Image forming system

Abstract

To perform punching processing at an appropriate position on a sheet to be conveyed regardless of the surface properties of the sheet in an image forming system.SOLUTION: An image forming system comprises: a punch unit that is provided in a post-processing apparatus and includes a punch rotating and performing punching processing on a sheet conveyed from an image forming apparatus; and a surface property detection section that detects the surface properties of the sheet conveyed on a conveyance path toward the punch unit. A control section controls the conveyance of the sheet so that the sheet is conveyed to the punch unit at a conveyance speed corresponding to the surface properties detected by the surface property detection section. The control section further controls the rotation of the punch so that the punch rotates at a rotation speed corresponding to the conveyance speed and performs punching processing on the sheet conveyed from the image forming apparatus.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image processing system including an image forming apparatus and a post-processing apparatus. [Background technology]

[0002] Patent Document 1 describes a technology in which, in an image forming system equipped with a rotary punch, the punch is rotated while a sheet is being conveyed, and the punch perforates the sheet at a state in which the sheet conveyance speed and the punch rotation speed are matched. In such an image forming system, if information about the sheet is not set by using an operation panel or the like, the sheet is generally conveyed at a predetermined speed.

[0003] Patent document 2 describes a technology in which a punching device that punches holes in a sheet detects the thickness of the sheet and stops the punching operation if the thickness is greater than a predetermined value, thereby avoiding damage to the sheet and malfunction of the device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-14355 [Patent Document 2] Japanese Patent Application Publication No. 6-183174 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the likelihood of slippage of the transport rollers transporting the sheet varies depending on the surface properties of the sheet. For example, if glossy paper, which has a smoother surface than plain paper, is transported at the same speed as plain paper, the transport rollers may slip. This type of transport roller slippage can cause the punch holes formed in the sheet by the punch unit (rotary punch) to be misaligned.

[0006] Furthermore, if the punch unit is overloaded during the punching process, the punch unit will malfunction, which will lead to a decrease in the quality of the punched holes formed by the punching process. Because the load on the punch unit changes depending on various conditions, it is desirable to appropriately control the punching process by taking such conditions into consideration.

[0007] Therefore, one of the objects of the present invention is to provide a technique that enables punching processing to be performed at appropriate positions on a sheet regardless of the surface properties of the sheet being conveyed. [Means for solving the problem]

[0008] An image forming system according to one aspect of the present invention comprises an image forming device and a post-processing device connected downstream of the image forming device in the sheet transport direction and performing a punching process to form punch holes in sheets transported from the image forming device through a transport path, and is characterized by comprising: a punch unit provided in the post-processing device and including a punch member that rotates to perform the punching process on sheets transported from the image forming device; a detection means for detecting the surface property of the sheet transported along the transport path toward the punch unit; and a control means for controlling the transport of the sheet so that the sheet is transported to the punch unit at a transport speed corresponding to the surface property detected by the detection means, and for controlling the rotation of the punch member so that the punch member performs the punching process on the sheet transported from the image forming device while rotating at a rotational speed corresponding to the transport speed.

[0009] Another aspect of the present invention provides an image forming system comprising an image forming apparatus and a post-processing apparatus connected downstream of the image forming apparatus in the sheet transport direction and performing a punching process to form punch holes in sheets transported from the image forming apparatus through a transport path, the image forming system comprising: a punch unit provided in the post-processing apparatus and including a punch member that rotates to perform the punching process on sheets transported from the image forming apparatus; a basis weight detection means that detects the basis weight of the sheets transported along the transport path toward the punch unit; a temperature and humidity sensor that detects the temperature and humidity in the installation environment of the image forming system; and a control means that controls the rotation of the punch member so that the punch member performs the punching process on the sheets transported from the image forming apparatus while rotating at a rotational speed corresponding to the transport speed of the sheets, and the control means further controls whether or not to perform the punching process on the sheets based on at least two of the basis weight detected by the basis weight detection means, the absolute moisture content in the air obtained based on information output from the temperature and humidity sensor, and the accumulated number of times the punching process has been performed by the punch unit. [Effects of the Invention]

[0010] According to the present invention, it is possible to perform punching at appropriate positions on a sheet regardless of the surface properties of the sheet being conveyed, and it is also possible to prevent an overload from being applied to the punch unit during punching. [Brief explanation of the drawings]

[0011] [Figure 1] Cross-sectional view showing an example of the configuration of an image forming system [Figure 2] Block diagram showing an example of the functional configuration of an image forming system [Figure 3] Cross-sectional view showing an example of punch unit operation [Figure 4] FIG. 1 is a plan view showing an example of the configuration of a post-processing device; [Figure 5] FIG. 10 is a diagram showing an example of a setting table for sheet conveyance speed and perforation motor rotation speed. [Figure 6] 1 is a flowchart showing a processing procedure for sheet transport control and punch control. [Figure 7] FIG. 10 is a diagram showing an example of a setting table used to determine whether or not to perform a punching operation by a punch unit. [Figure 8] 1 is a flowchart showing a processing procedure for sheet transport control and punch control. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0013] [First embodiment] <Image forming system> FIG. 1 is a cross-sectional view showing an example of the configuration of an electrophotographic image forming system according to an embodiment of the present disclosure. The image forming system 5 includes an image forming apparatus 1 that forms an image on a sheet, and a post-processing apparatus 4 connected downstream of the image forming apparatus 1 in the sheet transport direction. The post-processing apparatus 4 performs predetermined post-processing on the sheet on which the image is formed by the image forming apparatus 1 and which is transported from the image forming apparatus 1 through a transport path, and discharges the post-processed sheet to a tray. In this embodiment, the post-processing performed by the post-processing apparatus 4 is a punching process that punches holes (forms punch holes) at predetermined positions on the sheet transported from the image forming apparatus 1 through the transport path. The post-processing apparatus 4 may also be referred to as a sheet processing apparatus.

[0014] The image forming apparatus 1 includes a paper feeder 6 that can store multiple sheets, and a paper type discrimination device 114 that discriminates the type of the fed sheet. The paper feeder 6 feeds the stored sheets one by one to a conveyance path. The sheet fed from the paper feeder 6 stops temporarily at the position of the paper type discrimination device 114. The paper type discrimination device 114 discriminates the type of the stopped sheet and outputs the discrimination result. When conveyance of the sheet resumes from the position of the paper type discrimination device 114, it is conveyed to the transfer nip portion between the photosensitive drum 9 and the transfer roller 10.

[0015] The image forming cartridge 8 includes a charger, a developer, and a photosensitive drum 9. The photosensitive drum 9 is rotatably supported by the image forming cartridge 8. The image forming device 1 uniformly charges the surface of the photosensitive drum 9 using the charger, and exposes the charged surface of the photosensitive drum 9 to laser light based on image data, thereby forming an electrostatic latent image on the photosensitive drum 9. The exposure of the photosensitive drum 9 is performed by an exposure unit 15. The exposure unit 15 includes a light source that outputs laser light, a polygon mirror that reflects the laser light to scan the laser light, and a mirror and lens that guide the laser light to the surface of the photosensitive drum 9. In the image forming device 1, the electrostatic latent image formed on the photosensitive drum 9 is developed with toner using a developer, thereby forming a toner image on the photosensitive drum 9.

[0016] The transfer roller 10 is disposed opposite the photosensitive drum 9, forming a transfer nip between the transfer roller 10 and the photosensitive drum 9. When a predetermined voltage is applied to the transfer roller 10, the toner image on the photosensitive drum 9 is transferred to the transfer nip. The sheet on which the toner image has been formed is transported to the fixing unit 11. The fixing unit 11 applies heat and pressure to the transported sheet to fix the toner image to the sheet. After the fixing process by the fixing unit 11, the sheet is discharged to the paper output tray 7 or to the post-processing device 4. When the sheet is discharged to the post-processing device 4, the sheet is conveyed by the conveying rollers 23 along the conveying path 30 and delivered to the post-processing device 4. The conveying rollers 23 are driven by a motor (not shown). The conveying path 30 corresponds to a portion of the conveying path within the image forming apparatus 1 that is located downstream of the fixing unit 11 in the sheet conveying direction and horizontal to the installation surface of the image forming apparatus 1.

[0017] The post-processing device 4 includes, in order from the upstream side along a conveying path 40 for conveying sheets discharged from the image forming device 1, an upstream roller 21, an inlet sensor 27, a punch unit 62, and a downstream roller 22. The inlet sensor 27 and the punch unit 62 can be disposed between the upstream roller 21 and the downstream roller 22. The punch unit 62 is configured as a rotary punch unit. The upstream roller 21 is driven by a driving force transmitted from a conveying motor 104 via a gear. The downstream roller 22 is driven by a driving force transmitted from the upstream roller 21 via a belt.

[0018] A sheet discharged from the image forming apparatus 1 through the conveying path 30 is conveyed along the conveying path 40 by the upstream rollers 21 and downstream rollers 22 in the post-processing device 4. The post-processing device 4 detects the leading edge of the sheet using the inlet sensor 27, and after a predetermined time from the timing of the detection, causes the punch unit 62 to perform a punching operation by driving the punch unit 62 to rotate. In this way, a punching process is performed in which holes are punched in the sheet (punch holes are formed) while the sheet is being conveyed on the conveying path 40. The punched sheet is conveyed along the conveying path 40 by the downstream rollers 22, and is discharged (ejected) onto the paper output tray 25 by the paper output rollers 24.

[0019] <Functions of the image forming device> Fig. 2 is a block diagram showing an example of the functional configuration of the image forming apparatus 1 and post-processing apparatus 4 that make up the image forming system 5. Fig. 2 also shows the configuration related to the control described in this embodiment (the configuration related to sheet type determination in the image forming apparatus 1, and the configuration related to sheet conveyance and punching processing in the post-processing apparatus 4). In the configuration example of Fig. 2, the temperature and humidity sensor 141 and the storage unit 150 are provided in the image forming system 5 according to the second embodiment, but may not be provided in the image forming system 5 according to the first embodiment.

[0020] The image forming apparatus 1 has a control unit 111 that controls the image forming operation of the image forming apparatus 1. The control unit 111 controls the conveyance of sheets in the conveyance path 30 of the image forming apparatus 1 and the conveyance path 40 of the post-processing device 4, and controls image formation based on the detection results from the paper type discrimination device 114. The control unit 111 may be configured to include one or more CPUs and one or more memories. In this case, the processing by the control unit 111, which will be described later, can be realized by the CPU reading and executing a control program stored in the memory. Alternatively, the control unit 111 may be configured by a dedicated circuit (hardware module) such as an ASIC.

[0021] The paper type discrimination device 114 has a surface property detection unit 116 and a basis weight detection unit 131. In this embodiment, the surface property detection unit 116 is an example of a detection means that detects the surface property of a sheet transported on the transport path toward the punch unit 62. The basis weight detection unit 131 is an example of a basis weight detection means that detects the basis weight of a sheet transported on the transport path toward the punch unit 62.

[0022] The surface property detection unit 116 outputs the amount of reflected light when light is irradiated onto the sheet as a detection result to the control unit 111. The control unit 111 identifies the surface property of the sheet based on the detection result output from the surface property detection unit 116. In this embodiment, the control unit 111 identifies the surface property of the sheet based on whether the amount of reflected light indicated by the detection result falls within a range corresponding to "rough paper," "plain paper," or "gloss paper."

[0023] The basis weight detection unit 131 outputs the amount of transmitted light when light is irradiated onto the sheet as a detection result to the control unit 111. The control unit 111 determines (specifies) the basis weight of the sheet based on the detection result output from the basis weight detection unit 131. In this embodiment, the control unit 111 specifies the basis weight (basis weight range) of the sheet based on whether the amount of transmitted light indicated by the detection result falls within a range corresponding to "Heavy," "Normal," or "Light."

[0024] <Functions of post-processing device> The post-processing device 4 has a post-processing control unit 101 that controls the punching operation and sheet conveying operation of the post-processing device 4. The post-processing control unit 101 can control the punching operation and sheet conveying operation based on information output from the control unit 111 (e.g., paper type information, print job information, and temperature and humidity information). The print job can include settings related to the punching process (punch designation). The post-processing control unit 101 can be configured to include one or more CPUs and one or more memories. In this case, the processing by the post-processing control unit 101, which will be described later, can be realized by the CPU reading and executing a control program stored in the memory. Alternatively, the post-processing control unit 101 can be configured by a dedicated circuit (hardware module) such as an ASIC.

[0025] The post-processing control unit 101 controls the driving of the punching motor 102 and the conveying motor 104 to control the punching operation and the sheet conveying operation. The motor driver circuit 115 drives the punching motor 102 in accordance with a drive instruction from the post-processing control unit 101. The punching motor 102 is configured to rotate the punch unit 62 (punch 202 and die 205). The punch unit 62 is an example of a punch unit that includes a punch member (punch 202) that performs a punching process on a sheet conveyed from the image forming apparatus 1 while rotating.

[0026] The motor driver circuit 115 rotates the punch unit 62 (punch 202 and die 205) by driving the perforation motor 102. The motor driver circuit 103 drives the feed motor 104 in accordance with a drive instruction from the post-processing control unit 101. The feed motor 104 is configured to drive and rotate the upstream roller 21. The motor driver circuit 103 drives the feed motor 104 to rotate the upstream roller 21.

[0027] In this embodiment, the drilling motor 102 may be configured as a stepping motor. The conveyor motor 104 may be configured as a DC brushless motor. The DC brushless motor has a Hall element as a sensor for detecting the rotor position (phase), and the Hall element outputs an FG pulse at a period proportional to the rotor rotation speed. The motor driver circuit 103 controls the rotation speed of the conveyor motor 104 based on the FG pulse output from the conveyor motor 104.

[0028] The post-processing control unit 101 further detects the presence or absence of a sheet based on a signal output from the inlet sensor 27, and detects the rotational position of the punch 202 (punch member) based on a signal output from a home position (HP) sensor 130. The HP sensor 130 has a photointerrupter and a flag member (not shown), and is configured to output different signals depending on whether light from the light-emitting portion of the photointerrupter toward the light-receiving portion is blocked by the flag member. Specifically, the HP sensor 130 outputs either a signal indicating a light-blocking state (detection state) or a signal indicating a light-transmitting state (non-detection state). As will be described later, the HP sensor 130 is configured to output a signal indicating a light-blocking state when the rotational position of the punch 202 is within a predetermined range. That is, the HP 130 alternately outputs a signal indicating a light-blocking state and a signal indicating a light-transmitting state for each rotational period of the punch 202 (outputting a pulse signal with a period corresponding to the rotational period).

[0029] <Punch unit perforation section> FIG. 3 is a cross-sectional view showing an example of the operation of the punch unit 62. The punch unit 62 has a configuration in which a support shaft 65 of the punch 202 and a support shaft 66 of the die 205 are each rotatably supported by a casing (not shown). Gears (not shown) fixed to one end of the support shafts 65, 66 of the punch 202 and the die 205 mesh with a gear provided on the output shaft of the perforation motor 102. The punch 202 is configured to rotate in the clockwise direction in FIG. 3 by rotating the support shaft 65 in accordance with the rotation of the perforation motor 102. The die 205 is configured to rotate in the counterclockwise direction in FIG. 3 in synchronization with the rotation of the punch 202.

[0030] The die 205 has a die hole 206 provided at a position corresponding to the punch 202. Figures 3(A) to 3(D) show how the rotational positions of the punch 202 and the die 205 change, and how the positions of the punch 202 and the die hole 206 change over time, causing the punch 202 to perforate a sheet. Figure 3(C) shows that the punch 202 is in a position where it engages with the die hole 206 (perforation center position 75). The punch unit 62 is configured so that the punch 202 engages with the die hole 206 while the sheet passes through the perforation center position 75, thereby perforating the sheet with the punch 202.

[0031] 3A shows that the punch 202 is at a standby position 67, which corresponds to the home position (HP). The standby position 67 is at an angle θ HP The post-processing control unit 101 normally stops the punch 202 at the standby position 67 when the punch 202 is not performing a punching operation. HP is determined so that the punch 202 stopped at the standby position 67 does not interfere with the conveyance of the sheet.

[0032] 3(B) shows that the punch 202 is in a position where it starts to punch a sheet (punch start position 70). FIG. 3(D) shows that the punch 202 is in a position where it starts to separate from the sheet (punch end position 71) (punch end position 71). The HP sensor 130 is configured to output a signal indicating a light-blocking state (detection state) when the rotation position of the punch 202 is in the range of angle Δθ from the punch start position 70 to the punch end position 71. The HP sensor 130 outputs a signal indicating a light-transmitting state (non-detection state) when the rotation position of the punch 202 is in any other range.

[0033] The post-processing control unit 101 uses the motor driver circuit 115 to stop the punch 202 at the standby position 67 (HP) as follows. Specifically, the post-processing control unit 101 stops driving the punching motor 102 when the punching motor 102 has been driven a predetermined number of steps after the output of the HP sensor 130 switches from the light-blocking state to the light-transmitting state. As a result, the punch 202 rotates from the punching end position 71 shown in FIG. 3(D) to the standby position 67 shown in FIG. 3(A) and stops there.

[0034] <Sheet transport control and punching control in post-processing device> Next, an example of sheet transport control and punch control in post-processing device 4 will be described with reference to Fig. 4. Fig. 4 is a plan view showing an example of the configuration of post-processing device 4. Fig. 4(A) shows a state in which the leading edge of a sheet discharged from image forming apparatus 1 has reached upstream roller 21 in the sheet transport direction. Fig. 4(B) shows a state in which the sheet has reached a position detected by inlet sensor 27 in the sheet transport direction.

[0035] 4, dashed circles indicate ideal positions 119, 120, and 121 for punch holes (perforation positions) formed by punching when three punch holes are formed in sequence in a sheet using the punch unit 62. Furthermore, L1 to L4 respectively indicate the following distances (intervals) in the sheet conveyance direction: L1: the distance from the punching center position 75 of the punch unit 62 to the position of the entrance sensor 27. - L2: Ideal distance from the leading edge of the sheet to the first perforation location 119. - L3: Ideal spacing between drilling positions 119-121. - L4: distance between the edges of adjacent punched holes.

[0036] The post-processing control unit 101 controls the rotation speed of the feed motor 104 using the motor driver 103 in accordance with instructions (print job including punching instructions) from the control unit 111. The motor driver 103 controls the rotation speed of the feed motor 104 by controlling the drive current supplied to the feed motor 104 so that the period of the FG pulse output from the feed motor 104 becomes equal to a predetermined target period.

[0037] The sheet discharged from the image forming apparatus 1 by the conveying rollers 23 and supplied to the post-processing device 4 reaches the upstream rollers 21 as shown in FIG. 4A. The upstream rollers 21 and the downstream rollers 22 are rotated by the driving force of the conveying motor 104, thereby conveying the sheet in the conveying path 40. The sheet that has reached the upstream rollers 21 is conveyed by the upstream rollers 21 along the conveying path 40 to the punching unit 62. The sheet conveying speed V by the upstream rollers 21 and the downstream rollers 22 is s [mm / sec] is the rotation speed V of the conveyor motor 104 smotor [rpm], the reduction ratio K of the drive gear connecting the conveyor motor 104 and the upstream roller 21 s , the radius R of both the upstream roller 21 and the downstream roller 22 s can be calculated using the following: V s = R s ×2πV smotor ×K s (1)

[0038] As described above, the post-processing control unit 101 causes the punch 202 to wait in advance at the standby position 67 (FIG. 3A) before the punch unit 62 starts punching. As shown in FIG. 4B, when the leading edge of the sheet reaches the position of the inlet sensor 27, the leading edge of the sheet is detected by the inlet sensor 27. The post-processing control unit 101 waits for a predetermined waiting time T stop After this time has elapsed, the drilling motor 102 starts to be driven.

[0039] The post-processing control unit 101 controls the driving of the punching motor 102 using the motor driver circuit 115 so that the rotational speed of the punching motor 102 becomes equal to a predetermined target rotational speed (command speed) in accordance with a predetermined speed profile. When the punch 202 reaches the punching center position 75 shown in FIG. 3(C) by driving the punching motor 102, a punch hole is formed at a punching position 119 on the sheet by perforation by the punch 202. The target rotational speed (command speed) of the punching motor 102 is determined by the tangential speed V p is the sheet transport speed V s is determined to be equal to

[0040] The above-mentioned waiting time T stop is the time T s and time T p The time T s is the time from when the leading edge of the sheet is detected by the inlet sensor 27 until the first punch position 119 on the sheet reaches the punch center position 75. p is the time required for the punch 202 and the die 205 to rotate from the standby position 67 (FIG. 3A) to the punch center position 75 (FIG. 3C) according to a predetermined speed profile. s If is constant, time T s is calculated as follows: T s = L(1+L2) / V s (2) In addition, waiting time stop is calculated as follows: T stop = T s -T p (3)

[0041] For example, L1=50[mm], L2=31.7[mm], V s = 400 [mm / sec], T s = 204 [msec]. p = 50 [msec], the waiting time Tstop =154[msec].

[0042] Waiting time T stop The number of punch holes formed in the sheet by punching depends on the sheet size in the sheet conveyance direction. In this embodiment, an example is used in which three punch holes are formed in a letter-sized sheet.

[0043] In the example of Fig. 4, the post-processing control unit 101 forms three punch holes at positions 119 to 121 on one sheet by punching using the punch unit 62. When punching a single sheet multiple times in succession like this, the post-processing control unit 101 drives the punching motor 102 according to a predetermined speed profile each time one punching process is completed. In this way, the post-processing control unit 101 rotates and moves the punch 202 from the punching end position 71 (Fig. 3(D)) to the punching start position 70 (Fig. 3(B)).

[0044] Furthermore, when punching a plurality of sheets consecutively, the post-processing control unit 101 drives the punching motor 102 according to a predetermined speed profile and stops the punch 202 at the standby position 67 each time punching is completed for one sheet. After that, when the leading edge of the next sheet is detected by the inlet sensor 27, the post-processing control unit 101 again starts the waiting time T stop After the elapse of time, the punching motor 102 starts to be driven, and the punching process is performed on the sheet.

[0045] <Drilling position shift due to slippage> Next, we will explain the deviation of the punching position on the sheet by the punch unit 62 caused by slippage during sheet conveyance by the conveyance rollers (upstream roller 21, downstream roller 22, conveyance roller 23, and discharge roller 24) provided in the image forming system 5. Note that in the following explanation, it is assumed that the diameter of each conveyance roller and the set rotation speed of the motor that drives each conveyance roller are the same.

[0046] The following two conditions (1) and (2) are considered to be conditions under which slippage is likely to occur when a sheet is conveyed by a conveyance roller. (1) When conveying a sheet with a small coefficient of friction and a smooth surface, the smoother the surface of the sheet to be conveyed, the greater the possibility that slippage will occur during conveyance by the conveyance rollers. (2) When a difference occurs between the sheet conveying speed and the surface speed of the conveying roller. In particular, when the set rotation speed of the conveying roller is high, a difference may occur between the sheet conveying speed and the surface speed of the conveying roller due to load fluctuations on the conveying roller.

[0047] A load fluctuation on the conveyance rollers occurs, for example, when the leading edge of a sheet reaches the upstream roller 21, the downstream roller 22, and the discharge roller 24, or when the trailing edge of the sheet leaves the upstream roller 21 and the conveyance roller 23. For example, when a load fluctuation on the upstream roller 21 causes a fluctuation in the rotation speed of the conveyance motor 104, the motor driver circuit 103 controls the rotation speed of the conveyance motor 104 so that the rotation speed approaches the set rotation speed. The motor driver circuit 103 controls the rotation speed of the conveyance motor 104 by adjusting the drive current supplied to the motor through feedback control based on the FG pulse output from the conveyance motor 104. However, if the set rotation speed of the conveyance motor 104 is high, a delay occurs in the feedback control by the motor driver circuit 103, which can result in a difference between the sheet conveyance speed and the surface speed of the conveyance roller.

[0048] The post-processing control unit 101 drives the punching motor 102 according to a predetermined speed profile to perform punching processing using the punch unit 62. As described above, if a difference occurs between the sheet conveying speed and the surface speed of the conveying roller, an error occurs in the spacing between punched holes formed in the sheet by the punching processing using the punch unit 62, compared to the ideal spacing (for example, L3 in FIG. 4). In other words, a deviation occurs in the position of the holes punched on the sheet by the punch unit 62. Such an error occurs during a slip period when slippage occurs in the conveying roller and the sheet cannot be conveyed at the desired conveying speed.

[0049] One way to prevent slippage of the transport rollers during sheet transport is to increase the nip pressure (transport force) of the transport rollers. However, this can accelerate wear of the transport rollers and cause creep deformation in the parts that hold the transport rollers. Therefore, in this embodiment, as described below, the sheet transport speed is appropriately controlled to prevent deviations in the perforation positions due to slippage of the transport rollers.

[0050] <Conveyance control based on sheet surface properties> The image forming system 5 (image forming device 1 and post-processing device 4) of this embodiment controls the sheet conveyance so that the sheet to be processed is conveyed at a conveyance speed corresponding to the surface properties of the sheet in the conveyance paths 30 and 40 within the device. This prevents deviation of the perforation position due to slippage of the conveyance rollers.

[0051] To achieve this type of conveyance control, in this embodiment, a plurality of sheet conveyance speeds corresponding to a plurality of sheet types are prepared in advance, and a rotation speed of the perforation motor 102 corresponding to each sheet conveyance speed is also prepared in advance. Fig. 5 shows an example of a setting table of sheet conveyance speeds and rotation speeds of the perforation motor 102 associated with a plurality of sheet types (surface properties). The rotation speed of the perforation motor 102 is set based on the rotation speed V of the punch 202 and the die 206 at the perforation center position 75. p Corresponds to.

[0052] The image forming system 5 (image forming apparatus 1 and post-processing apparatus 4) of this embodiment sets the sheet conveying speed and the rotation speed of the punching motor 102 as shown in FIG. 5 based on the surface properties of the sheet to be processed. In the example of FIG. 5, if the surface properties of the sheet to be processed correspond to "plain paper," the sheet conveying speed is set to 400 [mm / sec] and the rotation speed of the punching motor 102 is set to 1000 [pps]. Also, if the surface properties of the sheet to be processed correspond to "gloss paper," the sheet surface speed is set to 100 [mm / sec] and the rotation speed of the punching motor 102 is set to 250 [pps].

[0053] When punching a conveyed sheet using the post-processing device 4, the image forming system 5 controls sheet transport so that the sheet is transported at a set transport speed. Furthermore, the image forming system 5 controls the drive of the punching motor 102 so that the punching motor 102 (its rotor) rotates at a set rotation speed. When punching multiple sheets consecutively, the image forming system 5 drives the punching motor 102 according to a speed profile corresponding to the sheet transport speed, thereby rotating the punch 202 from the punching end position 71 to the punching start position 70.

[0054] In this way, by performing the punching process by the post-processing device 4 while conveying the sheet at a conveying speed that matches the type (surface properties) of the sheet to be processed, slippage of the conveying rollers can be prevented. This prevents deviations in the punching positions on the sheet due to slippage of the conveying rollers. Furthermore, by conveying the sheet at a conveying speed that matches the type (surface properties) of the sheet to be processed, it is possible to reduce delays in the feedback control of the conveying motor 104 that are caused by fluctuations in the load on the conveying rollers. This reduces the impact of slippage of the conveying rollers on the punching process, even when conveying a sheet with a smooth surface such as gloss paper, which can lead to suppressing deviations in the punching positions on the sheet.

[0055] On the other hand, if the sheet conveyance speed differs from the conveyance speed corresponding to the type of sheet being processed, the above-mentioned deviation in the punch position occurs. When the print job to be executed does not specify the sheet type and size, the image forming system 5 may convey the sheet at a predetermined conveyance speed in the conveyance paths 30 and 40. For example, assume that the sheet actually being conveyed is "gloss paper," but is conveyed at a conveyance speed corresponding to "plain paper" (400 mm / sec in the example of FIG. 5). In this case, a sheet with a smooth surface is conveyed at a conveyance speed faster than the conveyance speed corresponding to the surface texture of the sheet, increasing the possibility of slippage of the conveyance rollers during sheet conveyance. If slippage occurs, the punch unit 6 will deviate from the punch position on the sheet, resulting in an error (deviation from the ideal spacing) in the spacing between punched holes formed in the sheet.

[0056] Therefore, the image forming system 5 of this embodiment detects the surface property of the sheet using the paper type discrimination device 114 while the sheet is being conveyed, controls the conveying speed of the sheet based on the detected surface property, and performs punching processing on the sheet. For example, when the image forming system 5 is conveying the sheet at a conveying speed different from the conveying speed corresponding to the surface property of the sheet to be processed, it changes the conveying speed to the conveying speed corresponding to the surface property of the sheet and performs punching processing.

[0057] As an example, it is assumed that after conveyance of a sheet is started at a conveyance speed corresponding to "plain paper" (e.g., 400 mm / sec), the paper type discrimination device 114 detects that the surface property of the sheet corresponds to "gloss paper." In this case, the sheet conveyance speed in the conveyance path 30 is decelerated to a conveyance speed corresponding to "gloss paper" (e.g., 100 mm / sec). On the other hand, it is assumed that after conveyance of a sheet is started at a conveyance speed corresponding to "gloss paper" (e.g., 100 mm / sec), the paper type discrimination device 114 detects that the surface property of the sheet corresponds to "plain paper." In this case, the sheet conveyance speed in the conveyance path 30 is accelerated to a conveyance speed corresponding to "plain paper" (e.g., 400 mm / sec).

[0058] In the image forming system 5 of this embodiment, the control unit 111 (post-processing control unit 101) drives the perforation motor 102 in accordance with a speed profile corresponding to the conveying speed of the sheet being conveyed, based on the timing when the inlet sensor 27 detects the leading edge of the sheet. This causes the punch unit 62 (punch 202) to perform the perforation process on the sheet. For this reason, it may be necessary to change the sheet conveying speed so that it is completed before the leading edge of the sheet being conveyed reaches the inlet sensor 27 (the leading edge of the sheet is detected by the inlet sensor 27).

[0059] In this embodiment, the conveying speed corresponding to the surface properties of the sheet is determined in advance for each of a plurality of types of sheets having different surface properties, as shown in Fig. 5. The conveying speed corresponding to the surface properties of the sheet is determined in advance as a conveying speed at which slippage does not occur between the conveying rollers and the sheet when the conveying rollers convey the sheet in the conveying path.

[0060] <Perforation control based on sheet basis weight> In punching processing using the punch unit 62, if the load on the punch 202 and the die 206 becomes excessive during punching operation, the operation (rotation) of the punch 202 may stop with the teeth of the punch 202 biting into the sheet. If the sheet is transported in such a state, a paper jam will occur in the post-processing device 4.

[0061] Furthermore, if the punching operation is continued under an overload condition in which the punch 202 and the die 206 are overloaded, the relationship between the distance and inclination between the support shaft 65 of the punch 202 and the support shaft 66 of the die 206 may change, which may cause a change in the meshing between the punch 202 and the die 206. If this change in the meshing between the punch 202 and the die 206 occurs, burrs may be generated at the perforation points on the sheet, reducing the quality of the punch holes formed by the punching operation. Furthermore, it may become impossible to punch holes even in sheets with low basis weight (for example, sheets with a basis weight corresponding to "Light").

[0062] Therefore, the image forming system 5 may perform punching control so as not to perform punching processing on the sheet when the condition for overloading the punch unit 62 (punch 202 and die 206) is satisfied. This prevents overloading of the punch unit 62 and prevents problems from occurring in the meshing between the punch 202 and the die 206.

[0063] One of the conditions for applying an overload to the punch 202 and the die 206 that changes the meshing between the punch 202 and the die 206 is that a sheet with a high basis weight is to be punched. The higher the basis weight of the sheet to be punched, the greater the load applied to the punch 202 and the die 206 during the punching operation.

[0064] Therefore, the image forming system 5 of this embodiment does not perform punching on a sheet when a condition that would cause an overload on the punch unit 62 is met, based on the basis weight or type of the sheet to be processed. For example, the image forming system 5 detects the basis weight of the sheet to be processed, and determines whether or not to perform punching operation by the punch unit 62 based on the detected basis weight. Furthermore, the image forming system 5 controls the operation of the punch unit 62 according to the determination result. The basis weight of the sheet can be detected using the paper type discrimination device 114 (basis weight detection unit 131).

[0065] When the detection result of the sheet basis weight indicates that the punch unit 62 will be overloaded, the image forming system 5 prevents the punch unit 62 from performing the punching operation. For example, when the output of the basis weight detection unit 131 indicates a basis weight within the basis weight range corresponding to "Heavy," the image forming system 5 prevents the punch unit 62 from performing the punching operation. On the other hand, when the output of the basis weight detection unit 131 indicates a basis weight within the basis weight range corresponding to "Light" or "Normal," the image forming system 5 performs the punching operation. In this embodiment, this control prevents changes in the meshing between the punch 202 and the die 206 and prevents a decrease in the quality of the punched holes formed by the punching operation.

[0066] <Processing Procedure> 6 is a flowchart showing a processing procedure for sheet transport control and punching control executed in the image forming system 5 of this embodiment. The processing of each step in FIG. 6 is executed by the control unit 111 or the post-processing control unit 101 in the image forming system 5. When the control unit 111 starts execution of a job including punching processing by the post-processing device 4, it executes the processing according to the procedure in FIG.

[0067] In S601, the control unit 111 feeds a sheet from the paper feeder 6 to the conveyance path and starts conveying the sheet at a predetermined conveyance speed. If the paper type is not specified in the job, as described above, sheet conveyance starts at a predetermined conveyance speed corresponding to, for example, "plain paper." Note that if the paper type is specified in the job, sheet conveyance may start at a conveyance speed corresponding to the specified paper type.

[0068] Next, in S602, the control unit 111 acquires the surface property and basis weight of the sheet being transported using the paper type discrimination device 114. As described above, the paper type discrimination device 114 outputs the detection results of the surface property and basis weight of the sheet on the transport path to the control unit 111. The control unit 111 acquires the surface property and basis weight of the sheet being transported based on the output of the paper type discrimination device 114.

[0069] In S603, the control unit 111 determines whether or not to perform punching on the sheet based on the basis weight of the sheet being transported. In this example, the control unit 111 makes this determination based on whether or not the basis weight of the sheet is within a range corresponding to "Heavy." The range corresponding to "Heavy" is defined as a range of basis weights greater than a predetermined basis weight threshold. For example, if the basis weight of the sheet is greater than the predetermined basis weight threshold, it is determined not to perform punching, and if the basis weight is less than or equal to the predetermined basis weight threshold, it is determined to perform punching. In this way, the control unit 111 controls whether or not to perform punching on the sheet based on the basis weight of the sheet being transported, which is detected by the paper type identification device 114 (basis weight detection unit 131).

[0070] If the control unit 111 determines that punching is not to be performed, the process proceeds to S604. In this case, the control unit 111 instructs the post-processing control unit 101 to discharge the sheet being conveyed without punching. In S604, the post-processing control unit 101 discharges the sheet, on which an image has been formed by the image forming apparatus 1 and which has been conveyed through the conveyance paths 30 and 40, to the sheet discharge tray 25 without punching, thereby completing the process according to the procedure in FIG. 6. In this manner, if the basis weight of the sheet being conveyed is greater than the basis weight threshold, the control unit 111 (post-processing control unit 101) controls the post-processing device 4 to discharge the sheet without punching. Note that the basis weight threshold is predetermined as a condition under which the punch unit 62 is overloaded during punching. By controlling whether or not to perform punching using such a basis weight threshold, it is possible to prevent the punch unit 62 from being overloaded during punching.

[0071] On the other hand, if the control unit 111 determines that punching processing is to be performed, the process proceeds from S603 to S605. In S605, the control unit 111 determines whether the conveying speed of the sheet being conveyed corresponds to the detected surface property. If the conveying speed of the sheet being conveyed corresponds to the detected surface property, the control unit 111 proceeds to S606. If the conveying speed of the sheet being conveyed does not correspond to the detected surface property, the control unit 111 proceeds to S607. In S607, the control unit 111 changes the conveying speed of the sheet on the conveying path 30 to a conveying speed corresponding to the surface property of the sheet, and proceeds to S606. In this way, the control unit 111 controls the conveyance of the sheet so that the sheet is conveyed to the punch unit 62 at a conveying speed corresponding to the surface property detected by the surface property detection unit 116.

[0072] When the process proceeds to S606, the control unit 111 controls the rotation of the punch 202 (punch member) so that the punch 202 performs a punching process while rotating at a rotation speed corresponding to the conveying speed of the sheet conveyed from the image forming apparatus 1. Specifically, the control unit 111 instructs the post-processing control unit 101 to perform sheet conveyance control using the conveying motor 104 and punching control using the punching motor 102 based on the sheet conveying speed.

[0073] In S606, the post-processing control unit 101 performs punching on the sheet based on the sheet conveying speed. Specifically, the post-processing control unit 101 drives the punching motor 102 at a rotation speed corresponding to the sheet conveying speed to perform punching on the sheet. Thereafter, the post-processing control unit 101 advances the process to S604, discharges the punched sheet to the discharge tray 25, and ends the process according to the procedure in FIG. 6.

[0074] It is also possible to configure the image forming system 5 so that at least a part of the processing executed by the control unit 111 in the procedure of FIG.

[0075] As described above, the image forming system 5 of this embodiment includes the punch unit 62 provided in the post-processing device 4, the surface property detection unit 116 that detects the surface property of a sheet conveyed along a conveyance path toward the punch unit 62, and the control unit 111. The punch unit 62 includes a punch 202 (punching member) that rotates to perform a hole punching process on a sheet conveyed from the image forming device 1. The control unit 111 controls the conveyance of the sheet so that the sheet is conveyed to the punch unit 62 at a conveyance speed corresponding to the surface property detected by the surface property detection unit 116. For example, if the conveyance speed of the sheet being conveyed along the conveyance path is not the conveyance speed corresponding to the surface property detected by the surface property detection unit 116, the control unit 111 (or the post-processing control unit 101) changes the conveyance speed of the sheet to the conveyance speed corresponding to the surface property. Furthermore, the control unit 111 (or the post-processing control unit 101) controls the rotation of the punch 202 so that the punch 202 performs a hole punching process on the sheet conveyed from the image forming device 1 while rotating at a rotation speed corresponding to the conveyance speed.

[0076] According to this embodiment, it is possible to prevent slippage (or reduce the possibility of slippage) between the conveyance rollers and the sheet when the conveyance rollers convey the sheet in the conveyance path. This prevents deviations in the punching positions on the sheet due to conveyance roller slippage. In other words, it is possible to prevent errors (deviations from ideal intervals) in the spacing between punch holes formed on the sheet. Therefore, the image forming system 5 of this embodiment makes it possible to perform punching processing at appropriate positions on the sheet regardless of the surface properties of the sheet being conveyed.

[0077] Furthermore, in the image forming system 5 of this embodiment, the control unit 111 (or the post-processing control unit 101) controls whether or not to perform punching processing on the sheet based on the basis weight of the sheet detected by the basis weight detection unit 131. Specifically, if the detected basis weight is greater than the basis weight threshold, the control unit 111 (or the post-processing control unit 101) controls the post-processing device 4 to discharge the sheet without performing punching processing on the sheet.

[0078] According to this embodiment, it is possible to prevent an overload from being applied to punch unit 62 during punching processing in image forming system 5. This makes it possible to prevent malfunctions in punch unit 62 due to an overload, and to prevent a decrease in the quality of punch holes formed during punching processing due to malfunctions in punch unit 62.

[0079] In this embodiment, the punching motor 102 is configured as a stepping motor and the conveying motor 104 is configured as a DC brushless motor, but other types of motors may be used as the punching motor 102 and the conveying motor 104. For example, the conveying motor 104 may also be configured as a stepping motor. Furthermore, the punching motor 102 may be configured as a DC brushless motor. In that case, an encoder may be used to detect the phase of the rotor so that the rotation of the punch 202 and the die 205 can be controlled more accurately.

[0080] 1, the paper type discrimination device 114 is disposed on the conveyance path between the paper feeder 6 and the transfer roller 10. However, the paper type discrimination device 114 may be disposed downstream of the transfer roller 10 in the sheet conveyance direction. In this case, the paper type discrimination device 114 may be disposed in a position before the upstream roller 21 so that the change in the sheet conveyance speed (S607) can be completed based on the detection result of the sheet surface property by the paper type discrimination device 114 before the leading edge of the sheet reaches the upstream roller 21. In addition, in the present embodiment, the sheet conveyance speed is changed as needed in the conveyance path 30 in the image forming apparatus 1 based on the detection result of the surface property of the sheet during conveyance. However, the sheet conveyance speed may be changed at a different timing or position. For example, immediately after the paper type discrimination device 114 detects the surface property and basis weight of the sheet (determines the type of the sheet), conveyance control may be performed to change the sheet conveyance speed based on the detection result.

[0081] [Second embodiment] In the second embodiment, an example will be described in which, in addition to the detection result of the sheet basis weight, the temperature and humidity (absolute moisture content) in the installation environment of the image forming system 5 and the cumulative number of punches by the punch unit 62 are further used to determine whether or not to perform punching processing on the sheet. In the following, a description of parts common to the first embodiment will be omitted.

[0082] <Functions of post-processing device> The temperature and humidity sensor 141 shown in FIG. 2 is a sensor used to measure the temperature and humidity in the installation environment of the image forming system 5 (image forming apparatus 1 and post-processing apparatus 4). The temperature and humidity sensor 141 includes an element that detects temperature and outputs a temperature detection signal, and an element that detects humidity and outputs a humidity detection signal. The control unit 111 receives the temperature detection signal and the humidity detection signal output from the temperature and humidity sensor 141. The control unit 111 calculates the amount of saturated water vapor based on the temperature detection signal, and calculates the absolute amount of moisture in the air based on the amount of saturated water vapor and the relative humidity obtained from the humidity detection signal. The control unit 111 can determine the amount of moisture contained in the sheets set (stacked) in the sheet feeder 6 based on the amount of moisture in the air obtained based on the information output from the temperature and humidity sensor 141.

[0083] The post-processing device 4 includes a memory unit 150 that stores an accumulated number of punching operations, which is the accumulated number of times punching operations are performed by the punch unit 62. When starting a job (punch job) that includes punching operations by the punch unit 62, the post-processing control unit 101 reads out from the memory unit 150 the accumulated number of punching operations performed at the time the previous job was completed and uses this information. Furthermore, when completing a punch job, the post-processing control unit 101 updates the accumulated number of punching operations by storing in the memory unit 150 the accumulated number of punching operations to which the number of times the punching operation was performed in the job (the accumulated number of times) has been added.

[0084] <Punching control based on punch unit load status> In the first embodiment, the basis weight of the sheet used in the punching process is taken into consideration as a condition for overloading the punch unit 62 during the punching operation. The load on the punch unit 62 during the punching operation depends not only on the basis weight of the sheet, but also on the amount of moisture contained in the sheet and the degree of wear (consumption) of the punch 202 and the die 206. The more moisture contained in the sheet, the more difficult it is to cut the sheet, and the greater the load on the punch unit 62 when punching holes in the sheet. Furthermore, when the punch 202 and the die 206 wear due to repeated punching operations, the meshing between the punch 202 and the die 206 becomes loose, and the sheet begins to be torn apart as it is punched. The looser the meshing between the punch 202 and the die 206, the greater the load on the punch unit 62 may be.

[0085] Therefore, the image forming system 5 of this embodiment controls punching by taking into consideration at least two parameters, the basis weight of the sheet, the absolute moisture content in the air, and the cumulative number of punches by the punching unit 62, as conditions for overloading the punching unit 62. Based on these parameters, when the conditions for overloading the punching unit 62 are met, the image forming system 5 does not perform punching processing on the sheet.

[0086] In this embodiment, the control unit 111 or the post-processing control unit 101 uses a setting table such as that shown in Fig. 7 to determine whether or not to perform punching on a sheet to be processed. Fig. 7 shows an example of a setting table used to determine whether or not to perform punching by the punch unit 62 based on the cumulative number of times punching has been performed by the punch unit 62, the basis weight of the sheet, and the absolute moisture content in the air. In the setting table of Fig. 7, "◯" indicates that punching is possible (punching is performed), and "X" indicates that punching is not possible (punching is not performed). The data in this setting table is created in advance and stored in advance in a non-volatile memory (not shown) of the image forming apparatus 1 or the post-processing device 4.

[0087] FIG. 7(A) shows an example of a setting table used when the integrated punching count of the punch unit 62 is less than a predetermined threshold value (in this example, 500,000 times). FIG. 7(B) shows an example of a setting table used when the integrated punching count is greater than or equal to a predetermined threshold value (in this example, 500,000 times). The integrated punching count of the punch unit 62 can be used as a parameter indicating the degree of wear of the punch unit 62. As the integrated punching count increases, the wear of the punch unit 62 progresses (the degree of wear increases), and as described above, the load applied to the punch unit 62 during the punching operation can increase.

[0088] In the example of FIG. 7, for the range of the absolute moisture content in the air (Z1, Z2, and Z3) and the range of the basis weight of the sheet ("Light", "Normal", and "Heavy"), it is determined whether or not to perform the punching operation by the punch unit 62. The range of the absolute moisture content in the air is defined as Z1 < Z2 < Z3. For example, Z1 is in the range less than 10 [g / m 3 , Z2 is in the range of [g / m 3 or more and less than 17 [g / m 3 , and Z3 is defined as the range of 17 [g / m 3 or more. The range of the basis weight of the sheet is defined as "Light" < "Normal" < "Heavy".

[0089] As described above, the greater the basis weight of the sheet to be subjected to the punching process, the greater the load applied to the punch unit 62 during the punching operation. Also, the greater the absolute moisture content in the air (that is, the greater the moisture content in the sheet), the greater the load applied to the punch unit 62 during the punching operation. Therefore, in the setting table of FIG. 7(A), the range of the basis weight of the sheet for which the punching operation is not performed is set to different ranges according to the absolute moisture content in the air.

[0090] Specifically, in the setting table of FIG. 7A, when the absolute moisture content is within the range of Z1, perforation processing is performed even if the sheet basis weight is within the range corresponding to "Heavy." On the other hand, when the absolute moisture content is within the range of Z2 or Z3, which is greater than Z1, perforation processing is not performed if the sheet basis weight is within the range corresponding to "Heavy." This means that when the absolute moisture content is within the range of Z2 or Z3, the basis weight threshold for determining whether or not to perforate the sheet is set to the boundary between the range corresponding to "Normal" and the range corresponding to "Heavy." In this way, the basis weight threshold can be set to a lower value as the absolute moisture content in the air increases.

[0091] Furthermore, as described above, as the cumulative number of times the punch unit 62 has punched holes increases, wear on the punch unit 62 progresses, and the load on the punch unit 62 during punching operations may increase. For this reason, in this example, when the cumulative number of times the punch unit 62 has punched holes reaches or exceeds a predetermined threshold, the basis weight threshold for determining whether or not to perform punching processing on the sheet is lowered, as shown in FIG. 7(B).

[0092] Specifically, in the setting table of FIG. 7(B), when the absolute moisture content is within the range of Z1 or Z2, the basis weight threshold for determining whether or not to perform perforation on the sheet is set as follows: That is, the basis weight threshold is set to the boundary between the range corresponding to "Normal" and the range corresponding to "Heavy." On the other hand, when the absolute moisture content is within the range of Z3, which is higher than Z2, the basis weight threshold is set to the boundary between the range corresponding to "Light" and the range corresponding to "Normal." In the setting table of FIG. 7(B), the basis weight threshold for determining whether or not to perform perforation on the sheet is set lower than in the setting table of FIG. 7(A). In this way, the basis weight threshold can be set to a lower value as the cumulative number of perforations increases.

[0093] 7A and 7B is used to determine whether or not to perform punching processing on a sheet by the punch unit 62. If the conditions for overloading the punch unit 62 are met based on the setting table, the punch unit 62 is prevented from performing punching processing, thereby preventing overloading of the punch unit 62 during punching operation.

[0094] <Operation flowchart> 8 is a flowchart showing the procedure of processing executed in the image forming system 5 of this embodiment. This flowchart shows the procedure of processing for sheet transport control and punching control executed in the image forming system 5 of this embodiment. The processing of each step in FIG. 8 is executed by the control unit 111 or the post-processing control unit 101 in the image forming system 5. The processing according to the procedure in FIG. 8 is executed for a job including punching processing by the post-processing device 4.

[0095] In S801, the control unit 111 feeds a sheet from the paper feeder 6 to the conveying path, as in S601, and starts conveying the sheet at a predetermined conveying speed. Next, in S802, the control unit 111 acquires the current cumulative number of punches by the punch unit 62, which is stored in the memory unit 150, via the post-processing control unit 101, and proceeds to S803. In S803, the control unit 111 acquires information (temperature and humidity information) output from the temperature and humidity sensor 141, acquires the absolute moisture content in the air based on the temperature and humidity information, and proceeds to S804. In S804, the control unit 111 uses the paper type identification device 114 to acquire the basis weight of the sheet being conveyed.

[0096] Thereafter, in S805, the control unit 111 determines (controls) whether or not to perform punching processing on the sheet based on the cumulative number of punchings by the punch unit 62, the absolute moisture content in the air, and the basis weight of the sheet being conveyed, which were acquired in S802 to S804. This determination is made as described above using the setting tables shown in Figures 7(A) and (B).

[0097] If the control unit 111 determines that punching processing will not be performed, the process proceeds to S806. In this case, the control unit 111 instructs the post-processing control unit 101 to discharge all sheets to be processed by the job being executed (the sheet being conveyed and the remaining sheets to be conveyed thereafter) without performing punching processing. In S806, the post-processing control unit 101 discharges all sheets on which images have been formed by the image forming apparatus 1 and which have been conveyed through the conveyance paths 30 and 40 to the paper discharge tray 25 without performing punching processing, and the process according to the procedure in FIG. 8 ends.

[0098] On the other hand, if the control unit 111 determines that punching processing is to be performed, the process proceeds from S805 to S807. In this case, the control unit 111 instructs the post-processing control unit 101 to perform sheet conveyance control using the conveyance motor 104 and punching control using the punching motor 102 based on the sheet conveyance speed. In S807, the post-processing control unit 111 drives the punching motor 102 at a rotation speed corresponding to the sheet conveyance speed to perform punching processing on the sheet. Next, in S808, the post-processing control unit 101 discharges the punched sheet to the discharge tray 25.

[0099] Thereafter, in S809, the post-processing control unit 101 determines whether punching has been completed for all sheets in the processing pair for the job being executed. If punching has not been completed for all sheets, the post-processing control unit 101 returns to S807, performs punching again on the next sheet conveyed from the image forming apparatus 1, and discharges that sheet to the discharge tray 25. On the other hand, if punching has been completed for all sheets, the post-processing control unit 101 proceeds to S810.

[0100] In S810, the post-processing control unit 101 updates the cumulative number of punches by adding the current number of punches performed by the punch unit 62 in the executed job to the cumulative number of punches stored in the memory unit 150, and terminates the processing according to the procedure in Figure 8.

[0101] 8 shows an example in which the sheet basis weight is detected, whether or not punching processing is performed, and the cumulative number of punching operations is updated for each job that is executed, but these processes may be performed for each sheet. Also, the image forming system 5 can be configured so that at least a part of the processing performed by the control unit 111 in the procedure of FIG. 8 is performed by the post-processing control unit 101.

[0102] As described above, in this embodiment, the control unit 111 (or the post-processing control unit 101) controls whether or not to perform punching on a sheet based on at least two of the detected basis weight, the absolute moisture content in the air, and the cumulative number of punching operations (cumulative number of punching operations) by the punching unit 62. According to this embodiment, it is possible to prevent the punching unit 62 from being overloaded during punching in the image forming system 5. This makes it possible to prevent malfunctions in the punching unit 62 due to overloading, and to prevent a decrease in the quality of punched holes formed during punching due to malfunctions in the punching unit 62.

[0103] The processing of this embodiment can also be combined with the processing of the first embodiment. That is, in the image processing device 5 of the first embodiment, the control unit 111 (or the post-processing control unit 101) may be configured to control whether or not to perform punching processing on a sheet based on at least two of the detected basis weight, the absolute moisture content in the air, and the cumulative number of punching processes by the punch unit 62 (cumulative number of punchings).

[0104] [Other embodiments] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0105] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0106] 1: image forming apparatus, 4: post-processing device, 5: image forming system, 30: conveying path, 40: conveying path, 21: upstream roller, 22: downstream roller, 27: inlet sensor, 101: post-processing control unit, 111: control unit, 102: perforation motor, 104: conveying motor, 114: paper type discriminator, 116: surface property detection unit, 131: basis weight detection unit, 62: punch unit, 202: punch, 205: die, 141: temperature and humidity sensor

Claims

1. An image forming system including an image forming apparatus and a post-processing apparatus connected downstream of the image forming apparatus in a sheet conveyance direction, the post-processing apparatus performing a punching process to form punch holes in a sheet conveyed from the image forming apparatus through a conveyance path, a punch unit provided in the post-processing device, the punch unit including a punch member that performs the punching process while rotating on the sheet conveyed from the image forming device; a detection means for detecting the surface property of the sheet conveyed along the conveyance path toward the punch unit; a control means for controlling the conveyance of the sheet so that the sheet is conveyed to the punch unit at a conveyance speed corresponding to the surface property detected by the detection means, and for controlling the rotation of the punch member so that the punch member performs the perforation process on the sheet conveyed from the image forming device while rotating at a rotational speed corresponding to the conveyance speed; An image forming system comprising:

2. a basis weight detection unit for detecting the basis weight of the sheet conveyed along the conveyance path toward the punch unit; The control means further controls whether or not to perform the punching process on the sheet based on the basis weight detected by the basis weight detection means.

2. The image forming system according to claim 1.

3. The control means further controls the post-processing device so that, if the basis weight detected by the basis weight detection means is greater than a basis weight threshold, the post-processing device discharges the sheet without performing the punching process on the sheet.

3. The image forming system according to claim 2.

4. The basis weight threshold is predetermined as a condition under which an overload is applied to the punch unit during the punching process.

4. The image forming system according to claim 3.

5. If the conveying speed of the sheet being conveyed in the conveying path is not a conveying speed corresponding to the surface property detected by the detecting means, the control means changes the conveying speed of the sheet to a conveying speed corresponding to the surface property.

5. The image forming system according to claim 1, wherein the image forming apparatus is a printer.

6. the post-processing device further includes a first conveying roller and a second conveying roller that are respectively provided upstream and downstream of the punching unit in the conveying path and that convey the sheet in the post-processing device; The control unit changes the conveying speed before the sheet conveyed along the conveying path reaches the first conveying roller.

6. The image forming system according to claim 5.

7. The post-treatment device includes: a sensor provided on the conveying path upstream of the punch unit, the sensor detecting the sheet being conveyed on the conveying path; a motor that rotates the punch member; Further provided with The control means drives the motor in accordance with a speed profile corresponding to the conveying speed based on the timing when the leading edge of the sheet is detected by the sensor, thereby causing the punch member to perform the punching process on the sheet.

7. The image forming system according to claim 1, wherein the image forming apparatus is a printer.

8. The conveying speed corresponding to the surface property is predetermined for each of a plurality of types of sheets having different surface properties.

8. The image forming system according to claim 1, wherein the image forming apparatus is a printer.

9. The conveying speed corresponding to the surface property is predetermined as a conveying speed at which slippage does not occur between the conveying roller and the sheet when the conveying roller conveys the sheet in the conveying path.

9. The image forming system according to claim 1, wherein the image forming apparatus is a printer.

10. a basis weight detection means for detecting the basis weight of the sheet conveyed along the conveyance path toward the punch unit; The image forming system further includes a temperature and humidity sensor that detects the temperature and humidity in an installation environment, The control means further controls whether or not to perform the punching process on the sheet based on at least two of the basis weight detected by the basis weight detection means, the absolute moisture content in the air obtained based on information output from the temperature and humidity sensor, and the cumulative number of times the punching process has been performed by the punch unit.

2. The image forming system according to claim 1.

11. the control means controls the post-processing device to discharge the sheet without performing the punching process on the sheet if the basis weight detected by the basis weight detection means is greater than a basis weight threshold value; The basis weight threshold is set to a lower value as the absolute moisture content increases.

11. The image forming system according to claim 10.

12. the control means controls the post-processing device to discharge the sheet without performing the punching process on the sheet if the basis weight detected by the basis weight detection means is greater than a basis weight threshold value; The basis weight threshold is set to a lower value as the number of integrations increases.

12. The image forming system according to claim 10, wherein the image forming system includes: a first image forming unit;

13. An image forming system including an image forming apparatus and a post-processing apparatus connected downstream of the image forming apparatus in a sheet conveyance direction, the post-processing apparatus performing a punching process to form punch holes in a sheet conveyed from the image forming apparatus through a conveyance path, a punch unit provided in the post-processing device, the punch unit including a punch member that performs the punching process while rotating on the sheet conveyed from the image forming device; a basis weight detection means for detecting the basis weight of the sheet conveyed along the conveyance path toward the punch unit; a temperature and humidity sensor that detects the temperature and humidity in the installation environment of the image forming system; a control unit that controls the rotation of the punching member so that the punching member performs the punching process on the sheet conveyed from the image forming device while rotating at a rotation speed corresponding to a conveying speed of the sheet, The control means further controls whether or not to perform the punching process on the sheet based on at least two of the basis weight detected by the basis weight detection means, the absolute moisture content in the air obtained based on information output from the temperature and humidity sensor, and the cumulative number of times the punching process has been performed by the punch unit. An image forming system comprising:

14. the control means controls the post-processing device to discharge the sheet without performing the punching process on the sheet if the basis weight detected by the basis weight detection means is greater than a basis weight threshold value; The basis weight threshold is set to a lower value as the absolute moisture content increases.

14. The image forming system according to claim 13.

15. the control means controls the post-processing device to discharge the sheet without performing the punching process on the sheet if the basis weight detected by the basis weight detection means is greater than a basis weight threshold value; The basis weight threshold is set to a lower value as the number of integrations increases.

15. The image forming system according to claim 13 or 14.

Images