JP5831074B2 - Preheating plate, fixing device and printing device provided with the same - Google Patents

Description

  The present invention relates to a preheating plate (preheater), a fixing device including the same, and a printing device, and more particularly to a heat source such as a heater built in the preheating plate and a configuration of a temperature sensor used for heat generation control of the heat source. is there.

FIG. 6 is a schematic configuration diagram of a conventional fixing device.
As shown in the figure, a recording medium (hereinafter abbreviated as printing paper) 1 such as a printing paper carrying a toner image 2 is preheated with a plurality of heaters 4a, 4b, 4c and 4d having a lamp structure. The toner image 2 heated from the back side of the sheet by the plate 3 and softened by the heating is sandwiched and conveyed by the heating roller 5 incorporating the next plurality of heat generation lamps 6 and the pressure roller 8 supported by the support 7. As a result, it is melted and fixed on the printing paper 1.

  Inside the preheating plate 3, a plurality of temperature sensors 9a, 9b, 9c, 9d made of, for example, thermistors are arranged, and the surface temperature of the preheating plate 3 depends on the width and type of the printing paper 1 used for printing. The heaters 4a, 4b, 4c, and 4d are controlled by the control unit 10 so that the temperature detected by the temperature sensors 9a, 9b, 9c, and 9d is kept within the temperature range necessary for softening the toner image 2 according to the above. Controlled by turning on / off.

  The heat generation area of each of the heaters 4a to 4d is divided into, for example, four in consideration of the width and type of the printing paper 1, and the temperature sensors 9a, 9b, 9c, and 9d are located at predetermined positions with respect to the heaters 4a to 4d. Are arranged one by one in each heat generating region.

  As a result, the preheating plate 3 has four different heat generation regions I, II, III, and IV as shown in FIG. 7, and each heat generation region I to IV is controlled within a certain temperature range. Become.

  The reason why the heat generating areas of the heaters 4a to 4d are divided as described above is that the temperature of the paper 1 itself and the control temperature of the preheating plate 3 generated in the printing paper 1 conveyed on the preheating plate 3. The amount of heat necessary to soften the toner image 2 before being held and conveyed by the heating roller 5 and the pressure roller 8, while minimizing damage such as shrinkage or deformation of the paper due to the difference between This is to prevent wasteful heat supply in the non-printing paper traveling area on the preheating plate 3 corresponding to the printing paper 1 having various widths and thicknesses.

  Therefore, for the reason described above, the control unit 10 generally sets and controls the same temperature range in the heat generation areas I and II and the heat generation areas III and IV aligned in the paper width direction, and further in the paper running direction. In FIG. 4, the heat generation regions III and IV are controlled by setting a higher temperature range than the heat generation regions I and II.

  Further, in a state where the adhesion with the preheating plate 3 is lowered due to the width or deformation of the printing paper 1, a control method different from the temperature control method in the control unit 10 in the heat generation region I and the heat generation region III, for example, temperature detection. The temperature sensor 9b and the temperature sensor 9d used for the above are not used, and the heater 4b and the heater 4d are turned on at a preset lighting rate to control the temperature of the heat generation area II and the heat generation area IV. There is also.

  In any case, in the prior art, the surface temperature of the preheating plate 3 is controlled by one temperature sensor 9 arranged in each heat generating region.

  In the prior art described above, the surface temperature of the preheating plate 3 is controlled by the control unit 10 within a certain temperature range so that the amount of heat necessary for softening the toner image 2 can be given to the printing paper 1.

  At that time, in the temperature control, each temperature sensor 9a, 9b, 9c, 9d is covered with the printing paper 1, and the surface temperature of the preheating plate 3 lowered by the heat supply to the printing paper 1 is properly detected. Is required.

  However, in the case of corresponding to the printing paper 1 having various widths, the heat generation area I and the heat generation area III are always covered with the printing paper 1, that is, even if the paper is divided so as to correspond to the minimum paper width. In the region II and the heat generation region IV, the temperature sensor 9 b and the temperature sensor 9 d are not necessarily covered with the printing paper 1.

  Depending on the width of the printing paper 1, the temperature sensor 9b and the temperature sensor 9d may exist outside the paper width area of the preheating plate 3, that is, in the non-printing paper traveling area.

  As described above, when the temperature sensor 9b and the temperature sensor 9d are present in the non-printing paper traveling region of the preheating plate 3, the preheating plate of the portion where heat is not supplied to the printing paper 1 in the heat generation region II and the heat generation region IV. 3 is controlled by a temperature sensor 9b and a temperature sensor 9d that detect the surface temperature of No. 3.

  However, in this case, printing is performed in the surface temperature of the preheating plate 3 detected by the temperature sensor 9b and the temperature sensor 9d provided, and in the printing paper traveling region in which the printing paper 1 actually travels in the heating region II and the heating region IV. A temperature difference is generated between the surface temperature of the preheating plate 3 in the portion where heat is supplied to the paper 1.

  Naturally, the surface temperature of the preheating plate 3 in the portion where heat is supplied to the printing paper 1 in the printing paper traveling region is the portion where the heat supply to the printing paper 1 is not performed, that is, the temperature sensor 9b and the temperature sensor. 9d is a temperature state far from a target temperature range than the surface temperature of the preheating plate 3 detected by 9d.

  Even in such a state, the control unit 10 controls the temperature of the heat generation area II and the heat generation area IV based on the temperature detected by the temperature sensor 9b and the temperature sensor 9d. In the traveling region, the amount of heat supplied from the preheating plate 3 is reduced.

  This state appears prominently in the continuous paper printing apparatus when printing on thick paper or when the thermal load on the preheating plate 3 is uneven due to the width of the printing paper.

  As described above, when printing is performed in a state where the amount of heat supplied to the printing paper 1 is partially reduced, the amount of heat necessary for the softening or fixing process of the toner image 2 cannot be supplied to the printing paper 1 from the preheating plate 3. This causes a problem of fixing failure due to partial heat loss, that is, non-uniform print quality.

  In order to solve this problem, a method of controlling the temperature of the heat generation region II and the heat generation region IV by a preset method without using the temperature sensor 9b and the temperature sensor 9d has been proposed (for example, patents). Reference 1).

  However, even in this method, in order to secure the amount of heat supplied to the printing paper without using the temperature detected by the temperature sensor, the amount of heat supplied to the printing paper may be excessive in the heat generating area II and the heat generating area IV. In such a case, there is a possibility of causing a problem of uneven printing quality, such as bleeding of images such as characters due to excessive heat.

  An object of the present invention is to provide a preheating plate that eliminates the drawbacks of the prior art and obtains stable printing quality, and a fixing device and a printing device including the preheating plate.

In order to achieve the above object, the present invention provides:
A heat source such as a heater is disposed inside, and the recording medium such as recording paper carrying the toner image is passed along the surface to preheat the toner image from the back side of the recording medium. In the preheating plate,
A plurality of heat generating regions divided in the traveling direction of the recording medium and the recording medium width direction orthogonal to the recording medium traveling direction;
Incorporating a plurality of temperature sensors arranged at predetermined intervals in the recording medium width direction for each heat generation area,
Control means for controlling the heat generation of the heat source based on the detection output of one temperature sensor selected from among a plurality of temperature sensors provided for each of the heat generation regions ;
The plurality of temperature sensors arranged for each of the heat generating areas are arranged according to the width of the recording medium,
The control means includes
By comparing the detection outputs of the plurality of temperature sensors while the recording medium is running, the width of the recording medium is estimated, and the heat source is generated in each heat generation area according to the estimated width of the recording medium. The temperature sensor used for the heat generation control is selected .

  The present invention is configured as described above, and can provide a preheating plate that can provide stable print quality.

1 is a schematic configuration diagram of a fixing device according to an embodiment of the present invention. FIG. 6 is a schematic plan view for explaining the arrangement relationship of a heater and a temperature sensor with respect to a heat generation area on a preheating plate used in the fixing device. 4 is a flowchart for explaining a heater temperature control method by a control unit in the embodiment of the present invention. It is a schematic plan view for demonstrating the arrangement | positioning relationship of the heater and temperature sensor with respect to the heat_generation | fever area | region on the preheating board which concerns on the other Example of this invention. 1 is a schematic overall configuration diagram of a laser beam printer to which the present invention is applied. It is a schematic block diagram of the conventional fixing device. It is the schematic for demonstrating the arrangement | positioning relationship of the heater and the temperature sensor with respect to the heat_generation | fever area | region on the preheating board of the fixing device.

Next, embodiments of the present invention will be described with reference to the drawings.
(Schematic configuration of the entire printing device)
First, a laser beam printer using an electrophotographic system will be exemplified as a printing apparatus to which the present invention is applied, and the overall configuration will be described with reference to FIG.

  In the figure, reference numeral 21 denotes a laser beam printer, and the photosensitive drum 23 starts to rotate in the direction of the arrow based on a printing operation start signal from the controller 22. The photosensitive drum 23 rotates at a speed corresponding to the printing speed of the laser beam printer 21 and continues to rotate until the printing operation is completed. When the photosensitive drum 23 starts to rotate, a high voltage is applied to the corona charger 24, and for example, positive charges are uniformly charged on the surface of the photosensitive drum 23.

  The rotary polygon mirror 25 starts rotating as soon as the laser beam printer 21 is turned on, and maintains constant speed rotation with high accuracy while the power is turned on. Light (laser beam) output from a light source 26 such as a semiconductor laser is reflected by a rotary polygon mirror 25 and irradiated while scanning on the photosensitive drum 23 through an fθ lens 27.

  When character data or image data converted into a dot image is sent from the controller 22 to the laser beam printer 21 as a laser beam ON / OFF signal, the surface of the photosensitive drum 23 is not irradiated with the portion irradiated with the laser beam. And an electrostatic latent image based on the data is formed.

  When the area of the photosensitive drum 23 on which the electrostatic latent image is formed reaches a position facing the developing device 28, the toner in the developing device 28 is supplied to the electrostatic latent image, and the photosensitive drum is irradiated with a laser beam. For example, toner charged with a positive charge is attracted by static electricity to a portion where the charge on 23 disappears, and a toner image is formed on the photosensitive drum 23.

  On the other hand, the continuous continuous printing paper 1 stored in the paper hopper 29 is synchronized with the timing at which the toner image formed on the photosensitive drum 23 reaches the transfer position by the paper transport tractor 31. It is conveyed and supplied between the photosensitive drum 23 and the transfer device 32.

  The toner image formed on the photosensitive drum 23 is sucked and transferred onto the printing paper 1 by the action of a transfer device 32 that applies a charge having a polarity opposite to that of the toner image to the back side of the printing paper 1.

  In this way, the printing paper 1 set in the paper hopper 29 is transported to the fixing device 35 through the paper transport tractor 31, the transfer device 32, the paper transport tractor 33, and the buffer plate 34.

  The printing paper 1 that has arrived at the fixing device 35 is preheated by a preheating plate (preheater) 3 having a plurality of heaters therein, and then a heating roller 5 and a pressure roller 8 each having a plurality of heating lamps 6 inside. The toner image is melted and fixed on the printing paper 1 by being sandwiched and conveyed while being heated and pressurized by a nip formed by a pair of fixing rollers.

The printing paper 1 sent out by the heating roller 5 and the pressure roller 8 is sent out to the stacker table 37 side by the paper feeding roller 36 and is alternately folded along the perforation by the swinging motion of the swing fin 38. Further, while being folded by the rotating paddle 39, it is stacked on the stacker table 37.
The surface of the region that has passed the transfer position of the photosensitive drum 23 is cleaned by the cleaning device 40 and is then prepared for a printing operation.

  Reference numeral 41 in the drawing is a display screen for displaying information based on the state of the laser beam printer 21 during the printing operation. Reference numeral 42 denotes a web member provided so as to be able to come into contact with the surface of the heating roller 5 and to be wound up, and for applying a release agent (oil) to the surface of the heating roller 5.

(Schematic configuration of fixing device)
FIG. 1 is a schematic configuration diagram of a fixing device 35 according to the present embodiment, and FIG. 2 is a schematic plan view for explaining the positional relationship between the heater 4 and the temperature sensor 12 with respect to a heat generation area on a preheating plate 3 used in the fixing device 35. FIG. In FIG. 2, the heater 4 and the temperature sensor 12 are built in the preheating plate 3 and are therefore indicated by dotted lines as in FIG. 1, but are shown by solid lines to clearly indicate the positions of the heater 4 and temperature sensor 12. ing.

  As shown in FIG. 1, a printing paper 1 carrying a toner image 2 is heated from the back side of the printing paper 1 by a preheating plate (preheater) 3, and the toner image 2 softened by this heating is composed of a plurality of heating lamps. 6 is sandwiched and conveyed by a heating roller 5 having a built-in member 6 and a pressure roller 8 supported by a support member 7, thereby being melted and fixed on the printing paper 1.

  As shown in FIG. 2, the preheating plate 3 has four heating regions I, II, III, and IV, that is, upstream of the printing paper running direction X, in the printing paper width direction (printing paper running direction). A first heat generation area I and a second heat generation area II are provided over a direction Y). Similarly, a third heat generation region III and a fourth heat generation region IV are provided on the downstream side in the printing paper traveling direction X over the printing paper width direction Y. The areas of the heat generating regions I to IV are equal, and each of the heat generating regions I to IV is controlled to a certain target temperature.

  The reason why the preheating plate 3 is divided into a plurality of heat generation regions I to IV in this way is that the temperature of the paper 1 itself and the control temperature of the preheating plate 3 generated in the printing paper 1 conveyed on the preheating plate 3. The amount of heat necessary to soften the toner image 2 before being held and conveyed by the heating roller 5 and the pressure roller 8 is minimized. This is to prevent wasteful heat supply in the non-printing paper travel region corresponding to the width printing paper 1.

  In the present embodiment, the printing paper 1 is conveyed on one side in the printing paper width direction Y regardless of the paper size (in this embodiment, on the right side in FIG. 1, that is, the first and third heat generating regions I and III). Side (see FIG. 2)).

  As shown in FIG. 2, two heaters 4 a to 4 d are arranged for each of the heat generation regions I to IV, but the heater 4 a arranged in the first heat generation region I and the third heat generation region III; The heaters 4c are arranged on the upstream side of the printing paper traveling direction X when the heat generation area is divided into two in the printing paper traveling direction X, respectively. On the other hand, the heater 4b and the heater 4d arranged in the second heat generation area II and the fourth heat generation area IV are respectively downstream in the printing paper traveling direction X when the heating area is divided into two in the printing paper traveling direction X. Is arranged. Accordingly, the heaters 4a to 4d are arranged in a staggered pattern as viewed from the preheating plate 3 as a whole.

This is because when all the heaters 4a to 4d are energized, the heat source (heater) of the same specification can be used while the heat is distributed almost evenly throughout the heat generation regions I to IV, and the wiring of the heaters 4a to 4d can be used. This is due to an efficient arrangement in which the handling can be taken out from one direction.
As shown in FIG. 1, the wires from the heaters 4 a to 4 d are taken out in the same direction and connected to the control unit 11.

  In each of the heat generating regions I to IV, temperature sensors 12a to 12j composed of a plurality of (two and three in this embodiment) thermistors are arranged at an arbitrary interval in the printing paper width direction Y. Each temperature sensor 12a-12j detects the surface temperature of the preheating plate 3 in each heat generating region I-IV.

  In the case of the present embodiment, as shown in FIG. 2, two temperature sensors 12a and 12b are provided between the two heaters 4a in the first heat generation area I on the paper running reference side, and the second heat generation. In the area II, three temperature sensors 12c, 12d, and 12e are provided between the two heaters 4b. In the third heat generating area III that is the paper running reference side, two temperature sensors 12c, 12d, and 12e are provided between the two heaters 4c. In the fourth heat generation region IV, three temperature sensors 12h, 12i, and 12j are arranged between the two heaters 4d, respectively.

  Note that the number of temperature sensors 12 installed in each of the heat generation regions I to IV is not limited to this, but two or more may be provided for each heat generation region. However, this is not the case when a specific heat generation area is configured not to use print sheets having different widths. Specifically, when the minimum sheet size is larger than or substantially equal to the width direction of the first and third heat generating regions I and III, the temperature sensor is used in the first and third heat generating regions I and III. It is also possible to set the number of 12 installed one by one.

  Regarding the arrangement position of each temperature sensor 12, in the printing paper width direction Y, the center position of the heat generating area of each heater 4 in the temperature monitoring area of each temperature sensor 12 is basically used.

  In the present embodiment, a preheating plate 3 having a width dimension A (see FIG. 2) of 20 inches is used, and is arranged in the first heat generation area I (the width dimension of the heat generation area I = A / 2) 2. Of the temperature sensors 12a and 12b, the temperature sensor 12a is disposed between the two heaters 4a and at the center of the sheet width (a position 5 inches from the end Z shown in FIG. 2). .

  This is a position that is covered with the minimum width of the corresponding printing paper 1 and, since it is necessary to check the temperature of the entire first heat generation region I, two are arranged at the center position in the width direction, It arrange | positions between the two heaters 4a which are the centers of a heat source.

  When the number of heaters 4 installed in each heat generating area is one or three, for the reasons described above, the position of the temperature sensor 12 in the printing paper running direction X should be as central as possible in the heater unit. desirable.

  In addition, the temperature sensor 12b disposed in the same first heat generation area I as the temperature sensor 12a is disposed in consideration of the printing paper 1 to be used. In this embodiment, the temperature sensor 12a is covered with the minimum width printing paper 1 (for example, 8 inches wide). The temperature sensor 12b performs more appropriate temperature control when a sheet having a width wider than the minimum width of 8 inches and a width of the heat generation area I smaller than 10 inches (for example, 9 inches) is used. Arranged to do. Therefore, it is desirable that the temperature sensor 12b be disposed closer to the second heat generation area II than the temperature sensor 12a and not covered when the paper to be used is the minimum width printing paper 1.

  On the other hand, of the three temperature sensors 12c, 12d, and 12e arranged in the second heat generation area II (the width dimension of the heat generation area II = A / 2), of the three temperature sensors 12c, 12d, and 12e, The temperature sensor 12d at the intermediate position is arranged at the center position of the heater 4b, similarly to the temperature sensor 12a. Further, the temperature sensors 12c and 12e are arranged at equal intervals on both sides of the temperature sensor 12d. Further, regarding the temperature sensors 12b, 12c, and 12e, the position in the printing paper width direction Y is the arrangement position of the temperature sensor 12 that is suitable for controlling the surface temperature of the preheating plate 3 according to the width and the continuous amount of the printing paper 1 to be used. To match.

  Here, in the present embodiment, the sensor surface is covered with each paper according to the typical printing paper 1 (standard paper: 12 inches wide, 15 inches wide, 19.5 inches wide) to be used. As described above, the temperature sensor 12c was disposed at a distance of 10.5 inches from the end Z, the temperature sensor 12d was disposed at a distance of 13.5 inches, and the temperature sensor 12e was disposed at a distance of 18 inches. In addition, considering the width of the standard paper to be used, the width of the heat generation areas I and III in the printing paper width direction Y is 9 inches, and similarly the width of the heat generation areas II and IV is 10.5 inches.

  As a matter of course, the position of the temperature sensor 12 may be changed depending on the size of the printing paper 1 to be used, and is not limited to the above position. For example, although the temperature sensor 12c is 13.5 inches in the above, it is disposed at a position of 14.5 inches, which is substantially the center position in the width direction of the heat generation regions II and IV, and is closer to the central region in each heat generation region. You may arrange as follows.

  Further, in the heat generation area where the printing paper 1 having the same width travels, such as the first heat generation area I and the third heat generation area III, and the second heat generation area II and the fourth heat generation area IV in the preheating plate 3. The temperature sensor 12 is preferably disposed at the same position from the viewpoint that the configuration of the heater 4 for supplying heat to the printing paper 1 is the same. That is, in this embodiment, the temperature sensors 12f and 12g in the third heat generation region III are arranged in the same manner as the temperature sensors 12a and 12b, and the temperature sensors 12h, 12i and 12j in the fourth heat generation region IV are the temperature sensors. The same arrangement as 12c, 12d, and 12e is desirable.

  In each of the heat generation regions I to IV, the plurality of temperature sensors 12a to 12j are arranged in a line in the printing paper width direction Y. This is because the detection state of the temperature sensor 12 in the paper running area and the non-paper running area is recognized in the printing paper 1 having a certain width.

Furthermore, in the thickness direction of the preheating plate 3, the temperature sensor 12 is installed at a position where the temperature detection performance of the temperature sensor 12 to be used is maximized, for example, a position closest to the paper running surface of the preheating plate 3. However, considering this position and the shape of the preheating plate 3 to be used and the protection of the temperature sensor 12 itself, in order to perform temperature control corresponding to the printing paper 1 of all widths and continuous quantities, for example, the paper of the preheating plate 3 Basically, the temperature sensor 12 is installed at a position submerged by several mm from the running surface.
As shown in FIG. 1, the signal lines of the temperature sensors 12 a to 12 j are connected to the control unit 11.

(The heater temperature control method by the control unit)
The control unit selects any one temperature sensor 12 for each of the heat generation regions I to IV from the temperature sensors 12a to 12j installed in the vicinity of the heaters 4a to 4d, and each of the selected temperature sensors 12a to 12j. Based on the output value of the temperature sensor 12, the heaters 4a to 4d are turned on / off (ON / OFF).

Next, a temperature control method for the heaters 4a to 4d by the control unit 11 will be described with reference to the flowchart of FIG.
First, in step (hereinafter abbreviated as S) 1, the heaters 4a to 4d are all turned on (energized). This has the purpose of heating the heater more quickly. In addition, if only one side of the heat generation area (heat generation areas I and III) is turned on, heat is applied to the other side (heat generation areas II and IV) where the other heater is not lit, in addition to the application of heat to the printing paper 1. As a result, the temperature control becomes inconvenient.

  Next, in S2, it is determined whether or not the width of the printing paper 1 to be used is a width that can cover all of the temperature sensor 12a to the temperature sensor 12j. The width of the printing paper 1 to be used is input to the control unit 11 by a paper width detection sensor (not shown), and the determination of S2 is made based on the input. If so (YES), in S3, all the temperature sensors 12a to 12j are arranged in the travel region of the printing paper 1, and “preheating plate 3≈the amount of heat supplied to the printing paper 1”. it is conceivable that. In that case, the temperature sensor 12 provided at the center in each of the heat generation regions I to IV is selected as the temperature sensor 12 that is allowed to operate in each of the heat generation regions I to IV.

  This is because when almost the entire heat generation area is covered, the temperature at the center (or near the center) of each heater reflects the temperature in each heat generation area, which is suitable for temperature control.

  In this embodiment, the temperature sensor 12a is used in the first heat generation area I, the temperature sensor 12d is used in the second heat generation area II, the temperature sensor 12f is used in the third heat generation area III, and the temperature sensor 12i is used in the fourth heat generation area IV. Selected.

  Next, in S4, the detected temperature from the selected temperature sensor 12 is input to the control unit 11, and individually compared with the set temperature in each of the heat generation regions I to IV stored in advance in the control unit 11, the detected temperature. Is continuously turned on for the heater 4 installed in the region where the set temperature has not reached the set temperature, and the heater 4 installed in the region where the detected temperature has reached the set temperature is turned off. As described above, the temperature sensors 12 perform the on / off control of the heaters 4a to 4d, and appropriately adjust and maintain the surface temperature of the preheating plate 3.

  In the heat generation areas I and II and the heat generation areas III and IV aligned in the printing paper width direction Y, the same temperature range is set, and in the paper running direction X, the heat generation areas I and II are more than the heat generation areas I and II. Heat generation areas III and IV are set to a high temperature range.

  If NO is determined in S2, the process proceeds to S5, where the width of the printing paper 1 to be used covers the temperature sensor 12c in the second heat generation area II and the temperature sensor 12h in the fourth heat generation area IV. It is determined whether or not the temperature sensors 12d and 12e in the second heat generation region II and the temperature sensors 12i and 12j in the fourth heat generation region IV have uncovered widths.

  If so (YES), there will be a non-paper travel area in the second heat generation area II and the fourth heat generation area IV, which is considered to be “preheating plate 3 ≠ amount of heat supplied to the printing paper 1”. There is a risk that the amount of heat supplied to the printing paper 1 will be excessive or insufficient.

  At this time, the temperature sensor 12 covered with the printing paper 1 in each of the heat generation regions I to IV is selected as the temperature sensor 12 selected one in each of the heat generation regions I to IV. When a plurality of temperature sensors 12 are covered with the printing paper 1 in the same heat generation area, the temperature sensor 12 closer to the center in the printing paper width direction Y is selected.

  Specifically, in the first heat generation area I, the temperature sensor 12a closer to the center, in the second heat generation area II, the temperature sensor 12c as the temperature sensor 12 covered with the printing paper 1, and in the third heat generation area III, In the temperature sensor 12f closer to the center and the fourth heat generation area IV, the temperature sensor 12h is selected as the temperature sensor 12 covered with the printing paper 1 (S6).

  When the temperature sensor 12 is selected in this way, the process proceeds to S4 described above, and on / off control of each heater 4a to 4d is performed based on the selected temperature sensor 12, and the surface temperature of the preheating plate 3 is set. Adjust and maintain appropriately.

  If NO is determined in S5, the process proceeds to S7, where the width of the printing paper 1 to be used is above the temperature sensors 12c, 12d in the second heat generation area II and the temperature sensors 12h, 12i in the fourth heat generation area IV. Although it is covered, it is determined whether the temperature sensor 12e in the second heat generation area II and the temperature sensor 12j in the fourth heat generation area IV have a width that does not cover.

  If so (YES), the temperature sensor 12 covered with the printing paper 1 in each of the heat generating regions I to IV is selected as the temperature sensor 12 selected one in each of the heat generating regions I to IV. When a plurality of temperature sensors 12 are covered with the printing paper 1 in the same heat generation area, the temperature sensor 12 closer to the center in the printing paper width direction Y is selected.

  Specifically, the temperature sensor 12a is used in the first heat generation region I, the temperature sensor 12d or 12c is used in the second heat generation region II, the temperature sensor 12f is used in the third heat generation region III, and the temperature sensor 12i is used in the fourth heat generation region IV. Alternatively, 12h is selected (S8).

  Specifically, when the left end in the paper width direction is close to the temperature sensor 12e side, for example, when the paper width is 17 inches, the right side 9 inches of the heat generation regions II and IV are covered. Therefore, among the temperature sensors 12d and 12c (and the temperature sensors 12i and 12h) covered with the paper, the temperature sensors 12d and 12i located at a position of 13.5 inches are respectively selected.

  Further, when the paper width is 14 inches, the right-hand side of the heat generation areas II and IV is covered by 5 inches, so the heat generation area of the temperature sensors 12d and 12c (and 12i and 12h) covered by the paper. The temperature sensors 12c and 12h closer to the center are selected in the width direction range covered with the II and IV sheets, respectively.

  When the temperature sensor 12 is selected in this way, the process proceeds to S4 described above, and on / off control of each heater 4a to 4d is performed based on the selected temperature sensor 12, and the surface temperature of the preheating plate 3 is set. Adjust and maintain appropriately.

  If NO is determined in S7, the width of the printing paper 1 to be used is any one of the paper having the same width as the width direction of the first and third heat generating regions I and III to the smallest paper. Therefore, in this embodiment, the temperature sensor 12a of the first heat generation region I and the temperature sensor 12f of the third heat generation region III closer to the center in the width direction are selected, and the second heat generation region II and the fourth heat generation region II are selected. Since all the temperature sensors 12 in the heat generation area IV are not covered with the printing paper 1, they are not selected as the temperature sensors 12 in this temperature control method (S9). The temperature sensors 12b and 12g can be used for more detailed temperature control as a control in addition to the control of the temperature control (temperature sensors 12a and 12f) when the non-traveling paper region is set. For example, in the non-running paper region, it is conceivable to perform control by raising the control temperature as compared with the case where the paper is covered with paper.

  When the temperature sensor 12 is selected in this way, the process proceeds to S4 described above, and on / off control of the present embodiment is performed for the heaters 4a to 4d based on the selected temperature sensor 12, and the preheating plate 3 is selected. Adjust and maintain the surface temperature appropriately.

Even in the case of passing through S9, the lighting control is performed so that the heaters 4b and 4d corresponding to the heat generation regions II and IV are kept at a constant temperature. The reason for this is that, as described in S1, only the heating by the heaters of the heat generating regions I and III causes more heat to be taken when the heat generating regions II and IV are turned off, which hinders the original temperature control of the heaters 4a and 4c. It is to come. In order to perform temperature control efficiently, ON / OFF control of each heater is performed so as to maintain a constant temperature even in a heat generating area not covered with paper.
In this manner, temperature control of the heaters 4a to 4d is performed by the control unit 11.

  In this embodiment, the temperature of the preheating plate 3 is simultaneously detected by the temperature sensor 12 in the non-traveling paper area, and based on this, the controller 11 monitors the excessive temperature rise due to the excessive heat in the non-paper traveling area. Yes.

  For example, if YES is determined in S5, the temperature sensors 12d and 12e in the second heat generation area II and the temperature sensors 12i and 12j in the fourth heat generation area IV are in the non-traveling paper area. The temperature of the non-paper running area is detected by all or part of these temperature sensors 12 and the detected value is input to the control unit 11. The control unit 11 is preset with an upper limit value for determining an excessive temperature rise in the non-paper running region, and the detection value input to the control unit 11 is compared with the upper limit value, and the detection value is the upper limit value. If the value is exceeded, it is determined that the temperature has risen.

  When there are a plurality of temperature sensors in the non-paper running area for each heat generation area, and more detailed temperature control is required, a plurality of temperature sensors are selected and the detected temperature values are used. However, the detection value of the central temperature sensor may be selected in the paper width direction of the non-paper traveling area, and the detection value may be used. Thereby, judgment control can be performed more easily.

  On the basis of this determination, in this embodiment, the lighting control of the heater 4 that handles the corresponding heat generation region is changed, for example, the lighting time of the heater 4 is shortened, and finer temperature control is performed, whereby non-paper Temperature rise due to surplus heat in the running area is suppressed.

  Further, similarly to the case where YES is determined in S5 described above, the same applies to the case where YES is determined in S7 (and in the case where the temperature sensors 12b and 12g are included, the case where NO is determined in S7). It is. The temperature of the non-paper running area is detected by all or part of these temperature sensors 12 and the detected value is input to the control unit 11. The control unit 11 is preset with an upper limit value for determining an excessive temperature rise in the non-paper running region, and the detected value input to the control unit 11 is compared with the upper limit value, and the detected value is set to the upper limit value. If the value is exceeded, it is determined that the temperature has risen.

  If continuous paper is used, the temperature of the non-traveling paper region is substantially constant during steady printing, and in this case, it is monitored whether there is a temperature change in the non-traveling paper region.

  In the case of a cut sheet, there may be a change in sheet width due to a sheet having a different sheet width during continuous printing on a sheet having a certain sheet width. In that case, in the configuration in which the heat generation area is divided into two in the printing paper traveling direction X, the upstream side and downstream side temperature sensors having the same positional relationship in the printing paper width direction Y show the same temperature change tendency. It can also be used to determine whether proper temperature detection is performed.

  The width of the printing paper 1 covers the temperature sensor 12b in the first heat generation area I and the temperature sensor 12g in the second heat generation area II, but the temperature sensor 12c and the fourth heat generation area IV in the third heat generation area III. Even if the temperature sensor 12h is not covered, the most suitable temperature sensor 12 covered with the printing paper 1 in each of the heat generation regions I to IV is selected based on the same idea as described above. Thus, it is possible to control the surface temperature of the residual heat and to monitor the excessive temperature rise by the temperature sensor 12 in the non-traveling paper region.

  As described above, in the present embodiment, the conveyance form of the printing paper 1 is the one-side reference conveyance, and the end position of the paper width can be recognized in advance. By providing a plurality of temperature sensors 12 in the printing paper width direction Y, the heater 4 is once heated when the paper is loaded, and the paper width is estimated from the detection state of the temperature sensor 12.

  In this embodiment, a temperature distribution table prepared by detecting the temperature state by, for example, temperature sensors 12a, 12b, 12c, 12d, and 12e arranged in the printing paper width direction Y and detecting in advance for each paper width. The paper width can be estimated by comparing with.

  As described above, in the temperature transition of each temperature sensor 12, the temperature sensor 12 covered with the printing paper 1 has a large temperature increase rate (temperature gradient), but is not covered with the printing paper 1. 12 detects a situation in which the rate of change in temperature rise (temperature gradient) is small, and if it is found that there is a paper edge between two temperature sensors 12 with different rate of change in temperature rise (temperature gradient), it becomes the target. The width of the printing paper 1 can be estimated from the position of the temperature sensor 12.

  In the above embodiment, the surface temperature control of the preheating plate 3 and the estimation of the width of the conveyed printing paper 1 are performed by the plurality of temperature sensors 12, but as another embodiment, the printing of the temperature sensor 12 is performed. A paper width detection sensor is provided on the upstream side of the paper transport direction X (or in the vicinity of the temperature sensor 12 or downstream of the temperature sensor 12 in the print paper transport direction X), and based on the detection result of the paper width, The temperature sensor 12 used for the surface temperature control of the preheating plate 3 can also be determined.

  In the case of a configuration in which the operator inputs and sets the type (continuous amount) of the printing paper 1 from the operation panel or the like when the printing paper 1 is loaded, a temperature distribution table created by detecting each paper width in advance is printed. A plurality of sheets 1 may be prepared for each type (continuous amount) of the sheet 1. In this case, there is an effect that a sheet width detection sensor is not necessary and heating by the temporary heater 4 is not necessary when loading a sheet.

  As described above, in the present invention, a temperature sensor covered with printing paper is selected from a plurality of temperature sensors received for each heat generation region, and the corresponding is based on the detection signal from the temperature sensor. Since the temperature control of the heater is performed, it is possible to perform preheating control based on a detection value that appropriately reflects the temperature of the printing paper.

  For this reason, the heat quantity necessary for softening the toner image can be supplied to the printing paper from the preheating plate without any excess regardless of the paper width. For this reason, it is possible to suppress non-uniform printing quality such as poor fixing due to partial insufficient heat and blurring of images due to excessive heat.

  Furthermore, since it is possible to prevent an increase in temperature due to excessive heat in the preheating plate, power consumption of the printing apparatus can be suppressed, and durability of the printing apparatus can be improved.

  Moreover, since temperature control is performed for each heater (heat source) using a detection value from a single temperature sensor, it is simpler than when temperature control is performed using a plurality of temperature sensors. Can control.

  FIG. 4 is a schematic plan view for explaining the arrangement relationship of the heater and the temperature sensor with respect to the heat generation area on the preheating plate according to another embodiment of the present invention.

 In this embodiment, the first heat generation area I and the second heat generation area II are positioned upstream of the printing paper traveling direction X, and the third heat generation area III and the fourth heat generation area II are intermediate positions of the printing paper traveling direction X. The heat generation area IV is provided with a fifth heat generation area V and a sixth heat generation area VI at positions downstream of the printing paper running direction X, and is divided into six heat generation areas in total.

  The areas of the heat generating regions I to VI are equal, and each of the heat generating regions I to VI is controlled to a certain target temperature. The reason for dividing the preheating plate 3 into a plurality of heat generating regions I to VI in this way is the same as in the above embodiment.

  Also in this embodiment, the printing paper 1 is transported on one side in the printing paper width direction Y regardless of the paper size (in this embodiment, on the right side in FIG. 4, that is, the first, third, and fifth This is carried out by a one-side reference conveyance system along the heat generation regions I, III, V side).

  As shown in FIG. 4, two heaters 4 a to 4 f are arranged for each of the heat generation regions I to VI, but in the first heat generation region I, the third heat generation region III, and the fifth heat generation region. The heater 4a, the heater 4c, and the heater 4e are arranged on the downstream side of the printing paper traveling direction X when the heat generation area is divided into two in the printing paper traveling direction X. On the other hand, the heater 4b, the heater 4d, and the heater 4f arranged in the second heat generation region II, the fourth heat generation region IV, and the sixth heat generation region VI are divided when the heat generation region is divided into two in the printing paper traveling direction X. The printing paper travel direction X is disposed upstream. Therefore, the heaters 4a to 4f are arranged in a staggered pattern as viewed from the preheating plate 3 as a whole.

This is because when all of the heaters 4a to 4f are energized, the heat source (heater) of the same specification can be used while the heat is distributed almost evenly throughout the heat generation regions I to VI, and the wiring of the heaters 4a to 4d can be used. This is due to an efficient arrangement in which the handling can be taken out from one direction.
In each of the heat generation regions I to VI, temperature sensors 12a to 12o composed of a plurality of (two and three in this embodiment) thermistors are arranged at an arbitrary interval in the printing paper width direction Y.

  In the case of this embodiment, as shown in FIG. 4, two temperature sensors 12a and 12b are provided between the two heaters 4a in the first heat generating region I, and two heat sensors in the second heat generating region II. Three temperature sensors 12c, 12d, and 12e are provided between the heaters 4b, and two temperature sensors 12f and 12g are provided between the two heaters 4c in the third heat generation region III on the paper running reference side. In the fourth heat generation region IV, three temperature sensors 12h, 12i, 12j are provided between the two heaters 4d, and in the fifth heat generation region V, two temperature sensors 12k are provided between the two heaters 4e. 12l are arranged in the sixth heat generation area VI between the two heaters 4f and three temperature sensors 12m, 12n, 12o, respectively.

  Since the lighting / extinguishing control of the heaters 4a to 4f based on the detection values from the temperature sensors 12a to 12o is the same as in the above embodiment, the description thereof is omitted.

  1: recording medium (printing paper), 2: toner image, 3: preheating plate (preheater), 4a-4d: heater, 5: heating roller, 8: pressure roller, 11: control unit, 12a-12j: temperature Sensor: 21: laser beam printer, 22: controller, 23: photosensitive drum, 24: corona charger, 26: light source, 28: developing device, 31: paper transport tractor, 32: transfer device, 33: paper transport tractor, 35: fixing device, X: printing paper running direction, Y: printing paper width direction, Z: edge of printing paper, I: first heat generation area, II: second heat generation area, III: third heat generation area , IV: fourth exothermic region.

JP 2008-46472 A

Claims (6)

In a preheating plate that preheats the toner image from the back side of the recording medium by disposing a heat source therein and passing the recording medium carrying the toner image along the surface,
A plurality of heat generating regions divided in the traveling direction of the recording medium and the recording medium width direction orthogonal to the recording medium traveling direction;
Incorporating a plurality of temperature sensors arranged at predetermined intervals in the recording medium width direction for each heat generation area,
Control means for controlling the heat generation of the heat source based on the detection output of one temperature sensor selected from among a plurality of temperature sensors provided for each of the heat generation regions ;
The plurality of temperature sensors arranged for each of the heat generating areas are arranged according to the width of the recording medium,
The control means includes
By comparing the detection outputs of the plurality of temperature sensors while the recording medium is running, the width of the recording medium is estimated, and the heat source is generated in each heat generation area according to the estimated width of the recording medium. A preheating plate , wherein a temperature sensor to be used for heat generation control is selected . In a preheating plate that preheats the toner image from the back side of the recording medium by disposing a heat source therein and passing the recording medium carrying the toner image along the surface,
A plurality of heat generating regions divided in the traveling direction of the recording medium and the recording medium width direction orthogonal to the recording medium traveling direction;
Incorporating a plurality of temperature sensors arranged at predetermined intervals in the recording medium width direction for each heat generation area,
Control means for controlling the heat generation of the heat source based on the detection output of one temperature sensor selected from among a plurality of temperature sensors provided for each of the heat generation regions;
Each of the heat generating regions is divided into at least two parts in the recording medium running direction and the recording medium width direction,
A first heat generating area on the upstream side and one side in the recording medium running direction;
A second heat generation area provided next to the first heat generation area in the recording medium width direction;
A third heat generation area provided downstream of the first heat generation area in the recording medium running direction;
A fourth heat generation area provided downstream of the second heat generation area in the recording medium running direction;
The recording target with reference to the vicinity of the end of the first heat generation area opposite to the second heat generation area and the vicinity of the end of the third heat generation area opposite to the fourth heat generation area. The medium has a configuration that runs on one side, and
The control means includes
By comparing the detection outputs of the plurality of temperature sensors while the recording medium is running, the width of the recording medium is estimated, and the heat source is generated in each heat generation area according to the estimated width of the recording medium. A preheating plate , wherein a temperature sensor to be used for heat generation control is selected . The preheating plate according to claim 1 ,
Each of the heat generating regions is divided into at least two parts in the recording medium running direction and the recording medium width direction,
A first heat generating area on the upstream side and one side in the recording medium running direction;
A second heat generation area provided next to the first heat generation area in the recording medium width direction;
A third heat generation area provided downstream of the first heat generation area in the recording medium running direction;
A fourth heat generation area provided downstream of the second heat generation area in the recording medium running direction;
Further, the first to fourth heat generation regions are formed by being divided into two along the recording medium running direction,
A heat source for the first heat generation area is disposed on the upstream side of the first heat generation area in the recording medium running direction;
A second heat generating area heat source is disposed on the downstream side of the second heat generating area in the recording medium running direction;
A third heat generation area heat source is disposed on the upstream side of the third heat generation area in the recording medium running direction;
A fourth heat generation area heat source is disposed at a downstream side portion of the fourth heat generation area in the recording medium running direction, or
A heat source for the first heat generation area is disposed on the downstream side of the first heat generation area in the recording medium running direction;
A second heat generation area heat source is disposed on the upstream side of the second heat generation area in the recording medium running direction;
A third heat generation area heat source is disposed on the downstream side of the third heat generation area in the recording medium running direction;
A preheating plate, wherein a fourth heat generation area heat source is disposed upstream of the fourth heat generation area in the recording medium running direction .   A preheating plate,
  A fixing unit composed of a heating unit and a pressing unit disposed downstream of the preheating plate in the recording medium running direction;
  After preheating the toner image carried on the recording medium on the preheating plate,
  In a fixing device for fixing the toner image on the recording medium by passing the recording medium through a nip formed by the heating unit and the pressing unit.
  The fixing device according to claim 1, wherein the preheating plate is the preheating plate according to claim 1.   A photoreceptor,
  Charging means for uniformly charging the surface of the photoreceptor;
  An exposure means for forming an electrostatic latent image by exposing the surface of the charged photoconductor based on image data;
  Developing means for forming a toner image by attaching toner to the electrostatic latent image;
  Conveying means for conveying and supplying a recording medium;
  Transfer means for transferring the toner image on the photoreceptor onto the recording medium that has been conveyed;
In a printing apparatus provided with fixing means for fixing the toner image on the recording medium to the recording medium,
  The printing apparatus according to claim 4, wherein the fixing unit is the fixing apparatus according to claim 4.   The printing apparatus according to claim 5, wherein
  The printing apparatus, wherein the recording medium is a long continuous sheet.

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