JP2022078907A - Image forming device - Google Patents

Abstract

To prevent occurrence of non-feed by controlling separating operation of a pair of conveyance rollers in accordance with a conveyance path of a sheet.SOLUTION: An image forming device comprises: a first storage cabinet (110); a second storage cabinet (111) provided below the first storage cabinet; a pair of conveyance rollers (120) for conveying a fed sheet; a pair of registration rollers (130) which are provided on the downstream in a conveyance direction of the pair of conveyance rollers and correct skew of a sheet to convey the sheet to an image forming part (150); a separation mechanism (140) for contacting or separating the pair of conveyance rollers; and control means (200) which controls the separation mechanism so as to, when an image is formed on the sheet fed from the first storage cabinet, let the pair of conveyance rollers contact regardless of the kind of the sheet stored in the first storage cabinet, and, when an image is formed on the sheet fed from the second storage cabinet, let the pair of conveyance rollers separate based on the kind of the sheet stored in the second storage cabinet.SELECTED DRAWING: Figure 9

Description

The present invention relates to an image forming apparatus.

Conventionally, some image forming devices include a skew correction unit that conveys the paper supplied from the paper storage unit to the image forming unit and corrects the skew of the paper. The skew correction unit includes a roller pair called a registration roller pair, and the skew correction is performed by abutting the tip of the paper against the nip portion of the roller pair and bending the paper.

In recent years, the image forming apparatus is also required to be compatible with small-sized paper, and the distance between the conveying rollers in the conveying path from the paper accommodating portion to the image forming portion tends to be narrowed. If the spacing between the transport rollers is narrowed, the kinks of the paper when the skew correction unit corrects the skew of the paper become large, and as a result, the paper may be wrinkled.

In Patent Document 1, when the tip of the paper is abutted against the registration roller pair to correct the skew, the transfer roller pair (pre-registration transfer roller pair) arranged upstream of the registration roller pair is temporarily used. A method of separating them from each other has been proposed. By adopting the method of Patent Document 1, the grip of the pre-registration transport roller pair is released, so that the distortion of the paper caused by the skew correction is eliminated and the occurrence of wrinkles is reduced.

Japanese Unexamined Patent Publication No. 2019-26552

According to the method of Patent Document 1, in order to reduce the occurrence of wrinkles on the paper, the pair of pre-registration transport rollers is separated when performing skew correction. However, when the pre-registration transport roller pair is separated, when the paper is fed to the registration roller pair, the paper is pushed downstream of the transport path by the transport force of the rollers provided upstream of the separated transport roller pair. become. Therefore, depending on the transport path, the paper cannot be correctly transported to the registration roller pair, and there is a possibility that paper jams due to non-feeding may occur. In particular, the problem is remarkable in the case of paper transported on a transport path in which the distance from the paper storage section to the image forming section is short.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the occurrence of non-feeding by appropriately controlling whether or not the transfer roller pair is separated from each other. be.

In order to achieve the above object, the image forming apparatus according to the present invention is provided with an image forming unit for forming an image on paper, a first storage for storing the paper, and a lower portion of the first storage. A transport roller for receiving the paper supplied from the second storage, the first storage, and the second storage for storing the paper, and transporting the received paper toward the image forming unit. The pair, the skew correction roller provided downstream of the transport roller pair in the transport direction for correcting the skew of the conveyed paper, and one roller in the transport roller pair abuts or separates from the other roller. When image formation is performed on the paper fed from the first storage, the one roller is brought into contact with the other roller regardless of the type of paper in the first storage. When forming an image on the paper fed from the second storage, the separation mechanism is used to separate the one roller from the other roller based on the type of paper in the second storage. It is characterized by having a control means for controlling the above.

According to the present invention, it is possible to suppress the occurrence of non-feeding by controlling the separation operation of the transport roller pair according to the paper feeding source.

Simple cross-sectional view of the image forming apparatus Block diagram of image forming device Schematic diagram of a state in which a pair of transport rollers before registration are separated. Schematic diagram of a state in which a pair of transport rollers before registration are in contact with each other. Drive configuration diagram with the transport roller pair separated before registration Drive configuration diagram with a pair of transport rollers in contact before registration Drive transmission diagram when rotating a pair of transport rollers before registration Drive transmission diagram when operating the separation mechanism Flow chart to explain the paper feed operation The figure which shows the separation judgment table of the transfer roller pair before registration Schematic diagram for explaining twisting of paper during skew correction The figure which shows the operation screen which is displayed in the operation part for setting the separation mode in front of a cash register.

[Example 1]
Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 forms an image on paper based on the image information received from the PC which is an external device and the image information read from the original. The image forming apparatus 100 includes an apparatus main body 100A that houses the image forming unit 150, and an image reading device 300 that is arranged in the information of the apparatus main body 100A and reads image information from a document. The image forming unit 150 includes four image forming stations Y, M, C, K, an intermediate transfer belt 155, and a fixing device 160.

Each image forming station YK performs an electrophotographic process to form a toner image on the surface of the photosensitive drum 151. That is, when the image forming stations Y to K are required to form the toner image, the photosensitive drum 151 is rotationally driven, and the charging device uniformly charges the surface of the photosensitive drum 151. The exposure apparatus 152 provided at the lower part of the apparatus main body 100A irradiates the photosensitive drum 151 with a laser beam corresponding to the image information to expose the surface of the drum, and writes an electrostatic latent image on the photosensitive drum 151. The developing device 153 supplies charged toner particles to the photosensitive drum 151, and develops an electrostatic latent image on the surface of the drum as a toner image. The toner images of each color formed by the image forming stations Y to K are primary transferred from the photosensitive drum 151 to the intermediate transfer belt 155 by the primary transfer roller 154. Adhesions such as toner remaining on the photosensitive drum 151 are removed by cleaning units provided in the image forming stations Y to K.

The intermediate transfer belt 155 is wound around a secondary transfer inner roller 156, a tension roller 157, and a tension roller 158, and is rotationally driven in the counterclockwise direction in FIG. The toner image supported on the intermediate transfer belt 155 is secondarily transferred to the paper S in the secondary transfer portion formed between the secondary transfer roller 159 facing the secondary transfer inner roller 156 and the intermediate transfer belt 155. Toner. Adhesions such as toner remaining on the intermediate transfer belt 155 are removed by the belt cleaner.

The paper S on which the toner image is transferred is delivered to the fuser 160. The fuser 160 includes a fixing roller, a pressure roller that sandwiches the paper S together with the fixing roller, and a halogen heater that heats the fixing roller. The fuser 160 melts the toner by applying heat and pressure to the toner image while conveying the paper S, and then the toner is fixed to fix the image on the paper S.

In parallel with such an image forming process, paper S is fed one by one from the paper cassette 110, 111 or the manual paper feed tray 112 toward the image forming unit 150.

The paper feed cassette 110 and the paper feed cassette 111 are examples of paper storages provided so as to be retractable with respect to the apparatus main body 100A. The paper cassette 110 and the paper cassette 111 are arranged side by side in the vertical direction. The paper stored in the upper paper cassette 110 (first paper storage) is separated one by one by the paper feed unit 113 (pickup roller 113a, feed roller 113b, retard roller 113c). The separated and conveyed paper is delivered to the pre-registration transfer roller pair 120. In the present embodiment, the transport path from the paper feed cassette 110, which is the first storage, to the pre-registration transport roller pair 120 is referred to as the first transport path for convenience. Since the length of the first transport path is relatively short, the paper transported through the first transport path is conveyed only by the transport force of the paper feed roller 113. In the first transport path, the roller located most upstream in the transport direction with respect to the pre-registration transport roller pair 120 is the feed roller 113b, which is different from the second transport path described later. In the following description, for convenience, the "pre-registration transfer roller pair" may be referred to as the "pre-registration transfer roller pair".

The paper cassette 111 provided below the paper cassette 110 is an example of a second paper storage. The paper in the paper feed cassette 111, which is an example of the second paper storage, is separated one by one by the paper feed unit 114 (pickup roller 114a, feed roller 114b, retard roller 115b) and received by the extraction roller pair 121. Passed. The drawing roller 121 conveys the paper received from the paper feeding roller 114 toward the image forming unit 150. In the present embodiment, the transport path from the paper feed cassette 111, which is the second paper storage, to the pre-registration transport roller pair 120 is referred to as a second transport path for convenience. The second transport path is a transport path having a shorter distance than the first transport path, and if the paper fed by the paper feed roller 114 is a small size paper, the paper is received up to the pre-registration transport roller pair 120. I can't pass it. Therefore, the cassette extraction roller 121 is arranged in the second transport path.

Similarly, the paper placed on the manual paper feed tray 112 is separated one by one by the paper feed roller 115 and delivered to the extraction drive roller 122.

The paper S that has been fed from the paper cassettes 110 and 111 and the manual paper feed tray 112 and has reached the pre-registration transport roller pair 120 is transported to the registration roller pair 130. The registration roller pair 130 corrects the skew of the paper S and feeds the paper S to the secondary transfer unit at a timing synchronized with the image forming process by the image forming unit 150. A description of this registration roller pair will be described later.

The paper S on which the image is formed by passing through the secondary transfer unit and the fixing device 160 is conveyed to the paper ejection roller pair 171 in the paper ejection unit 170 via the paper ejection path 172. In the case of single-sided printing, the paper S is ejected to the output tray 180 provided between the apparatus main body 100A and the image reading apparatus 300 by the output roller pair 171. In the case of double-sided printing, the paper S on which the image is formed on the first side is switched back and conveyed by the paper ejection roller 171 and delivered to the double-sided transfer unit 190. Then, the paper S that has reached the registration roller pair 130 again is discharged to the paper output tray 180 by the paper ejection roller pair 171 after the image is formed on the second surface by the image forming unit 150.

FIG. 2 is a control block diagram of the image forming apparatus 100. The image forming apparatus 100 has a control unit 200. The control unit 200 includes at least one processor including a CPU 201, a read-only memory (ROM) 202, a random access memory (RAM) 203, a motor drive circuit 204, and a sensor output detection circuit 205.

The ROM 202 stores a control program for controlling each process executed by the image forming apparatus 100. The RAM 203 is a system work memory used by the CPU 201 to execute a control program.

The motor drive circuit 204 is connected to the paper feed motor 181, the cash register drive motor 133, the pre-register transfer drive motor 145, and the extraction motor 116, and controls each of the connected motors. The motor drive circuit 204 outputs a control signal to each motor according to the rotation speed and rotation direction of the motor instructed by the CPU 201. The motor drive circuit 204 specifies the rotation direction (CW / CCW) for the paper feed motor 113 and the pre-registration transfer drive motor 145. On the other hand, for the cash register drive motor 133 and the extraction motor 116, only one rotation direction (transportation direction) is specified.

The sensor output detection circuit 205 outputs a high level or low level signal to the CPU 201 based on the output signal of each connected sensor. Specifically, the sensor output detection circuit 205 outputs a high-level signal if the amount of light received by each sensor is equal to or greater than a threshold value. On the other hand, if the amount of light received by each sensor is less than the threshold value, a low-level signal is output. The CPU 201 recognizes that the separation sensor 129 turns on the sensor when the pre-registration transfer roller pair 120 is separated, and the registration detection sensor 132 recognizes that the paper reaches the registration roller position.

The operation unit 301 notifies the user of the state of the image forming apparatus 100 based on the signal received from the CPU 201. Further, the operation unit 301 receives an operation instruction of the image forming apparatus 100 from the user.

[Slanting correction and wrinkles]
With reference to FIG. 3, the skew correction in the contact state of the pre-registration transport roller pair 120 will be described. The paper S supplied from each paper storage is conveyed downstream of the transfer path by the pre-registration transfer roller pair 120. After that, the conveyed paper S is abutted against the nip portion of the stopped registration roller pair 130 so that the tip of the paper S is aligned with the nip portion. As a result, the paper S is looped by the pre-registration transfer roller pair 120 and the registration roller pair 130. As a result, the skew of the tip of the paper S is corrected.

FIG. 11 is a schematic view showing a state of the paper when the skewed paper is abutted against the registration roller pair 130 and the skew correction is performed while the pre-registration transport roller pair 120 is in contact with the registration roller pair 120. The tip of the skewed paper abuts against the registration roller pair 130 to correct the skew, but the paper twists between the registration roller pair 130 and the pre-registration transport roller pair 120 to form a loop. .. The amount of this kinking increases as the input skew of the paper S reaching the registration roller pair 130 increases. If the paper S is conveyed downstream of the registration roller pair 130 in a twisted state, stress may be applied to the paper S and wrinkles may occur. The rate of occurrence of this wrinkle changes depending on the amount of kinking, the basis weight of the paper, the roller pitch of the section where kinking is occurring, and the like. When the roller pitch is widened, the stress applied to the paper is dispersed, so that the occurrence of wrinkles can be avoided. Therefore, this patent has a separation mechanism for the pre-registration transfer roller.

[Separation operation of transport roller before registration]
The configuration and operation of the pre-registration transfer roller pair 120 according to the present embodiment will be described with reference to FIGS. 3 to 8. 3 and 4 are views showing a cross-sectional configuration of a transport path until the fed paper reaches the register roller pair 130. FIG. 3 is a schematic view showing a state in which the pre-registration transport roller pair 120 is in contact with each other. FIG. 4 is a schematic view showing a state in which the pre-registration transport roller pair 120 is separated from each other. FIG. 5 is a perspective view showing a drive mechanism of the pre-registration transfer roller pair 120 corresponding to a state in which the pre-registration transfer roller pair 120 is in contact with each other. FIG. 6 is a perspective view showing a drive mechanism of the pre-registration transfer roller pair 120 corresponding to a state in which the pre-registration transfer roller pair 120 is separated. FIG. 7 is a drive transmission diagram when the pre-registration transfer roller pair 120 is rotated, and FIG. 8 is a drive transmission diagram when the pre-registration transfer roller pair 120 is separated.

First, with reference to FIGS. 7 and 8, the rotation of the pre-registration transfer roller pair 121 and the drive configuration for operating the separation mechanism 140 will be described. The pre-registration drive gear 147 is provided with a one-way clutch (not shown) so that the drive is transmitted to the output shaft only when the pre-registration transfer drive motor 145 rotates to CW. Further, the separation gear 146 is provided with a one-way clutch (not shown) so that the drive is transmitted to the output shaft only when the pre-registration transfer drive motor 145 turns to CCW.

As shown in FIG. 7, when the pre-registration transfer drive motor 145 rotates in the CW direction (first direction), the driving force is transmitted to the pre-registration transfer roller pair 120 via the pre-registration drive gear 147. At this time, the driving force is not transmitted to the separation transmission shaft 148, and the separation mechanism 140 does not operate, so that the front roller pair 121 is maintained in the contact state or the separation state.

On the other hand, as shown in FIG. 8, when the pre-registration drive motor 145 rotates in the CCW direction (the second direction, the direction opposite to the CW direction), the driving force is transmitted to the separation transmission shaft 148 via the separation gear 146. Will be done. Then, the separation mechanism 140 switches between the contact state and the separation state of the pre-registration transfer roller pair 120. At this time, the driving force is not transmitted to the drive shaft 121c, and the pre-registration transfer roller pair 120 is not driven. As described above, the drive configuration of the pre-registration transfer roller pair 120 includes the rotational drive of the pre-registration transfer roller pair 120 and the drive of the separation mechanism 140 by switching the rotation direction of the pre-registration drive motor 145, which is a drive motor. Can be switched.

The details of the operation of the separation mechanism will be described with reference to FIGS. 5 and 6. When the pre-registration transfer roller pair 120 is brought into contact with each other, the pre-registration transfer drive motor 145 is rotated to CCW until the separation sensor 129 is turned off.

More specifically, the drive of the pre-registration transfer drive motor 145 is transmitted to the separation gear 146, the separation transmission shaft 148, and the separation cam 149, and the separation cam 149 rotates. In conjunction with this, the angle of the separation operation lever 127 urged to the separation cam 149 by the separation posture determining spring 128 changes. By integrating the separation operation lever 127, the separation mechanism shaft 141, and the separation arm 142, the angle of the separation arm 142 also changes at the same time. When the pre-registration transfer drive motor 145 is stopped at the timing when the separation operation lever 127 is removed from the detection range of the separation sensor 129, the state shown in FIG. 5 is obtained. The pre-registration transfer driven roller 120b is urged against the pre-registration transfer drive roller 120a by the pre-registration pressurizing spring 143 held between the spring seat surface sheet metal 144 and the spring seat surface sheet metal 144. The roller pair 120 abuts. In this way, the separation mechanism 140 abuts or separates the pre-registration transfer driven roller 120b, which is an example of one roller, from the pre-registration transfer drive roller 120a, which is an example of the other roller. In this embodiment, the pre-registration transfer driven roller 120b is configured to be in contact with or separated from the pre-registration transfer drive roller 120a. However, the pre-registration transfer drive roller 120a may be in contact with or separated from the pre-registration transfer driven roller 120b. Further, both rollers may be moved to abut or separate from each other.

When the pre-registration transfer roller pair 120 is separated, the pre-registration transfer drive motor 145 is rotated to CCW until the separation sensor 129 is turned on. Specifically, by rotating the pre-registration transfer drive motor 145 and stopping the rotation at the timing when the separation operation lever 127 enters the detection range of the separation sensor 129, the state shown in FIG. 6 is obtained, and the pre-registration transfer roller pair 120 are separated.

[Explanation of paper feeding operation from CST2 (conveyance path with independent drawing roller)]
Using FIG. 4, in the transport path (second transport path) in which the cassette extraction roller 121 is provided between the paper feed roller 114 and the pre-registration transfer roller pair 120, the transferred paper S is the registration transfer roller. The operation of being transported to the pair 130 will be described.

The paper S fed downstream of the paper transport path by the paper feed roller 114a and the separation roller 114b is sandwiched between the cassette extraction rollers 121. The paper S sandwiched between the cassette pull-out rollers 121 is pulled out further downstream. The paper S drawn downstream passes through or is sandwiched between the pre-registration transfer rollers 120 and reaches the registration roller pair 130. Whether the pair of pre-registration transport rollers 120 are separated from each other or abutted against each other is determined based on the paper type such as the length and basis weight of the paper S to be transported. Further, the separation or contact processing is performed before the paper S of the cassette S is fed by the pickup roller 114a.

The pickup roller 114a and the separation roller 114b are rollers whose main purpose is to send only one sheet of the uppermost paper S of the paper feed cassette 111 to the transport path. Therefore, in general, the transfer efficiency (the amount of paper advance with respect to the roller rotation amount) is lower than that of the cassette extraction roller 121 and the pre-registration transfer roller pair 120. Therefore, when the paper S is conveyed only by the pickup roller 114a and the separation roller 114b, it is difficult to accurately control the advancing amount of the paper. On the other hand, the cassette drawing roller 121 and the transport roller downstream thereof are provided so that the paper transport efficiency is almost 100%, and the advancing amount of the paper can be controlled with high accuracy. Therefore, although the paper S drawn by the cassette extraction roller 121 depends on the basis weight and length of the paper, the paper can be correctly fed to the registration roller pair 130 even if it is not sandwiched between the pre-registration transport rollers pair 120. Is possible.

[Explanation of paper feeding operation from CST1 (conveyance path without independent drawing roller)]
Next, the operation in which the paper S conveyed from the paper feed cassette 110 is conveyed to the registration transfer roller pair 130 will be described with reference to FIG. The paper transport path (first transport path) fed from the paper feed cassette 110 is different from the above-mentioned second transport path, and the cassette is pulled out between the paper feed roller 113 and the pre-registration transport roller 120. No rollers are provided.

The paper S sent out downstream of the paper transport path by the pickup roller 113a and the separation roller 113b is sandwiched between the pre-registration transport rollers pair 120 and reaches the registration roller pair 130.

As described above, the advance amount of the paper cannot be accurately controlled only by the pickup roller 113a and the separation roller 113b. Therefore, the intrusion amount of the registration roller cannot be controlled accurately, and the skew correction cannot be performed correctly. Therefore, the pre-registration transfer roller pair 120 needs to be in contact with each other. The contact operation is performed before the pickup roller 113a feeds the paper S of the cassette S.

[Explanation of separation mode for transport roller pair before registration]
Next, the separation operation of the pre-registration transfer roller pair 120 will be described. In the present embodiment, there are two modes, "wrinkle avoidance priority mode" and "productivity priority mode", as modes relating to the separation of the pre-registration transfer roller pair 120 (hereinafter, may be referred to as "pre-registration separation mode" for convenience). There are two modes. In the present embodiment, the pre-registration separation mode is preset by a user, an administrator, or the like as a setting of the image forming apparatus 100. When the user selects the pre-registration separation mode, the selection is made via the user operation screen 200 shown in FIG.

The "wrinkle avoidance priority mode" is a mode for preventing the occurrence of wrinkles on the paper. In order to prevent wrinkling of the paper, a separation operation of the pre-registration transfer roller pair 120 is performed as necessary. The operating conditions and details of the "wrinkle avoidance priority mode" will be described with reference to the flowchart of FIG. The mechanism by which paper wrinkles occur has already been described in FIG.

The "productivity priority mode" is a mode for preventing a decrease in productivity due to the separation operation of the pre-registration transfer roller pair 120. When the separation in front of the cash register is attached / detached, the paper transport must be interrupted, which reduces the productivity. Therefore, in order to maintain productivity, it is a mode in which the separation operation of the pre-registration transfer roller pair 120 is not performed. If the pre-registration transfer roller pair 120 is not separated from each other, wrinkles may occur on the paper depending on the setting state of the paper. Therefore, a message for preventing wrinkles on the paper is displayed in 203 of FIG. It encourages users to avoid rough sets. The operating conditions and details of the "productivity priority mode" will be described with reference to the flowchart of FIG.

[Explanation of the flow chart of paper feed operation]
FIG. 9 is a flowchart showing a process executed by the CPU 201 according to a program stored in the ROM 202 and the RAM 203. This flowchart is executed according to the input of the print job. The size information and the basis weight information of the paper S stored in each paper storage are input in advance by the user from the operation unit 301, and the information is stored in the RAM 203.

First, the pre-registration transfer roller pair 120 is separated from each other to ensure that paper wrinkles are avoided, or the pre-registration transfer roller pair 120 is not separated and productivity is prioritized. Determine if it works. Specifically, it is determined whether the pre-registration separation mode is the "wrinkle avoidance priority mode" or the "productivity priority mode" (S1000). This determination is made based on the setting of the pre-registration separation mode input from the operation unit 301. When the pre-registration separation mode is not the “wrinkle avoidance priority mode” (which is the “productivity priority mode”), the pre-registration transfer roller pair 120 always maintains the contact state. Therefore, the processing of S1001 to S1009 is not performed, and the process proceeds to S1010, and the CPU 201 starts the paper feeding operation from the paper feeding cassette of the paper feeding source. On the other hand, when the pre-registration separation mode is the "wrinkle avoidance priority mode", it is determined whether the paper storage of the paper feed source is the "cassette 1" (S1001). The term "cassette 1" as used herein corresponds to the paper feed cassette 110 in FIG. 1, and indicates that there is no independent cassette extraction roller in the transport path from the storage to the registration roller pair 130. ing. If YES in S1001, it is determined whether or not the pre-registration transfer roller pair 120 is in the contact state (S1002). When the state of the pre-registration transfer roller pair 120 is the contact state, the CPU 201 starts the paper feeding operation (S1010). The paper feeding operation is to drive the paper feeding motor 181 and rotate the paper feeding roller and the separation roller (113, 114). When the pre-registration transfer roller pair 120 is in a separated state, the CPU 201 determines whether or not the pre-registration transfer roller pair 120 is transferring paper (S1003). If it is determined that the paper is being conveyed by the pre-registration transfer roller pair 120, the process waits until the paper transfer by the pre-registration transfer roller pair 120 for the paper is completed. After that, the CPU 201 executes a contact operation of the pre-registration transfer roller pair 120 (S1004). After shifting to the contact state of the transfer roller pair 120 before registration, the CPU 201 starts the paper feeding operation (S1010).

In S1001, when the paper is fed from the paper storage other than the cassette 1, the separation / arrival determination described later is executed (S1005). The paper storage other than the cassette 1 corresponds to the paper feed cassette 111 or the manual feed tray 112 in FIG. In the transport path of the paper supplied from these paper storages, an independent drawing roller is arranged between the registration rollers and the registration rollers 130. If the determination result of S1005 is "contact", the process proceeds to S1002. When the determination result is "separation", it is determined whether or not the pre-registration transfer roller pair 120 is in the separation state (S1007). When the pre-registration transfer roller pair 120 is in a separated state (YES in S1007), the CPU 201 starts the paper feeding operation (S1010). On the other hand, when the pre-registration transfer roller pair 120 is in the contact state, the CPU 201 determines whether or not the paper is being conveyed by the pre-registration transfer roller pair 120 (S1008). When the paper is being conveyed by the pre-registration transfer roller pair 120, the CPU 201 waits until the paper transfer by the pre-registration transfer roller pair 120 is completed. After that, the CPU 201 executes a separation operation of the pre-registration transfer roller pair 120 (S1009). After the pre-registration transfer roller pair 120 shifts to the contact state, the CPU 201 starts the paper feeding operation (S1010).

[Separation / contact judgment processing]
Hereinafter, the determination process of S1005 will be described. In the present embodiment, when the pre-registration separation mode is the "wrinkle avoidance priority mode", when the length of the paper in the transport direction is X [mm] or more and the basis weight of the paper is less than M [gsm], the "separation" is performed. ". As a result, even if the basis weight of the paper is less than M [gsm], the occurrence of wrinkles can be reduced by separating the pre-registration transport roller pair 120. In addition, the pre-registration transfer roller pair 120 is always in a separated state, and the contact / separation switching operation of the pre-registration transfer roller pair 120 is not performed while continuously printing paper of the same size / basis weight. .. Therefore, it is not necessary to stop the transportation, and it is possible to prevent a decrease in productivity.

Further, when the length of the paper in the transport direction is less than X [mm] and the basis weight of the paper is M [gsm] or more, it is regarded as "contact". That is, in the case of a paper having a basis weight of M [gsm] or more and a strong stiffness, it is judged that the wrinkle occurrence rate is small, and the pre-registration transport roller pair 120 is not separated from each other and is always in a contact state. .. As a result, it is possible to prevent a decrease in productivity.

If the length of the paper in the transport direction is less than X [mm], it is regarded as "contact" regardless of the basis weight of the paper. Since the length of the paper in the transport direction is less than X [mm], it is judged that the occurrence of kinking is small and the occurrence of wrinkles is small even when the pre-registration transport roller pair 120 is still in contact with the paper. As a result, it is possible to prevent a decrease in productivity by keeping the transfer roller pair 120 before registration separated from each other and keeping the contact state at all times.

The threshold value X, which is the threshold value of the length in the transport direction of the paper, is the length of the paper that can be transported by the upstream transport roller (pulling drive roller 122 or cassette drawing roller 121) even if the pre-registration transport roller pair 120 is separated. .. Further, the basis weight M, which is the threshold value of the basis weight of the paper, is the basis weight at the boundary where wrinkles may occur when the pre-registration transfer roller pair 120 is conveyed without being separated.

[effect]
As described above, in the present embodiment, the separation and contact of the pre-registration transport roller pair 120 are switched according to the configuration of the paper transport path. With such a configuration, even if the paper transport path has both the pre-registration transport roller pair and the cassette extraction roller pair, it is possible to transport the paper without causing non-feed. Further, in the paper transport path fed from the paper feed cassette 110, the pre-registration transport roller pair and the cassette extraction roller pair can be used in combination, and the cost can be reduced.

Further, according to the present embodiment, there is a demerit that productivity is lowered by switching the separation and contact of the transfer roller pair 120 before registration, so productivity is provided by providing a mode setting for switching the presence / absence of the separation operation. It becomes possible to avoid the decrease of.

(Other examples)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 Image forming device 110 Paper cassette (first storage)
111 Paper cassette (second storage)
113 Paper feed roller 114 Paper feed roller 116 Extraction motor 120 Pre-registration transfer roller vs. 121 Cassette extraction roller 129 Separation sensor 130 Registration roller vs. 131 Registration detection sensor 140 Separation mechanism 145 Pre-registration transfer motor 150 Image forming unit 160 Fuser 181 Paper feed motor 133 Cash register drive motor 145 Pre-registration transfer drive motor 200 Control unit 201 CPU
202 ROM
203 RAM
204 Motor drive circuit 205 Sensor output detection circuit 301 Operation unit

Claims (6)

An image forming part that forms an image on paper,
The first storage for storing paper and
A second storage, which is provided below the first storage and stores paper,
A pair of transport rollers for transporting the paper fed from the first storage and the second storage, and
A registration roller pair provided downstream in the transport direction from the transport roller pair, which corrects the skew of the conveyed paper and conveys the corrected paper to the image forming unit.
A separation mechanism that causes one roller in the transport roller pair to abut or separate from the other roller.
When forming an image on the paper supplied from the first storage, the one roller is brought into contact with the other roller regardless of the type of the paper stored in the first storage. When image formation is performed on the paper supplied from the second storage, the separation mechanism is used so as to separate the one roller from the other roller based on the type of the paper stored in the second storage. Control means to control and
An image forming apparatus characterized by having. It has a setting means for setting whether or not to perform the separating operation of the transport roller pair.
When the control means is set not to perform the separating operation of the transport roller pair by the setting means, even when the image is formed on the paper fed from the second storage. The image forming apparatus according to claim 1, wherein the separation mechanism is controlled so that the one roller is brought into contact with the other roller regardless of the type of paper. A drive motor that rotates the other roller by rotating in the first direction and causes the one roller to abut or separate from the other roller by rotating in the second direction opposite to the first direction. The image forming apparatus according to claim 1 or 2, further comprising. The image forming apparatus according to any one of claims 1 to 3, wherein the type of the paper includes a basis weight of the paper and a size of the paper. A feed roller for separating and transporting the fed paper one by one is provided in the transport path between the first paper storage and the transport roller pair, and the feed roller is provided with the feed roller. The image forming apparatus according to any one of claims 1 to 4, wherein the rollers are arranged most upstream in the transport direction with respect to the roller pair. In the transport path between the second paper storage and the transport roller pair, a feed roller that separates and transports the fed paper one by one and a paper conveyed by the feed roller are received. The image forming apparatus according to any one of claims 1 to 5, wherein a drawing roller for transporting toward the transport roller pair is provided.

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