording paper (recording medium) set in the direction corresponding to the original document image information 21 is the paper feed control. The selected recording paper (recording medium) selected by the means 25 (ST3 in FIG. 3) is fed into the image recording means 26 from either one of the paper feed cassettes 13 or 14 to form an image. (ST4 in FIG. 3).

  On the other hand, the converted image information generated and stored in the above-described image converting means 24 when the above-described line detection determining means 23 determines that the amount (number) of “horizontal lines” is large in the original document image information 21. That is, image information in a state in which the original document image information 21 is rotated by 90 degrees vertically and horizontally is selected (ST5 in FIG. 3), and the converted image information is sent to the image recording means 26. At the same time, the paper feed control means 25 selects one of the two-stage paper feed cassettes 13 and 14 that holds the recording paper (recording medium) set in the direction corresponding to the converted image information. Then, the selected recording paper (recording medium) is sent to the image recording means 26 from the other side of the paper feed cassette 13 or 14 to perform image formation (ST4 in FIG. 3).

  As described above, according to the present embodiment, when the line detection determination unit 23 detects that “horizontal line” is larger than “vertical line” in the original document image information 21 stored in the image recording unit 21, The converted image information obtained by rotating the original image information 21 vertically and horizontally by the image conversion means by about 90 degrees is sent from the line detection determination means 23 to the image recording means 26, and also has a recording medium corresponding to the converted image information. A paper feed control operation from the cassette 13 or 14 is performed by the paper feed control means 25. Therefore, in the image recording means 26, the image forming operation is always performed so that the amount of “vertical lines” is larger than the amount of “horizontal lines”. As a result, even in the case of a biased image with many “horizontal lines”, the occurrence of the “fixing explosion or tailing phenomenon” and “shadow” as in the prior art can be satisfactorily suppressed, and a high-quality image can be obtained.

  At this time, when the converted image information is adopted by the above-described line detection discriminating means 23, if a display unit for displaying that the converted image information is adopted is provided, the converted image rotated approximately 90 degrees. The state of image formation using information is immediately confirmed by the user, and the usability of the image forming apparatus by the user is improved.

  Further, when the converted image information is adopted by the line detection determining means 23, the paper feed control means 25 is configured so that the user can select the adoption of the converted image information. If the configuration is such that whether or not to adopt the image is determined by the user's intention, the usability of the image forming apparatus by the user is further improved.

  Furthermore, when the converted image information is adopted by the above-described line detection discriminating means 23, a discharge control means 27 for aligning the direction of the recording medium to be discharged is provided, and the converted image information rotated approximately 90 degrees is provided. Even if it is adopted, if the configuration is such that the direction of the finally discharged recording medium is aligned, the usability of the image forming apparatus by the user is further improved.

  Here, in the case where the laser printer as the image forming apparatus in the above-described embodiment is provided with a humidity sensor as a humidity detection unit, the above-described operation is performed when the humidity sensor detects that the environmental condition is high humidity. It is preferable to execute such a paper feed control operation. For example, if the paper feed control operation as in the above-described embodiment is executed on condition that a humidity environment of RH 70% or more is detected by the humidity sensor, the recording paper P as a recording medium is oriented in the longitudinal direction as much as possible Therefore, an efficient image forming operation can be maintained without causing unnecessary throughput reduction.

  Similarly, when a laser printer as an image forming apparatus is provided with image density detection means such as a patch density sensor (see reference numeral 31 in FIG. 1), the value of the image density detected by the patch density sensor If the execution / non-execution of the paper feed control operation according to the above-described embodiment is determined based on the above, it is possible to set so that the recording paper P as a recording medium is not sent in the vertical direction as much as possible. Thus, an efficient image forming operation can be maintained without causing unnecessary throughput reduction.

  As mentioned above, although the embodiment of the invention made by the present inventor has been specifically described, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Not too long.

  For example, in the above-described embodiment, the present invention is applied to a printer, but the present invention can be similarly applied to other image forming apparatuses such as a copying machine.

  The image forming apparatus according to the present invention described above can be widely applied to a wide variety of image forming apparatuses such as copying machines as well as image forming apparatuses such as printers.

FIG. 2 is an explanatory side view illustrating a schematic structure of a printer to which the invention is applied. It is a block diagram showing the schematic structure of the control apparatus in one Embodiment of this invention. FIG. 6 is a flowchart showing a processing operation until document image information is sent to an image recording unit. The output image state is represented, (a) is a schematic explanatory diagram showing a “horizontal line”, and (b) is a schematic explanatory diagram showing a “vertical line”.

Explanation of symbols

10 Laser printer (image forming device)
12 Process Cartridge 121 Photosensitive Drum 122 Developing Device 13, 14 Paper Feed Cassette (Recording Medium Loading Unit of Paper Feed Unit)
P1, P2 recording paper (recording medium)
21 Document Image Information 22 Image Information Storage Unit 23 Line Detection Discrimination Unit 24 Image Conversion Unit 25 Paper Feed Control Unit 26 Image Recording Unit

Claims (6)

Image information storage means for storing document image information;
Image recording means for outputting an image to a recording medium based on the document image information stored in the image information storage means;
A plurality of recording medium stacking units for holding the recording medium in different states rotated approximately 90 degrees in length and width, and a paper feeding unit for feeding the recording medium from any of the recording medium stacking units to the image recording unit ,
Paper feed control means for controlling the feeding operation of the recording medium in the paper feed means;
In an image forming apparatus comprising:
Image conversion means for generating converted image information in a state in which the vertical and horizontal directions of the document image information stored in the image information storage means are rotated by approximately 90 degrees;
The amount of horizontal lines extending in the main scanning direction and the amount of vertical lines extending in the sub-scanning direction in the original document image information stored in the image information storage means are compared, and the document image information and the converted image are compared. Line detection determination means for selecting the image information with the larger amount of vertical lines from the information and sending it to the image recording means,
The line detection determination unit is configured to select a recording medium stacking unit that holds a recording medium corresponding to the selected image information and cause the sheet feeding control unit to perform a sheet feeding operation. Image forming apparatus. The image forming apparatus according to claim 1, wherein the line detection determination unit is configured to execute a paper feed control operation according to claim 1 when the humidity detection unit detects that the environmental condition is high humidity. 2. The image according to claim 1, wherein the line detection discriminating unit is configured to determine execution / non-execution of the paper feed control operation according to claim 1 based on an image density value detected by the image density detecting unit. Forming equipment. 2. The sheet feeding control unit is configured to allow a user to select adoption of the converted image information when the converted image information is adopted by the line detection determination unit. Image forming apparatus. 2. The image forming apparatus according to claim 1, further comprising a discharge control unit configured to align the direction of the recording medium to be discharged when the converted image information is adopted by the line detection determination unit. The image forming apparatus according to claim 1, further comprising: a display unit that displays that the converted image information is adopted when the converted image information is adopted by the line detection determination unit.

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