JP4206028B2 - Printer and image forming method - Google Patents

Description

  The present invention forms an electrostatic latent image on the surface of an image carrier, forms a toner image on the surface of the image carrier by adsorbing toner to the electrostatic latent image, and the toner image on a recording medium. The present invention relates to a printer that forms an image on a recording medium by performing transfer and fixing of the image, and an image forming method that is performed by the printer.

  Film development and photo printing taken with a camera have been carried out in a so-called laboratory (development laboratory), which is a separate facility from general stores such as photo shops, but in recent years, printing required for photo printing has been carried out. A photo shop that develops a film and prints a photo in a store is equipped with a small apparatus (hereinafter referred to as a minilab) that performs processing from the development to the development. As a minilab installed in such a photo shop, an image is exposed on a photographic paper based on image data read from a film or the like, and the photographic paper is passed through a liquid such as a developer or a fixing solution. An apparatus for obtaining an image is generally used. However, in such a minilab, it is necessary to replenish the developer, the fixing solution, and water, and regularly clean the tank in which these solutions are stored, and further, waste liquid processing that requires labor and cost for processing is required. There is a problem that it is necessary.

  On the other hand, so-called electrophotographic printers that do not require any processing relating to the developer, the fixing solution, the water, and the waste solution are widely used in copying machines and the like (see, for example, Patent Document 1). . An electrophotographic printer forms an electrostatic latent image on the surface of an image carrier and forms a toner image on the surface of the image carrier by adsorbing toner to the electrostatic latent image. The apparatus forms an image on the recording medium by transferring and fixing the toner image. However, the images obtained with electrophotographic printers are inferior to conventional minilabs in terms of image quality, such as the gloss of the image surface, and cannot withstand viewing as photographic images. Therefore, electrophotographic printers are applicable to minilabs. Has been postponed.

However, in recent years, technologies related to the image quality of such electrophotographic printers have improved, and application to minilabs has been considered. For example, a primary fixing device that performs primary fixing for fixing a toner image transferred to a recording medium to the recording medium, and a surface of the toner image that is disposed and fixed downstream of the primary fixing device in the conveyance path of the recording medium There has been proposed a printer provided with a secondary fixing device that performs secondary fixing to smooth the surface and give gloss (for example, see Patent Document 2). The printer shown in Patent Document 2 is an apparatus that is supposed to be applied to a copying machine or the like, but the image quality obtained by the printer is close to the image quality of a photographic image obtained in a conventional minilab. The printer disclosed in Patent Document 2 is considered to have sufficient performance to withstand application to the above-described minilab.
Japanese Patent Laid-Open No. 2003-98851 JP 2003-5545 A (page 2-4, FIG. 1)

  The printer shown in Patent Document 2 is provided with a fixing device having an endless belt member as a secondary fixing device for obtaining an image quality approaching that of a photographic image. This belt member circulates and moves via a contact point whose surface is in contact with the toner image fixed by the primary fixing device. In the secondary fixing, the toner image fixed on the recording medium by the primary fixing device is first heated to melt the toner, and the surface of the belt member that circulates and moves on the surface of the toner image in which the toner is melted. Press. Then, the toner image is cooled while being pressed by the belt member, and the molten toner is solidified. Thereafter, the toner image is peeled off from the belt member surface. By undergoing such processing, a high-quality image having a gloss approaching that of a photographic image can be obtained.

  By the way, in order to obtain a gloss that is closer to a photographic image, it is necessary to keep the flatness of the belt member surface of the secondary fixing device at a high level. If dust adheres to the surface of the belt member or scratches are generated, the flatness of the belt member is lowered and the glossiness of the image is deteriorated.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a printer capable of always maintaining the flatness of the belt member surface of a secondary fixing device at a high level, and an image forming method implemented by the printer. And

The printer of the present invention is a printer that forms an image on a recording medium while conveying the sheet-shaped recording medium along a predetermined conveying path.
An electrostatic latent image is formed on the surface of the image carrier, and a toner image is formed on the surface of the image carrier by adsorbing toner to the electrostatic latent image. In contrast, an image forming unit that transfers the toner image;
An endless belt member disposed on the downstream side of the image forming unit in the conveyance path and circulated through a contact point in contact with the toner image on the recording medium and having a flat surface in contact with the toner image. A fixing unit for fixing the toner image on the recording medium, having a function of obtaining a photographic image quality by glossing the surface of the toner image with the belt member;
It is provided with the sensor which detects the unevenness | corrugation of the surface of the said belt member.

  In the printer of the present invention, if the surface of the belt member is uneven due to dust or scratches, the sensor detects the surface unevenness. For this reason, the flatness of the belt member surface can always be kept high.

  The fixing unit is disposed on the downstream side of the image forming unit in the conveyance path, and a primary fixing unit that fixes the toner image transferred to the recording medium by the image forming unit to the recording medium; Toner fixed by the primary fixing unit that is arranged on the downstream side of the primary fixing unit in the conveyance path and circulates via a contact point that contacts the toner image fixed by the primary fixing unit. A separate fixing unit called a secondary fixing unit that has an endless belt member having a flat surface in contact with the image and melts at least the surface portion of the toner image fixed by the primary fixing unit to adjust the surface properties by the belt member. The fixing unit may be configured by two fixing units, or the secondary fixing unit may be configured by a single fixing unit that also functions as the primary fixing unit.

  In the printer of the present invention, it is preferable that the printer includes a notification unit that notifies that the unevenness is detected when the sensor detects unevenness on the surface of the belt member.

  By providing such a notification unit, it is possible to reliably notify the user that irregularities have occurred on the surface of the belt member, and it is possible to prompt the user to clean the belt member or replace the belt member.

Furthermore, in the printer of the present invention, the belt member has a circumferential length longer than the length of the recording medium,
When unevenness is detected on the surface of the belt member by the sensor, the timing at which the portion of the surface where the unevenness is detected reaches the contact point, and the toner image on the recording medium at the contact point. An aspect provided with a control unit that performs control to relatively shift the timing at which the signal reaches is also preferable.

  According to this aspect, even if irregularities occur on the surface of the belt member, it is possible to continue forming a high-quality image having a gloss approaching that of photographic quality without interrupting image formation. For this reason, it is possible to take provisional measures when the image formation is interrupted and the belt member cannot be cleaned or replaced.

  Furthermore, in the printer of the present invention, when irregularities are detected on the surface of the belt member by the sensor, a predetermined sheet-like object is conveyed along the conveyance path, and the sheet-like object is used as the contact point. It is also preferable that a control unit for feeding is provided.

  When dust adheres to the surface of the belt member, the dust can be removed by passing the sheet-like material in contact with the surface of the belt member. Here, the sheet-like material is preferably an adhesive paper (dedicated cleaning paper), but may be a recording paper (coated paper or plain paper).

A first image forming method of the present invention is an image forming method for forming an image on a recording medium while conveying a sheet-like recording medium along a predetermined conveying path.
An electrostatic latent image is formed on the surface of the image carrier, and a toner image is formed on the surface of the image carrier by adsorbing toner to the electrostatic latent image. In contrast, an image forming step for transferring the toner image;
The toner image transferred onto the recording medium by the image forming step is fixed, and the endless belt member having a flat surface in contact with the toner image is circulated through a contact point in contact with the toner image. A fixing step for obtaining a photographic image quality by glossing the surface of the toner image;
A detection step of detecting irregularities on the surface of the belt member;
And an alarming step for notifying that the irregularities are detected when irregularities are detected on the surface of the belt member by the detecting step.

A second image forming method of the present invention is an image forming method for forming an image on a recording medium while conveying a sheet-like recording medium along a predetermined conveying path.
An electrostatic latent image is formed on the surface of the image carrier, and a toner image is formed on the surface of the image carrier by adsorbing toner to the electrostatic latent image. In contrast, an image forming step for transferring the toner image;
The toner image transferred on the recording medium by the image forming step is fixed and circulated through a contact point in contact with the toner image. The surface in contact with the toner image is flat and the circumference is A fixing step of obtaining a photographic image quality by glossing the surface of the toner image with an endless belt member longer than the length of the recording medium;
A detection step of detecting irregularities on the surface of the belt member;
When unevenness is detected on the surface of the belt member by the detecting step, the timing at which the surface of the surface where the unevenness is detected reaches the contact point, and the toner on the recording medium at the contact point. And a temporary avoidance step for performing a control for relatively shifting the timing at which the image arrives.

A third image forming method of the present invention is an image forming method for forming an image on a recording medium while conveying the sheet-shaped recording medium along a predetermined conveying path.
An electrostatic latent image is formed on the surface of the image carrier, and a toner image is formed on the surface of the image carrier by adsorbing toner to the electrostatic latent image. In contrast, an image forming step for transferring the toner image;
The toner image transferred onto the recording medium by the image forming step is fixed, and the endless belt member having a flat surface in contact with the toner image is circulated through a contact point in contact with the toner image. A fixing step for obtaining a photographic image quality by glossing the surface of the toner image;
A detection step of detecting irregularities on the surface of the belt member;
A cleaning step of transporting a predetermined sheet material along the transport path and sending the sheet material to the contact point when irregularities are detected on the surface of the belt member by the detection step. Features.

  Here, in any of the image forming methods of the present invention, in the fixing step, the toner image transferred to the recording medium by the image forming step is fixed to the recording medium, and the toner is formed by the belt member. Glossing the image surface to obtain photographic quality may be performed separately or simultaneously.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating an embodiment of a printer according to the present invention.

  FIG. 1 shows a minilab system including a printer 100 and an image input device 300.

  The image input device 300 optically reads a photographic image recorded on a photographic film and obtains photographic image data, and photographic image data that is photographed by a digital camera or the like and recorded on a small recording medium. A small recording medium drive 302 that reads from the small recording medium. The image input device 300 generates output image data by performing correction processing such as color tone correction and white balance correction on the captured image data obtained through the scanner 301 or the small recording medium drive 302, and outputs the output image data. Send to printer 100.

  A printer 100 shown in FIG. 1 forms an electrostatic latent image, develops it with toner, forms a toner image, and finally transfers and fixes the toner image on a recording medium, thereby fixing toner on the recording medium. The printer forms an image composed of images. Specifically, the printer 100 is a printer including a developing device for each color of yellow (Y), magenta (M), cyan (C), and black (B), and can print a single color image. In addition, it is possible to print a full color image composed of the four color toner images.

  The printer 100 includes a control unit 110 including a laser light modulation unit 111 that modulates laser light emitted from a laser based on output image data output from the image input device 300. The control unit 110 controls the operation of each component of the printer 100 described below. In FIG. 1, the flow of the control signal is indicated by a one-dot chain line.

  The printer 100 also includes an image forming unit 120 that transfers a toner image to a sheet-like recording medium that is conveyed along a predetermined conveyance path.

  The image forming unit 120 includes an exposure unit 121, an image carrier roll 122, a charging roll 123, a developing unit 124, a cleaner 125, an intermediate transfer unit 126, and a secondary transfer roll 127.

  The surface of the image carrier roll 122 rotating in the direction of the arrow A is charged by the charging roll 123, and the exposure unit 121 (described later) outputs image data from the image input device 300 to the surface of the charged image carrier roll 122. The scanning exposure is performed with the laser beam modulated based on the above. As a result, an electrostatic latent image having a predetermined surface potential is formed on the surface of the image carrier roll 122.

  The exposure unit 121 internally scans and exposes a light source such as a semiconductor laser (not shown) or laser light emitted from the light source based on output image data from the image input device 300 onto the image carrier roll 122. In addition, an optical system including a polygon mirror, a reflecting mirror, and various lenses is appropriately arranged. An electrostatic latent image is written on the image carrier roll 122 by such an exposure unit 121.

  The developing unit 124 is provided with developing devices 124Y, 124M, 124C, and 124B for each color of YMCB that are arranged at 90 ° intervals. Each of the developing devices 124Y, 124M, 124C, and 124B employs a so-called magnetic brush developing method, and a two-component developer containing toner and carrier is accommodated in the device. The developing unit 124 rotates at 90 ° intervals in the direction of arrow B, and any one of the built-in developing devices 124Y, 124M, 124C, and 124B is closely opposed to the image carrier roll 122 at a predetermined minute interval. Let Then, the toner is electrostatically attached to the electrostatic latent image formed on the surface of the image carrier roll 122 from the developing device close to and opposed to the image carrier roll 122 by the magnetic brush effect, and the image carrier roll 122. A toner image of a color corresponding to the developing device is formed on the surface of the toner.

  The intermediate transfer unit 126 is configured such that an intermediate transfer belt 126a is stretched so as to be movable in an arrow C direction by a tension roll 126b disposed on the inner side. Further, a primary transfer roll 126c is disposed at a primary transfer position where the intermediate transfer belt 126a and the image carrier roll 122 are closest to each other, and a transfer voltage is applied to the intermediate transfer belt 126a by the primary transfer roll 126c. . The toner image formed on the surface of the image carrier roll 122 by the developing devices 124Y, 124M, 124C, and 124B built in the developing unit 124 is transferred to the intermediate transfer belt 126a by the transfer voltage at the primary transfer position.

  When the image to be formed is a color image, first, an electrostatic latent image for yellow (Y) is formed on the surface of the image carrier roll 122 by the exposure unit 121, and the electrostatic latent image is As the developing unit 124 rotates, toner is adsorbed from the yellow developing device 124Y that is in close proximity to the image carrier roll 122, and a yellow toner image is formed on the surface of the image carrier roll 122. Then, the image is transferred to the intermediate transfer belt 126a. Thereafter, an electrostatic latent image for magenta (M) is formed on the surface of the image carrier roll 122 by the exposure unit 121 on the surface of the image carrier roll 122 from which the residual toner on the surface has been removed by the cleaner 125. At this time, toner is adsorbed to the electrostatic latent image from the magenta developing device 124M that is close to and opposed to the image carrier roll 122 by the 90 ° rotation of the developing unit 124, and the surface of the image carrier roll 122 is magenta. A toner image is formed, and the magenta toner image is transferred onto the intermediate transfer belt 126a so as to overlap the already transferred yellow toner image. Thereafter, through the same operation, the remaining cyan (C) and black (B) toner images are sequentially transferred onto the intermediate transfer belt 126a. Here, the tension roll 126b that moves the intermediate transfer belt 126a is controlled by the control unit 110 so that the toner images of the respective colors that are sequentially transferred overlap each other accurately.

  When the image to be formed is a monochrome image, only the black (B) toner image is transferred to the intermediate transfer belt 126a through the same operation as described above.

  The toner image transferred to the intermediate transfer belt 126a through the above-described operation is transferred by the secondary transfer roll 127 disposed so as to face one of the above-described stretching rolls 126b and the intermediate transfer belt 126a. Then, the image is further transferred to a sheet-like recording medium conveyed from a medium supply unit 130 described later. As a result, a color or monochrome toner image is formed on the surface of the recording medium.

  Next, the medium supply unit 130 that supplies the sheet-like recording medium to the image forming unit 120 provided in the printer 100 shown in FIG. 1 will be described.

  The medium supply unit 130 includes a roll paper storage unit 131 into which a wound long roll paper 131a is loaded as a recording medium. In addition, although the example provided with the two roll paper storage parts 131 is shown by FIG. 1, this invention is not limited to this. The printer according to the present invention may include, for example, one roll paper storage unit 131, and may include three or more roll paper storage units loaded with roll papers 131a having different sizes and types in the width direction. It may be a thing.

  The roll paper 131a is pulled out by the positioning roll 101 provided in the vicinity of the roll paper outlet of the roll paper storage unit 131, and is conveyed to the roll paper cutter 134 disposed on the downstream side of the positioning roll 101 in the medium conveyance path. Is done. The roll paper 131a is positioned by the positioning roll 101 and then cut into a predetermined dimension in the longitudinal direction by the roll paper cutter 134. Here, the positioning roll 101 is controlled by the control unit 110 so as to position the roll paper 131a according to the size to be cut.

  The recording paper cut out from the roll paper storage unit 131 and formed into a sheet is transported by the transport rolls 102 on a transport path formed by a plurality of transport rolls 102 arranged at various locations in the printer 100.

  The medium supply unit 130 also includes a sheet cassette 132 in which cleaning paper 132a different from the recording medium is stored. Although the surface of the cleaning paper 132a has adhesiveness, the back surface has releasability from the surface. In the sheet cassette 132 shown in FIG. 1, cleaning paper 132a is stacked with the adhesive surface facing down. Although FIG. 1 shows an example in which one sheet cassette 132 is provided, the present invention is not limited to this. The printer of the present invention may include, for example, a sheet cassette that stores recording sheets such as coated paper and plain paper having different sizes and types.

  The cleaning paper 132a is taken out by the transport roll 102 arranged in the vicinity of the take-out port of the sheet cassette 132, and is transported downstream in the transport path. The driving of the transport roll 102 is controlled by the control unit 110 as will be described later.

  The conveyance path from the roll paper cutter 134 and the conveyance path from the sheet cassette 132 merge into one path on the downstream side, and various print information is printed on the reverse side of the conveyed recording paper on the one path. A print head 135 for printing is disposed. The print information printed by the print head 135 includes, for example, a frame number indicating which image on the film corresponds to an image to be printed on the recording paper, a date when the image was taken, and the like. In addition, information such as various setting parameters in image formation set by the operator is included.

  The recording paper that has been printed on the back surface by the print head 135 is moved further downstream of the conveyance path by the registration roll 103 disposed on the downstream side of the print head 135. Up to 127, the color or monochrome toner image already formed on the intermediate transfer belt 126a is transferred by the secondary transfer roll 127 onto the recording paper that has been conveyed in time as will be described later. .

  As described above, when a color toner image is formed on the intermediate transfer belt 126a, the intermediate transfer belt 126a is rotated four times in the direction of the arrow C, and the YMCB four-color toner image matches the intermediate transfer belt 126a. Each color is transferred to the intermediate transfer belt 126a one color at a time. In this embodiment, when a color toner image is formed on the intermediate transfer belt 126a, the recording paper is transported to the secondary transfer roll 127 by the resist roll 103 so that all four color toner images are transferred to the intermediate transfer belt 126a. The color toner image formed on the transfer belt 126 a is executed so that the recording paper is conveyed to the secondary transfer roll 127 at a timing when the color toner image first faces the secondary transfer roll 127. The registration roll 103 is controlled by the control unit 110 so as to convey the recording paper at such timing.

  Through the procedure described above, the recording paper on which the toner image has been transferred is placed on the conveyance belt 104 arranged on the downstream side of the secondary transfer roll 127, and the primary paper arranged on the further downstream side of the conveyance path. It is conveyed to the fixing unit 140. The recording paper to which the toner image has been transferred is subjected to heating and pressing processes by the primary fixing unit 140, and the toner image is fixed to the recording paper by these processes.

  The recording paper processed by the primary fixing unit 140 is conveyed to a secondary fixing unit 170 disposed on the downstream side of the primary fixing unit 140 in the conveyance path.

  The secondary fixing unit 170 includes a pair of heat and pressure rolls 171 disposed above and below, an endless secondary fixing belt 172 having a flat surface, a cooler 173, and a driven roll 174. . The position sandwiched between the pair of heat and pressure rolls 171 is a contact point C where the surface of the secondary fixing belt 172 contacts the toner image fixed by the primary fixing device 140. Moreover, the upper roll of the pair of heating and pressing rolls 171 is a heating roll 1711 having a heating source inside. A driving force from a motor 220 having a rotary encoder 210 attached to a rotating shaft is transmitted to the heating roll 1711, and the heating roll 1711 receives the driving force and is driven to rotate. The secondary fixing belt 172 is wound around the heating roll 1711 and the driven roll 174, and circulates and moves via the contact point C according to the rotation driving of the heating roll 1711.

  In the secondary fixing unit 170, first, the toner image fixed on the recording paper by the primary fixing unit 140 is heated and melted by the heating and pressing roll 171 and the surface of the melted toner image is subjected to secondary fixing. It is pressed against the surface of the belt 172. Then, the recording paper is conveyed to the downstream side while sticking to the surface of the secondary fixing belt 172, and further, the recording paper attached to the surface is disposed on the downstream side of the heating and pressing roll 171. Cooled by the cooler 173. As a result, the melted toner image on the recording paper is solidified. Thereafter, the recording paper is further conveyed to the downstream side, and peels off from the surface of the secondary fixing belt 172 due to the rigidity of the recording paper itself as the secondary fixing belt 172 bends and returns.

  Here, a transparent resin layer is formed on the surface of the recording paper in advance, and after the processing by the primary fixing unit 140, the toner image is fixed on the surface of the recording paper on the resin layer. It is in the state. When the recording paper in this state is subjected to the processing by the secondary fixing unit 170, the resin layer and the toner image are melted together, and both are integrated and the surface is a flat surface of the secondary fixing belt 172. It solidifies in a state where it is pressed and uniformly leveled. By undergoing such processing by the secondary fixing unit 170, a high-quality image having a gloss approaching that of a photographic image can be obtained.

  Although not shown, the secondary fixing unit 170 is also provided with a lift-up mechanism that lifts up the two rolls of the heating roll 1711 and the driven roll 174 in response to an instruction from the control unit 110. When the roll 1711 and the driven roll 174 are lifted up, the surface of the secondary fixing belt 172 and the toner image on the conveyed recording paper are not in contact with each other.

  The recording paper whose surface texture has been adjusted by the secondary fixing unit 170 is conveyed to an XY cutter 180 disposed on the downstream side of the secondary fixing unit 170 in the conveyance path. The XY cutter 180 includes a first cutter 181 that cuts the recording paper perpendicularly to the transport direction, and a second cutter 182 that cuts the recording paper along the transport direction. The first cutter 181 and the second cutter 182 include It is arranged in series on the transport path. A positioning roll 101 is disposed between the first cutter 181 and the second cutter 182 and on the downstream side of the second cutter 182, and these positioning rolls 101 position the recording paper with respect to the XY cutter 180.

  Further, the cutting of the recording paper by the XY cutter 180 is performed by an operator setting according to the customer's request. For example, the recording paper conveyed to the XY cutter 180 is cut out from the long roll paper 131a, and the size of the recording paper cut out from the roll paper 131a is larger than the photo size. In some cases, cutting according to the photo size is performed by the XY cutter 180. Further, when what the customer ultimately desires is a borderless photographic print, cutting is performed by the XY cutter 180 so as to cut a frame surrounding the photographic image on the recording paper.

  The recording paper that has undergone the processes such as fixing and cutting as described above is conveyed and stacked as a photographic print on the sorter 190 disposed on the most downstream side of the conveyance path. The stacking of recording sheets on the sorter 190 is executed as follows. For example, when a sheet of recording paper obtained from one film is stored in the storage unit 191 at a predetermined storage position of the sorter 190, the sorter 190 rotates in the direction of arrow D, and the empty sheet The storage unit 191 moves to the storage position. The empty storage unit 191 stores the next recording paper. As a result, all the recording sheets are sorted for each case and stored in each storage unit 191.

  The printer 100 shown in FIG. 1 also includes an unevenness detection unit 230, an origin detection unit 240, and a notification unit 250. Of these components, the reporting unit 250 has a liquid crystal display panel, and displays various messages from the control unit 110. The notification unit may be a speaker that emits an alarm sound.

  FIG. 2 is a schematic enlarged view of the secondary fixing unit provided in the printer shown in FIG. 1 including its periphery.

  FIG. 2 also shows a pair of heat and pressure rolls 171, a secondary fixing belt 172 having a flat surface 172 a, a cooler 173, and a driven roll 174 that constitute the secondary fixing unit 170. Yes. FIG. 2 also shows the recording paper P conveyed from the left to the right in the drawing. Further, FIG. 2 also shows an unevenness detection unit 230 and an origin detection unit 240.

  The unevenness detection unit 230 illustrated in FIG. 2 includes an observation optical system 231 including a lens 2311 and a light receiving sensor 2312, and a light source 232. The light source 232 is a dark field illumination system provided with its optical axis greatly inclined from the optical axis of the observation optical system 231. The unevenness detecting unit 230 detects unevenness of the secondary fixing belt surface 172a. The light source 232 illuminates the entire width direction of the secondary fixing belt surface 172a and reflects light reflected by the surface 172a to the lens 2311. The light is condensed on the light receiving surface of the light receiving sensor 2312. The light receiving sensor 2312 outputs a signal having a magnitude corresponding to the intensity of the received light to the control unit 110 shown in FIG.

  FIG. 3 is a diagram illustrating an example of a signal waveform output from the light receiving sensor illustrated in FIG. 2.

  FIG. 3 shows a signal waveform S1 output when the light receiving sensor shown in FIG. 2 receives light reflected by the flat surface of the secondary fixing belt, and dust adheres to the surface of the secondary fixing belt or scratches. Two signal waveforms are shown, including a signal waveform S2 that is output when light reflected from the surface having the irregularities caused by the occurrence of light is received. If the surface of the secondary fixing belt is uneven, as shown in FIG. 3, the output signal from the light receiving sensor 2102 becomes a signal having a magnitude exceeding a predetermined threshold value. In the secondary fixing belt having irregularities on the surface, the irregularities are transferred to the surface of the toner image in a molten state in the secondary fixing portion, and the surface property of the toner image becomes non-uniform and the glossiness of the image deteriorates. Therefore, in the printer of the present embodiment, when a signal having a magnitude exceeding the predetermined threshold is input to the control unit 110 shown in FIG. 1, the control unit sends the signal to the notification unit 250 shown in FIG. Then, a warning message indicating that irregularities are detected on the surface of the secondary fixing belt is displayed. The user of the printer according to the present embodiment interrupts the printing operation according to the warning message displayed on the reporting unit, performs the cleaning operation of the secondary fixing belt, or replaces the belt with a new belt. . However, there is a case where it is desired to continue the printing work due to a delivery date or the like. In order to cope with such a case, provisional measures are taken in the printer of this embodiment. That is, this printer is provided with a temporary avoidance mode in which, when irregularities are detected on the surface of the secondary fixing belt, secondary fixing can be continued while avoiding the portion where the irregularities are detected. Hereinafter, the temporary avoidance mode will be described, but before that, the position detection of the secondary fixing belt will be described.

  FIG. 4 is a view of the secondary fixing belt shown in FIG. 1 when viewed from the front surface side.

  FIG. 4 shows a part of the secondary fixing belt 172. In FIG. 4, the vertical direction in the figure is the moving direction of the secondary fixing belt 172. FIG. 4 shows a region T sandwiched between two two-dot chain lines. The width of the secondary fixing belt 172 (the horizontal length in the figure) is longer than the width of the recording paper, and this region T is a toner image fixed by the primary fixing device on the surface of the secondary fixing belt 172a. This is the area that touches A cutout 1721 is provided at a part of one edge of the secondary fixing belt 172. The notch 172 is provided outside the region in contact with the toner image, and the control unit 110 treats the position where the notch 1721 is provided as the origin of the secondary fixing belt 172. The origin detector 240 shown in FIG. 1 detects this notch 1721.

  Here, the operation of the origin detection unit 240 will be described with reference to FIGS. 1 and 2 again.

  The origin detection unit 240 includes a light projecting element 241 and a light receiving element 242 that are disposed across the edge of the secondary fixing belt 172 on the side where the notch 1721 is provided (see FIG. 2). When the notch 1721 shown in FIG. 4 is positioned on the optical axis of the light projecting element 241, the light emitted from the light projecting element 241 reaches the light receiving element 242. Light emitted from the element 241 is blocked by the secondary fixing belt 172 and does not reach the light receiving element 242. When the light receiving element 242 receives the light emitted from the light projecting element 241, the light receiving element 242 outputs an origin detection signal to the control unit 110. From the rotary encoder 220 shown in FIG. 1, a signal corresponding to the rotation position or rotation amount of the rotation shaft of the motor 210 is output to the control unit 110.

  In the printer 100 shown in FIG. 1, a temporary avoidance operator (not shown) is temporarily turned on while a warning message indicating that irregularities are detected on the surface of the secondary fixing belt is displayed on the alarm unit 250. Enter avoidance mode.

  FIG. 5 is a flowchart showing a processing routine of the control unit in the temporary avoidance mode.

  First, from the timing of receiving an output signal indicating that irregularities are detected on the surface of the secondary fixing belt, the position of the irregularities generated on the surface of the secondary fixing belt in the circumferential direction of the belt is specified (step S1). The position specification here is performed by calculating the distance in the belt circumferential direction from the notch 172 (origin) to the place where the unevenness is detected using an output signal from the rotary encoder 220.

  Next, drive control of the registration roll 103 provided in front of the image forming unit 120 and drive control of the secondary fixing belt are performed (step S2). That is, the timing at which the portion of the secondary fixing belt surface where the irregularities are detected reaches the contact point C and the timing at which the toner image fixed by the primary fixing unit 140 reaches the contact point C relatively. Control to shift. The control unit 110 adjusts the toner image formation timing by the image forming unit 120 by controlling the driving of the registration roll 103. This adjustment is a timing adjustment at which the toner image fixed by the primary fixing unit 140 reaches the contact point C. The control unit 110 adjusts the circulation speed of the secondary fixing belt by controlling the rotation speed of the motor 210. The adjustment of the circulation speed is a timing adjustment at which the portion of the secondary fixing belt surface where the irregularities are detected reaches the contact point C.

  Note that the timing at which the portion of the secondary fixing belt surface where the irregularities are detected reaches the contact point C only by performing either one of the drive control of the registration roll 103 and the drive control of the secondary fixing belt. In addition, it is possible to control to shift the timing at which the toner image fixed by the primary fixing unit 140 reaches the contact point C. Further, instead of performing drive control of the resist roll 103 provided in front of the image forming unit 120, drive control of the transport roll 102 provided between the primary fixing unit 140 and the secondary fixing unit 170 may be performed. In this case, the toner image fixed by the primary fixing unit 140 is kept waiting in front of the secondary fixing unit 170, and the portion of the secondary fixing belt surface where the irregularities are detected reaches the contact point C. Control is performed to relatively shift the timing and the timing at which the toner image fixed by the primary fixing unit 140 reaches the contact point C.

  In this way, even if the secondary fixing belt surface 172a has irregularities, a flat portion of the secondary fixing belt surface 172a avoiding the irregularities is fixed by the primary fixing unit 140. And a high-quality image having a gloss approaching that of a photographic image is obtained.

  Further, the printer is also provided with a cleaning mode in which the cleaning paper 132a stored in the sheet cassette 132 is sent to the secondary fixing unit 170 when unevenness is detected on the surface of the secondary fixing belt.

  This cleaning mode can also be entered by turning on a cleaning operator (not shown) in a state where a warning message indicating that irregularities are detected on the surface of the secondary fixing belt is displayed on the alarm unit 250. . In the cleaning mode, the control unit 110 drives the transport roll 102 disposed in the vicinity of the take-out port of the sheet cassette 132 shown in FIG. 1, and sends the cleaning paper 132a to the transport path. Since the cleaning paper 132a is stored in the sheet cassette 132 with the adhesive surface facing down, the cleaning paper 132a is conveyed along the conveyance path so that the adhesive surface is in contact with the surface 172a of the secondary fixing belt 172. . Here, if the irregularities generated on the surface 172a of the secondary fixing belt 172 are caused by the adhesion of foreign matter such as dust, the cleaning paper 132a passes through the secondary fixing unit 170, and the foreign matter such as dust is adhered to the surface. The surface of the secondary fixing belt is removed from the secondary fixing belt surface 172a, and the flatness of the surface of the secondary fixing belt is restored to a good one. By using this cleaning mode, the cleaning operation of the secondary fixing belt can be performed without disassembling the printer, and the cleaning operation of the surface of the secondary fixing belt can be completed with a slight interruption of the printing operation.

  Although the cleaning paper 132 is passed through the secondary fixing unit 170 here, the secondary fixing can be performed even if recording paper (coated paper or plain paper) is passed instead of the cleaning paper, although the cleaning ability is reduced. A belt surface cleaning effect can be obtained.

  In the printer of the present invention, it is not always necessary to provide the alarm unit 250 shown in FIG. 1, and it is not always necessary to have the temporary avoidance mode and the cleaning mode, and the unevenness detecting unit described with reference to FIG. As long as 230 is provided, the flatness of the belt member surface of the secondary fixing device can be maintained at a high level. Further, here, the primary fixing unit 140 and the secondary fixing unit 170 have been described as separate devices. However, an unfixed toner image is fixed on the recording paper using the secondary fixing belt 172 and simultaneously with the fixing. It is also possible to perform gloss processing on the surface of the toner image. In this case, of the primary fixing unit 140 and the secondary fixing unit 170, the primary fixing unit 140 may be omitted and only the secondary fixing unit 170 may be provided.

  Finally, the image forming process in the printer 100 shown in FIG.

  FIG. 6 is a flowchart showing a processing routine of image forming processing in the printer shown in FIG.

  The processing routine of the image forming process shown in FIG. 6 is started when the main power supply of the printer 100 shown in FIG. 1 is turned on, and is executed by the control unit 110 shown in FIG. This processing routine ends when the main power is turned off.

  First, in this processing routine, it is determined whether or not a warning message indicating that irregularities have been detected on the surface of the secondary fixing belt is displayed on the liquid crystal display panel of the reporting unit 250 (step S101). If a message is displayed, it is next determined whether or not a temporary avoidance operator (not shown) is in an on state (step S102). If the temporary avoidance operator is in the on state, the printer shown in FIG. 1 is set to the temporary avoidance mode described above. First, the control unit 110 determines whether or not output image data has been received from the image input device 300. (Step S103). Here, when the output image data is not received, this step S103 is repeatedly executed, and when the output image data is received, the processing routine in the temporary avoidance mode shown in FIG. 5 is executed (step S103). S104). At this stage, the secondary fixing belt 172 stops circulating, but the control unit 110 gives a rotation instruction to the motor 210 that circulates and moves the secondary fixing belt 172, and the origin detecting unit 240 shown in FIG. The notch 172 (origin) is detected, and the unevenness generated on the surface of the secondary fixing belt is also detected by the unevenness detection unit 230, and the position specification (step S1) shown in FIG. 5 is performed. 103 and the secondary fixing belt 172 are controlled (step S2).

  Subsequently, an electrostatic latent image is formed on the surface of the image carrier roll 122 in the image forming unit 120, and a toner image is formed on the surface of the image carrier roll 122 by adsorbing toner to the electrostatic latent image. Then, the start of image forming processing for transferring the toner image to the recording paper conveyed through the conveyance path is instructed (step S105). In response to this instruction, the image forming unit 120 executes image forming processing.

  Next, the primary fixing unit 140 is instructed to start a primary fixing process for fixing the toner image transferred to the recording medium by the image forming unit 120 to the recording medium (step S106). In response to the instruction in step S106, the primary fixing unit 140 executes primary fixing processing.

  Next, the secondary fixing unit 170 is instructed to start a secondary fixing process in which the surface portion of the toner image fixed by the primary fixing unit 140 is melted and the surface properties are adjusted by the secondary fixing belt 172 ( Step S107). In response to the instruction in step S106, the secondary fixing unit 170 executes a secondary fixing process. In the secondary fixing process, a flat portion of the secondary fixing belt surface 172a is pressed against the toner image fixed by the primary fixing unit 140, avoiding the uneven portion.

  When the secondary fixing process in the secondary fixing unit 170 is completed, a rotation stop instruction is issued to the motor 210 that circulates and moves the secondary fixing belt 172, and the process returns to step S101.

  On the other hand, if it is determined in step S101 that no warning message is displayed, the process proceeds to step S111. In this step S111, as in step S103, it is determined whether or not output image data has been received from the image input device 300. This step S111 is repeatedly executed until the output image data is received. The start of the image forming process is instructed as in step S105 (step S112), and then the start of the primary fixing process is instructed as in step S106 (step S113). When the primary fixing process in the primary fixing unit 140 is completed, the recording paper reaches the transport roll 102 provided between the primary fixing unit 140 and the secondary fixing unit 170. When the recording paper reaches the transport roll 102, the control unit 110 issues a rotation start instruction to the motor 210 that circulates and moves the secondary fixing belt 172, and executes the process of step S114. In step S114, the unevenness detection unit 240 shown in FIG. 2 is instructed to detect unevenness on the surface of the secondary fixing belt 172a that circulates and moves. In response to this instruction, the unevenness detection unit 240 starts detection. In step S115 subsequent to step S114, as described with reference to FIG. 3, it is determined whether or not irregularities are detected on the secondary fixing belt surface 172a based on a signal input from the light receiving sensor 2312 of the irregularity detection unit 240. To do. If the unevenness is not detected, the process proceeds to step S107 to start the secondary fixing process, and if the unevenness is detected, the process proceeds to step S116. In step S116, the alarm unit 250 shown in FIG. 1 is instructed to display a warning message indicating that irregularities are detected on the secondary fixing belt surface 172a. The notification unit 250 includes a nonvolatile memory. When this instruction is input, a flag prepared in the nonvolatile memory is set. This flag remains set until instructed to end the display of the warning message. As long as this flag is set, the reporting unit 250 continues to display the warning message. Therefore, in this printer 100, even if the main power is turned off while the warning message is displayed on the alarm unit 250, the alarm message is displayed again on the alarm unit 250 when it is turned on next time. When the process of step S116 ends, the start of the lift-up process is instructed (step S117), and the process returns to step S101. In step S117, a lift-up mechanism (not shown) is instructed to start lift-up of the heating roll 1711 and the driven roll 174. By doing so, the surface of the secondary fixing belt 172 and the toner image on the recording paper that has been conveyed become non-contact, and the surface of the secondary fixing belt 172 is placed on the conveying roll 102 disposed between the primary fixing unit 140 and the secondary fixing unit 170. The secondary fixing process for the reached toner image on the recording paper is skipped.

  If it is determined in step S102 that the temporary avoidance operator is in an off state (not an on state), in step S121, whether or not a cleaning operator (not shown) is in an on state is determined. Determine. If the cleaning operator is off, the process returns to step S101. In the printer 100, when a warning message is displayed on the alarm unit 250, the temporary avoidance operator must be operated to be turned on or the cleaning operator should be operated to be turned on. The printer 100 does not operate. If the cleaning operator is in the ON state, the printer 100 is set to the above-described cleaning mode, and the control unit 110 instructs the start of the cleaning process (step S122). That is, as described above, the control unit 110 drives the transport roll 102 disposed in the vicinity of the take-out port of the sheet cassette 132 shown in FIG. 1, and sends the cleaning paper 132a into the transport path. During this cleaning process, the controller 110 does not issue an image forming process instruction or a primary fixing process instruction, but issues a rotation start instruction to the motor 210. The cleaning paper 132a reaches the contact point C of the secondary fixing unit 170 and passes through the secondary fixing unit 170 in a state of being in contact with the surface of the secondary fixing belt 172 that circulates. Thereafter, the start of the unevenness detection process is instructed in the same manner as in step S114 (step S123), and it is then determined whether unevenness is detected in the secondary fixing belt surface 172a, as in step S115 (step S124). If foreign matter such as dust is removed from the secondary fixing belt surface 172a by the cleaning process described above, the unevenness is not detected. In step S125, the display of the warning message is instructed, and the secondary fixing belt surface 172a is uneven. Is still detected, the process returns to step S101. When the determination process in step S124 is completed, an instruction to stop rotation is output from the control unit 110 to the motor 210.

It is a figure which shows an example of embodiment of the printer of this invention. FIG. 2 is a schematic enlarged view of a secondary fixing unit provided in the printer illustrated in FIG. 1 including its periphery. It is a figure which shows an example of the signal waveform output from the light receiving sensor shown in FIG. FIG. 2 is a view when the secondary fixing belt shown in FIG. 1 is viewed from the surface side. It is a flowchart which shows the processing routine of the control part in temporary avoidance mode. 3 is a flowchart showing a processing routine of image forming processing in the printer shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Printer 102 Conveyance roll 103 Registration roll 104 Conveyance belt 110 Control part 120 Image formation part 126 Primary transfer part 127 Secondary transfer roll 130 Medium supply part 131 Roll paper storage part 131a Roll paper 132 Sheet cassette 132a Cleaning paper 140 Primary fixing part 170 Secondary fixing unit 171 Heating and pressing roll 172 Secondary fixing belt 1721 Notch 173 Cooler 174 Driven roll 180 XY cutter 190 Sorter 210 Rotary encoder 220 Motor 230 Concavity and convexity detection unit 2311 Lens 2312 Light receiving sensor 232 Light source 240 Origin detection unit 241 Throw Optical element 242 Light receiving element 250 Reporting unit 300 Image input device

Claims (5)

In a printer that forms an image on a recording medium while conveying a sheet-shaped recording medium along a predetermined conveyance path,
An electrostatic latent image is formed on the surface of the image carrier, and a toner image is formed on the surface of the image carrier by adsorbing toner to the electrostatic latent image. An image forming unit for transferring the toner image to the image forming unit;
The recording medium is disposed on the downstream side of the image forming unit in the conveyance path, and circulates through a contact point in contact with the toner image on the recording medium. The surface in contact with the toner image has a flat endless shape and the recording medium. A fixing unit comprising a belt member having a circumferential length longer than the length of the medium, and having a function of obtaining a photographic image quality by glossing the surface of the toner image with the belt member; and fixing the toner image to the recording medium;
A sensor for detecting irregularities on the surface of the belt member ;
When unevenness is detected on the surface of the belt member by the sensor, the timing at which the surface of the surface where the unevenness is detected reaches the contact point, and the toner image on the recording medium at the contact point. And a control unit that performs control to relatively shift the timing of the arrival of the printer.   The fixing unit is disposed on the downstream side of the image forming unit in the conveyance path, and a primary fixing unit that fixes the toner image transferred to the recording medium by the image forming unit on the recording medium; Arranged on the downstream side of the primary fixing unit, the toner image fixed by the primary fixing unit is contacted with the toner image fixed by the primary fixing unit and circulates via a contact point that contacts the toner image fixed by the primary fixing unit. It has an endless belt member having a flat surface, and a secondary fixing portion that melts at least the surface portion of the toner image fixed by the primary fixing portion and adjusts the surface properties by the belt member. The printer according to claim 1.   The printer according to claim 1, further comprising a notification unit that reports that the unevenness is detected when the sensor detects unevenness on the surface of the belt member. When the sensor detects irregularities on the surface of the belt member , the apparatus includes a control unit that conveys a predetermined sheet-like object along the conveyance path and sends the sheet-like object to the contact point. The printer according to claim 1. In an image forming method for forming an image on a recording medium while conveying a sheet-like recording medium along a predetermined conveying path,
An electrostatic latent image is formed on the surface of the image carrier, and a toner image is formed on the surface of the image carrier by adsorbing toner to the electrostatic latent image. An image forming step of transferring the toner image to the
The toner image transferred onto the recording medium by the image forming step is fixed and circulated through a contact point in contact with the toner image, the surface in contact with the toner image is flat and the circumference is A fixing step of obtaining a photographic image quality by glossing the surface of the toner image with an endless belt member longer than the length of the recording medium;
A detection step of detecting irregularities on the surface of the belt member;
When unevenness is detected on the surface of the belt member by the detection step, the timing at which the portion of the surface where the unevenness is detected reaches the contact point, and the toner on the recording medium at the contact point An image forming method comprising: a temporary avoidance step for performing a control of relatively shifting a timing at which an image arrives .

Images