JP2013057865A - Sheet loading device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet loading device that prevents the occurrence of a blocking phenomenon, and an image forming apparatus.SOLUTION: A sheet loading device includes: a tray on which sheets ejected from a body part M1 of an image forming apparatus; determination means 201 for determining whether or not a loading state of the sheets loaded on the tray has reached a blocking condition that induces a blocking phenomenon; and notification control means 202 for controlling notification of information for prompting elimination of or blowing air between the sheets loaded on the tray.

Description

  The present invention relates to a sheet stacking apparatus that stacks sheets discharged from an image forming apparatus, and an image forming apparatus including the sheet stacking apparatus.

  2. Description of the Related Art Conventionally, a sheet stacking apparatus that stacks a sheet-like image recording medium (hereinafter simply referred to as “sheet”) discharged from an image forming apparatus is known. The sheet stacking apparatus includes, for example, a tray that can be raised and lowered according to the stacking height of sheets, and stacks up to 5000 sheets on which images are formed by an electrophotographic image forming apparatus or the like on the tray.

  In an electrophotographic image forming apparatus, a toner image formed in accordance with an image signal is transferred to a sheet, and the toner image transferred to the sheet is fixed to the sheet by a heat fixing type fixing device. The sheet on which the toner image is fixed is then conveyed while maintaining heat and stacked on the tray of the sheet stacking apparatus. Here, since the toner has adhesiveness until it is sufficiently cooled, the stacked sheets may be combined to form a block depending on the stacked state of the sheets. Such a phenomenon is called a blocking phenomenon. When the blocking phenomenon occurs, problems such as toner peeling off occur when the blocked sheet is separated, resulting in a reduction in image quality.

  Therefore, in order to suppress the occurrence of such a blocking phenomenon, measures are taken such as cooling the sheet by blowing cooling air to the sheets stacked on the tray of the sheet stacking apparatus with a cooling device. Has been proposed (see, for example, Patent Document 1).

  However, when a large number of sheets are discharged from the image forming apparatus one after another at short time intervals, the temperature of the sheets stacked on the sheet stacking apparatus can be sufficiently lowered even if the cooling apparatus is operated. Therefore, it is difficult to reliably prevent the blocking phenomenon.

  The present invention has been made in view of the above, and an object thereof is to provide a sheet stacking apparatus and an image forming apparatus that can prevent the occurrence of a blocking phenomenon.

  In order to solve the above-described problems and achieve the object, a sheet stacking apparatus according to the present invention includes a tray on which sheets discharged from the image forming apparatus are stacked, and a stacking state of the sheets stacked on the tray Determining means for determining whether or not a blocking condition which is a condition for inducing a blocking phenomenon has been reached, and when it is determined that the blocking condition has been reached, removal of the sheets stacked on the tray or And a notifying control means for performing control for notifying information for encouraging paper separation.

  An image forming apparatus according to the present invention includes the sheet stacking apparatus according to the present invention.

  According to the present invention, when the stacking state of the sheets stacked on the tray reaches the blocking condition, the information that prompts the removal or separation of the sheets stacked on the tray is notified, so that the occurrence of the blocking phenomenon is prevented. There is an effect that it can be prevented in advance.

FIG. 1 is a configuration diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. FIG. 2 is a configuration diagram showing a mechanical configuration of the main body. FIG. 3 is a configuration diagram illustrating a mechanical configuration of the sheet stacking apparatus according to the embodiment. FIG. 4 is a block diagram illustrating a configuration of a control system of the sheet stacking apparatus according to the embodiment. FIG. 5 is a flowchart illustrating a processing procedure of the control unit when the tray is lowered according to the sheet stacking amount on the tray. FIG. 6 is a flowchart illustrating an example of a processing procedure of the control unit that determines the blocking phenomenon. FIG. 7 is a flowchart illustrating an example of a processing procedure of the control unit that determines the blocking phenomenon. FIG. 8 is a flowchart illustrating an example of a processing procedure of the control unit that determines the blocking phenomenon. FIG. 9 is a flowchart illustrating an example of a processing procedure of the control unit that determines the blocking phenomenon. FIG. 10 is a block diagram illustrating an outline of the first modification. FIG. 11 is a block diagram illustrating an outline of the second modification. FIG. 12 is a block diagram illustrating an outline of the third modification. FIG. 13 is a block diagram illustrating an outline of the fourth modification.

  Hereinafter, embodiments of a sheet stacking apparatus and an image forming apparatus will be described in detail with reference to the accompanying drawings. In the following, an electrophotographic image forming apparatus will be described as an example of an image forming apparatus, but the present invention can be applied to other types of image forming apparatuses, for example, an ink jet type image forming apparatus. Inkjet image forming devices form an image by attaching ink to a sheet, but the ink that adheres to this sheet remains adhesive until it dries, so the blocking phenomenon is the same as when an image is formed with toner. Can occur.

  FIG. 1 is a configuration diagram showing a schematic configuration of an image forming apparatus according to the present embodiment. The image forming apparatus according to the present embodiment forms a full-color image of four colors, and is particularly an image forming apparatus suitable for production use in which a large number of sheets S are continuously conveyed and printed at high speed. . As shown in FIG. 1, the image forming apparatus includes a main body M1, a sheet stacking device M2, and an operation panel M3.

  The main body M1 forms an image on a sheet as an image forming medium by electrophotography. The sheet stacking device M2 stacks the sheet on which the image is formed by the main body unit M1 on the tray. The operation panel M3 accepts various input operations by the operator and displays various information. Note that a cooling device for cooling the sheet on which an image is formed by the main body M1 may be disposed between the main body M1 and the sheet stacking device M2.

  The main unit M1, the sheet stacking apparatus M2, and the operation panel M3 are provided with control units 100, 200, and 300, respectively. The control unit 100 comprehensively controls the operation of the main body unit M1. The control unit 200 comprehensively controls the operation of the sheet stacking device M2. The control unit 300 comprehensively controls the operation of the operation panel M3.

  FIG. 2 is a configuration diagram showing a mechanical configuration of the main body M1. As shown in FIG. 2, the main body M1 includes four image forming units 1a, 1b, 1c, and 1d arranged along the traveling direction of the intermediate transfer belt 10 (the direction of arrow B in the figure).

  The image forming unit 1a includes a photosensitive drum 2a, a drum charger 3a, an optical writing unit 4a, a developing device 5a, a primary transfer device 6a, and a cleaning device 7a. Similarly to the image forming unit 1a, the image forming units 1b to 1d are also photosensitive drums 2b to 2d, drum chargers 3b to 3d, optical writing units 4b to 4d, developing units 5b to 5d, primary transfer units 6b to 6d, Cleaning devices 7b to 7d are provided. The image forming units 1a to 1d form images of different colors, for example, the image forming unit 1a is yellow, the image forming unit 1b is magenta, the image forming unit 1c is cyan, and the image forming unit 1d is black.

  The photosensitive drum 2a starts to rotate in the direction of arrow A in the figure at the time of image formation, and continues to rotate until the image forming operation is completed. When the photosensitive drum 2a starts rotating, a high voltage is applied to the drum charger 3a, and negative charges are uniformly charged on the surface of the photosensitive drum 2a. Thereafter, the surface of the charged photosensitive drum 2a is irradiated with laser light modulated and scanned in accordance with image data from the optical writing unit 4a, and an electrostatic latent image corresponding to the image data is formed on the photosensitive drum 2a. The When the portion where the electrostatic latent image is formed by the rotation of the photosensitive drum 2a reaches a position facing the developing device 5a, the negatively charged toner is attracted from the developing device 5a to the electrostatic latent image, thereby The electrostatic latent image is developed with toner to form a toner image on the photosensitive drum 2a.

  When the toner image formed on the photosensitive drum 2a reaches a position facing the primary transfer device 6a across the intermediate transfer belt 10, the toner image is moved to the intermediate transfer belt 10 side by the action of a high voltage applied to the primary transfer device 6a. Attracted and primarily transferred onto the intermediate transfer belt 10 moving in the direction of arrow B in the figure. The toner remaining on the photosensitive drum 2a without being transferred to the intermediate transfer belt 10 is cleaned by the cleaning device 7a.

  The image forming operation is similarly performed in the image forming unit 1b following the image forming unit 1a, and the toner image formed on the photosensitive drum 2b is applied to the intermediate transfer belt 10 by the action of a high voltage applied to the primary transfer unit 6b. Primary transferred onto. At this time, the timing at which the toner image formed on the photosensitive drum 2 b reaches the position facing the primary transfer device 6 b is the timing at which the toner image primarily transferred from the photosensitive drum 2 a to the intermediate transfer belt 10 is transferred to the intermediate transfer belt 10. The toner image that is primarily transferred from the photosensitive drum 2a and the toner image that is primarily transferred from the photosensitive drum 2b are controlled on the intermediate transfer belt 10 by being controlled so as to match the timing of reaching the position of the primary transfer device 6b. It is overlapped with.

  Similarly, the toner image formed on the photosensitive drum 2c of the image forming unit 1c and the toner image formed on the photosensitive drum 2d of the image forming unit 1d are sequentially primary transferred onto the intermediate transfer belt 10, A full-color toner image is formed on the intermediate transfer belt 10.

  When the full-color toner image formed on the intermediate transfer belt 10 reaches the position of the secondary transfer device 11, it is conveyed in the direction of arrow H in the figure by the action of a high voltage applied to the secondary transfer device 11. Secondary transfer is performed on the sheet S passing between the intermediate transfer belt 10 and the secondary transfer unit 11. The toner remaining on the intermediate transfer belt 10 without being secondarily transferred to the sheet S is cleaned by the belt cleaning mechanism 12.

  The sheet S on which the full-color toner image is secondarily transferred is conveyed to the fixing device 20. The fixing device 20 includes a fixing roller 21 that is heated by the heat of the heater, and a pressure roller 22 that is disposed adjacent to the fixing roller 21. In the process in which the sheet S passes through the nip portion between the fixing roller 21 and the pressure roller 22, the fixing device 20 performs toner on the sheet S by heat from the fixing roller 21 and pressure by the pressure roller 22. The toner image is fixed on the sheet S by melting the image and pressing it on the sheet S. The sheet S on which the toner image is fixed is sent to a sheet stacking device M2 described later.

  FIG. 3 is a configuration diagram illustrating a mechanical configuration of the sheet stacking apparatus M2 according to the present embodiment. As illustrated in FIG. 3, the sheet stacking apparatus M <b> 2 includes a sheet introduction roller 31, a sheet discharge roller 32, and a tray 33.

  The sheet introduction roller 31 conveys the sheet S discharged from the main body M1 of the image forming apparatus and introduced into the sheet stacking apparatus M2 downstream (in the direction of arrow C in the figure). The sheet discharge roller 32 conveys the sheet S together with the sheet introduction roller 31 to discharge the sheet S from the discharge port onto the tray 33.

  A sheet passing sensor 34 is provided between the sheet introduction roller 31 and the sheet discharge roller 32. The paper passing sensor 34 detects the passage of the sheet S. A detection signal of the paper passing sensor 34 is input to the control unit 200. The notification sensor 34 functions as a detection unit that detects the number of sheets S discharged from the main body M1 of the image forming apparatus after the stacked height of the sheets S stacked on the tray 33 reaches a predetermined height. .

  The tray 33 is transported by the sheet introduction roller 31 and the sheet discharge roller 32 and stacks the discharged sheets S. The tray 33 can be moved up and down (in the direction of arrow D in the figure) along the direction in which the sheets S are stacked by a motor and tray lifting mechanism (not shown) under the control of the control unit 200. .

  Above the tray 33, an actuator 35 and a stack detection sensor 36 are provided. The actuator 35 abuts on the sheets S stacked on the tray 33 and acts so as to be gradually pushed up as the amount of sheets S stacked on the tray 33 increases. When the position of the uppermost sheet S stacked on the tray 33 approaches the discharge port, the stack detection sensor 36 is opened or blocked by the actuator 35 so that a predetermined amount of sheets S is stacked on the tray 33. Is detected. A detection signal of the stack detection sensor 36 is input to the control unit 200.

  When a detection signal (sensor ON signal) indicating that a predetermined amount of sheets S are stacked on the tray 33 is input from the stack detection sensor 36, the control unit 200 operates a motor and a tray lifting mechanism (not shown), The tray 33 is lowered by a predetermined amount. Thereafter, when the stacking amount of the sheets S on the tray 33 further increases and the sensor ON signal is input again from the stacking detection sensor 36, the control unit 200 further lowers the tray 33 by a predetermined amount. When the control unit 200 repeats such control, the discharge port is not blocked by the sheet S stacked on the tray 33, and the sheet S is continuously discharged and stacked on the tray 33.

  Further, in the vicinity of the tray 33, a middle sensor (upper) 37a, a middle sensor (middle) 37b, a middle sensor (lower) 37c, and a lower sensor 38 are provided along the vertical direction indicated by the arrow D in the drawing. ing. These middle sensor (upper) 37 a, middle sensor (middle) 37 b, middle sensor (lower) 37 c, and lower sensor 38 detect the height position of the tray 33 that is lowered by the control of the control unit 200.

  That is, when the height position of the tray 33 that is lowered by a predetermined amount under the control of the control unit 200 reaches the position of the middle sensor (upper) 37a, the height position of the tray 33 is the position of the middle sensor (upper) 37a. It is detected by the middle sensor (upper) 37a. Further, when the tray 33 is further lowered and the height position of the tray 33 reaches the position of the middle stage sensor (middle) 37b, it is determined that the height position of the tray 33 is the position of the middle stage sensor (middle) 37b. It is detected by the sensor (medium) 37b. Further, when the tray 33 is further lowered and the height position of the tray 33 reaches the position of the middle sensor (lower) 37c, the height position of the tray 33 is the position of the middle sensor (lower) 37c. It is detected by the sensor (lower) 37c. When the tray 33 is further lowered and the height position of the tray 33 reaches the position of the lower sensor 38, the lower sensor 38 detects that the height position of the tray 33 is the position of the lower sensor 38. .

  Detection signals from the middle sensor (upper) 37 a, middle sensor (middle) 37 b, middle sensor (lower) 37 c, and lower sensor 38 are input to the control unit 200. The control unit 200 recognizes the stacking height of the sheets S on the tray 33 based on the detection signals of the middle sensor (upper) 37a, the middle sensor (middle) 37b, the middle sensor (lower) 37c, and the lower sensor 38. To do. That is, the middle sensor (upper) 37a, middle sensor (middle) 37b, middle sensor (lower) 37c, and lower sensor 38 function as detection means for detecting the stacking height of the sheets S stacked on the tray 33. To do.

  A limit sensor 39 that detects that the height position of the tray 33 has reached the lower limit position is provided further below the lower sensor 38. That is, the tray 33 is further lowered after reaching the position of the lower sensor 38, and when the position of the limit sensor 39 is reached, the limit sensor 39 detects that the height position of the tray 33 has reached the lower limit position. .

  The tray 33 is provided with a weight sensor 40. The weight sensor 40 detects the weight of the sheets S stacked on the tray 33. A detection signal of the weight sensor 40 is input to the control unit 200.

  The sheet stacking device M2 includes a temperature sensor 41, a humidity sensor 42, a timer 43, a warning lamp 44, and a buzzer 45.

  The temperature sensor 41 detects a temperature in the vicinity of the tray 33 (hereinafter referred to as an environmental temperature). The humidity sensor 42 detects the humidity in the vicinity of the tray 33 (hereinafter referred to as environmental humidity). The environmental temperature detected by the temperature sensor 41 and the environmental humidity detected by the humidity sensor 42 are input to the control unit 200.

  The timer 43 measures time under the control of the control unit 200. The measured value of the timer 43 is referred to by the control unit 200 as needed. The timer 43 functions as a detection unit that detects an elapsed time after the stacking height of the sheets S stacked on the tray 33 reaches a predetermined height.

  The warning lamp 44 is constituted by, for example, an LED or the like, and lights or blinks when the control unit 200 determines that the stacked state of the sheets S stacked on the tray 33 has reached the blocking condition. Further, the buzzer 45 sounds when the control unit 200 determines that the stacked state of the sheets S stacked on the tray 33 has reached the blocking condition. The lighting or blinking of these warning lamps 44 and the sound of the buzzer 45 notify the operator that the stacked state of the sheets S stacked on the tray 33 has reached the blocking condition.

  As described above, the control unit 200 controls the operation of lowering the tray 33 based on the detection signal input from the stack detection sensor 36.

  Further, the control unit 200 determines whether or not the stacked state of the sheets S stacked on the tray 33 has reached a blocking condition that is a condition for inducing a blocking phenomenon, and the sheets S stacked on the tray 33 are determined. When the stacking state reaches the blocking condition, it has a function of performing control for notifying the operator of information for removing the sheet S stacked on the tray 33 or separating the paper.

  The stacking state that induces the blocking phenomenon includes, for example, a state in which the number and weight of the sheets S stacked on the tray 33 increase and a large pressure is applied to the sheets S, and a sheet S exceeding a predetermined amount on the tray 33. In a state where it is left loaded. In these states, for example, the stacking height of the sheets S stacked on the tray 33, the weight of the sheets S stacked on the tray 33, and the stacking height of the sheets S stacked on the tray 33 are predetermined heights. And the elapsed time after the stacking height of the sheets S stacked on the tray 33 reaches a predetermined height can be determined. . The control unit 200 includes detection signals and timers of the paper passing sensor 34, the middle sensor (upper) 37a, the middle sensor (middle) 37b, the middle sensor (lower) 37c, the lower sensor 38, and the weight sensor 40 described above. Based on the measured value of 43 or the like, it is determined whether or not any of the above has reached a predetermined standard, thereby determining whether or not the stacking state of the sheets S on the tray 33 has reached the blocking condition. To do.

  Further, when the sheet S is a thick paper or a coated paper, the toner fixing property is inferior to that of a plain paper having a general thickness, so that a blocking phenomenon is likely to occur. Since the thickness of the thick paper makes it difficult for the heat of the fixing device 20 to be transmitted, the toner fixing property is poor. Coated paper is a paper with a coating on the surface of the base paper to obtain high print quality, and the inorganic material with high thermal conductivity contained in the surface coating takes heat extremely quickly compared to the base paper. Therefore, the toner fixing property is poor. The coated paper has a matte tone and a glossy tone. However, due to the difference in the content of an inorganic substance having a high thermal conductivity, the glossy tone has a lower fixability than the matte tone.

  Therefore, when the sheet S is thick paper or coated paper, the toner is not sufficiently fixed, and there is a high possibility that the sheet S is stacked on the tray 33 with high adhesiveness. For this reason, the blocking phenomenon is more likely to occur than when the sheet S is a plain paper having a general thickness. Accordingly, the control unit 200 determines whether or not the blocking condition has been reached when the sheet S used for image formation in the main body M1 of the image forming apparatus has poor toner fixing properties such as thick paper or coated paper. Change the judgment criteria. Note that the type of sheet S can be realized, for example, when the control unit 200 acquires the print setting information input to the operation panel M3 from the control unit 300 of the operation panel M3. That is, when using thick paper or coated paper instead of standard thickness plain paper as the sheet S for forming an image, the operator sets the type of the sheet S to be used (thick paper or coated paper) as print setting information. Since the information is input to the operation panel M3, the type of the sheet S can be determined by acquiring this information.

  Further, when the environmental temperature and humidity are higher than the standard temperature and humidity, the toner is difficult to dry, and thus a blocking phenomenon is likely to occur. Therefore, the control unit 200 detects the environmental humidity detected by the humidity sensor 42 when the environmental temperature detected by the temperature sensor 41 is significantly higher (eg, 40 ° C. or higher) than a standard value (eg, 25 ° C.). When it is significantly higher (for example, 80% or more) than a standard value (for example, 50%), the criterion for determining whether or not the blocking condition has been reached is changed.

  FIG. 4 is a block diagram illustrating a configuration of a control system of the sheet stacking apparatus M2 according to the present embodiment. As shown in FIG. 4, the control unit 200 of the sheet stacking apparatus M <b> 2 includes functional configurations of a determination unit 201, a notification control unit 202, and an interruption control unit 203. When the control unit 200 is configured as a microcomputer having a CPU, a ROM, a RAM, an input / output interface circuit, etc., each of these functional configurations is stored in a ROM or the like using the RAM as a work area. This can be realized by executing a predetermined control program. In addition, a part or all of the functional configurations of the control unit 200 can be configured by dedicated hardware.

  The determination means 201 includes a sheet passing sensor 34, a middle sensor (upper) 37 a, a middle sensor (middle) 37 b, a middle sensor (lower) 37 c, a detection signal from each sensor of the weight sensor 40, and a timer 43 measurement. Information such as the value, print setting information (sheet S type information) acquired from the control unit 300 of the operation panel M3, the environmental temperature detected by the temperature sensor 41, the environmental humidity detected by the humidity sensor 42, and the like ( By the methods 1) to (4), it is determined whether or not the stacked state of the sheets S stacked on the tray 33 has reached the blocking condition. The following methods (1) to (4) are specific examples of a method for determining whether or not the stacked state of the sheets S stacked on the tray 33 has reached the blocking condition, and is limited to this. It is not a thing. Moreover, the determination means 201 does not need to perform all the determinations by the following methods (1) to (4), and may determine by any one method. In this case, the sheet stacking apparatus M2 of the present embodiment does not necessarily include a sensor or the like necessary for determination by another method.

(1) Determination based on stacking height of sheets S The determination unit 201 stacks the sheets S stacked on the tray 33 when the stacking height of the sheets S stacked on the tray 33 reaches a reference height. It is determined that the state has reached the blocking condition.

  The determination unit 201 includes detection signals from the middle sensor (upper) 37a, middle sensor (middle) 37b, middle sensor (lower) 37c, and lower sensor 38, print setting information (information on the type of the sheet S), and a temperature sensor. The environmental temperature detected by 41 and the environmental humidity detected by the humidity sensor 42 are input. Then, the determination unit 201 first determines a reference height that is a determination criterion based on the print setting information (information on the type of the sheet S), the environmental temperature detected by the temperature sensor 41, and the environmental humidity detected by the humidity sensor 42. Set the size.

  Specifically, the determination unit 201 is a plain paper having a general thickness of the sheet S used for image formation, the environmental temperature is lower than a preset high temperature threshold (for example, 40 ° C.), and the environment If the humidity is less than a preset high humidity threshold (for example, 80%), for example, the stacking height of the sheets S when the tray 33 reaches the height position of the lower sensor 38 is set as the reference height. . On the other hand, the determination unit 201 determines the reference height when the type of the sheet S used for image formation is thick paper or coated paper, when the environmental temperature is higher than the high temperature threshold, or when the environmental humidity is higher than the high humidity threshold. And the stacking height of the sheet S when the tray 33 reaches the height position of the middle sensor (upper) 37a, or the stacking of the sheet S when the tray 33 reaches the height position of the middle sensor (middle) 37b. The stacking height of the sheets S when the height or the height position of the middle stage sensor (lower) 37c is reached is set as the reference height. The changed reference height set here may be determined in advance, for example, depending on the degree of deviation of the environmental temperature from the high temperature threshold or the degree of deviation of the environmental humidity from the high humidity threshold. You may make it select.

  After setting the reference height as described above, the determination unit 201 uses the sensors used for determining the reference height (the lower sensor 38 or the middle sensor (upper) 37a, the middle sensor (middle) 37b, the middle sensor (lower ) The detection signal of 37c) is monitored, the tray 33 gradually descends as the stacking amount of the sheets S on the tray 33 increases, and the height position of the tray 33 is the position of the sensor used for determining the reference height. Is reached and the sensor is turned on, it is determined that the stacked state of the sheets S stacked on the tray 33 has reached the blocking condition.

(2) Determination Based on Stacked Weight of Sheet S The determination unit 201 blocks the stacked state of the sheet S stacked on the tray 33 when the stacked weight of the sheet S stacked on the tray 33 reaches the reference weight. It is determined that the condition has been reached.

  The determination unit 201 inputs the detection signal of the weight sensor 40, the environmental temperature detected by the temperature sensor 41, and the environmental humidity detected by the humidity sensor 42. The determination unit 201 first determines a reference weight as a determination criterion based on the print setting information (information on the type of the sheet S), the environmental temperature detected by the temperature sensor 41, and the environmental humidity detected by the humidity sensor 42. Set.

  Specifically, the determination unit 201 is a plain paper having a general thickness of the sheet S used for image formation, the environmental temperature is lower than a preset high temperature threshold (for example, 40 ° C.), and the environment When the humidity is less than a preset high humidity threshold (for example, 80%), a predetermined first weight (for example, 1 kg) is set as the reference weight. On the other hand, the determination unit 201 determines the reference weight when the type of the sheet S used for image formation is thick paper or coated paper, when the environmental temperature is higher than the high temperature threshold, or when the environmental humidity is higher than the high humidity threshold. A second weight smaller than the first weight (for example, 800 g) is set as the reference flow rate. The changed reference weight set here may be a fixed value determined in advance. For example, the reference weight may change according to the degree of deviation of the environmental temperature from the high temperature threshold or the degree of deviation of the environmental humidity from the high humidity threshold. The value may be changed automatically.

  The determination unit 201 monitors the detection signal of the weight sensor 40 after setting the reference weight as described above, and the weight sensor 40 detects the weight as the stacking amount of the sheets S on the tray 33 increases. When the stacked weight reaches the reference weight, it is determined that the stacked state of the sheets S stacked on the tray 33 has reached the blocking condition.

(3) Determination based on the number of sheets S discharged from the main body M1 of the image forming apparatus after the stacked height of the sheets S stacked on the tray 33 reaches a predetermined height. 34, detection signal of middle stage sensor (upper) 37a, middle stage sensor (middle) 37b, middle stage sensor (lower) 37c, and lower stage sensor 38, print setting information (information of sheet S type), and temperature sensor 41 detect And the ambient humidity detected by the humidity sensor 42 are input. The determination unit 201 first counts the sheet passing sensor 34 based on the print setting information (information on the type of the sheet S), the environmental temperature detected by the temperature sensor 41, and the environmental humidity detected by the humidity sensor 42. Set the count start height that is the reference for starting.

  Specifically, the determination unit 201 is a plain paper having a general thickness of the sheet S used for image formation, the environmental temperature is lower than a preset high temperature threshold (for example, 40 ° C.), and the environment When the humidity is less than a preset high humidity threshold (for example, 80%), for example, the stacking height of the sheets S when the tray 33 reaches the height position of the middle sensor (lower) 37c is counted as the start height. Set as On the other hand, when the type of the sheet S used for image formation is thick paper or coated paper, when the environmental temperature is equal to or higher than the high temperature threshold, or when the environmental humidity is equal to or higher than the high humidity threshold, the determining unit 201 The stacking height of the sheet S when the tray 33 reaches the height position of the middle sensor (upper) 37a or the height of the sheet S when the tray 33 reaches the height position of the middle sensor (middle) 37b is changed. Set the loading height as the count start height. Note that the changed count start height set here may be determined in advance, for example, depending on the degree of deviation of the environmental temperature from the high temperature threshold or the degree of deviation of the environmental humidity from the high humidity threshold. You may make it choose.

  After setting the count start height as described above, the determination unit 201 determines whether the sensor used for determining the count start height (the middle sensor (lower) 37c, or the middle sensor (upper) 37a and the middle sensor (middle) 37b Any detection signal is monitored. Then, as the stacking amount of sheets S on the tray 33 increases, the tray 33 gradually descends, the height position of the tray 33 reaches the position of the sensor used for determination of the count start height, and the sensor is turned on. Sometimes, the counting of the number of sheets S discharged from the main body M1 of the image forming apparatus is started. The sheet S discharged from the main body M1 of the image forming apparatus is detected by the sheet passing sensor 34 when the sheet S passes between the sheet introduction roller 31 and the sheet discharge roller 32. The determination unit 201 monitors the detection signal of the sheet passing sensor 34, and the sheet S discharged from the main body M1 of the image forming apparatus after the stacked height of the sheet S on the tray 33 reaches the count start height. Count the number of sheets. Then, when the value counted based on the detection signal of the paper passing sensor 34 reaches a reference number (for example, 100), the determination unit 201 determines that the stacking state of the sheets S stacked on the tray 33 is the blocking condition. Judge that it has reached.

(4) Determination by Elapsed Time after Sheet S Stacked on Tray 33 reaches Predetermined Height Determination means 201 includes middle sensor (upper) 37a, middle sensor (middle) 37b, middle stage Detection signals of the sensor (lower) 37c and the lower sensor 38, the measured value of the timer 43, print setting information (information on the type of the sheet S), the environmental temperature detected by the temperature sensor 41, and the humidity sensor 42 detect Enter the environmental humidity. The determination unit 201 first measures the time by the timer 43 based on the print setting information (information on the type of the sheet S), the environmental temperature detected by the temperature sensor 41, and the environmental humidity detected by the humidity sensor 42. Sets the measurement start height, which is the reference for starting

  Specifically, the determination unit 201 is a plain paper having a general thickness of the sheet S used for image formation, the environmental temperature is lower than a preset high temperature threshold (for example, 40 ° C.), and the environment When the humidity is less than a preset high humidity threshold value (for example, 80%), for example, the measurement start height of the sheet S when the tray 33 reaches the height position of the middle sensor (lower) 37c is measured. Set as On the other hand, if the type of the sheet S used for image formation is thick paper or coated paper, the environmental temperature is higher than the high temperature threshold, or the environmental humidity is higher than the high humidity threshold, the determination unit 201 The stacking height of the sheet S when the tray 33 reaches the height position of the middle sensor (upper) 37a or the height of the sheet S when the tray 33 reaches the height position of the middle sensor (middle) 37b is changed. Set the loading height as the measurement start height. The changed measurement start height set here may be determined in advance, for example, depending on the degree of deviation of the environmental temperature from the high temperature threshold or the degree of deviation of the environmental humidity from the high humidity threshold. You may make it choose.

  The determination means 201 sets the measurement start height as described above, and then uses a sensor (middle sensor (lower) 37c, or middle sensor (upper) 37a and middle sensor (middle) 37b used for determination of the measurement start height. Any detection signal is monitored. Then, as the stacking amount of sheets S on the tray 33 increases, the tray 33 gradually descends, the height position of the tray 33 reaches the position of the sensor used for determination of the measurement start height, and the sensor is turned on. Sometimes, the timer 43 starts measuring time. The determination unit 201 monitors the measurement value by the timer 43, and when the measurement value by the timer 43 reaches a reference time (for example, 5 minutes), the stacking state of the sheets S stacked on the tray 33 is the blocking condition. It is determined that it has reached.

  The notification control unit 202 provides information that prompts the removal or separation of the sheets S stacked on the tray 33 when the determination unit 201 determines that the stacked state of the sheets S on the tray 33 has reached the blocking condition. Control for notification is performed. Specifically, the notification control unit 202 displays, for example, on the control unit 300 of the operation panel M3 when the determination unit 201 determines that the stacked state of the sheets S on the tray 33 has reached the blocking condition. The command is output, and a message such as “There is a possibility of blocking. Please remove the paper from the tray or separate the paper.” Is displayed on the display unit of the operation panel M3. This message is stored, for example, in a storage unit in the operation panel M3. The control unit 300 of the operation panel M3 reads the message as described above from the storage unit and displays it on the display unit in accordance with the display command from the notification control unit 202. By referring to the message displayed on the display unit of the operation panel M3, the operator can recognize that there is a high possibility that a blocking phenomenon will occur if the sheet S on the tray 33 is left unattended. It is possible to take necessary measures for preventing the blocking phenomenon, such as removing the sheet S or performing paper separation.

  In addition, the notification control unit 202 controls to display the message as described above on the display unit of the operation panel M3, and at the same time, turns on or blinks the warning lamp 44 and further sounds the buzzer 45. Thereby, the notification to the operator can be ensured.

  In the above example, information that prompts the removal or separation of the sheets S stacked on the tray 33 is displayed on the display unit of the operation panel M3. However, characters and the like can be displayed on the sheet stacking device M2. When such a display unit is provided, the above message may be displayed on the display unit of the sheet stacking apparatus M2. Further, the display on the display unit of the operation panel M3 and the display on the display unit of the sheet stacking apparatus M2 may be performed together.

  The interruption control unit 203 interrupts the image formation by the main body M1 of the image forming apparatus when the determination unit 201 determines that the stacked state of the sheets S on the tray 33 has reached the blocking condition. Specifically, when the determination unit 201 determines that the stacking state of the sheets S on the tray 33 has reached the blocking condition, the interruption control unit 203 performs printing on the control unit 100 of the main body unit M1, for example. Outputs an interruption command. The control unit 100 of the main body M1 performs image formation until a sufficient time has passed for the operator to remove the sheet S on the tray 33, paper separation, or the like in accordance with a print interruption command from the interruption control unit 203. The operations of the units 1a to 1d and the supply of the sheet S are interrupted. As a result, it is possible to prevent inconveniences such as new sheets S being discharged one after another while the operator is performing removal of the sheets S on the tray 33, paper separation, and the like, which hinders work.

  Note that the time for interrupting the operation of the image forming units 1a to 1d of the main body M1 and the supply of the sheet S may be set in advance as an empirically determined time, or the sheet S on the tray 33 may be set in advance. The completion of the removal or paper separation may be detected by some method, and the interruption may be canceled based on the detection signal.

  Next, an outline of operations performed by the control unit 200 of the sheet stacking apparatus M2 according to the present embodiment will be described with reference to FIGS.

  First, control for lowering the tray 33 in accordance with the stacking amount of sheets S on the tray 33 will be described with reference to FIG. FIG. 5 is a flowchart illustrating a processing procedure of the control unit 200 when the tray 33 is lowered according to the stacking amount of the sheets S on the tray 33.

  When image formation by the main body M1 of the image forming apparatus is started, the control unit 200 of the sheet stacking apparatus M2 inputs a detection signal of the stack detection sensor 36 (step S101), and the detection signal of the stack detection sensor 36 is received. It is determined whether the signal is a sensor ON signal (a signal indicating that a predetermined amount of sheets S are stacked on the tray 33) (step S102). If the detection signal of the stack detection sensor 36 is not a sensor ON signal (step S102: No), the control unit 200 returns to step S101 and repeats the input of the detection signal of the stack detection sensor 36. If the detection signal is a sensor ON signal (step S102: Yes), a motor and a tray lifting mechanism (not shown) are operated to lower the tray 33 by a predetermined amount (step S103).

  Next, the control unit 200 inputs a detection signal of the limit sensor 39 and determines whether or not the limit sensor 39 is turned on (step S104). If the limit sensor 39 remains OFF (step S104: No), the process returns to step S101 and the subsequent processing is repeated. If the limit sensor 39 is ON (step S104: Yes), the tray 33 is returned. In order to detect the stacking amount of the sheets S after the height position reaches the lower limit position, the detection signal of the stack detection sensor 36 is input again (step S105), and the detection signal of the stack detection sensor 36 is the sensor ON signal. It is determined whether or not (step S106). Then, if the detection signal of the stack detection sensor 36 is not a sensor ON signal (step S106: No), the control unit 200 returns to step S105 and repeats the input of the detection signal of the stack detection sensor 36. If the detection signal is a sensor ON signal (step S106: Yes), the operator is notified that the tray 33 is full (step S107), and the series of processing ends.

  Next, the operation of the control unit 200 when the blocking phenomenon is determined by the method (1) will be described with reference to FIG. FIG. 6 is a flowchart illustrating an example of a processing procedure of the control unit 200 that determines the blocking phenomenon. FIG. 6 shows plain paper having a general thickness of the sheet S used for image formation, the environmental temperature is less than a preset high temperature threshold, and the ambient humidity is a preset high humidity threshold. However, if the type of the sheet S used for image formation is thick paper or coated paper, the environmental temperature is higher than the high temperature threshold, or the environmental humidity is higher than the high humidity threshold, The sensor used for the determination in S204 is changed from the lower sensor 38 to the middle sensor (upper) 37a, the middle sensor (middle) 37b, or the middle sensor (lower) 37c.

  When image formation by the main body M1 of the image forming apparatus is started, the control unit 200 of the sheet stacking apparatus M2 inputs a detection signal of the stack detection sensor 36 (step S201), and the detection signal of the stack detection sensor 36 is received. It is determined whether or not it is a sensor ON signal (step S202). If the detection signal of the stack detection sensor 36 is not a sensor ON signal (step S202: No), the control unit 200 returns to step S201 and repeats the input of the detection signal of the stack detection sensor 36. If the detection signal is a sensor ON signal (step S202: Yes), a motor and a tray lifting mechanism (not shown) are operated to lower the tray 33 by a predetermined amount (step S203).

  Next, the control part 200 inputs the detection signal of the lower stage sensor 38, and determines whether the lower stage sensor 38 was set to ON (step S204). If the lower sensor 38 remains off (step S204: No), the process returns to step S201 and the subsequent processing is repeated. If the lower sensor 38 is turned on (step S204: Yes), the tray 33 is returned. A control for notifying the information that prompts the removal of the stacked sheets S or the paper separation is performed (step S205), and the image formation by the main body M1 is interrupted (step S206), and the series of processing ends. To do.

  Next, the operation of the control unit 200 when the blocking phenomenon is determined by the method (2) will be described with reference to FIG. FIG. 7 is a flowchart illustrating an example of a processing procedure of the control unit 200 that determines the blocking phenomenon. FIG. 7 shows plain paper having a general thickness of the sheet S used for image formation, the environmental temperature is less than a preset high temperature threshold, and the ambient humidity is a preset high humidity threshold. However, if the type of the sheet S used for image formation is thick paper or coated paper, the environmental temperature is higher than the high temperature threshold, or the environmental humidity is higher than the high humidity threshold, The reference weight used for the determination in S302 is changed from the first weight to a second weight that is smaller than the first weight.

  When image formation by the main body M1 of the image forming apparatus is started, the control unit 200 of the sheet stacking apparatus M2 inputs a detection signal of the weight sensor 40 (step S301), and the tray 33 detected by the weight sensor 40 is detected. It is determined whether or not the loaded weight of the sheet S has reached the reference weight (step S302). If the stacking weight of the sheets S on the tray 33 detected by the weight sensor 40 is less than the reference weight (step S302: No), the control unit 200 returns to step S301 and inputs the detection signal of the weight sensor 40. repeat. On the other hand, when the stacking weight of the sheet S on the tray 33 detected by the weight detection sensor 40 reaches the reference weight (step S302: Yes), the control unit 200 removes the sheet S stacked on the tray 33 or performs paper separation. Is performed (step S303), the image formation by the main body M1 is interrupted (step S304), and the series of processing ends.

  Next, the operation of the control unit 200 when the blocking phenomenon is determined by the method (3) will be described with reference to FIG. FIG. 8 is a flowchart illustrating an example of a processing procedure of the control unit 200 that determines the blocking phenomenon. FIG. 8 shows plain paper having a general thickness of the sheet S used for image formation, the environmental temperature is less than a preset high temperature threshold, and the ambient humidity is a preset high humidity threshold. However, if the type of the sheet S used for image formation is thick paper or coated paper, the environmental temperature is higher than the high temperature threshold, or the environmental humidity is higher than the high humidity threshold, The sensor used for the determination in S404 is changed from the middle sensor (lower) 37c to the middle sensor (upper) 37a or middle sensor (middle) 37b.

  When image formation by the main body M1 of the image forming apparatus is started, the control unit 200 of the sheet stacking apparatus M2 inputs a detection signal of the stack detection sensor 36 (step S401), and the detection signal of the stack detection sensor 36 is received. It is determined whether it is a sensor ON signal (step S402). If the detection signal of the stack detection sensor 36 is not a sensor ON signal (step S402: No), the control unit 200 returns to step S401 and repeats the input of the detection signal of the stack detection sensor 36. If the detection signal is a sensor ON signal (step S402: Yes), a motor and a tray lifting mechanism (not shown) are operated to lower the tray 33 by a predetermined amount (step S403).

  Next, the control unit 200 inputs a detection signal of the middle sensor (lower) 37c and determines whether or not the middle sensor (lower) 37c is turned on (step S404). If the middle sensor (lower) 37c remains off (step S404: No), the process returns to step S401 and the subsequent processing is repeated. If the middle sensor (lower) 37c is turned on (step S404). : Yes), the counting of the number of sheets S based on the detection signal of the paper passing sensor 34 is started (step S405). Then, the control unit 200 determines whether or not the counted number of sheets S has reached the reference number (step S406), and continues counting until the number of sheets S reaches the reference number (step S406: No). . Then, when the number of sheets S reaches the reference number (step S406: Yes), the control unit 200 performs control for notifying information that prompts the removal or separation of the sheets S stacked on the tray 33. (Step S407), the image formation by the main body M1 is interrupted (Step S408), and the series of processing ends.

  Next, the operation of the control unit 200 when the blocking phenomenon is determined by the method (4) will be described with reference to FIG. FIG. 9 is a flowchart illustrating an example of a processing procedure of the control unit 200 that determines the blocking phenomenon. Note that FIG. 9 is a plain paper having a general thickness of the sheet S used for image formation, the environmental temperature is less than a preset high temperature threshold, and the ambient humidity is a preset high humidity threshold. However, if the type of the sheet S used for image formation is thick paper or coated paper, the environmental temperature is higher than the high temperature threshold, or the environmental humidity is higher than the high humidity threshold, The sensor used for the determination in S504 is changed from the middle sensor (lower) 37c to the middle sensor (upper) 37a or middle sensor (middle) 37b.

  When image formation by the main body M1 of the image forming apparatus is started, the control unit 200 of the sheet stacking apparatus M2 inputs a detection signal of the stack detection sensor 36 (step S501), and the detection signal of the stack detection sensor 36 is received. It is determined whether the signal is a sensor ON signal (step S502). If the detection signal of the stack detection sensor 36 is not a sensor ON signal (step S502: No), the control unit 200 returns to step S501 and repeats the input of the detection signal of the stack detection sensor 36. If the detection signal is a sensor ON signal (step S502: Yes), a motor and a tray lifting mechanism (not shown) are operated to lower the tray 33 by a predetermined amount (step S503).

  Next, the control unit 200 inputs a detection signal of the middle sensor (lower) 37c and determines whether or not the middle sensor (lower) 37c is turned on (step S504). If the middle sensor (lower) 37c remains off (step S504: No), the process returns to step S501 and the subsequent processing is repeated. If the middle sensor (lower) 37c is turned on (step S504). : Yes), the time measurement by the timer 43 is started (step S505).

  Thereafter, the control unit 200 inputs a detection signal of the middle sensor (lower) 37c and determines whether or not the middle sensor (lower) 37c remains ON (step S506). If the middle sensor (lower) 37c has been switched from ON to OFF (step S506: No), it is determined that the sheet S has been removed from the tray 33, and the process returns to step S501 to repeat the subsequent processing.

  On the other hand, if the middle sensor (lower) 37c remains ON (step S506: Yes), the control unit 200 determines whether or not the measurement value by the timer 43 has reached the reference time (step S507). If the measured value by the timer 43 has not reached the reference time (step S507: No), the process returns to step S506 and the detection signal of the middle sensor (lower) 37c is confirmed again. On the other hand, when the measured value by the timer 43 reaches the reference time (step S507: Yes), control is performed to notify information that prompts the removal of the sheets S stacked on the tray 33 or the paper separation ( In step S508), the image formation by the main body M1 is interrupted (step S509), and the series of processing ends.

  As described above in detail with specific examples, according to the sheet stacking apparatus M2 of the present embodiment, the determination unit 201 of the control unit 200 determines whether the stacking state of the sheets S stacked on the tray 33 is the same. It is determined whether or not a blocking condition that is a condition for inducing a blocking phenomenon has been reached. When the determination unit 201 determines that the stacking state of the sheets S has reached the blocking condition, the notification control unit 202 of the control unit 200 prompts the removal or separation of the sheets S stacked on the tray 33. Control for reporting information is performed. Accordingly, since the operator can quickly remove the sheet S and separate the sheet S when the stacked state of the sheets S stacked on the tray 33 reaches the blocking condition, the occurrence of the blocking phenomenon can be prevented in advance. Can do.

  Further, according to the sheet stacking apparatus M2 of the present embodiment, when the determination unit 201 determines that the stacking state of the sheets S has reached the blocking condition, the interruption control unit 203 of the control unit 200 includes the image forming apparatus. Since the image formation by the main body M1 is interrupted, new sheets S are discharged one after another while the operator performs removal of the sheets S on the tray 33, paper separation, and the like, thereby hindering the work. Inconvenience such as can be prevented.

  Further, according to the sheet stacking apparatus M2 of the present embodiment, the determination unit 201 of the control unit 200 determines the stacking height of the sheets S stacked on the tray 33, the weight of the sheets S stacked on the tray 33, the tray The number of sheets S discharged from the main body M1 of the image forming apparatus after the stacked height of the sheets S stacked on the sheet 33 reaches the reference height, and the stacked height of the sheets S stacked on the tray 33 are When at least one of the elapsed time since reaching the reference height reaches a predetermined reference, it is determined that the stacked state of the sheets S on the tray 33 has reached the blocking condition. Therefore, it is possible to determine whether or not the stacked state of the sheets S on the tray 33 has reached the blocking condition, and a highly accurate determination is possible.

  Further, according to the sheet stacking apparatus M2 of the present embodiment, the determination unit 201 of the control unit 200 determines that the type of the sheet S used for image formation is thick paper or coated paper, or the environmental temperature is equal to or higher than the high temperature threshold. Since the criterion for determination is changed when the environmental humidity is equal to or higher than the high humidity threshold, it is determined with higher accuracy whether or not the stacked state of the sheets S on the tray 33 has reached the blocking condition. Can do.

  When the image forming apparatus includes a mechanism for suppressing the occurrence of the blocking phenomenon (hereinafter referred to as a blocking suppression mechanism), the control unit 200 of the sheet stacking apparatus M2 uses the determination unit 201 to stack the sheets S. When it is determined that the blocking condition has been reached, the control for operating the blocking suppression mechanism may be performed together with the control by the notification control unit 202. Hereinafter, specific examples of the blocking suppression mechanism and some of its control examples will be described as modified examples.

(Modification 1)
FIG. 10 is a block diagram illustrating an outline of the first modification. The first modification includes a cooling device M4 for cooling the sheet S on which an image is formed by the main body M1 of the image forming apparatus as a blocking suppression mechanism. For example, the cooling device M4 is disposed between the main body M1 and the sheet stacking device M2, and the sheet S discharged from the main body M1 is introduced into the sheet stacking device M2 until the sheet S is introduced into the sheet stacking device M2. The sheet S is cooled, for example, by blowing an airflow. Further, the cooling device M4 may be provided inside the sheet stacking device M2, and may be configured to cool the sheet S by blowing an airflow directly on the sheets S stacked on the tray 33, for example.

  In the case of the first modification, as illustrated in FIG. 10, the control unit 200-1 of the sheet stacking device M2 includes a cooling control unit 204 that controls the start of the cooling device M4. The cooling control unit 204 starts the cooling device M4 when the determination unit 201 determines that the stacked state of the sheets S has reached the blocking condition. Accordingly, it is possible to lengthen the time from when the determination unit 201 determines that the stacked state of the sheets S has reached the blocking condition until the actual blocking phenomenon occurs, and the operator can increase the sheet S on the tray 33. Even when removal and paper separation cannot be performed immediately, the occurrence of the blocking phenomenon can be effectively suppressed.

(Modification 2)
FIG. 11 is a block diagram illustrating an outline of the second modification. Modification 2 is an example in which a plurality of trays 33 on which sheets S are stacked are provided. A path switching claw 51 that selectively switches between these transport paths is provided at a branch point of the transport path to each tray 33.

  In the case of the second modification, as illustrated in FIG. 11, the control unit 200-2 of the sheet stacking apparatus M2 includes a tray changing unit 205 that performs control to change the tray 33 on which the sheets S are stacked. When the determination unit 201 determines that the stacking state of the sheet S has reached the blocking condition, the tray changing unit 205 operates the path switching claw 51 to switch the conveyance path of the sheet S, thereby stacking the sheet S. The tray 33 to be changed is changed. As a result, even if image formation by the main body M1 is continued after the determination unit 201 determines that the stacking state of the sheets S has reached the blocking condition, the operator can remove the sheet S on the tray 33 or perform paper separation. There is no inconvenience that hinders work to be performed, and work efficiency is good.

(Modification 3)
FIG. 12 is a block diagram illustrating an outline of the third modification. The third modification is an example in which the conveyance speed of the sheet S conveyed to the tray 33 of the sheet stacking apparatus M2 after an image is formed by the main body M1 is variable. The change of the conveyance speed can be realized by changing the rotation speed of the sheet introduction roller 31 or the sheet discharge roller 32, for example.

  In the case of the third modification, as illustrated in FIG. 12, the control unit 200-3 of the sheet stacking apparatus M2 includes a conveyance speed control unit 206 that performs control for changing the conveyance speed of the sheet S. When the determination unit 201 determines that the stacking state of the sheets S has reached the blocking condition, the conveyance speed control unit 206 decreases the rotation speed of the sheet introduction roller 31 and the sheet discharge roller 32 to thereby reduce the main body M1. The conveyance speed of the sheet S conveyed from the tray to the tray 33 is reduced. As a result, it is possible to lengthen the time from when the image is formed on the sheet S to when the sheet S is stacked on the tray 33, and to promote cooling and drying of the toner.

(Modification 4)
FIG. 13 is a block diagram illustrating an outline of the fourth modification. In the fourth modification, the first conveyance path and the second conveyance path that is longer than the first conveyance path are used as the conveyance path of the sheet S that is conveyed to the tray 33 of the sheet stacking apparatus M2 after an image is formed by the main body M1. Is provided. A path switching claw 52 that selectively switches between the first transport path and the second transport path is provided at a branch point between the first transport path and the second transport path.

  In the case of the modification 4, as illustrated in FIG. 12, the control unit 200-4 of the sheet stacking apparatus M <b> 2 includes a conveyance path changing unit 207 that performs control for changing the conveyance path of the sheet S. The conveyance path changing unit 207 operates the path switching claw 52 when the determination unit 201 determines that the stacked state of the sheets S has reached the blocking condition, thereby changing the conveyance path of the sheet S to the first conveyance path. To the second transport path. As a result, it is possible to lengthen the time from when the image is formed on the sheet S to when the sheet S is stacked on the tray 33, and to promote cooling and drying of the toner.

  In addition, said modification 1-4 can also be implement | achieved combining the one part or all part. The embodiment described above is not limited to the first to fourth modifications described above, and can be embodied with various modifications without departing from the spirit of the present invention. For example, in the above-described embodiment, the sheet stacking apparatus M2 is described as an apparatus independent of the main body M1 of the image forming apparatus. However, the sheet stacking apparatus M2 may be integrated with the main body M1.

M1 Main unit M2 Sheet stacking device M3 Operation panel 33 Tray 34 Paper feed sensor 37a Middle sensor (upper)
37b Middle sensor (middle)
37c Middle sensor (bottom)
38 Lower sensor 40 Weight sensor 41 Temperature sensor 42 Humidity sensor 43 Timer 44 Warning light 45 Buzzer 200 Control unit 201 Determination means 202 Notification control means 203 Interruption control means 204 Cooling control means 205 Tray change means 206 Conveyance speed control means 207 Conveyance path change means

JP 2007-79310 A

Claims (11)

A tray on which sheets discharged from the image forming apparatus are stacked;
Determining means for determining whether or not the stacked state of the sheets stacked on the tray has reached a blocking condition that is a condition for inducing a blocking phenomenon;
And a notification control means for performing control for notifying information for prompting removal or separation of the sheets stacked on the tray when it is determined that the blocking condition has been reached. Sheet stacking device.   The sheet stacking apparatus according to claim 1, further comprising an interruption control unit that interrupts image formation by the image forming apparatus when it is determined that the blocking condition is reached. The stacking height of the sheets stacked on the tray, the weight of the sheets stacked on the tray, and the stacking height of the sheets stacked on the tray after reaching a predetermined height Detection that detects at least one of the number of sheets discharged from the image forming apparatus and an elapsed time after the stacked height of the sheets stacked on the tray reaches a predetermined height Further comprising means,
The sheet stacking apparatus according to claim 1, wherein the determination unit determines that the blocking condition has been reached when a detection result of the detection unit reaches a predetermined reference.   The sheet stacking apparatus according to claim 3, wherein the determination unit changes the reference according to a type of the sheet. Further comprising temperature detecting means for detecting the temperature in the vicinity of the tray;
The sheet stacking apparatus according to claim 3, wherein the determination unit changes the reference according to the detected temperature. Further comprising humidity detecting means for detecting the humidity in the vicinity of the tray;
The sheet stacking apparatus according to claim 3, wherein the determination unit changes the reference according to the detected humidity. A plurality of the trays;
The sheet stacking apparatus according to claim 1, further comprising a tray changing unit that changes a tray on which the sheets are stacked when it is determined that the blocking condition is reached.   2. The conveyance speed control unit according to claim 1, further comprising a conveyance speed control unit configured to reduce a conveyance speed of the sheet conveyed from the image forming apparatus to the tray when it is determined that the blocking condition has been reached. Sheet stacking device.   When it is determined that the blocking condition has been reached, the sheet conveyance path from the image forming apparatus to the tray is changed from the first conveyance path to a second conveyance path that is longer than the first conveyance path. The sheet stacking apparatus according to claim 1, further comprising a conveyance path changing unit for changing the sheet. Cooling means for cooling the sheet;
The sheet stacking apparatus according to claim 1, further comprising: a cooling control unit that starts the cooling unit when it is determined that the blocking condition is reached.
  An image forming apparatus comprising the sheet stacking device according to claim 1.

Images