JP2010197668A - Image forming apparatus with color fading function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus with a color fading function which selectively fades color of an image of color fadable toner and thereby achieves reduction in temperature rise and power consumption for forming an image by the color fadable toner or normal toner. <P>SOLUTION: For paper 49 supplied from a paper feed cassette 22 to a paper feeding path 27, presence/absence of marks 54 on four corners is detected by an upper reading sensor 28 and a lower reading sensor 29, presence absence of a printed image 53 is continuously detected, a part to be faded of a first surface is faded by a heating roller 32 and a color fading optical head 33, a part to be faded of a second surface is faded by a heating roller 34 and a fading optical head 35, secondary transfer of a fadable toner image developed by an image forming unit 7S of the fadable toner or a normal toner image developed by image forming units 7M, 7C, 7Y of three-color toner of a subtractive color process is performed by an opposite part between a transfer belt 15 and a secondary transfer roller 37, fixed by a belt type thermal fixing device 38, returned to a conveyance unit 6 for double-side printing, or ejected to an ejection tray 41 as it is. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, the image of the erasable toner is erased entirely or selectively by a series of continuous processes, and an erasable image is formed by forming a new erasable toner or non-erasable toner image on the erasable portion. The present invention relates to an image forming apparatus with a color function.

  Decolorization using a decolorizable toner using a near-infrared photosensitive dye and erasing the paper on which an image is formed with this decolorable toner by irradiating light with a decoloring light source An apparatus is known as a prior art (see, for example, Patent Documents 1, 2, and 3).

  As a decolorizable toner used in these decoloring apparatuses, a toner using a near-infrared photosensitive dye is known as a prior art (see, for example, Patent Documents 4, 5, and 6).

  These erasing devices are devices in which a light source for erasing is incorporated into a conventional printer, and the above-described erasable toner is filled in a conventional toner cartridge or the like, printed, and printed. A printed material consisting of an image is obtained.

  Subsequently, at the time of erasing, the printed matter is heated by the heat from the heater incorporated in the apparatus, and the printed matter is irradiated with light from a light source to erase the color. In such an apparatus, a heater and a light source are installed in the paper path. When a paper already printed with the decoloring toner passes through the path, the paper is heated by the heater to emit light. It has a mechanism to irradiate.

  It has been disclosed that a temperature as high as 130 ° C. to 420 ° C. is applied as the temperature at the time of decoloring when the printed matter is heated by the heater (see, for example, Patent Document 7).

Japanese Patent Laid-Open No. 07-175379 Japanese Patent Application Laid-Open No. 07-199753 JP 05-289576 A JP 05-197195 A JP-A-12-314984 Japanese Patent Application Laid-Open No. 07-126559 Japanese Patent Laid-Open No. 12-081816

  However, although the above-mentioned light source is described in Patent Document 1 or Patent Document 3 as having a wavelength of about 830 nm or near 820 nm, the type and details of the light source are not disclosed, so it will be realized immediately. There is a problem that is difficult.

  Further, a halogen lamp is mainly used as the light source of the conventional decoloring apparatus. In general, it is well known that the wavelength distribution range of halogen lamps is wide. Therefore, the halogen lamp also emits a wavelength unnecessary for decoloring. There is a problem that problems such as a rise in temperature in the apparatus main body due to generation of light having a wavelength unnecessary for decoloring and large power consumption remain unsolved.

  Furthermore, as in the prior art of Patent Document 7, even when the printed matter is heated at a high temperature of 130 ° C. to 420 ° C., the temperature rise in the apparatus main body and large power consumption are required. This problem becomes a major problem in printer design, but there is a problem that this problem is left unsolved without any description.

  In order to solve the above-described problems, an image forming apparatus with a color erasing function according to the present invention is formed on a recording paper in an image forming apparatus with a color erasing function that performs image formation by an electrophotographic method and has a color erasing function. A sensor for detecting a non-erasable part of an image being erased, a erasing part comprising a heating part and a erasing light source for erasing a decolorable part based on detection by the sensor, and an erasable toner in the image erasing part Alternatively, the image forming unit includes an image forming unit that forms an image with non-decolorable toner.

  The decolorizable toner is, for example, a photosensitive toner containing a near-infrared photosensitive dye that is sensitive to light having a wavelength of 817 nm, and has, for example, characteristics of a glass transition point of 50.3 ° C. and a softening point of 106 ° C. Configured as follows.

  The erasing unit is, for example, a line type including a heating roller extending as the heating unit corresponding to the main scanning direction of the recording paper, and an LED (light emitting diode) array that emits near infrared rays as the decoloring light source. It is comprised so that it may be equipped with.

  In this case, the heating roller is composed of, for example, a roller incorporating a heater that heats the image paper surface of the decolorizable toner on the recording paper at a temperature not lower than the glass transition point and not higher than the softening point of the decolorable toner. For example, the temperature above the glass transition point and below the softening point is configured to be a temperature of 50 ° C to 100 ° C.

  The LEDs of the LED array of the erasing unit are configured to irradiate light having a wavelength distribution with a center wavelength of 810 nm to 850 nm and a half width of 50 nm or less, for example.

  In the image forming apparatus with a color erasing function, for example, the sensor detects the presence or absence of a color erasing mark printed on the recording paper or a predesignated image shape immediately after the recording paper starts to be conveyed. Then, the presence or absence of a non-erasable portion is detected, and the erasing unit is configured to selectively erase the erasable portion of the recording paper based on detection by the sensor.

  In this case, the selective erasing can be configured to be irradiation scanning in the main scanning direction of the recording paper by the erasing unit, for example.

  Further, the erasing unit may be configured to include, for example, a heating roller extending corresponding to the main scanning direction of the recording paper and a laser light irradiation device using a polygon mirror that emits near infrared rays. good.

  In the image forming apparatus with a decoloring function, the non-decolorable toner is composed of, for example, at least subtractive three-primary color toners capable of forming a full-color image.

  According to the present invention, the image of the erasable toner is completely or selectively erased by a series of continuous processes, and an image of a new erasable toner or non-erasable toner is formed on the erasable portion. Thus, there is an effect that it is possible to provide an image forming apparatus with a color erasing function with a small temperature rise and low power consumption.

It is sectional drawing which shows the structure of the image forming apparatus with a decoloring function which concerns on Example 1 of this invention. 5 is a wavelength comparison diagram with a halogen lamp for explaining light emission characteristics of a decoloring light head of a decoloring part in an image forming apparatus with a decoloring function. FIG. It is a figure which shows typically an example of the near-infrared irradiation state in the decoloring light head of a decoloring part. 6 is a chart showing the result of a decoloring experiment on a solid image of decolorable toner by a decoloring part heating roller and a decoloring light head. FIG. 3 is a diagram illustrating a mode of sheets stored in a sheet feeding cassette of a sheet feeding unit in an image forming apparatus with a color erasing function. (a) is a diagram showing a data table showing a general relationship between a sheet mark and a print image, and (b) is a flowchart of processing for printing on a reused sheet performed based on the data table. (a), (b) is a diagram showing a configuration and method for selectively erasing the image surface itself of the erasable toner. It is a figure which shows the example which uses a laser as another structural example of a decoloring light head.

  Hereinafter, embodiments of the present invention will be described in detail.

<Internal configuration of image forming apparatus with erasing function>
FIG. 1 is a cross-sectional view illustrating an internal configuration of an image forming apparatus with a color erasing function according to Embodiment 1 of the present invention.

  An image forming apparatus 1 with a color erasing function shown in FIG. 1 is an electrophotographic and secondary transfer type tandem color image forming apparatus, and includes an image forming unit 2, an intermediate transfer belt unit 3, a paper feeding unit 4, an erasing unit. It comprises a color part 5 and a transport unit 6 for duplex printing.

  The image forming unit 2 has a configuration in which four image forming units 7 (7M, 7C, 7Y, 7S) are arranged in a multistage manner from right to left in FIG. The three image forming units 7M, 7C, and 7Y on the upstream side (the right side in the figure) respectively generate monocolor images with magenta (M), cyan (C), and yellow (Y) color toners that are the three primary colors of subtractive color mixing. Form.

  Then, the image forming unit 7S forms a monochrome image with the erasable toner. If this image forming unit 7S is replaced with an image forming unit containing non-decolorable black toner, normal black (K), magenta (M), cyan (C), and yellow (Y) toners are used. Thus, an image forming apparatus that forms a non-decolorable full color image can be configured.

  Even in this state, the black color can be expressed by a mixture of three colors of magenta (M), cyan (C), and yellow (Y), so there is no problem in using it as a normal full-color image forming apparatus.

  Each of the image forming units 7 has the same configuration except for the color of the toner stored in the toner container (toner cartridge). Therefore, the configuration of the image forming unit 7S for the decolorizable toner (S) will be described below as an example.

  The image forming unit 7 includes a photosensitive drum 8 at the bottom. The photosensitive drum 8 has a peripheral surface made of, for example, an organic photoconductive material. A cleaner 9, a charging roller 11, an optical writing head 12, and a developing roller 14 of the developing device 13 are arranged around the periphery of the photosensitive drum 8.

  In the upper toner container, the developing unit 13 is one of magenta (M), cyan (C), yellow (Y), and decolorizable toner (S) as indicated by M, C, Y, and S in the figure. And a toner replenishing mechanism for the lower part is provided in the intermediate part.

  Further, the developing roller 14 is provided in the lower side of the developing unit 13 at the side opening, and a toner stirring member, a toner supply roller for supplying toner to the developing roller 14, and a toner layer on the developing roller 14 are fixed layers. It has a doctor blade that regulates the thickness.

  The intermediate transfer belt unit 3 has an endless transfer belt 15 extending in a flat loop shape from substantially the left and right sides of the figure at the center of the main body, and the transfer belt 15 is stretched over the transfer belt 15. A driving roller 16 and a driven roller 17 are provided to circulate and move the belt 15 counterclockwise in the figure.

  The transfer belt 15 transfers the toner image directly onto the belt surface (primary transfer) and conveys the toner image to the transfer position to the paper for further transfer (secondary transfer). The whole is called an intermediate transfer belt unit.

  The intermediate transfer belt unit 3 includes a belt position control mechanism 18 in the loop of the flat loop-shaped transfer belt 15. The belt position control mechanism 18 includes a primary transfer roller 19 made of a conductive foam sponge that presses against the lower peripheral surface of the photosensitive drum 8 via the transfer belt 15.

  The belt position control mechanism 18 has three primary transfer rollers 19 corresponding to the three image forming units 7M, 6C, and 6Y of magenta (M), cyan (C), and yellow (Y) as a vertical support shaft. Rotate to the center with the same period.

  The belt position control mechanism 18 rotates and moves one primary transfer roller 19 corresponding to the image forming unit 7S of the decolorable toner (S) with a rotation movement period different from the period of the three primary transfer rollers 19. As a result, the transfer belt 15 is moved away from the photosensitive drum 8.

  That is, the belt position control mechanism 18 changes the position of the transfer belt 15 of the intermediate transfer belt unit 3 to a decoloring / non-decoloring mixed color mode (all four primary transfer rollers 19 are in contact with the transfer belt 15). Monochrome mode with erasable toner (only the primary transfer roller 19 corresponding to the image forming unit 7S is in contact with the transfer belt 15) and all non-transfer modes (all four primary transfer rollers 19 are separated from the transfer belt 15). ).

  In the intermediate transfer belt unit 3, a belt cleaner unit is disposed further upstream of the uppermost image forming unit 7M in the belt moving direction on the upper surface, and is flat so as to be along an appropriate position on the lower surface. A thin waste toner collecting container 21 is detachably disposed.

  The paper feed unit 4 includes a single paper feed cassette 22, and a paper take-out roller 23, a feed roller 24, a separating roller 25, and standby conveyance are provided near the paper feed port (right side of the drawing) of the paper feed cassette 22. A roller pair 26 is disposed.

  An upper reading sensor 28 and a lower reading sensor 29 are arranged between the feeding roller 24 and the separating roller 25 and the standby conveying roller pair 26 so as to sandwich the sheet feeding path 27 from above and below. Each of the upper reading sensor 28 and the lower reading sensor 29 is a line type sensor having a length corresponding to the maximum conveyance width of the sheet.

  The erasing unit 5 is disposed following the standby conveyance roller pair 26 on the downstream side in the sheet conveyance direction (vertically upward in the drawing). The decoloring unit 5 includes a heating roller 32 of the first surface decoloring unit, a decoloring light head 33, and a heating roller 34 of the second surface decoloring unit, which are arranged at two locations above and below so as to sandwich the vertical conveyance path 31 from both sides. A decoloring light head 35 is provided.

  A conveyance roller pair 36 is disposed downstream of the erasing unit 5 (upward in the figure, the same applies hereinafter), and a secondary transfer roller 37 that presses against the driven roller 17 via the transfer belt 15 is disposed immediately downstream thereof. Thus, a secondary transfer portion to the paper is formed.

  A belt-type heat fixing device 38 is disposed downstream of the secondary transfer unit, and a pair of carry-out rollers for carrying the fixed sheet out of the belt-type heat fixing device 38 further downstream of the belt-type heat fixing device 38. 39 and a discharge roller pair 42 for discharging the discharged paper to a discharge tray 41 formed on the upper surface of the apparatus.

  The duplex printing conveyance unit 6 includes a return start path 43a branched from the intermediate conveyance path between the carry-out roller pair 39 and the discharge roller pair 42 to the right lateral direction in the figure, and then an intermediate vertical return path 43b bent downward. Further, a terminal return path 43c is formed which is bent in the left lateral direction opposite to the above and finally reverses the return sheet.

  The duplex printing transport unit 6 includes four pairs of return rollers 44a, 44b, 44c, and 44d disposed in the middle of the return paths. The exit of the end return path 43 c communicates with a conveyance path to the standby conveyance roller pair 26 corresponding to the sheet feeding from the sheet feeding cassette 22 of the sheet feeding unit 4.

  A cleaning unit 45, a take-in roller 46, and a pressure roller 47 for pressing the transfer belt 15 against the take-in roller 46 with an appropriate pressure are disposed on the upper surface of the intermediate transfer belt unit 3.

  The cleaning unit 45 comes into contact with the upper surface of the transfer belt 15 to scrape and remove the waste toner, and the take-in roller 46 takes over the waste toner removed by the cleaning unit 45 and is not shown in FIG. The waste toner thus collected is fed into a waste toner collecting container 21 by a conveying screw.

<Method for producing decolorizable toner>
Here, in the present example, a method for producing a decolorable toner that is housed and used in the image forming unit 7S will be described. First, 1.5 parts by mass of an infrared photosensitive dye “IRT” (manufactured by Showa Denko) having a sensitivity of 817 nm, 7.5 parts by mass of an organic boron compound decoloring agent “P3B” (manufactured by Showa Denko), and a polyester bond for toner. 87 parts by weight of resin (made by Kao), 1.5 parts by weight of negative charge regulator “LR-147” (manufactured by Nippon Carlit), 2.5 parts by weight of Carnauba WAX 1 powder (imported by Kato Yoko Co., Ltd.) It was put into a mixer (Mitsui Mine) and mixed.

  Next, the above mixture was melt kneaded with a twin-screw kneader. The kneaded material thus obtained was roughly crushed with a Rotoplex (manufactured by Hosokawa Micron) to obtain a coarsely crushed material. The coarsely pulverized product was pulverized by an impact pulverizer so that the average particle size became 9 μm. One part by mass of silica “RA972” (manufactured by Nippon Aerosil Co., Ltd.) as an external additive was added to 100 parts by mass of the pulverized product obtained by this pulverization, and mixed with a Henschel mixer to obtain a decolorizable toner. This decolorable toner had a glass transition point of 50.3 ° C. and a softening point of 106 ° C.

<Configuration of heating roller of erasing section>
The decoloring heater built in the heating rollers 32 and 34 shown in FIG. 1 is composed of a halogen lamp. The wavelength distribution of the halogen lamp is wide and includes a wide wavelength distribution of near infrared rays, so that it is suitable as a heat source for heat radiation.

  In this example, the temperature of the heat radiation of the halogen lamp can be varied, and the heating temperature for the paper surface to be decolored can be set in the range of 50 ° C to 100 ° C. This temperature range is set based on the result of a decolorization test described later performed for the decolorizable toner produced in this example and having a glass transition point of 50.3 ° C. and a softening point of 106 ° C. It was done.

<Configuration of erasing light head of erasing section>
FIG. 2 is a wavelength comparison diagram with a halogen lamp for explaining the emission characteristics of the decoloring light heads 33 and 35 of the decoloring section 5 in the above-described configuration. As shown in the figure, the halogen lamp has a wide wavelength distribution ranging from about 400 nm to over 1100 nm. For this reason, as described above, there are problems such as a rise in temperature in the apparatus main body due to generation of light having a wavelength unnecessary for decoloring and large power consumption.

  On the other hand, the decoloring heads 33 and 35 used in the first embodiment are constituted by LED arrays. As shown in FIG. 2, the LED has a very narrow wavelength distribution. That is, the LED is considered to generate very little light having a wavelength unnecessary for decoloring depending on the selection. Also, LEDs are well known for their high efficiency of electricity / light conversion and not generating large heat.

  Therefore, in order to cope with an infrared photosensitive dye having a sensitivity of 817 nm, a decoloring light head is conceived in which LED array chips having a central wavelength of 830 nm having a wavelength distribution with a half width of 50 nm or less are arranged in the longitudinal direction of the head. It was.

  FIG. 3 is a diagram schematically illustrating an example of a state of near-infrared irradiation in the decoloring light head 33 (or 35, the same applies hereinafter) of the decoloring unit 5. As shown in FIG. 3, the decoloring light head 33 is configured by arranging LED array chips 48 in the longitudinal direction of the head. The distance between the paper 49 and the LED array chip 48 is about 20 mm.

  Thus, since the distance between the paper 49 and the LED array chip 48 is about 20 mm, which is relatively long, the irradiation light 51 from the decoloring light head 33 extends radially and the irradiation range 52 on the paper 49 is expanded. While the paper 49 is transported in the direction indicated by the arrow a (the color erasing unit 5 is passed), the main scanning line portion of the paper 49 receives the decoloring light without any interruption corresponding to the wide irradiation range 52. Irradiated.

  In general, LED lights with a center wavelength close to 820 nm, which is the absorption wavelength of the dye, are superior. However, as an actual decoloring characteristic, the half width is considered even if the center wavelength is 850 nm. Then, if sufficient light emission intensity is obtained, there is no problem as a decoloring characteristic.

  That is, it can be seen that the LED light having a center wavelength of 810 nm to 850 nm is suitable for decoloring. Also in this case, it is preferable to select one having a wavelength distribution with a half width of 50 nm or less as described above.

  In particular, an LED lamp having a center wavelength of 850 nm is one of the most popular LED lamps in the near-infrared region, and is advantageous in terms of device design in terms of energy efficiency and cost.

  For example, as an example of an LED lamp with a center wavelength of 850 nm, there is “OP6-8510HP2” using a high-intensity reflective LED, a center wavelength of 850 nm, Δλ40 nm, Po (light output) = 50 mW @ 350 mA, and the like. Such an LED lamp can also be used for the above-described decoloring without any trouble.

  As described above, according to the configuration of the image forming apparatus with the color erasing function according to the first embodiment, the conventional color erasing light source is changed from the halogen lamp to the LED, and the heating temperature for color erasing is changed to the glass transition of the color erasing toner. Above the point and below the softening point.

  As a result, “the power consumption can be reduced”, “the irradiation with a single wavelength light source with a half-width of 50 nm does not affect the heat generation in the apparatus”, and “the speed of the decoloring process is increased by heating and light”. effective.

  As a result, the entire erasing apparatus can be reduced in size. Further, since the erasing apparatus is small, it is possible to design a small-sized image forming apparatus with a erasing function as shown in FIG. 1 by incorporating the erasing apparatus into a small printer.

<Decoloration test of decolorable toner>
Subsequently, in order to test the decoloring property of the above-described decoloring toner, the image forming unit of the page printer N3500 (manufactured by Casio Computer Co., Ltd.) is filled with the decoloring toner obtained as described above. A solid image with a decolorable toner was formed on an appropriate sheet.

  Here, since the N3500 is a quadruple tandem development system, it is possible to mount four image forming units as developing units. However, in this test, only one image forming unit is mounted, and this one An image forming unit was accommodated in the image forming unit to form an image.

  Next, N3500 was remodeled, and the decoloring part 5 was prepared in the vertical conveyance path 31 as a decoloring apparatus as shown in FIG. The decoloring optical heads 33 and 35 for decoloring shown in FIG. 1 are line-shaped heads extending in the main scanning line direction of the paper as described above. Further, the temperature of the decoloring heater (halogen lamp) built in the heating rollers 32 and 34 can be varied.

  Subsequently, the decoloring test was performed using the paper on which the solid image with the decolorable toner obtained earlier was formed. First, a plurality of sheets on which a solid image is formed with the erasable toner is stored in the sheet feeding cassette 22. Then, the paper is passed through the erasing unit 5.

  Note that when the erasable toner is printed on the white paper, which is the preliminary printing of this test, the function of the erasing unit 5 is stopped, and transfer after paper feeding and development is performed in the same procedure as in normal toner printing. The toner on the belt is printed in the order of secondary transfer, fixing, and discharging.

  When the paper used for the erasing test is passed through the erasing unit 5, the development by the image forming unit is stopped. Therefore, the secondary paper is fed to the paper after the erasing unit 5 is passed through. The decolorizable toner is not transferred at the transfer portion.

  Further, in order to correspond to a glass transition point of 50.3 ° C. and a softening point of 106 ° C. of the previously obtained decolorizable toner used in this test, the heater temperature of the heating roller was changed from 40 ° C. to 50 ° C. from the off state. An experiment was conducted to evaluate the decoloring degree of a solid image with a decolorable toner by sequentially increasing the temperature to 60 ° C., 60 ° C., 80 ° C., 100 ° C., 110 ° C., and 120 ° C.

  FIG. 4 is a chart showing the results of a decoloring experiment on a solid image of decolorable toner using a decoloring light head composed of an LED having a central wavelength of 830 nm and a heating roller in which the heater temperature is sequentially increased from OFF to 40 ° C. to 120 ° C. It is.

  “×” shown in the right column of the chart of FIG. 4 indicates an evaluation when the color is hardly erased, “△” indicates an evaluation when a certain amount of color is erased, and “◯” indicates completely. The evaluation when the color is erased is shown. This decolorization degree was measured by x-rite (manufactured by x-rite).

  As shown in the evaluation of the experimental results shown in FIG. 4, when an LED having a center wavelength of 830 nm having a wavelength distribution with a half width of 50 nm or less is used for the decoloring head, the heater temperature of the heating roller is 60 ° C. to 100 ° C. It turns out that it works sufficiently effectively for decoloring in a range.

  If energy saving is important, erasing using only the erasing light head without using a heating roller is more effective. However, when importance is attached to the decoloring speed, heating the decolorable toner by the heating roller is more effective.

  As for the heater temperature of the heating roller, the decoloring effect is seen from about 60 ° C. on the paper surface as described above, but the decoloring speed increases as the temperature increases to 80 degrees and 100 degrees. That is, the entire processing speed including the later printing can be increased. This heating may be controlled on the apparatus main body side or may be selected by the user.

  According to the chart of FIG. 4, the color erasure is more advanced when the temperature is higher than the glass transition point of the color erasable toner and lower than the softening point. It can be presumed that this is because the movement of molecules becomes relatively free by heat, and the dye and the decoloring agent are easily brought into contact. Further, when the temperature is equal to or higher than the softening point, it can be presumed that the toner resin sinks into the paper, and the arrival of the LED light becomes insufficient, resulting in a decoloring failure.

  The decoloring light heads 33 and 35 and the heating rollers 32 and 34 shown in FIG. 1 of this example are based on the above experiment and evaluation results, and finally the LED having a wavelength of 830 nm and the heater temperature of 60 ° C. to 100 ° C. It is comprised so that it may become a range.

  Further, according to the subsequent experiments, it has been found that good results can be obtained even with about 4 parts by mass of the color erasing agent for producing the color erasing toner.

<Embodiment 1 of Image Forming Apparatus with Decoloring Function>
Here, in the image forming apparatus with a decoloring function having the above-described configuration, the image of the decolorable toner is completely or selectively decolored by a series of continuous processes, and a new decolorable toner or A specific process for forming an image with non-decolorable toner will be described.

  FIG. 5 is a view showing a mode of the paper 49 accommodated in the paper feed cassette 22 of the paper feed unit 4 shown in FIG. As shown in FIG. 5, at the four corners of the paper 49, marks 54 are printed with the erasable toner indicating that the print image 53 of the erasable toner is formed on the paper 49.

  In this example, the marks 54 are printed at the four corners of the paper 49 because the marks 54 are at the four corners of the paper 49, and the reusable paper (decolorable toner or non-erasable toner prints the printed image. This is because there is no restriction in mounting the paper feed cassette 22 containing the formed paper (which is now unnecessary) in the apparatus main body.

  That is, the user simply installs the paper feed cassette 22 containing paper of a required size into the apparatus main body without considering the paper orientation, and can feed the paper regardless of the orientation. This is because the mark 54 at the leading end of the paper 49 can be read by the upper reading sensor 28 or the lower reading sensor 29 immediately downstream from the paper feed port of the cassette 22.

  Note that the mark 54 may be a circle or a simple number as shown in the figure, or a line may be added one by one each time reprinting is performed. In short, any mark may be used as long as the use status of the paper 49 can be read by the upper reading sensor 28 or the lower reading sensor 29.

  Depending on the usage situation of the paper 49, that is, whether the printed matter is simply erasable toner, whether the usage status history of the front and back of the paper is used, etc. It is preferable to print with a combination of a plurality of characters, a combination of two-digit numbers, and other symbols.

  The mark 54 is for distinguishing between the paper on which the print image is formed with the decolorable toner and the paper on which the print image is formed with the non-decolorable toner. It is applied to the paper on which the image is formed, but is not applied to the paper on which the image of the non-erasable toner is formed.

  FIG. 6A is a diagram showing a data table showing a general relationship between the mark 54 of the paper 49 and the print image stored in the storage device of the control unit (not shown). ) Is a flowchart of a process for printing on a reused sheet performed based on the data table.

  In this process, the reusable paper shown in FIG. 5 is stored in the paper feed cassette 22 of the paper feed unit 4 shown in FIG. 1, and power is input to the image forming apparatus 1 with the erasing function. The operation is started by driving all internal devices of the image forming apparatus 1 with a color erasing function under the control.

  Further, in this example, in order to explain the basic processing for printing on reused paper, the mark 54 is a simple form of a circle indicating whether or not the paper 49 is a printed matter of decolored toner. To do.

  In FIG. 6B, a paper feed process is first performed (step S1). In this process, the paper is taken out from the paper cassette 22 by the paper take-out roller 23, and one paper 49 is sent out to the paper feed path 27 by the cooperation of the feed roller 24 and the separating roller 25. Note that the image information of the normal print image is notified to the image forming unit 2 at the stage of the paper feed process.

  Subsequently, an image and a mark are discriminated (step S2). In this process, the upper reading sensor 28 or the lower reading sensor 29 detects the presence or absence of the mark 54 printed at the leading portion of the paper 49 sent out to the paper feeding path 27.

  Here, the first setting of single-sided printing or double-sided printing, and the setting of whether or not the second side, which is not printed even if it is single-sided printing of the first side, is also erased for confidentiality. The detection method of the presence or absence of the mark 54 by the upper reading sensor 28 or the lower reading sensor 29 differs depending on the type.

  In the case of duplex printing, or when confidentiality is maintained on a surface that is not printed even in single-sided printing, both the upper reading sensor 28 and the lower reading sensor 29 detect the presence or absence of the mark 54. In the case of single-sided printing, when it is not necessary to maintain confidentiality on the non-printed side, only the upper reading sensor 28 detects the presence or absence of the mark 54.

  Hereinafter, in order to simplify the description, a case will be described in which single-sided printing is not necessary and it is not necessary to perform confidentiality preservation on a non-printed side.

  In the mark determination at step S2, if there is a mark, it corresponds to “1” in FIG. 6 (a). In this case, erasing is performed according to the processing operation instruction shown on the right side of the data table regardless of the presence or absence of an image. And print. In this case, prior to decoloring, first, information such as the mark printing format indicating the reuse status and the setting of the toner used is determined, and this information is notified to the image forming unit 2 (step S3).

  Next, a decoloring operation is performed (step S4). In this process, as described above, since it is a single-sided printing and it is not necessary to keep the non-printing side secret, only the heating roller 32 and the decoloring light head 33 of the first surface decoloring part are driven. The first surface of the paper 49 (the surface facing upward in the paper feed cassette 22) is erased.

  If it is necessary to keep the non-printed side secret even in the case of single-sided printing, not only the heating roller 32 and the erasing light head 33 of the first side erasing unit but also the second side based on the instruction. It goes without saying that the heating roller 34 and the erasing light head 35 in the surface erasing part also participate in the erasing operation.

  Subsequently, a printing operation is performed (step S5). In this process, the toner image is formed on the first surface of the paper 49 that has been decolored in the process of step S4 in the secondary transfer portion formed by the secondary transfer roller 37 that is in pressure contact with the driven roller 17 via the transfer belt 15. Is transferred, the toner image is fixed by the belt-type heat fixing device 38, and the sheet 49 on which the toner image is fixed is discharged onto the discharge tray 41.

  In this printing process, before entering the decoloring operation, information necessary for printing is notified to the image forming unit 2 based on the information read by the upper reading sensor 28, and the image designated at that time is designated. Since the forming unit 7 performs development on the photosensitive drum 8 and primary transfer to the transfer belt 15, and the transfer belt 15 conveys the primary transfer toner image toward the secondary transfer unit, printing on the paper 49 is performed. The operation can be executed only by a short pause at the pair of standby conveyance rollers 26.

  If the image is not marked in step S2, the upper reading sensor 28 detects whether or not the print image 53 is further printed on the paper surface. When the image 53 is detected, it corresponds to “2” in FIG.

  Since this is an image formed on an unmarked paper, this image is an image printed with non-erasable toner. Therefore, the paper cannot be erased and cannot be reused. In this case, according to the instruction of the processing operation shown on the right side of the row “2” of the data table, neither erasing nor printing is performed, a warning sound indicating that printing is impossible is issued (step S6), and the paper is discharged .

  Although only the paper discharge tray 41 is shown as the paper discharge unit in FIG. 1, for example, a paper conveyance direction switching flap is disposed downstream of the paper discharge roller pair 42 and another paper discharge tray is disposed downstream thereof. In this way, the non-printable paper can be discharged to a paper discharge tray different from the paper discharge tray 41.

  Further, when there is no mark in the determination of the image and the mark in step S2 and there is no image in the determination of the presence or absence of the next print image 53, this corresponds to “3” in FIG. This indicates that it is a normal white paper.

  In this case, according to the instruction of the processing operation shown on the right side of the row “3” of the data table, the decoloring operation is turned off in order to avoid unnecessary decoloring (step S8), and the printing operation of step S5 is immediately started. enter.

  In this printing process, the normal toner (which becomes non-decolorable) and the decolorable toner are selectively used regardless of whether the process proceeds to step S5 after the decoloring process in step S4 or the process proceeds from step S8. Can be used for

  Depending on the usage status of the printed document, use normal toner for printing documents for long-term storage, and use decolorable toner for printing documents that may be reused after use. A normal toner and a decolorizable toner may be selectively used.

  Although the processing operation is not particularly illustrated, in the case of double-sided printing, after the above-described single-sided printing, the sheet is passed through the double-sided printing transport unit 6 and printing on the second side is performed.

  In this case, the information acquisition result of the information on the first side and the information on the second side of the paper read by the upper reading sensor 28 and the lower reading sensor 29, and the same data table shown in FIG. Thus, the same processing as shown in FIG. 6B is determined.

  In this case, the heating roller 32 and the decoloring light head 33 of the first surface decoloring part are driven when printing the first surface, but the heating roller 34 and the decoloring light head 35 of the second surface decoloring part are driven. May be determined at the same time when printing the first side or when the paper is returned via the duplex printing conveyance unit 6.

  As described above, according to the first embodiment of the image forming apparatus 1 with a color erasing function according to the first example, since the plain paper printed with the color erasable toner is reused, there are many economic advantages for the user. Further, since the erasable toner and the normal toner can be selectively used, there is an advantage that the amount of the erasable toner can be reduced.

  Further, since the normal toner can be used, it is possible to deal with important documents such as official documents. In addition, since erasing and printing are performed at the same time, and the history of paper usage can be managed, paper that is waiting to be erased can be smoothly erased (erased, the same shall apply hereinafter) to become a new printed matter, thereby improving confidentiality. Get higher.

  In addition, since marks are made at the four corners of the paper, it can be used without worrying about the orientation of the front and back of the paper and the left and right sides, and is easy to use. In addition, since the mark has various types of information on both the front and back sides, it is possible to adjust erasing conditions such as erasing only one side or erasing both sides.

  In addition, since the determination of the presence / absence of the mark and the presence / absence of the image is performed immediately after the sheet feeding, it is possible to quickly determine whether or not the sheet can be reused and to speed up the processing. In addition, in the case of single-sided printing using double-sided printed paper, it is possible to erase unnecessary surfaces at the same time as necessary, which is effective for preventing leakage of unnecessary information.

  Similarly, in the case of single-sided printing using paper that has already been printed on both sides, it is possible to avoid erasing unnecessary surfaces, so it is possible to reduce power consumption by operating the decoloring mechanism only on surfaces that require decoloring. .

<Embodiment 2 of image forming apparatus with decoloring function>
In the first embodiment, the paper on which the image of the erasable toner is printed is selectively used as the reuse paper, and the entire image surface is erased (decolored). Is not limited to this.

  FIGS. 7A and 7B are diagrams showing a configuration and method for selectively erasing the image surface itself of the erasable toner. As shown in FIGS. 7A and 7B, the decoloring light head 33 (or 35, the same hereinafter) of this example has a plurality of small LED array chips 48 arranged in the direction of the main scanning line.

  As a result, similar to the LED head used for exposure of the photosensitive drum during the development process, each LED is selectively turned on to erase any position of the sheet 49 conveyed as indicated by the arrow b. It becomes possible to do.

  FIG. 7A shows a state in which the print image 53 is simply erased entirely while the paper 49 is being conveyed in the direction of the arrow b to form a blank sheet-erased portion 55. FIG. 7B also shows a state in which only the half surface of the print image 53 is erased while the paper 49 is being conveyed in the direction of the arrow b, and the blank color erasable portion 55 is formed on the other half surface. Yes.

  FIGS. 7 (a) and 7 (b) show that the image surface itself of the erasable toner can be selectively erased so that the entire surface and the half surface can be easily compared and contrasted. Depending on the lighting timing of the LED, not only control in the main scanning line direction shown in FIG. 7B but also selective erasing control in the sub scanning line direction (arrow b direction) is possible.

  By making the LED chip itself a small thing, the selectivity of the decoloring area becomes higher definition. LED with a central wavelength of 850 nm, “SMT850N”, AA = 40 nm, Po = 20 mW, LED of about 3 mm mouth is arranged in the main scanning direction, and the selectivity is achieved by monochromatic light irradiation from a distance of about several mm Becomes even higher definition.

  Further, the LED arrangement interval is narrowed and mounted at high density, and as shown in FIGS. 7 (a) and 7 (b), the light emitted from the LED is narrowed down by the self-fox lens 54, so that selective erasure can be performed with higher definition. Is also possible.

  Using this erasing mechanism, for example, the border of a format such as a form is printed with normal toner, and the content information is printed with erasable toner. By selectively erasing compared to a format in which information is erased and reprinted, selective erasing can be performed using only a erasable toner.

  Using the method of this example, a form created with an image forming apparatus with a simple erasing function equipped with only erasable toner can be used within the border of the form while saving the amount of erasable toner used. Only the contents of can be rewritten.

<Another configuration example of the decoloring light head>
In the description so far, a linear LED light source has been used as the light source for erasing. However, in terms of selective erasing in the main scanning line direction and efficient generation of near infrared rays, A laser can also be used as the light source.

  FIG. 8 is a diagram illustrating an example in which a laser is used as another configuration example of the decoloring light head. As shown in FIG. 8, the decoloring head of this example is basically the same in principle as a semiconductor laser generally used for exposure of a laser printer.

  That is, this decoloring light head includes a laser light oscillator 56, a collimator 57, a polygon mirror 58, an fθ lens 59, and a cylinder lens 61. The laser beam oscillator 56 oscillates a laser beam as indicated by an oscillation waveform 62.

  In the figure, the laser light oscillated from the laser light oscillator 56 in accordance with the basic timing of erasing (video signal) passes through an optical system such as a collimator 57, a polygon mirror 58, an fθ lens 59, a cylinder lens 61, and the like. A state in which the laser beam reaches the paper surface of the paper 49 through the optical paths indicated by c, d, e, f, and g and is irradiated once for each main scanning unit 63 for each surface of the polygon mirror 58 is shown. ing.

  Each time laser irradiation is performed for each main scanning unit 63, the fθ lens 59 and the cylinder lens 61 are moved by a predetermined angle, and laser light is emitted to a target point on the main scanning line of the paper 49 moving in the arrow b direction. Irradiation can be performed. That is, also in this case, a desired portion on the entire surface of the paper can be selectively erased.

  The present invention can be used for an image forming apparatus with a color erasing function that has a small temperature rise and low power consumption.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus with erasing function 2 Image forming part 3 Intermediate transfer belt unit 4 Paper feed part 5 Erasing part 6 Duplex printing conveyance unit 7 (7M, 7C, 7Y, 7S) Image forming unit 8 Photosensitive drum 9 Cleaner DESCRIPTION OF SYMBOLS 11 Charging roller 12 Optical writing head 13 Developing device 14 Developing roller 15 Transfer belt 16 Drive roller 17 Driven roller 18 Belt position control mechanism 19 Primary transfer roller 21 Waste toner collection container 22 Paper feed cassette 23 Paper take-out roller 24 Feed roller 25 Separation roller 26 Standby conveyance roller pair 27 Paper feed path 28 Upper reading sensor 29 Lower reading sensor 31 Vertical conveyance path 32, 34 Heating roller 33, 35 Decoloring light head 36 Conveying roller pair 37 Secondary transfer roller 38 Belt type heat fixing device 39 Unloading roller pair 41 Discharging tray 42 Discharging roller pair 43a Return start path 43b Intermediate vertical return path 43c End return path 44a, 44b, 44c, 44d Return roller pair 45 Cleaning unit 46 Capture roller 47 Press roller 48 LED array chip 49 Paper 51 Irradiation light 52 Irradiation range 53 Print image 54 Cellfox lens 55 Decoloring section 56 Laser transmitter 57 Collimator 58 Polygon mirror 59 fθ lens 61 Cylinder lens 62 Transmission waveform 63 Main scanning section during decoloring

Claims (11)

In an image forming apparatus with a decoloring function that performs image formation by an electrophotographic method and has a decoloring function,
A sensor for detecting a non-erased portion of the image formed on the recording paper;
An erasing unit comprising a heating unit and a erasing light source that erases a decolorable portion based on detection by the sensor,
An image forming unit for forming an image with an erasable toner or a non-erasable toner on an image erasure part by the erasure unit;
An image forming apparatus with a color erasing function.   2. The image forming apparatus with a color erasing function according to claim 1, wherein the color erasable toner is a photosensitive toner containing a near infrared photosensitive dye having sensitivity to light having a wavelength of 817 nm.   3. The image forming apparatus with a decoloring function according to claim 2, wherein the decolorizable toner has characteristics of a glass transition point of 50.3 ° C. and a softening point of 106 ° C.   The erasing unit is a line type light composed of a heating roller that extends as the heating unit corresponding to the main scanning direction of the recording paper, and an LED (light emitting diode) array that emits near infrared rays as the decoloring light source. The image forming apparatus with a decoloring function according to claim 1, further comprising an irradiation device.   The heating roller is a roller having a built-in heater that heats the image paper surface of the decolorizable toner on the recording paper at a temperature not lower than the glass transition point and not higher than the softening point of the decolorable toner. The image forming apparatus with a decoloring function according to claim 4.   The image forming apparatus with a color erasing function according to claim 5, wherein the temperature not lower than the glass transition point and not higher than the softening point is a temperature of 50C to 100C.   5. The image forming apparatus with a decoloring function according to claim 4, wherein the LEDs of the LED array are LEDs that emit light having a wavelength distribution with a center wavelength of 810 nm to 850 nm and a half-value width of 50 nm or less.   The sensor detects the presence / absence of a non-erased portion by detecting the presence / absence of a decolored mark printed on the recording paper or a shape of a pre-designated image immediately after the start of conveyance of the recording paper, The image forming apparatus with a color erasing function according to claim 1, wherein the color erasable portion of the recording paper is selectively erased based on detection by the sensor.   9. The image forming apparatus with a decoloring function according to claim 8, wherein the selective erasing is irradiation scanning in the main scanning direction with respect to the recording paper by the erasing unit.   2. The erasing unit includes a heating roller extending corresponding to a main scanning direction of the recording paper, and a laser light irradiation device using a polygon mirror that emits near infrared rays. The image forming apparatus with a decoloring function as described.   2. The image forming apparatus with a decoloring function according to claim 1, wherein the non-decolorable toner is at least a subtractive color primary toner capable of forming a full color image.