JP2005181407A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an excellent image on whatever pre-printing paper it is by eliminating a situation that trouble such as the winding of the pre-printing paper round a fixing roller related to the melting point of toner or the value of a printing rate in forming the image (overprinting or the like) by using the pre-printing paper on which the image has been formed by another image forming apparatus causes the loss of the pre-printing paper and the fault (mainly, in a fixing part) of an image forming apparatus itself when things come to the worst. <P>SOLUTION: In pre-printing, a dot pattern is formed on transfer material and data on the type of a machine by which pre-printing is performed is recorded according to the array of the dot pattern. In the case of performing copying on the pre-printing paper, the array of the dot pattern is read in so as to detect the characteristic of the type of the image forming apparatus by which pre-printing is performed and the printing rate by a detection means such as a CIS (Contact Image Sensor), then a fixing condition in forming the image is controlled in accordance with the characteristic of toner in the image forming apparatus by which pre-printing is performed and the printing rate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer that heats and fixes a toner image to a recording material.

2. Description of the Related Art Conventionally, a fixing device in an image forming apparatus in electrophotography transmits heat from a heating element through a fixing roller and a fixing film, and heats and melts toner to fix it on a recording material. In the case of forming an image on a recording material on which an image has already been formed (hereinafter referred to as preprinted paper), the image is formed under the same image forming conditions as in normal image formation (see, for example, Patent Document 1).
JP 2003-276285 A

  However, when the toner of the image formed on the preprint paper has a melting point lower than that of the toner of the image forming apparatus, excessive heat is supplied to the toner on the preprint paper in the fixing unit, and the toner is transferred between the preprint paper and the heating roller. Insufficient separation occurred, preprinted paper was wound around the heating roller, and there was a problem that the preprinted paper was lost or, in the worst case, the fixing device was destroyed.

  Further, even when the image forming conditions are input by the user, there is a problem that it is difficult to input appropriate conditions without specifying the model on which the image is formed on the preprinted paper.

  The present invention has been made in view of such problems, and its purpose is to automatically read image information and image forming apparatus tracking data when image formation is performed on preprinted paper. Another object of the present invention is to provide a stable image forming apparatus in which appropriate image forming conditions are set, and the preprint paper does not wrap around the fixing unit, and the preprint paper is not lost or the fixing device is not destroyed.

  The present invention has achieved the above object by the following technical configuration.

  (1) In an image forming apparatus including a reading device that reads information on a recording material, image information previously formed on the recording material and tracking data of the image forming device are read by the reading device, and read image information An image forming apparatus characterized in that a condition at the time of image formation is changed according to model information.

  (2) The image forming apparatus according to (1), wherein the image forming condition is a fixing temperature.

  (3) The image forming apparatus according to (1), wherein the image forming condition is a conveyance speed at the fixing unit.

  (4) Based on the model information, when the melting point of the developer of the image formed in advance on the recording material is lower than the melting point of the developer of the image forming apparatus, the condition at the time of image formation is changed. The image forming apparatus according to any one of (1) to (3), wherein

  (5) The conditions (1) to (4) are characterized in that, based on the image information, when the printing rate of an image formed in advance on a recording material is equal to or greater than a predetermined value, the conditions at the time of image formation are changed. Any one of the image forming apparatuses.

  (6) The above-described (1) is characterized in that, based on the image information, when the printing rate of an image formed in advance at a predetermined location on a recording material is equal to or higher than a predetermined value, the conditions at the time of image formation are changed. The image forming apparatus according to any one of (4) to (4).

  According to the present invention, when image formation is performed on preprinted paper, image information and image forming apparatus tracking data are automatically read, appropriate image forming conditions are set, and the preprinted paper is wound around the fixing unit. Therefore, it is possible to provide a stable image forming apparatus in which preprint paper is not lost and the fixing device is not destroyed.

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

  A first embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS. The image forming apparatus of this example is a transfer type laser printer or copying machine using an electrophotographic process.

  The image forming apparatus has a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 1 as an image carrier, and the photosensitive drum 1 has a conductive base layer 1b made of aluminum, iron, or the like, and an outer peripheral surface thereof. The provided photoconductive layer 1a made of, for example, an organic photoconductor serves as a basic constituent layer, and is rotationally driven at a predetermined speed (process speed) in the clockwise direction of an arrow about the support shaft 1d. The conductive base layer 1b is grounded.

  The photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by the primary charging device 2 during the rotation process.

The primary charging device 2 in this example is a contact charging roller, and is a conductive roller 2c such as a metal roller serving as a metal core, a conductive layer 2b formed on the outer peripheral surface thereof, and a resistance layer 2a ₁ formed on the outer peripheral surface thereof. 2 a _2, and both ends of the conductive roller 2 c are rotatably supported by a bearing member (not shown) and arranged in parallel with the photosensitive drum 1, and are exposed by pressing means such as a spring (not shown). The drum 1 is pressed against the drum 1 with a predetermined pressing force, and is driven as the photosensitive drum 1 rotates.

  Then, by applying a predetermined bias voltage (DC voltage or vibration voltage) from the power source 3 via the electric contact 3a of the conductive roller 2c, the peripheral surface of the photosensitive drum 1 has a predetermined polarity and potential by the contact charging method. Are uniformly charged.

  Next, the image exposure unit 5 of the laser scanner / slit exposure unit performs image exposure processing of target image information on the charging processing surface, and an electrostatic latent image of target image information is formed on the surface of the photosensitive drum 1. .

  The electrostatic latent image becomes a visible image (toner image) developed by the developer (toner) carried in a thin layer on the developing sleeve 6 a of the developing device 6.

  In the transfer portion N, which is a contact nip portion between the photosensitive drum 1 and the transfer member 7 brought into contact with the photosensitive drum 1, the pre-print is fed to the transfer portion N from the paper supply portion side at a predetermined timing. The images are sequentially transferred to the paper 9.

  The transfer member 7 of this example is a contact charging transfer roller, and is composed of a conductive roller 7a such as a metal roller serving as a core metal, and a cylindrical conductive layer 7b formed on the outer peripheral surface thereof. Both end portions are rotatably supported by a bearing member (not shown) and are arranged in parallel with the photosensitive drum 1, and are pressed against the photosensitive drum 1 by pressing means such as a spring (not shown). Follow and rotate. A contact nip portion between the photosensitive drum 1 and the transfer roller 7 is a transfer portion N.

  The preprinted paper 9 is fed from a paper feeding cassette (not shown) by a paper feed roller 15, then transported by transport rollers 16 a and 16 b, and further fed to a transfer unit N through transfer upper and lower guides 11 and 12.

  When the leading edge of the preprint paper 9 enters the transfer portion N, a predetermined bias voltage for transfer is applied from the power source 4 to the conductive roller 7a, and the back surface of the transfer material with which the transfer roller 7 is in contact is in reverse polarity with the toner. The toner image on the photosensitive drum 1 is transferred to the surface of the preprint paper 9 by charging.

  The preprint paper 9 that has received the transfer of the toner image when passing through the transfer portion N is separated from the surface of the photosensitive drum 1 and sent to the heat fixing device.

  In the transfer device, a bias for forming an electric field for transferring the dirt on the preprinted paper 9 due to toner to the photosensitive drum 1 is -500 V for 2 sec at the initial rotation before the operation, -500 V for 0.6 sec between the paper, and after During rotation, it is applied at −1000 V for 4 seconds.

  The heat fixing device of this example is a tension-less type film heating type heat fixing device.

  In this type of device, at least a part of the circumference of the film is always tension-free (in a state where no tension is applied), and the traveling movement of the film is obtained from the rotational driving force of the pressure member. Even with this type of device, the control and mechanism for driving and running the film is simplified and the drive torque is greatly increased compared to the tension type that always moves the film with tension applied to the entire circumference. There is an advantage that can be reduced.

  Reference numeral 17 denotes a horizontally long stay made of a heat resistant resin, which serves as an inner surface guide member of the following endless heat resistant film (fixing film) 18.

  The endless heat resistant film 18 is externally fitted to the stay 17 including a heater 21 as a heating member. The inner peripheral length of the endless heat-resistant film 18 and the outer peripheral length of the stay 17 including the heater 21 are larger than the film 18 by, for example, about 3 mm. Therefore, the film 18 is longer than the stay 17 including the heater 21. Is fitted loosely outside.

  The film 18 has a film thickness of about 100 μm in order to reduce heat capacity and improve quick start properties, and has a single layer of PTFE, PFA, FEP, etc. that has heat resistance, releasability, strength, durability, etc. Alternatively, an outer peripheral surface of polyimide, polyamideimide, PEEK, PES, PPS or the like coated with PTFE, PFA, FEP or the like, having a layer thickness of 60 μm was used.

  The heater 21 has an electric resistance material (heating element) 21b such as Ag / Pd (silver palladium), for example, a thickness of about 10 μm and a width of 1 to 3 mm along the longitudinal center of the surface of the substrate 21a made of alumina or the like. Is coated by screen printing or the like, and a protective layer 22 is coated thereon with glass, fluororesin or the like.

  Reference numeral 19 denotes a film pressure roller as a rotating body that drives the film 18 by forming a fixing nip portion Nt by sandwiching the film 18 with the heater 21, and a core shaft 19 a such as iron or stainless steel, and the shaft It comprises a roller part 19b made of a heat-resistant rubber elastic body having good releasability such as an outer silicone rubber, and is driven to rotate counterclockwise as indicated by an arrow when the end of the cored bar 19a is driven by driving means. . When the pressure roller 19 is rotated, the endless heat-resistant film 18 is also rotated in the clockwise direction indicated by the arrow.

  The pressure roller 19 of this example has a hardness of 50 ° (Asker C hardness) obtained by coating a cored bar 19a having an outer diameter of 10 mm, a silicon rubber layer having a length of 220 mm, and a thickness of about 3 mm with a fluorine latex coat of 30 μm and firing. It comprises a roller portion 19b and is driven to rotate at a predetermined speed in a predetermined direction.

  When the endless heat-resistant film 18 is not driven, the remaining portion of the endless heat-resistant film 18 except for the portion sandwiched between the nip portion Nt between the heater 21 and the pressure roller 19 is tension-free.

  When the pressure roller 19 is driven to rotate, a moving force is applied to the film 18 by the frictional force with the rotation pressure roller 19 at the nip portion Nt, and the film 18 has the same speed as the rotation peripheral speed of the pressure roller 19 on the back surface of the film. Is driven to rotate clockwise while sliding on the heater 21 surface (= protective layer 22 surface). At the time of driving the film, tension is applied to the film only at the nip portion Nt and the nip portion Nt upstream of the nip portion Nt and in the portion between the film inner surface guide portion and the nip portion in the vicinity of the nip portion.

  In the state where the film driving and the heating element layer 21b of the heater 21 are energized, the preprinted paper 9 carrying the unfixed toner T is formed between the rotating film 18 and the rotating roller 19 in the nip portion Nt. When introduced onto the carrying surface, the transfer material P passes through the nip portion Nt together with the film 18, and the thermal energy of the heater 21 in contact with the back surface of the film at the nip portion Nt passes through the film 18. The toner image T is heat-fixed by being applied to the print paper 9 and by the applied pressure at the nip portion Nt.

  In the heater 21, voltage application (power supply) is applied between both longitudinal ends of the heating element layer 21 b, whereby the heating element layer 21 b generates heat, the substrate 21 a is pressurized, and the temperature of the entire heater 21 having a low heat capacity is increased. The temperature rises rapidly.

  In the temperature control of the heater 21, the output of the thermistor 20a provided on the heater 21 is A / D converted and taken into the CPU 23. Based on the information, the AC voltage applied to the heating element layer 21b of the heater 21 by the triac 24 is obtained. This is performed by controlling the heater energization power by phase / wave number control or the like. Reference numeral 25 denotes an AC power source.

  The position of the thermistor 20a is such that the temperature of the transfer material sheet passing portion is always detected in the vicinity of the conveyance reference portion in order to ensure stable fixability, and when the detected temperature of the thermistor 20a is lower than a predetermined set temperature, the heater 21 By controlling the energization so that the temperature rises, and when the temperature is high, the heater 21 is controlled to have a constant temperature at the time of fixing.

  As shown in FIG. 2, image information and tracking data of the image forming apparatus are formed as dot patterns on the printing surface side of the preprinted paper 9.

  The reading device 13 is arranged between the paper feed roller 15 and the conveyance roller 16 and reads image information formed on the printing surface of the preprinted paper 9 and tracking data of the image forming device.

  In this embodiment, a contact image sensor is used as a reading device.

  The read data is sent to the CPU 23, the model that has been preprinted is determined from the tracking data, and the image forming conditions are changed based on the toner information of the corresponding model stored in advance.

  In this embodiment, when the melting point of the toner of the image forming apparatus is T0 and the toner of the preprinted model is Tp, if T0> Tp, the triac 24 generates the heating element 21b of the heater 21. The electric current supplied to is controlled to a fixing temperature T-10 ° C. As a result, when an image is formed on preprinted paper, an appropriate fixing temperature is automatically determined, and a stable image can be formed without being wound around the fixing film.

  In Example 1, fixing was performed by lowering the fixing temperature T below normal when T0> Tp. However, when Tp is considerably smaller than T0, if the fixing temperature is lowered to a temperature at which the preprinted paper does not wind, the toner for image formation does not melt and a sufficient fixing property cannot be secured. . Therefore, in this embodiment, when T0> Tp> T0-15 ° C., in addition to setting the fixing temperature equivalent to that of Example 1 to T-10 ° C., when T0-15 ° C ≧ Tp, the fixing portion The transport speed at is reduced from the normal transport speed V0 to V0 / 2.

  Thereby, even when the melting point Tp of the toner of the preprinted image is sufficiently smaller than the melting point T0 of the image forming toner, when the image is formed on the preprinted paper, it is not wound around the fixing film and is sufficient. Fixability can be secured and stable image formation can be performed.

  In the second embodiment, the conveyance speed V0 at the fixing unit is reduced to V0 / 2 based on the melting point of the toner of the preprint image and the toner of the image forming apparatus in order to prevent the winding. Even when the image printing rate is small and the preprint paper does not wind around the fixing film, there is a problem that the conveyance speed is halved and the image productivity of the image forming apparatus is significantly reduced.

  Accordingly, in this embodiment, in addition to the change in the fixing temperature T and the conveyance speed V0 of the fixing portion described in the first and second embodiments, the image formation is performed based on the printing rate of the image information read by the image reading device 13 in FIG. Change the condition.

  The printing rate may be based on image information formed on the preprinted paper, or the image area on the preprinted paper may be read directly.

  The printing ratio read by the image reading device 13 is sent to the CPU 23 to determine an appropriate fixing condition.

  In this embodiment, the conditions are as shown in FIG.

  When the melting point Tp of the preprint toner and the melting point T0 of the image forming toner are T0 ≦ Tp, the fixing is performed at the normal fixing temperature T and the normal fixing unit conveyance speed V0 regardless of the preprint printing rate. I do.

  In the case of T0-15 ° C <Tp <T0, when the preprint printing rate is 30% or less, the fixing temperature is T-10 ° C and the fixing portion conveyance speed is V0, but the preprint printing rate is 30% or more. In this case, the fixing unit conveyance speed is V0 / 2.

  When Tp ≦ T0−15 ° C., the fixing temperature T−10 ° C. is used when the preprint printing rate is 10% or less, and the fixing unit conveyance speed is V0. V0 / 2.

  As a result, when the printing rate of the preprinted paper is low and does not wind around the fixing film, the image productivity of the image forming apparatus is not lowered, and even if the printing rate of the preprinting is high, the paper is wound around the fixing film. And stable image formation can be performed.

  In the third embodiment, the image forming conditions are changed based on the printing rate over the entire surface of the preprinted paper. For example, even when the printing rate of the preprint is 10% or less, If the preprint is made locally, it will wrap around the fixing film. Conversely, even if the preprint coverage is 30% or more, the preprint is made at the rear end in the transport direction. In spite of no winding, there is a problem that the image productivity of the image forming apparatus is lowered.

  Therefore, in this embodiment, the area for reading the preprint coverage is set to a range from the front end in the transport direction to 75 mm.

  As a result, even when the preprint coverage is low overall but locally high, it is possible to determine an appropriate fixing temperature and perform stable image formation without winding around the fixing film.

Schematic sectional view of the image forming apparatus of Example 1 The dot pattern of Example 1 Fixing conditions in Example 3

Explanation of symbols

1 Photosensitive drum 2 Primary charging device 3 Power supply (charging)
4 Power supply (transfer)
5 Image exposure means 6 Developing device 7 Transfer member 8 Cleaner 9 Transfer material 11 Transfer upper and lower guide 12 Transfer upper and lower guide 13 Reading device 16 Conveying roller 17 Guide member 18 Fixing film 19 Pressure roller 20 Thermistor 21 Heater 23 CPU

Claims (6)

  In an image forming apparatus equipped with a reading device that reads information on a recording material, image information previously formed on the recording material and tracking data of the image forming device are read by the reading device, and the read image information and model information are Accordingly, an image forming apparatus characterized in that the conditions at the time of image formation are changed.   The image forming apparatus according to claim 1, wherein the image forming condition is a fixing temperature.   The image forming apparatus according to claim 1, wherein the image forming condition is a conveyance speed at a fixing unit.   Based on the model information, the image forming condition is changed when the melting point of the image developer previously formed on the recording material is lower than the melting point of the developer of the image forming apparatus. The image forming apparatus according to claim 1.   5. The image formation according to claim 1, wherein, based on the image information, when the printing rate of an image formed in advance on a recording material is equal to or greater than a predetermined value, the image forming condition is changed. apparatus.   5. The condition at the time of image formation is changed when a printing rate of an image formed in advance at a predetermined location on a recording material is greater than or equal to a predetermined value based on the image information. The image forming apparatus described.

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