JP2017215454A - Image forming apparatus and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce curling of a sheet by supplying a sheet preferentially from a cassette provided with a heater.SOLUTION: Heater presence sensors 8a and 8b detect if dehumidification means reducing moisture absorbed in a sheet S is provided respectively in a plurality of sheet supply devices 102 and 103. A laser beam printer 1 causes the sheet supply device provided with a heater 60, of the plurality of sheet supply devices 102 and 103, to preferentially supply a sheet.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus including a sheet dehumidifying means and a control method.

  In an image forming apparatus that uses heat to form an image, the sheet may be curled by heat. This is because the moisture absorbed in the sheet evaporates rapidly when heat is applied to the sheet. The more water that evaporates, the easier it is to curl. In addition, the larger the temperature difference between the temperature of the sheet before heating and the temperature of the sheet after heating, the more the amount of moisture that evaporates, so curling is likely to occur. According to Patent Document 1, there is described an invention for reducing sheet curl by reducing in advance moisture contained in a sheet by a heater provided in a sheet feeding tray. Patent Document 1 also describes that when the heater is attached, the fixing temperature is lowered than when the heater is not attached.

JP 2009-151021 A

  In Patent Document 1, it is assumed that there is only one cassette, but the image forming apparatus can be equipped with a plurality of sheet supply trays and sheet supply cassettes. These may be sold as optional devices. Accordingly, a mixed state may occur in which a certain cassette includes a heater and another cassette does not include a heater.

  In this case, there is a problem that the curl reduction effect varies depending on which cassette among the plurality of cassettes is used to supply the sheet. Therefore, the present invention provides an image forming apparatus capable of effectively reducing the influence of curling in an image forming apparatus in which a sheet supply unit having a dehumidifying unit and a sheet supply unit not having a dehumidifying unit can coexist. For the purpose.

The present invention is, for example,
A plurality of sheet supply means for supplying sheets for image formation;
Detecting means for detecting whether or not a dehumidifying means for reducing the moisture of the sheets stored in the plurality of sheet supply means is provided in each of the plurality of sheet supply means;
A control unit that preferentially supplies a sheet for image formation from the sheet supply unit detected by the detection unit as being provided with the dehumidifying unit among the plurality of sheet supply units. An image forming apparatus is provided.

  According to the present invention, an image forming apparatus capable of effectively reducing the influence of curling is provided in an image forming apparatus in which a sheet supply unit having a dehumidifying unit and a sheet supply unit not having a dehumidifying unit can coexist. The

Cross section of image forming apparatus Control system block diagram Flow chart showing paper feed control Flow chart showing paper feed control Flow chart showing paper feed control Flow chart showing paper feed control

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the values used in the following description are examples, and the scope of the present invention is not limited to only those values.

<Image forming apparatus>
FIG. 1 is a cross-sectional view of a laser beam printer (LBP) which is an example of an image forming apparatus. Reference numeral 1 denotes a laser beam printer. Reference numeral 100 denotes a laser beam printer main body (hereinafter referred to as a printer main body). The printer main body 100 includes an image forming unit 101 that forms an image on a sheet. In the lower part of the printer main body 100, sheet supply devices 102 and 103 are provided as storage means for storing the sheet S. The sheet supply apparatus 102 has a cassette 2a. The sheet supply apparatus 103 may be an optional apparatus having a cassette 2b, for example. Each of the sheet feeding apparatuses 102 and 103 supplies the sheet S to the image forming unit 101.

  Here, the image forming unit 101 includes a photosensitive drum 121, a charger 122, a developing device 123, and the like. The charger 122 uniformly charges the surface of the photosensitive drum 121 that is an image carrier. The laser scanner 13 irradiates the surface of the photosensitive drum 121 with light corresponding to the image information to form an electrostatic latent image. The developing device 123 develops the electrostatic latent image using toner to form a toner image. The transfer device 124 transfers the toner image carried on the photosensitive drum 121 onto the sheet S. The fixing device 14 applies heat and pressure to the sheet S carrying an unfixed toner image, and fixes the toner image on the sheet S. Thereafter, the sheet S is discharged to the discharge tray 19 and stacked.

  In the sheet feeding apparatuses 102 and 103, the pickup rollers 3a and 3b are sheet feeding units that feed the sheets S stacked on the cassettes 2a and 2b, which are sheet storage units. Further, the sheet S sent out by the pickup rollers 3a and 3b is conveyed toward the downstream in the conveying direction by the feed rollers 4a and 4b. The retard rollers 5a and 5b are pressed against the feed rollers 4a and 4b to separate the uppermost sheets S1a and S1b from the plurality of sheets S. The sheet presence / absence sensors 6a and 6b are sensors that detect whether or not the sheets S are stacked on the cassettes 2a and 2b. The size sensors 7a and 7b are sensors that detect the sizes (eg, A4, A4R, and B4) of the sheets S stacked on the cassettes 2a and 2b. The heater presence / absence sensors 8a and 8b are sensors that detect whether or not a heater 60 for applying heat to the sheet S in order to dehumidify moisture contained in the sheet S is attached.

  Since the sheet supply apparatus 102 is disposed near the image forming unit 101, it may be called an upper tray or an upper cassette. Since the sheet supply apparatus 103 is arranged far away from the image forming unit 101, it may be called a lower tray or a lower cassette. The sheet supply apparatus 103 may be an optional apparatus provided to the laser beam printer 1. The heater 60 may also be an optional device.

  The registration sensor 10 is a sheet sensor disposed upstream of the registration roller pair 11. The registration sensor 10 has a light emitting element and a light receiving element arranged so as to face each other, and further has a light shielding plate that rotates when the sheet S comes into contact therewith. While the sheet S is passing, the registration sensor 10 detects the sheet S by rotating the light shielding plate to block the light. The sheet S is conveyed to the registration roller pair 11 that has stopped rotating. When the leading edge of the sheet S is pressed against the registration roller pair 11, leading edge alignment (skew correction) is performed. When the registration sensor 10 outputs a detection signal indicating that the sheet S has been detected, the laser scanner 13 starts outputting laser light. The registration roller pair 11 starts to rotate so that the timing at which the image formed on the photoconductive drum 121 arrives at the transfer device 124 coincides with the timing at which the sheet S arrives at the transfer device 124. As a result, the image is transferred to a desired position on the sheet S.

  The flapper 27 switches the conveyance destination of the sheet S discharged from the fixing device 14. When the single-sided printing (single-sided mode) is completed and when the second-side printing in the double-sided printing (double-sided mode) is completed, the flapper 27 guides the sheet S to the discharge tray 19. On the other hand, when the printing on the first side in the duplex printing is completed, the flapper 27 guides the sheet S to the reverse roller 32. The reverse roller 32 feeds the sheet S into the reverse retreat path 23. Thereafter, the reverse roller 32 reverses the rotation direction and feeds the sheet S into the double-sided path 26. The double-sided rollers 33 and 34 return the sheet S to the conveyance path merging point and bring the sheet S into contact with the registration roller pair 11. Thereafter, the image forming unit 101 forms an image on the second surface of the sheet S. The flapper 27 guides the sheet S on which double-sided printing has been completed to the discharge tray 19.

  The printer main body 100 includes a temperature sensor 71 and a humidity sensor 72 as environment detection means for detecting environmental parameters. Generally, environmental parameters are used to determine the fusing temperature of the fuser 14. In this embodiment, the environmental parameter may be used to select one of the sheet supply apparatuses 102 and 103.

<Control system>
FIG. 2 is a block diagram showing functions of a control system for controlling the laser beam printer 1. The microcomputer 500 is a microcontroller (hereinafter referred to as a microcomputer) as a control unit of the printer main body 100. The CPU 501 controls each unit of the laser beam printer 1 by executing a control procedure (control program) stored in the ROM 502. A RAM 503 is a main storage device or a random access memory that stores input data or provides a working storage area.

  The I / O 504 is an input / output control unit for outputting a control signal for a load such as a motor or inputting a detection signal for a sensor or the like. The CPU 501 functions as a sheet determination unit that determines the presence / absence of the sheet S based on detection signals from the sheet presence / absence sensors 6a and 6b. The CPU 501 functions as a size specifying unit that specifies the size of the sheet S based on the detection signals from the size sensors 7a and 7b. The CPU 501 functions as a heater determination unit that determines the presence / absence of the heater 60 based on detection signals from the heater presence / absence sensors 8a and 8b. Further, the CPU 501 may function as a curl determination unit that determines whether curl is likely to occur based on environmental parameters.

  The CPU 501 selects one of the sheet supply apparatuses 102 and 103 according to the environmental parameter, the presence or absence of the sheet S, the size of the sheet S, the presence or absence of the heater 60, and the like. When the sheet supply apparatus 102 is selected, the CPU 501 drives the feed motor M1a to rotate the pickup roller 3a, the feed roller 4a, and the retard roller 5a. When the sheet supply device 103 is selected, the CPU 501 drives the feed motor M1b to rotate the pickup roller 3b, the feed roller 4b, and the retard roller 5b. The CPU 501 rotates the registration roller pair 11 and the photosensitive drum 121 by driving the main motor M2. The CPU 501 rotates the fixing film and the pressure roller of the fixing device 14 by driving the fixing motor M3. Further, the CPU 501 drives the reverse motor M4 to rotate the reverse roller 32 and the double-sided rollers 33 and 34. The CPU 501 switches the position of the flapper 27 by driving the reverse solenoid SL.

  The controller 600 is a control unit that outputs information to the operation unit 550 and the host computer PC and receives instructions from them. The controller 600 transmits a print instruction to the microcomputer 500 via the interface IF.

<Flowchart>
(1) Priority control based on presence / absence of heater A control for preferentially supplying sheets from a sheet supply apparatus provided with a heater 60 among a plurality of sheet supply apparatuses will be described with reference to FIG. When the CPU 501 receives a sheet supply request from the controller 600, the CPU 501 executes the following processing. Note that the CPU 501 may determine the presence / absence and the sheet size of all the sheet supply apparatuses in advance, and may select a sheet supply apparatus that accommodates a sheet of a requested size as a supply candidate. In the following, it is assumed that multiple supply candidates have been found. This is because if there is only one supply candidate, there is no room for selection. Although only two sheet supply apparatuses are illustrated in FIGS. 1 and 2, the technical idea of the present invention can be applied to an image forming apparatus having three or more sheet supply apparatuses.

  In S101, the CPU 501 specifies the presence or absence of the heater 60 for each of a plurality of supply candidates (sheet supply apparatuses). The CPU 501 specifies the presence / absence of the heater 60 using the heater presence / absence sensors 8a and 8b.

  In S102, the CPU 501 determines whether or not the heater 60 exists only in some of the supply candidates. When the heater 60 exists only in some supply candidates, the process proceeds to S103.

  In step S <b> 103, the CPU 501 preferentially supplies the sheet S from the sheet supply apparatus including the heater 60. For example, when the sheet supply apparatus 102 does not have the heater 60 and the sheet supply apparatus 103 has the heater 60, the CPU 501 drives the supply motor M1b to supply the sheet S from the sheet supply apparatus 103. Thereby, since the sheet S dehumidified in advance by the heater 60 is supplied, curling of the sheet S is reduced.

  On the other hand, when all the supply candidates are equipped with the heater 60, or when all the supply candidates are not equipped with the heater 60, it progresses to S104. In step S <b> 104, the CPU 501 preferentially supplies sheets from a plurality of supply candidates that are close to the image forming unit 101. For example, if both the sheet supply device 102 and the sheet supply device 103 include the heater 60, the CPU 501 causes the sheet S to be supplied from the sheet supply device 102 close to the image forming unit 101. Accordingly, it is possible to shorten the conveyance time and image formation time of the sheet S while reducing the curl of the sheet S. If neither the sheet supply apparatus 102 nor the sheet supply apparatus 103 includes the heater 60, the CPU 501 causes the sheet S to be supplied from the sheet supply apparatus 102 close to the image forming unit 101. As a result, curling of the sheet S cannot be reduced, but it is possible to shorten the transport time and image forming time of the sheet S.

(2) Preferential control based on presence / absence of heater and curl condition A control that further considers the curl condition will be described with reference to FIG. Here, an environmental parameter in which curl is likely to occur in the sheet S is referred to as a curl condition. If the curl condition is satisfied, the sheet S is preferentially supplied from the sheet supply apparatus provided with the heater 60 in order to reduce the curl. On the other hand, if the curl condition is not satisfied, the sheet is preferentially supplied from a sheet supply apparatus not provided with the heater 60 in order to save the dehumidified sheet S. In addition, the overlapping description of what was demonstrated using FIG. 3 is abbreviate | omitted.

  As can be seen by comparing FIG. 4 and FIG. 3, S201 and S202 are added between S102 and S103. That is, when only a part of the supply candidates has the heater 60, the process proceeds to S201.

  In step S201, the CPU 501 acquires environmental parameters using environmental sensors (eg, temperature sensor 71, humidity sensor 72).

  In step S202, the CPU 501 determines whether the environmental parameter satisfies the curl condition. For example, the curling condition is that the internal temperature of the laser beam printer 1 is 70 ° C. or higher and the internal humidity is 80% or higher. If the curl condition is satisfied, the CPU 501 proceeds to S103 to reduce the curl. Thereby, the dehumidified sheet S is supplied from the sheet supply apparatus having the heater 60, and curling is reduced. On the other hand, if the curl condition is not satisfied, the process proceeds to S303. As a result, the sheet S is preferentially supplied from a sheet supply apparatus that does not have the heater 60, so that the sheet S sufficiently dehumidified by the heater 60 can be preserved (stored). That is, the sheet S sufficiently dehumidified by the heater 60 is saved.

(3) Preferential control based on presence / absence of heater and printing mode (single-sided printing / double-sided printing) The control in consideration of the printing mode will be described with reference to FIG. Here, when a single-side printing instruction is received, the sheet S is preferentially supplied from the sheet supply apparatus provided with the heater 60. On the other hand, when a double-sided printing instruction is received, the sheet S is preferentially supplied from a sheet supply apparatus in which the heater 60 is not provided. It should be noted that the duplicate description already described with reference to FIG. 3 and the like is omitted.

  As can be seen by comparing FIG. 5 and FIG. 3, S301 and S302 are added between S102 and S103. Furthermore, S303 is also added. In addition, when the heater 60 exists only in some supply candidates among several supply candidates, it progresses to S301 from S102.

  In step S301, the CPU 501 analyzes the print job and print instruction received from the controller 600, and specifies the print mode.

  In step S302, the CPU 501 determines whether the print mode is single-sided printing. If the print mode is single-sided printing, the CPU 501 proceeds to S103 to reduce curl. Thereby, the dehumidified sheet S is supplied from the sheet supply apparatus having the heater 60, and curling is reduced. On the other hand, if the print mode is duplex printing, the CPU 501 proceeds to S303.

  In step S <b> 303, the CPU 501 supplies the sheet S with priority from supply candidates without the heater 60. The amount of curl generated in the duplex printing mode is smaller than the amount of curl generated in the single-sided printing mode. In addition, the amount of curling in single-sided printing can be reduced by sufficiently dehumidifying the heater 60 or storing the dehumidified sheet S for single-sided printing. Therefore, in the double-sided printing mode, the sheet S is preferentially supplied from supply candidates without the heater 60.

(4) Preferential control based on presence / absence of heater, curl condition and print mode Control using the presence / absence of heater, curl condition and print mode will be described with reference to FIG. The duplicate description already described with reference to FIG. 5 is omitted.

  As can be seen by comparing FIGS. 3 to 6, S201, S202, S301, and S302 are added between S102 and S103. Furthermore, S303 is also added. If the curl condition is satisfied, the process proceeds from S202 to S301.

  Therefore, when all the supply candidates are provided with the heater 60, or when all the supply candidates are not provided with the heater 60, the CPU 501 proceeds to S104. As a result, the sheet S is preferentially supplied from the supply candidates closest to the image forming unit 101 among the plurality of supply candidates. Further, it is possible to shorten the conveyance time and image formation time of the sheet S.

  When the heater 60 exists only in some supply candidates, the curling condition is satisfied, and single-sided printing is instructed, the CPU 501 proceeds to S103. The CPU 501 preferentially supplies the sheet S from the sheet supply apparatus having the heater 60. Thereby, since the sheet S dehumidified in advance by the heater 60 is supplied, curling of the sheet S is reduced.

  On the other hand, when the heater 60 exists only in some supply candidates, the curl condition is satisfied, and when duplex printing is instructed, or when the curl condition is not satisfied, the CPU 501 performs S303. Proceed to In step S <b> 303, the CPU 501 preferentially supplies the sheet S from supply candidates without the heater 60. Thereby, the sheet S sufficiently dehumidified by the heater 60 can be preserved (stored) for single-sided printing. That is, the sheet S sufficiently dehumidified by the heater 60 is saved.

(5) Others In S103, the sheet S is preferentially supplied from the sheet supply apparatus including the heater 60. Even if this is a sheet supply apparatus provided with a heater 60, the heater 60 is not provided when all the sheets S are used up or when a sheet S different from the designated sheet S is accommodated. This implies that the sheet supply device supplies the sheet S. This is because execution of image formation is prioritized over curling reduction.

  In step S <b> 104, the sheet S is preferentially supplied from the sheet supply apparatus close to the image forming unit 101. However, if the closest sheet supply device has used up all the sheets S or contains a sheet S different from the designated sheet S, the second closest sheet supply device supplies the sheet S. Is implied.

  In S303, sheets are preferentially supplied from a sheet supply apparatus that does not have the heater 60. However, if there is no sheet supply apparatus that does not have the heater 60, it implies that the sheet supply apparatus that has the heater 60 supplies the sheet S.

  When there are a plurality of supply candidates in S103 and S303, the CPU 501 selects the supply candidate closest to the image forming unit 101 among them. Note that the CPU 501 stores and manages information indicating the connection position of each sheet supply apparatus (which stage is connected) in the ROM 502 or the RAM 503. The sheet supply apparatus connected to the uppermost stage is the sheet supply apparatus closest to the image forming unit 101. On the contrary, the sheet supply apparatus connected to the lowermost stage is the sheet supply apparatus farthest from the image forming unit 101. The CPU 501 may determine the sheet supply device closest to the image forming unit 101 with reference to information indicating the position of each sheet supply device.

<Summary>
As described with reference to FIG. 1 and the like, the sheet supply apparatuses 102 and 103 are an example of a plurality of sheet supply units that store sheets S. The heater presence / absence sensors 8a and 8b are an example of a detection unit that detects whether or not a dehumidifying unit (for example, a heater 60) that reduces the moisture of the sheet S is provided in each of the plurality of sheet supply apparatuses 102 and 103. The heater presence / absence sensors 8a and 8b may be switches that are turned on when the heater 60 is attached and turned off when the heater 60 is removed. As described with reference to FIG. 3, the CPU 501 functions as a determination unit that determines whether or not an image forming condition is likely to cause sheet curling, and is determined to be an image forming condition that is likely to cause sheet curling. Function as control means for preferentially supplying sheets from the sheet supply apparatus in which the heater 60 is detected by the sensor among the plurality of sheet supply apparatuses 102 and 103. As a result, the sheet is preferentially supplied from the sheet supply unit provided with the dehumidifying unit in the case of an image forming condition where the sheet is likely to be curled, so that the influence of the curl of the sheet S is effectively reduced. The

  Further, when it is not determined that the image forming condition is likely to cause sheet curling, the sheet is fed preferentially from the sheet feeding apparatus in which it is detected that the heater 60 is not provided. Therefore, a sheet that has been sufficiently dehumidified can be used in an image forming condition in which sheet dehumidification is saved and sheet curling is likely to occur.

  Note that in this embodiment, single-sided printing is given as an example of an image forming condition in which sheet curling is likely to occur.However, when the fixing temperature is higher, a lot of moisture is evaporated and curling is likely to occur. It may be determined that the image forming conditions are likely to cause curling when the fixing temperature is high.

  Further, depending on the type of sheet, it may be determined that the image forming condition is likely to cause curling in the case of a sheet material that easily absorbs moisture.

  DESCRIPTION OF SYMBOLS 1 ... Laser beam printer, 102, 103 ... Sheet supply apparatus, 101 ... Image forming part, 14 ... Image forming part, 8a, 8b ... Heater presence sensor, 501 ... CPU

Claims (9)

A plurality of sheet supply means for supplying sheets for image formation;
Detecting means for detecting whether or not a dehumidifying means for reducing the moisture of the sheets stored in the plurality of sheet supply means is provided in each of the plurality of sheet supply means;
A control unit that preferentially supplies a sheet for image formation from the sheet supply unit detected by the detection unit as being provided with the dehumidifying unit among the plurality of sheet supply units. Image forming apparatus. A determination means for determining whether or not the sheet is likely to be curled;
The control means includes
The image forming apparatus according to claim 1, wherein when the determination unit determines that the sheet is likely to be curled, the sheet is supplied preferentially from a sheet supply unit provided with the dehumidifying unit. It further has an environment detection means for detecting the temperature and humidity inside the image forming apparatus,
The image forming apparatus according to claim 2, wherein the determination unit determines whether or not the sheet is likely to curl based on temperature and humidity detected by the environment detection unit. Image forming means capable of executing a single-sided mode for forming an image on one side of the sheet and a double-sided mode for forming an image on both sides of the sheet;
The image forming apparatus according to claim 2, wherein the determination unit determines whether or not the sheet is likely to be curled based on a mode executed by the image forming unit. Environment detecting means for detecting the temperature and humidity inside the image forming apparatus;
An image forming unit capable of executing a single-sided mode for forming an image on one side of the sheet and a double-sided mode for forming an image on both sides of the sheet;
The determination unit determines whether or not the sheet is likely to be curled based on a temperature and humidity detected by the environment detection unit and a mode executed by the image forming unit. The image forming apparatus described in 1.   The image forming apparatus according to claim 4, wherein the determination unit determines that the sheet is likely to be curled when the one-side mode is executed by the image forming unit.   When the dehumidifying unit is provided in any of the plurality of sheet supply units, or when the dehumidifying unit is not provided in any of the plurality of sheet supply units, the control unit 7. The image forming apparatus according to claim 4, wherein a sheet is supplied from a sheet supply unit closest to the image forming unit among the sheet supply units.   3. The control unit according to claim 2, wherein if the determination unit does not determine that the sheet is likely to curl, the control unit preferentially supplies the sheet from a sheet supply unit not provided with the dehumidifying unit. 8. The image forming apparatus according to any one of items 1 to 7. A plurality of sheet supply means for supplying sheets for image formation;
In a control method of an image forming apparatus, comprising: a dehumidifying unit that reduces the moisture of sheets stored in the plurality of sheet supply units.
A detection step of detecting whether or not the dehumidifying means is provided in each of the plurality of sheet supply means;
And a supplying step of preferentially supplying a sheet for image formation from the sheet supplying unit detected that the dehumidifying unit is provided in the detecting step.

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