JP2006306584A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing any excessive cost from being incurred on a user and preventing slowdown in the printing speed of a resin sheet without increasing the cost by using a multi-stage discharge tray. <P>SOLUTION: The image forming device comprises at least two discharge units 13, a branching means F to branch sheets to be discharged into each discharge unit, a driving means to operate the branching means F, and a branch control means to control the operation of the branching means F. The sheets are resin sheets, and when the resin sheets are continuously printed, the resin sheets are successively branched and discharged one by one to the discharge units 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, and a composite device for discharging discharged media such as plain paper and resin sheets to two or more discharge trays. .

  Conventionally, as shown in FIG. 10, there is a full-color image forming apparatus including four image carriers.

  The color image forming apparatus shown in FIG. 1 includes four photosensitive drums 1 (1a, 1b, 1c, 1d), and the photosensitive drums are sequentially arranged around each photosensitive drum 1 in accordance with the rotation direction. Charging means 2 (2a, 2b, 2c, 2d) for uniformly charging the surface of the drum 1, and exposure means 3 (3a, 2a) for forming an electrostatic latent image on the photosensitive drum 1 by irradiating a laser beam based on image information 3b, 3c, 3d), developing means 4 (4a, 4b, 4c, 4d) for making the toner image adhere to the electrostatic latent image on the photosensitive drum 1 to be visualized, and toner on the photosensitive drum 1 Transfer means (transfer rollers) 5 (5a, 5b, 5c, 5d) for transferring an image to a sheet, and cleaning means 6 (6a, 6b, 6c, 6) for removing post-transfer toner remaining on the surface of the photosensitive drum 1 after transfer. 6d) etc. are arranged to form an image Means is configured.

  Here, the photosensitive drum 1, the charging unit 2, the developing unit 4, and the cleaning unit 6 for removing the toner are integrally formed into a cartridge to form a process cartridge 7 (7a, 7b, 7c, 7d).

  Further, the sheet fed from the sheet supply unit 8 is conveyed to the image forming means by the conveyance unit 9 constituted by a transfer conveyance belt 9a and the like, and the color toner images are sequentially transferred to record the color image on the sheet. Thereafter, the image is fixed by the fixing unit 10 and discharged to the discharge stacking unit 13 by the discharge roller 12.

  In double-sided printing, the sheet S is conveyed to the double-sided conveyance path 15 by reversing the discharge roller 12 before the sheet S is fixed by the fixing unit 10 and discharged by the discharge roller 12. The sheet S conveyed to the double-sided conveyance path 15 passes through the oblique feeding roller 16 on the front surface of the apparatus main body, and is conveyed vertically downward to the U-turn roller 17, and is again conveyed by the U-turn roller 17 and the registration roller 8d. 9 and image formation is performed on the second surface.

  Here, in general, one of the problems in printing on resin sheets is sticking between resin sheets.

  The toner image transferred to the sheet is heated and pressurized by the fixing means 10, so that the toner melts and is fixed to the sheet. When the sheet is plain paper, the melted toner image penetrates between the fibers of the plain paper, and the melted toner image tends to harden.

  On the other hand, since the melted toner image does not penetrate into the resin sheet in the resin sheet, the toner image exists only on the surface of the resin sheet, and the melted toner image is hard to be solidified.

  As described above, when the resin sheet is continuously printed with the toner image not solidified, the resin sheet is not stuck on the resin sheet discharged immediately before and the resin sheet discharged next. The toner image comes into contact. When the toner image is cooled in this state, the resin sheet discharged immediately before and the resin sheet discharged next are stuck through the toner image.

  In order to solve this problem, a technology for preventing sticking of resin sheets by sandwiching plain paper between the resin sheets is known so that the resin sheets do not overlap and be discharged when continuously printing the resin sheets. (For example, refer to Patent Document 1).

Also, when printing resin sheets continuously without sandwiching plain paper between them, after waiting for a certain period of time for the toner image of the resin sheet discharged earlier to cool and harden, A technique for discharging a resin sheet is known.
Japanese Patent Laid-Open No. 08-268595

  However, as in Patent Document 1, if plain paper is sandwiched between resin sheets, the number of prints to be output increases, and it takes a long time to actually complete the output, resulting in a decrease in print speed.

  Furthermore, since plain paper is output in addition to the resin sheet, the user is required to spend extra cost.

  Even in continuous printing using only the resin sheet, the printing interval between the resin sheets becomes long, and the printing speed decreases.

  The present invention has been made in order to solve the above-described problems of the prior art, and the object of the present invention is to use a multi-stage discharge tray without reducing the printing speed of the resin sheet without increasing the cost. Another object of the present invention is to provide an image forming apparatus that does not cause an extra cost to the user.

In order to achieve the above object, the present invention
(1) An image having at least two or more discharge units, a branch unit for branching discharged sheets to the respective discharge units, a drive unit for operating the branch unit, and a branch control unit for controlling the operation of the branch unit. A forming device,
The sheet is a resin sheet, and when the resin sheet is continuously printed, the sheet is branched and discharged one by one to each discharge unit.

  (2) In the above (1), when the resin sheets are continuously printed, the order of printing on the sheets is controlled by the number of branches discharged to the discharge unit and the number of sheets to be printed.

  (3) In the above (1) or (2), it has a media sensor that detects the type of the sheet, and the branching control unit controls the branching unit in accordance with the detection result of the media sensor. The number of branches to the discharge unit is automatically controlled.

  (4) In any one of the above (1) to (3), one of the discharge units among the at least two discharge units is a double-sided tray.

  According to the present invention, when printing a resin sheet continuously, the use of a plurality of discharge trays prevents the resin sheet from sticking, and without increasing the cost, the printing speed of the resin sheet does not slow down, and the user can Therefore, it is possible to provide an image forming apparatus that does not add extra cost.

  Embodiments of the present invention are illustratively described in detail below with reference to the drawings. In the description, the overall configuration of the color image forming apparatus embodying the invention will be described with reference to FIG. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

[First embodiment]
(overall structure)
FIG. 1 shows a first embodiment of a multicolor image forming apparatus according to the present invention.

  FIG. 1 is a longitudinal sectional view showing an overall configuration of a full-color laser beam printer which is an embodiment of a multicolor image forming apparatus.

  It has four photosensitive drums 1a to 1d as image bearing members. Around each photosensitive drum 1, charging means 2 a to 2 d for uniformly charging the surface of the photosensitive drum 1 in order according to the rotation direction, and a laser beam is irradiated on the photosensitive drum 1 electrostatically on the basis of image information. Exposure means 3a to 3d for forming a latent image, development means 4a to 4d for making toner adhere to the electrostatic latent image and developing it as a toner image, and a transfer member for transferring the toner image on the photosensitive drum 1 to the sheet S 5a to 5d and cleaning means 6a to 6d for removing the post-transfer toner remaining on the surface of the photosensitive drum 1 after the transfer are disposed to constitute an image forming means.

  Here, the photosensitive drum 1, the charging unit 2, the developing unit 4, and the cleaning unit 6 are integrally formed into a cartridge to form process cartridges 7a to 7d.

  The sheet S fed from the feeding unit 8 is conveyed to the image forming unit by a conveying unit 9 constituted by a transfer conveying belt 9a, and toner images of respective colors are sequentially transferred to form a multicolor image. The toner is heated and fixed by the fixing unit 10 and discharged and stacked on the discharge unit 13 by the discharge roller pair 12.

  In double-sided recording, the sheet S is fixed by the fixing unit 10 and then reversed before being discharged by the discharge roller pair 12 to be conveyed to the double-sided conveyance path 15 (in the direction of arrow A). The sheet S conveyed to the double-sided conveyance path 15 passes through the oblique feeding roller 16 at the front of the apparatus main body, is conveyed vertically downward to the U-turn roller 17, and reaches the image forming unit by the U-turn roller 17 and the registration roller 8d. Be transported.

(Feeding department)
The feeding unit 8 includes a feeding cassette 8a, a manual feeding tray 8b, a manual feeding unit 8c, and a registration roller 8d. The feeding cassette 8a stores a plurality of sheets S and is loaded on the inner bottom of the apparatus main body. When forming an image from the feeding cassette 8a, the sheets S are separated and fed one by one by the cassette pickup roller 8a1, and conveyed to the conveying means 9 by the cassette conveying roller 8a2 and the registration roller 8d.

  The manual feed tray 8b is normally stored in front of the apparatus main body, but is rotated and opened from the apparatus main body when used, and a plurality of sheets S are stacked. When forming an image from the manual feed tray 8b, the sheets S are separated and fed one by one by the manual pickup roller 8c1, and conveyed to the conveying means 9 by the manual conveyance roller 8c2 and the registration roller 8d.

  Separation and conveyance of the sheet S in the feeding cassette 8a and the manual feeding unit 8c are performed by a feeding motor (not shown) in the feeding unit 8 via a gear drive train.

(Image forming part)
The photosensitive drum 1 as an image carrier is configured by applying an organic photoconductor layer (OPC) to the outer peripheral surface of an aluminum cylinder. The photosensitive drum 1 is rotatably supported at both ends by flanges, and is driven to rotate counterclockwise (in the direction of the arrow in the figure) by transmitting a driving force from a driving motor (not shown) to one end. The

  Each charging unit 2 is a conductive roller formed in a roller shape. The charging roller 2 is brought into contact with the surface of the photosensitive drum 1 and a charging bias voltage is applied by a power source (not shown) to thereby fix the surface of the photosensitive drum 1. It is charged uniformly.

  The exposure means 3 has a polygon mirror. The polygon mirror is irradiated with image light corresponding to an image signal from a laser diode (not shown).

  The developing unit 4 is adjacent to the toner storage units 4a1 to 4d1 that store toners of black, cyan, magenta, and yellow, respectively, and is rotated by a driving unit (not shown), and a developing bias power source (not shown) Are constituted by developing rollers 4a2 to 4d2 and the like that perform development by applying a developing bias voltage.

  In addition, transfer members 5a to 5d that are in contact with the transfer and transport belt 9a are provided adjacent to the four photosensitive drums 1a to 1d, respectively, inside a transfer and transport belt 9a described later. These transfer members 5a to 5d are connected by a power supply for transfer bias (not shown), and positive electrification is applied from the transfer members 5a to 5d to the sheet via the transfer conveyance belt 9a. The negative color toner images on the photosensitive drum 1 are sequentially transferred to the sheet S in contact, and a multicolor image is formed.

(Sheet conveying means)
The sheet S fed from the feeding unit 8 is conveyed to the image forming area by the conveying unit 9. A transfer conveyance belt 9a as a sheet carrier constituting the conveyance means 9 is stretched and supported by four rollers of a driving roller 9b and driven rollers 9c to 9e, and is arranged to face all the photosensitive drums 1a to 1d. It is installed.

  The transfer / conveying belt 9a is circulated and moved by a driving roller 9b so that the sheet S is electrostatically attracted to the outer peripheral surface facing the photosensitive drum 1 and the sheet S is brought into contact with the photosensitive drum 1. As a result, the sheet S is conveyed to the transfer position by the transfer conveyance belt 9a, and the toner image on the photosensitive drum 1 is transferred.

  An adsorption roller 9f that holds the sheet S together with the belt 9a and adsorbs the sheet S to the belt 9a is disposed at the most upstream position of the transfer conveyance belt 9a. When the sheet is conveyed, a voltage is applied to the suction roller 9f to form an electric field between the opposed driven roller 9c and generate dielectric polarization between the transfer conveyance belt 9a and the sheet. Thus, electrostatic attracting force is generated in both.

(Fixing part)
The fixing unit 10 applies heat and pressure to the image formed on the sheet S to fix the toner image, and includes a fixing belt 10a and an elastic pressure roller 10b. The fixing belt 10a is a cylindrical belt having an electromagnetic induction heat generating layer, and is guided by a belt guide member 10c having a built-in magnetic field generating means including an exciting coil and a T-shaped magnetic core. The elastic pressure roller 10b sandwiches the fixing belt 10a, and forms a fixing nip portion N having a predetermined width with a predetermined pressure contact force with the belt guide member 10c.

  The elastic pressure roller 10b is rotationally driven by a driving means (not shown), and the cylindrical fixing belt 10a rotates accordingly, and electromagnetic induction heat generation of the fixing belt 10a is performed by feeding power from an excitation circuit (not shown) to the excitation coil.

  In a state where the fixing nip N rises to a predetermined temperature and is temperature-controlled, the sheet S on which the unfixed toner image conveyed from the image forming unit is formed is fixed to the fixing belt 10a and the elastic pressure roller 10b of the fixing nip N. The image surface faces upward, i.e., faces the fixing belt surface, and the fixing nip portion N holds the fixing nip portion N together with the fixing belt 10a with the image surface closely contacting the outer surface of the fixing belt 10a. It will be done.

  In the process where the sheet S is nipped and conveyed through the fixing nip N together with the fixing belt 10a, the fixing belt 10a is heated by electromagnetic induction heat generation, and the unfixed toner image on the sheet S is heated and fixed.

(Discharge part)
The sheet S on which the toner image is heated and fixed is discharged and stacked on the discharge unit 13 by the discharge roller pair 12.

  When the sheets are continuously printed, the next printed sheet is discharged so as to overlap the previously discharged sheet. When the sheet to be printed is plain paper, the toner image heated on the plain paper enters the fiber as the toner melts, and the toner image is likely to cool and harden. On the other hand, when the printed sheet is a resin sheet, the toner image heated and melted on the resin sheet does not soak into the interior of the sheet like plain paper, and all the toner images remain on the surface of the resin sheet. The center of the image is difficult to cool and the toner image is difficult to solidify. Also, the temperature of the resin sheet itself is less likely to cool than plain paper and the toner image is less likely to harden. Therefore, on the resin sheet that has been printed and discharged first, the toner image of the next printed resin sheet is discharged in a semi-fixed state, and the semi-fixed toner image is discharged first, and the resin is not completely cooled. When the toner image comes into contact with the sheet and then cools, the toner image is fixed, and the resin sheets stick to each other. In addition, since the temperature of the resin sheet discharged first is less likely to be lower than that of plain paper, the toner image is less likely to cool and the toner image is less likely to harden.

  Also, compared to plain paper, the resin sheet has a very high surface smoothness, the resin sheets are very close to each other, and the toner image of the resin sheet discharged later can be found on the back surface of the resin sheet discharged earlier. The contact area increases and the resin sheets are easily stuck to each other.

  In the case of the present embodiment, since the printing surface of the sheet is in a direction in contact with the discharge portion, the first sheet of the resin sheet may stick to the discharge portion, but the shape and surface roughness of the discharge portion are By devising, the contact area with the resin sheet is suppressed, and at the same time, the adhesiveness is also reduced, and the first resin sheet is prevented from sticking to the discharge portion. Moreover, since the temperature of the discharge part is lower than that of the resin sheet, sticking hardly occurs.

  FIG. 2 is a longitudinal sectional view of a multi-color image forming apparatus provided with a multi-stage discharge device.

  The sheet fixed by the fixing unit is normally discharged to 13-1, which is a discharge unit provided in advance in the main body. When the sheet is discharged to the discharge unit 13-2 provided in the multistage discharge device, the flapper F-1, which is a branching means provided in the multistage discharge device, is switched by a drive source (drive means) (not shown). Is controlled by a control unit (branch control means) (not shown) so as to guide the gas to the discharge unit 13-2. Similarly, when discharging to the discharge unit 13-3, the flappers F-1 and F-2 are switched to control the sheet to the discharge unit 13-3.

  When the resin sheets are continuously printed, the discharge unit for discharging the resin sheet is not discharged to only one discharge unit, for example, the discharge unit 13-1, but the discharge units 13-1, 13-2, 13- 3 to discharge sequentially. As described above, since the sticking of the resin sheet is more likely to occur as the temperature of the previously discharged sheet becomes higher, the resin sheet is more likely to stick to each discharging part by sequentially discharging to each discharging part. If the time from when a single resin sheet is discharged to when the next resin sheet is discharged becomes longer, the first discharged resin sheet at each discharge section becomes easier to cool, and the next discharged resin sheet is stuck. It can be prevented.

  This is not only the face-down discharge method as shown in FIG. 2 where the printing surface faces downward, but also in the face-up discharge method where the printing surface faces upward as shown in FIG. Since the resin sheet discharged first in the discharge section is easily cooled, it is possible to prevent the resin sheet from sticking.

[Second Embodiment]
FIG. 4 is a simplified diagram showing the order in which six sheets of one job are stacked on the discharge tray T of the discharge unit as an example.

  Normally, when stacking continuously on one tray, the sheets are stacked on the tray in the order of printing as shown in FIG. 4, so the sheets S1, S2, S3, S4, S5, and S6 are stacked from the bottom.

  When the resin sheets are continuously printed and sequentially discharged to the respective discharge portions as in the first embodiment, the discharge portions are alternately discharged to the trays T1 and T2 as shown in FIG. The sheets S1, S3, and S5 are stacked on the tray T2, and the sheets S2, S4, and S6 are stacked on the tray T2. When the sheet bundle stacked on the tray T1 and the sheet bundle stacked on the tray T2 are overlapped, it becomes S1, S3, S5, S2, S4, and S6 from the bottom. .

  Therefore, since the sheets S1, S2, and S3 are stacked on the tray T1 and the sheets S4, S5, and S6 are sequentially stacked on the tray T2 as shown in FIG. 6, the printing order on the sheets is S1, S4, S2, S5, S3, and S6. Then, by alternately discharging to the trays T1 and T2, the order of the sheets when discharged can be made uniform.

  Even when the number of discharge trays is three as shown in FIG. 7, it is possible to perform printing without changing the order of sheets by setting the printing order to S1, S3, S5, S2, S4, and S6. It becomes possible to prevent sticking of the resin sheet without impairing usability.

  If the number of sheets to be printed is the same as or less than the number of discharge trays, printing is performed without changing the order of printing on the sheets.

  In the present embodiment, two and three discharge trays are taken up, but the effect of the present invention can be obtained by changing the order of printing on sheets regardless of the number of discharge trays. it can.

[Third embodiment]
FIG. 8 is a longitudinal sectional view of a multi-color image forming apparatus provided with a media sensor M that detects the type, thickness, and surface property of a sheet, and a multi-stage discharge device.

  When printing is performed by the multicolor image forming apparatus shown in FIG. 8, the sheet type and thickness of the sheet fed by the feeding unit are detected by the media sensor M, and the optimum sheet type, thickness and surface property are detected. Printing under various conditions (printing speed, bias voltage, fixing temperature, etc.).

In the case where the sheet detected by the media sensor M is a thick resin sheet, the temperature of the resin sheet itself heated by the fixing unit is not easily lowered, and the discharge trays 13-8, 13-9, 13 Use -10-3 to prevent sticking.
When the detected sheet is a thin resin sheet, the sheet temperature is more likely to be lower than that of a thick resin sheet. Therefore, two discharge trays 13-8 and 13-9 are used to prevent sticking.

  Further, when the surface property of the sheet detected by the media sensor M is fine, the resin sheets are very close to each other, and the toner image of the resin sheet discharged later comes into contact with the back surface of the resin sheet discharged first. Since the area increases and the resin sheets easily adhere to each other, the three discharge trays 13-8, 13-9, and 13-10 are used to prevent sticking.

  When the surface property of the detected sheet is rough, the adhesion between the resin sheets is lower than that when the surface property is fine, and the degree of sticking is also reduced. Therefore, the two discharge trays 13-8 and 13-9 are used. Use to prevent sticking.

  Here, various types of sensors can be applied as the media sensor M. For example, as a sensor for detecting the thickness of the sheet, light from an LED as a light emitting element is irradiated from the back side of the sheet and passes through the sheet. It is only necessary to use a sensor that detects the amount of light to be detected and detects the thickness of the sheet based on the detection result. Also, the amount of light reflected or reflected from the surface of the surface sheet is reflected. What is necessary is just to use the sensor which detects surface property, for example, by catching the light to perform as a two-dimensional image | video.

[Fourth embodiment]
FIG. 9 is a longitudinal cross-sectional view of a multicolor image forming apparatus provided with an image forming apparatus having a duplex printing unit as a duplex conveying apparatus D in the image forming apparatus according to the first embodiment.

  The double-sided conveying device D has a drive source (not shown) for rotating the reversing roller pair (discharge roller pair) RD at high speed, and can perform printing at a higher speed than the double-sided printing speed of the first embodiment. The double-sided tray 13-12 has an effect of preventing the ejection of the discharged sheets stacked on the 13-11 due to the sagging of the sheets when the sheets are reversed during double-sided printing. In addition to preventing extrusion, it can also be used as a discharge tray.

  When printing resin sheets continuously, the flapper F-9 is switched and the double-sided tray is used as the second discharge tray, and the resin sheet is discharged not only to the discharge tray 13-11 but also to the tray 13-12. Thus, as in the first embodiment, it is possible to prevent the resin sheet from sticking.

1 is an overall configuration diagram of a first example of an image forming apparatus according to an exemplary embodiment; 1 is a configuration diagram relating to a multicolor image forming apparatus including a multistage discharge device according to the present embodiment. 1 is a configuration diagram relating to a multicolor image forming apparatus including a multistage discharge device according to the present embodiment. It is explanatory drawing regarding the discharge tray which concerns on this embodiment. It is explanatory drawing regarding the discharge tray which concerns on this embodiment. It is explanatory drawing regarding the discharge tray which concerns on this embodiment. It is explanatory drawing regarding the discharge tray which concerns on this embodiment. 1 is a configuration diagram of only a main part related to a multicolor image forming apparatus including a media sensor according to the present embodiment. It is a block diagram which shows only the principal part structure regarding the multicolor image forming apparatus provided with the double-sided conveying apparatus which concerns on this embodiment. 1 is an explanatory cross-sectional view illustrating a general configuration of an image forming apparatus.

Explanation of symbols

13 Discharge part D Double-sided conveyance device F Branch means M Media sensor S Sheet T Discharge tray

Claims (4)

An image forming apparatus having at least two or more discharge units, a branch unit for branching discharged sheets to the respective discharge units, a drive unit for operating the branch unit, and a branch control unit for controlling the operation of the branch unit. There,
An image forming apparatus, wherein the sheet is a resin sheet, and when the resin sheet is continuously printed, the sheets are branched and discharged one by one to the discharge sections.   The image forming apparatus according to claim 1, wherein when the resin sheets are continuously printed, the order of printing on the sheets is controlled by the number of branches to be discharged to the discharge unit and the number of sheets to be printed.   A media sensor that detects a type of the sheet, and the branch control unit controls the branch unit according to a detection result of the media sensor, and automatically controls the number of branches to the discharge unit according to the type of the sheet. The image forming apparatus according to claim 1, wherein:   4. The image forming apparatus according to claim 1, wherein one of the at least two discharge units is a double-sided tray. 5.

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