JP2003040466A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out paper feeding action of a recording sheet inexpensively and favorably. SOLUTION: A paper feeding control part is provided for feeding paper with the shortest or the longest paper feeding interval chosen in response to the paper length detected by a paper feeding part 25, regardless of the paper length information sent form a higher device 11, even if paper length information sent from the higher device 11 is different from the size of a recording paper S actually set in the paper feeding part 25, so that the shortest throughput paper feeding from the first sheet is enabled without causing a jam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus capable of continuous sheet feeding by adjusting a sheet feeding interval from a sheet feeding section in which recording sheets are set.

[0002]

2. Description of the Related Art Generally, in various image forming apparatuses such as copiers, paper size information included in image information sent from a higher-level device to a paper feed control unit is used to transfer paper from a paper feed unit to a conveyance path. There is known an apparatus capable of continuous sheet feeding operation by appropriately determining the sheet feeding interval to be sent out and performing the sheet feeding operation according to the sheet feeding interval.

However, if the paper size instruction information sent from the host device and the size of the recording paper actually set in the paper feed cassette mounted in the paper feed unit are different, for example, , The next paper feed timing comes before the trailing edge of the recording paper completely comes out of the paper feed section, and a jam occurs, or the interval between the next recording paper and There is a risk that jam detection such as stagnant jam will be activated and jam paper will be left in the transport path while being left behind.

Therefore, conventionally, in order to prevent the occurrence of the jammed state as described above when performing continuous paper feeding,
The paper length of the first recording paper when the paper feeding operation is started is measured by a TOP sensor provided in the conveyance path, and the actual paper length obtained from the detection signal from the TOP sensor is If it is different from the paper length indicated by the paper information instructed by the higher-level device, stop feeding the paper after that or switch to the actually measured paper length after that, and try to remove jammed paper as much as possible. A device has been developed that does not leave jam paper and does not leave jammed paper in the transport path.

For example, in the conventional example shown in FIG.
First of all, when feeding the first first recording sheet,
The paper feed clutch 21 of the paper feed roller provided in the paper feed unit,
Although the rotational driving force is applied to the paper feed roller by turning on based on the print command PC from the host device, the second and subsequent recording papers are provided in the conveyance path. The paper feed clutch is switched on based on the paper length detection signal from the TOP sensor TS. In this way, the paper feed interval between the second, third, and subsequent paper feed sheets is adjusted to a jam-free interval.

[0006]

However, if the former of the above-mentioned conventional apparatuses, that is, the sheet length of the recording sheet actually used is different from the sheet information from the host apparatus, the sheet feeding is performed. In the device that is set to stop
Since a processing operation for returning from the stop state is required, the operability tends to be troublesome and inefficient. In particular, when the host device is installed at a distant place, it is often inconvenient to go to the distant place and perform a process operation for restoration. Even if the return processing operation is performed, if the specified paper size is not at hand, the job may no longer be output.

On the other hand, the latter of the above-mentioned conventional apparatuses, that is, an apparatus which switches the paper feed timing to the measured paper length when the actual paper length is different from the paper information from the host device According to this, the feeding operation of the second recording sheet is started only after the measurement of the total length of the recording sheet of the first feeding sheet is completed.
There is a problem that the sheet feeding interval between the first sheet and the second sheet is significantly extended, and so-called throughput is significantly reduced.

Therefore, according to the present invention, even if the size of the recording paper actually set in the paper feeding unit is different from the paper size designated by the host device, continuous feeding is favorably maintained. It is an object of the present invention to provide an image forming apparatus in which the so-called throughput is not reduced.

[0009]

In order to achieve the above object, in an image forming apparatus according to a first aspect of the present invention, paper length information indicating the length of a recording paper to be used for image formation is sent from a host device. Then, based on the paper length information, the paper feed control unit that enables continuous paper feed is adjusted by adjusting the paper feed interval of the recording paper sent from the paper feed unit in which the recording paper is set to the transport path. In the provided image forming apparatus, whether the length of the recording sheets set in the sheet feeding unit is longer or shorter than the reference sheet length that can be fed at the shortest sheet feeding interval in the image forming apparatus is supplied. The paper feed unit has a paper length detection sensor for detecting before the paper, and the paper feed control unit is a signal indicating that the detection signal from the paper feed unit paper length detection sensor is shorter than the reference paper length. If you recognize that This is a signal indicating that the detection signal from the paper length detection sensor of the paper feed unit is longer than the reference paper length while the paper feed operation is started at the shortest possible paper feed interval for short length recording paper. When recognizing that, it is determined that the paper cannot be fed at the shortest paper feeding interval, regardless of the paper length information sent from the host device,
The image forming apparatus has a function of performing a paper feeding operation at a paper feeding interval that matches the longest paper feeding interval that can be fed by the image forming apparatus.

According to the image forming apparatus of the first aspect having such a structure, the paper length information sent from the higher-level device is different from the size of the recording paper actually set in the paper feeding section. Even if it is, the paper feeding operation is performed at the shortest or longest paper feeding interval selected corresponding to the paper length detected by the paper feeding unit, regardless of the paper length information sent from the host device. Since this is performed, it is possible to feed the shortest throughput from the first sheet without causing a jam.

Further, in the image forming apparatus according to the second aspect, the sheet feeding control section according to the first aspect is a signal indicating that the detection signal from the sheet length detecting sensor of the sheet feeding section is shorter than the reference sheet length. If the paper length information sent from the host device indicates that the recording paper cannot be fed at the shortest paper feed interval, the paper sent from the host device Since it has a function to perform the paper feed operation at the designated paper feed interval based on the long information, it is short like the statement size recording paper,
An appropriate paper feeding operation can be performed even for recording paper that cannot be set to the shortest paper feeding interval.

Further, in the image forming apparatus according to the third aspect, when the paper length information for instructing the length of the recording paper to be used for image formation is sent from the host device, the paper length information is sent based on the paper length information. In an image forming apparatus equipped with a paper feed control unit that adjusts the paper feed interval of the recording paper sent from the paper feed unit in which the recording paper is set to the transport path and enables continuous paper feed to the transport path, Paper feed for detecting whether the paper length of the recording paper set in the paper feed unit is longer or shorter than the reference paper length that can be fed at the shortest paper feed interval in the image forming apparatus before the paper feed Paper length detection sensor,
A recording sheet sent from the sheet feeding section into the conveyance path is provided with a conveyance path sheet length detection sensor that measures the time taken for the recording sheet to pass through the conveyance path and detects the sheet length of the recording sheet. When the paper feed control unit recognizes that the detection signal from the paper length detection sensor of the paper feed unit is a signal indicating that it is shorter than the reference paper length, the paper sent from the higher-level device After starting the paper feed at the paper feed interval based on the length information, an appropriate paper feed interval suitable for the recording paper that started the paper feed is obtained based on the detection signal from the conveyance path paper length detection sensor. When the proper paper feeding interval is larger than the shortest paper feeding interval as compared with the shortest paper feeding interval, the subsequent paper feeding interval is changed to the proper paper feeding interval.

According to the image forming apparatus of the third aspect having such a configuration, the paper length information sent from the host device and the size of the recording paper actually set in the paper feeding section are different. Even if it is, the paper feed interval selected from the second and subsequent paper feeds is selected according to the paper length detected in the transport path, regardless of the paper length information sent from the host device. Since the paper feeding operation is performed in the above, it is possible to perform the shortest paper feeding from the first sheet without causing a jam.

Further, in the image forming apparatus according to the fourth aspect, the paper feed control unit according to the third aspect is a signal indicating that the detection signal from the paper length detection sensor of the paper feeding unit is longer than the reference paper length. If it is recognized that the sheet cannot be fed at the shortest sheet feeding interval, the image forming apparatus starts the sheet feeding operation at the sheet feeding interval that matches the longest recording sheet that can be fed by the image forming apparatus. Since it has a function to do so, the possibility of causing a jam from the first sheet of paper is completely avoided.

Further, in the image forming apparatus according to the fifth aspect, the sheet feeding control section according to the fourth aspect starts the sheet feeding operation at the sheet feeding interval matched with the sheet feeding interval of the longest recording sheet,
Based on the detection signal from the conveyance path sheet length detection sensor, an appropriate sheet feeding interval suitable for the recording sheet that has started feeding is obtained, and the appropriate sheet feeding interval is set in the sheet information sent from the host device. If the appropriate paper feed interval is larger than the corresponding designated paper feed interval, the subsequent paper feed interval has the function of changing to the appropriate paper feed interval. Since the proper paper feed interval determined based on the recording paper of No. 1 is maintained only when it is larger than the paper feed instruction interval indicated by the paper information from the higher-level device, the possibility of jamming is further avoided. ing.

Further, in the image forming apparatus according to the sixth aspect of the present invention, the paper length information indicating the length of the recording paper to be used for image formation is not sent from the upper-level device, and the paper is set with the recording paper set. In an image forming apparatus equipped with a paper feed control unit capable of continuously feeding paper by adjusting the paper feed interval of the recording paper fed from the paper unit to the conveyance path, the paper of the recording paper set in the paper feeding unit A paper length detection sensor that detects whether the length is longer or shorter than a reference paper length that can be fed at the shortest paper feed interval in the image forming apparatus before feeding, and the paper feed unit The recording sheet sent out into the conveyance path is provided with a conveyance path sheet length detection sensor that measures the time taken for the recording sheet to pass through the conveyance path and detects the sheet length of the recording sheet. Section is the paper length detection section above If it is recognized that the detection signal from the sensor is a signal indicating that it is longer than the reference sheet length, it is determined that the sheet cannot be fed at the shortest sheet feeding interval, and the image forming apparatus can feed the longest sheet. Recognizes that the detection signal from the paper length detection sensor is a signal indicating that the paper length is shorter than the reference paper length while the paper feed operation is performed at the paper feed interval corresponding to the recording paper feed interval of In this case, it is determined that the sheet can be fed at the shortest sheet feeding interval, and the image forming apparatus starts the sheet feeding operation at the sheet feeding interval that matches the shortest sheet feeding interval of the recording sheet. After that, a function of obtaining an appropriate sheet feeding interval suitable for the recording sheet which has started feeding based on the detection signal from the sheet length sensor for the conveyance path, and changing the sheet feeding interval thereafter to the appropriate sheet feeding interval. have.

According to the image forming apparatus of the sixth aspect having such a configuration, even if there is no sheet length information sent from the host apparatus, the sheet length detected by the sheet feeding unit can be dealt with. Since the paper feeding operation is performed at the shortest or the longest paper feeding interval selected as described above, it is possible to perform the shortest throughput paper feeding from the first sheet without causing a jam.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. First, a general description will be given of the overall configuration of a control system relating to a sheet feeding operation of image forming of a copying machine to which the present invention is applied. As shown in FIG. Is sent to a CPU (Central Processing Unit) 13 constituting a paper feed control section and a laser scanner unit 14 as an image writing device via an interface 12. The CPU 13 has
ROM 1 storing and storing various data such as a control program and a management table relating to sheet feeding control as described later
5 and a RAM 16 for temporarily storing various data for data processing are path-connected.

In the laser scanner unit 14 connected to the output side of the CPU 13, the CPU
A polygon mirror that is driven to rotate based on a command signal from 13 is provided, and in accordance with an image signal sent from the higher-level device 11 in synchronization with an image synchronization signal created inside the laser scanner unit 14, The laser scanner unit 14 forms a latent image on a photosensitive drum (not shown).

The various image information sent from the host device 11 at this time includes the paper size information of the recording paper to be used when forming an image, and is recognized by the device according to the present embodiment. As the size of the recording paper to be used, six types of paper size information of letter size, statement size, legal size, foolscap size, and free size (unspecified) are included.

On the other hand, the output side of the CPU 13 is connected to a driver circuit of a sheet feeding clutch 21 for interrupting the rotational driving force with respect to a sheet feeding roller provided in a sheet feeding cassette 25 mounted in a sheet feeding section. The paper feed clutch 21
When the switch is turned on, a rotational driving force is applied to the paper feed roller, whereby the recording paper set in the paper feed cassette 25 is picked up and sent into a predetermined conveyance path. It is supposed to be.

The recording paper thus fed into the conveyance path is fed to the transfer section through an appropriate path by the rotational driving of a plurality of conveyance rollers provided in the middle of the conveyance path. Each of the transport rollers is driven by rotating the transport motor 22 based on a drive signal sent from the CPU 13 through a driver circuit.

At this time, a TOP detection sensor 23 for detecting the edge of the recording paper is provided in the conveying path, and the detection signal on the leading end side of the recording paper detected by the TOP detection sensor 23 is By outputting to the input side of the CPU 13, the leading edge writing timing of the image is determined. Further, the detection signal on the trailing edge side of the recording paper detected by the TOP detection sensor 23 is output to the input side of the CPU 13 to measure the paper length of the actual recording paper fed into the conveyance path. It has become so.

Next, on the input side of the CPU 13, a paper for detecting whether the recording paper set in the paper feed cassette 25 mounted in the paper feed unit is longer or shorter than a predetermined reference paper length. The long detection sensor 24 is connected. The paper length detection sensor 24 is arranged so as to be located on the rear end side of the paper feed cassette 25 attached to the paper feed section as shown in FIG. 6, for example.
In the inside, a length guide portion 25 that abuts on the rear end side (the left end side in the drawing) of the recording paper S stored in the paper feed cassette 25 is provided.
a is erected so as to be reciprocally movable in the length direction of the recording sheet S (left and right direction in the drawing).

On the other hand, the paper length detection sensor 24 is provided with a sensor flag 24a, which contacts and separates from the length guide portion 25a on the side of the paper feed cassette 25, hanging from the rotary shaft 24b as shown in FIG. 6A. Is provided. The sensor flag 24a is formed of a plate-shaped member, and when the length guide portion 25a comes into contact with the sensor flag 24a, the sensor flag 24a is changed to the one shown in FIG.
The rotary shaft 24b is pushed upward as shown in FIG.
Is rotated, and the shield fin 24c attached to one end side (the left end side in the drawing) of the rotation shaft 24b enters into the shield sensor 24d having an optical structure or the like, so that the signal from the shield sensor 24d becomes The on-state can be switched to the off-state.

That is, in the present embodiment, the length of the recording paper S stored in the paper feed cassette 25 is detected by classifying it into two types, short and long with respect to the reference paper length. As shown in FIG. 6A, the recording paper S having a short length such as a letter size or a statement size is the paper feed cassette 2.
In the case of being stored in 5, the length guide portion 25
When a is located on the front side indicated by the symbols "a" and "b" in the figure, it is separated from the sensor flag 24a described above, and an ON signal, that is, a short paper signal, is output from the shielding sensor 24d. Is output to the CPU 13. On the other hand, when a long recording paper S such as a legal size or foolscap size is stored in the paper feed cassette 25, the length guide portion 25a is
By being located on the rear side indicated by the reference signs "c" and "d" in the figure, the sensor flag 24a is contacted,
An off signal, that is, a long paper signal is output from the shielding sensor 24d to the CPU 13.

With respect to such a detection signal from the paper length detection sensor 24, management is performed in which an optimum paper interval time (paper feed interval time) relating to the size of the recording paper S as shown in Table 1 below is determined. The table is stored in the ROM 15 shown in FIG.

[Table 1]

That is, in this management table, for letter size and statement size with a short paper length, the optimum paper interval time (paper feed interval time) is set to be short, and the legal size and fools with a long paper length are set. The optimum paper interval time (paper feed interval time) is set long for the cap size. At this time, the statement size recording paper is shorter than the letter size, but the paper width is considerably narrow, so the optimum paper interval time (paper feed interval time) is set to the longest. An abnormal heating state at the width end portion of the roller is avoided to prevent seizure or damage. The paper size information that can be specified can be appropriately increased or decreased according to the scale of the device.

Further, as shown in FIG. 1, on the input side of the CPU 13, a sheet interval timer 26 for measuring the time for determining the sheet feed timing of each recording sheet S,
And a paper length measuring timer 2 for measuring the length of the recording paper S
7 are connected to each other, and the CPU 13
A high-voltage controller 28 for realizing the electrophotographic process and a fixing controller 29 for controlling the temperature when the toner is melted by the heater and fixed on the recording sheet S are connected to the output side of.

On the other hand, in the ROM 15 described above,
A control program as shown in FIG. 5 is stored.

First, as shown in FIG. 2, when the apparatus according to this embodiment is in the standby state, a print command is received from the host apparatus 11 and the image formation of the first sheet is started ( Step 1) First, the paper length detection sensor 24 arranged on the side of the paper feed cassette 25 is checked (step 2), and the paper length of the recording paper S stored in the paper feed cassette 25 is the reference paper. It is determined whether the next recording sheet S can be fed at the shortest sheet feeding interval by detecting whether it is longer or shorter than the length before feeding.

That is, when the recording paper S stored in the paper feed cassette 25 is the shorter recording paper S such as letter size or statement size, an off signal from the paper length detection sensor 24, That is, the short paper signal is output to the CPU 13, and in this case, the length of the recording paper S used is such that the jam does not occur even if the paper is fed at the shortest timing that allows continuous feeding. It is determined that the sheet can be fed, and the time value representing the shortest sheet feeding interval is substituted for the variable X (step 3). If not, that is, if the recording paper S stored in the paper feed cassette 25 is the longer recording paper S such as the legal size or the foolscap size, the paper length detection sensor 24 turns on. The signal, that is, the long paper signal is the C
It is output to the PU 13 side, and in that case, if the paper length of the recording paper S used is fed at the timing of the shortest paper feed interval that allows continuous feeding, there is a risk of causing a jam. Therefore, the time value representing the maximum paper feed interval is substituted into the variable X (step 4).

Next, in order to give priority to the case where the designation from the host device is larger than the optimum paper interval time consisting of the above-mentioned shortest paper feed interval or the maximum paper feed interval, whether or not there is a size designation from the host device is determined. When it is determined (step 5) and the paper size indicated in the paper interval management table in Table 1 is specified (Yes in step 5), the optimum paper interval time according to the specified size is substituted as described above. Variable X
(Step 6), if the optimum paper interval time for the specified size is large (step 6 N
o), and substitute it in the variable X (step 7).

After substituting the value of the variable X into the variable S (step 8), the paper feed clutch 21 is turned on (step 9), and the recording paper S is fed to the paper feed cassette 25.
Picked up from and delivered to the side of the transport path. Further, immediately after turning on the paper feed clutch 21, the paper interval timer 2
After clearing 6, the sheet interval timer 26 is restarted (step 10). At this time, the sheet interval timer 26 is a timer that performs addition in a predetermined time unit.

Then, when the TOP sensor 23 detects the leading edge of the recording paper S (step 11 is ON), the paper length measuring timer 27 is started immediately (step 1).
2). The paper length measuring timer 27 is a timer that performs addition in a predetermined time unit from the start to the stop.

Then, the print instruction acceptance permission status is transmitted to the host device (step 13). As a result, the higher-level device is in a state in which it is possible to send print commands for the second and subsequent sheets in succession, and when a print command is received from the higher-level device, the 2
The processing of the subsequent start flowchart of the first sheet is processed in parallel with the processing described below.

That is, when the TPO sensor 23 detects the trailing edge of the recording paper S (step 14 OFF), the paper length measuring timer 27 stops (step 1
5) Then, the counted timer time is substituted into the variable y (step 16). Next, shifting to FIG. 3, the paper size is derived from the closest value between the value of the variable y and the TOP sensor passage scheduled time set in the paper interval management table in Table 1 described above, and the appropriate value corresponding thereto is derived. The time corresponding to the paper feed interval is substituted into the variable Y (step 1
7).

In this case, when the paper size is designated by the host device (Yes in step 18), the time corresponding to the optimum paper interval based on the paper size designated by the host device is substituted into the variable S. After that (step 19), that value is compared with the time (variable Y) corresponding to the above-mentioned proper paper feeding interval derived from the measured paper size (step 2).
0), and the larger one is set as the variable S (step 2)
1). On the other hand, when the paper size is not designated by the host device, the variable Y is substituted into the variable S (step 22). The sheet feeding operation for the first sheet is started at the sheet feeding interval thus determined.

In this embodiment, in order to arbitrate the print management time of the host device and the writing position of the leading edge of the image, when the paper size is instructed by the host device, the paper feed interval is designated. Although it cannot be made narrower than the sheet feeding interval of the size, it is also possible to omit the processing of steps 18 to 21 depending on the host device.

Next, as shown in FIG.
The case of the first and subsequent sheets will be described. First, when the sheet feeding control for the second and subsequent sheets is started (step 1), the value of the sheet interval timer 26 becomes equal to or larger than the variable S described above in order to maintain the sheet interval with the preceding recording sheet S. By the way (Yes in step 2), the paper feed clutch 21 is turned on (step 3). Then, after the value of the paper interval timer 26 is cleared, the paper interval timer 26 is restarted (step 4).

Next, wait until the top edge of the recording paper S is detected by the TOP sensor 23. When the top edge of the recording paper S is detected by the TOP sensor 23 (step 5 ON), a print instruction acceptance permission is transmitted to the host device. (Step 6). Then, the TOP sensor 23 detects the trailing edge of the recording sheet S and waits until it is turned off (step 7). The above control operation is the same for the second and subsequent sheets.

When carrying out such a flow, for example,
When the paper size is designated as the letter size from the host device, the letter size recording paper S is also stored in the paper feed cassette 25.
When is set, the print command, the paper feed clutch, and the detection signal from the TOP sensor from the host device are associated with each other as shown in FIG. To be done. Further, although the paper size from the host device is designated as the letter size, the paper cassette 25
When the statement-size recording sheet S is set in, the switching operation is performed as shown in FIG. Furthermore, when the paper size from the host device is designated as the statement size and the statement size recording paper S is also set in the paper feed cassette 25, as shown in FIG. 5C. Then, the switching operation is performed. Furthermore, when the paper size from the host device is designated as the legal size and the recording paper S of the legal size is also set in the paper feeding cassette 25, as shown in FIG. Then, the switching operation is performed.

On the other hand, if there is no size designation from the host device and letter size recording paper S is set in the paper feed cassette 25, the same timing as in FIG. 5A can be fed. Is. Similarly, the paper feed cassette 2
If the statement size recording paper S is set in 5, it is possible to feed paper with the same timing as in FIG. Similarly, if the recording paper S of legal size is set in the paper feeding cassette 25, the same timing as in FIG. 5D can be fed.

As described above, in the apparatus according to this embodiment,
Even if the paper length information sent from the host device 11 and the size of the recording paper S actually set in the paper feed cassette 25 attached to the paper feed unit are different, Irrespective of the paper length information sent from the device 11, the paper feeding operation is performed at the shortest or longest paper feeding interval selected corresponding to the paper length detected by the paper feeding unit.
It is possible to feed the shortest throughput from the first sheet without causing a jam.

Further, in this embodiment, the detection signal from the paper length detection sensor 24 of the paper feed section is recognized as a signal indicating that it is shorter than the reference paper length, and the paper length sent from the host device 11 is recognized. When the information indicates that the recording paper cannot be fed at the shortest paper feed interval, the paper feed operation is performed at the designated paper feed interval based on the paper length information sent from the host device 11. Since it has a function of making it possible, it is possible to perform an appropriate paper feeding operation even for a recording paper which is short, such as a statement size recording paper, but cannot have a shortest paper feeding interval.

Further, in the apparatus according to the present embodiment, the sheet length information sent from the upper level apparatus 11 and the size of the recording sheet S actually set in the sheet feeding cassette 25 mounted in the sheet feeding section. Even if and are different,
Since the second and subsequent sheets of paper are fed, the paper feeding operation is performed at the paper feeding interval selected corresponding to the paper length detected in the transport path, regardless of the paper length information sent from the host device. It is possible to feed the shortest throughput from the first sheet without causing a jam.

Furthermore, in the present embodiment, when it is recognized that the detection signal from the paper length detection sensor 24 of the paper feed unit is a signal indicating that the paper length is longer than the reference paper length, the paper feed is performed at the shortest paper feed interval. Since it has a function to start the paper feed operation at the paper feed interval that matches the longest recording paper feed interval that can be fed by the device, the jam can be detected from the first paper feed. The possibility of occurring is completely avoided.

Further, in this embodiment, after the paper feeding operation is started at the paper feeding interval matched with the paper feeding interval of the longest recording paper, the optimum paper feeding interval suitable for the recording paper having started the feeding is TOP. Based on the detection signal from the detection sensor 23, the appropriate paper feed interval is compared with the instructed paper feed interval corresponding to the paper information sent from the higher-level device 11, and the appropriate paper feed interval has a large value. In some cases, since it has a function to change the subsequent paper feeding interval to the appropriate paper feeding interval,
Since the proper sheet feeding interval determined based on the first recording sheet to be fed is maintained only when it is larger than the sheet feeding interval designated by the sheet information from the higher-level device 11, a jam may occur. It is becoming more evasive.

Further, in the present embodiment, even if there is no paper length information sent from the host device 11, the selection is made in correspondence with the paper length detected in the paper feed cassette 25 mounted in the paper feed section. Since the sheet feeding operation is performed at the shortest or longest sheet feeding interval, it is possible to perform the shortest sheet feeding from the first sheet without causing a jam.

Although the embodiments of the present invention have been specifically described above, it is needless to say that the present invention is not limited to the above-mentioned embodiments and various modifications can be made without departing from the scope of the invention. Nor.

For example, the present invention is not limited to the copying machine as in the above-described embodiment, but can be similarly applied to various other image forming apparatuses.

[0052]

As described above, the image forming apparatus according to the first aspect of the present invention includes the sheet length information sent from the host device,
Even if the size of the recording paper actually set in the paper feed unit is different, the paper length detected by the paper feed unit is used regardless of the paper length information sent from the host device. By providing a paper feed control unit that performs a paper feed operation at the shortest or longest paper feed interval selected correspondingly, it is possible to feed the shortest throughput from the first sheet without causing a jam. The recording paper feeding operation can be inexpensively and suitably performed.

The image forming apparatus according to claim 2 is
In addition to the above claim 1, the detection signal from the paper length detection sensor of the paper feed unit is recognized as a signal indicating that it is shorter than the reference paper length, and the paper length information sent from the host device is the shortest. When it is instructed that the recording paper cannot be fed at the paper feed interval, it has a function to perform the paper feed operation at the designated paper feed interval based on the paper length information sent from the host device. A paper control unit is provided to enable proper feeding operation even for recording sheets that are short in length, such as statement size recording sheets, but cannot be made the shortest feeding interval. Therefore, the effects described above can be further enhanced.

Further, in the image forming apparatus according to the third aspect, the paper length information sent from the higher-level device is different from the size of the recording paper actually set in the paper feeding section. Even from the second sheet onward, the sheet feeding operation is performed at the sheet feeding interval selected corresponding to the sheet length detected in the transport path, regardless of the sheet length information sent from the host device. Since the paper feed control unit is provided to enable the shortest throughput paper feed from the first sheet without causing a jam, the above-described effect can be further improved.

Furthermore, in addition to the above-mentioned claim 3, the image forming apparatus according to claim 4 recognizes that the detection signal from the paper length detection sensor of the paper feed section is a signal indicating that it is longer than the reference paper length. In this case, it is determined that the paper cannot be fed at the shortest paper feed interval, and the paper feed operation has a function to start the paper feed operation at the paper feed interval that matches the longest recording paper feed interval that the device can feed. By providing a paper control unit, from the first sheet of paper feeding,
Since the possibility of jamming is completely avoided, the recording paper feeding operation can be performed inexpensively and suitably.

The image forming apparatus according to claim 5 is
In addition to the above-mentioned claim 4, after the paper feeding operation is started at a paper feeding interval matched with the paper feeding interval of the longest recording paper, a proper paper feeding interval suitable for the recording paper which started the paper feeding is set to a conveyance path paper. The proper paper feed interval is obtained based on the detection signal from the length detection sensor, and the proper paper feed interval is larger than the instructed paper feed interval corresponding to the paper information sent from the upper apparatus. In this case, a paper feed control unit having a function of changing the subsequent paper feed interval to the proper paper feed interval is provided, and the proper paper feed interval determined based on the first recording sheet of the paper feed is Since it is maintained only when it is longer than the sheet feeding interval designated by the sheet information from the host device, and the possibility of jamming is further avoided, the above-mentioned effect can be further improved.

Further, in the image forming apparatus according to the sixth aspect, even if there is no paper length information sent from the host device, the shortest or longest selected according to the paper length detected in the paper feeding unit. By providing a paper feed control unit that performs paper feed operation at a paper feed interval of 1
Since it is possible to feed the shortest throughput from the first sheet, it is possible to inexpensively and suitably perform the feeding operation of the recording sheet.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a paper feed control unit of a copying machine as an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control operation of a first sheet by a sheet feeding control section shown in FIG.

FIG. 3 is a flowchart showing a continuation of the control operation by the paper feed controller shown in FIG.

FIG. 4 is a flowchart showing the control operation of the second and subsequent sheets by the sheet feeding control section shown in FIG.

FIG. 5 is a diagram showing operation timing in each specific case.

FIG. 6 is a side view illustrating a structure of a paper length detection sensor provided in a paper feeding unit according to another embodiment of the present invention.

FIG. 7 is a timing chart showing an example of a conventional paper feed control operation.

[Explanation of symbols]

11 Host device 13 CPU (Central Processing Unit) that constitutes the paper feed controller 14 Laser scanner unit 15 ROM 16 RAM 25 paper cassettes 25a Length guide part 21 Paper feed clutch 22 Conveyor motor 23 TOP detection sensor 24 Paper length detection sensor 24a sensor flag 24c shielding fin 24d shield sensor S recording paper

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C061 AP01 AP04 AQ06 AS02 HJ03                       HK05 HK07 HN17                 3F048 AA02 AB01 BA07 BB02 CA03                       CC03 CC04 DA03 DA06 DB07                       DC13 EB30                 3F343 FA01 FB02 FB04 GA01 GB01                       GC01 GD01 HA01 HA17 HB04                       HC04 HC11 HD07 KB03 KB06                       LA04 LD10 MA04 MA08 MA09                       MA26 MA44 MA54 MB04 MB09                       MC06 MC08 MC23                 5C062 AA05 AA14 AB32 AB38 AC13                       AC67 AE16 AF10 BA04

Claims (6)

[Claims] 1. When paper length information for instructing the length of a recording paper to be used for image formation is sent from a higher-level device, based on the paper length information, the paper feed unit in which the recording paper is set In an image forming apparatus equipped with a paper feed control unit capable of continuously feeding paper by adjusting the paper feed interval of the recording paper fed to the conveyance path, the paper length of the recording paper set in the paper feed unit is The image forming apparatus is provided with a paper length detection sensor for a paper feed unit that detects whether the paper length is shorter or longer than the reference paper length that can be fed at the shortest paper feed interval, and the paper feed control is also provided. When the unit recognizes that the detection signal from the paper length detection sensor of the paper feeding unit is a signal indicating that the length is shorter than the reference paper length, the shortest possible length for the recording paper of the short length. While starting the paper feed operation at the paper feed interval When recognizing that the detection signal from the paper length detection sensor of the paper feed unit is a signal indicating that the paper length is longer than the reference paper length, it is determined that the paper cannot be fed at the shortest paper feed interval, and the upper device It has a function of performing a paper feed operation at a paper feed interval that matches the longest recording paper feed interval that can be fed by the image forming apparatus, regardless of the paper length information sent from Image forming apparatus. 2. The paper feed control unit recognizes that the detection signal from the paper length detection sensor of the paper feed unit is a signal indicating that it is shorter than a reference paper length, and is sent from the host device. When the paper length information indicates that the recording paper cannot be fed at the shortest paper feed interval, the paper feeding operation is performed at the designated paper feed interval based on the paper length information sent from the host device. The image forming apparatus according to claim 1, having a function of performing the following. 3. When paper length information for instructing the length of a recording paper to be used for image formation is sent from a higher-level device, based on the paper length information, a paper feed unit in which the recording paper is set In an image forming apparatus equipped with a paper feed control unit capable of continuously feeding paper to the transport path by adjusting the paper feed interval of the recording paper fed to the transport path, the recording paper set in the paper feed unit. The paper length detection sensor for detecting whether the paper length of the paper is longer or shorter than the reference paper length that can be fed at the shortest paper feed interval in the image forming apparatus before the paper feeding, A recording sheet sent out from the section into the conveyance path, and a conveyance path sheet length detection sensor for measuring the time taken for the recording sheet to pass through the conveyance path and detecting the sheet length of the recording sheet. The paper control unit uses the paper length detection sensor When recognizing that the detection signal from them is a signal indicating that the length is shorter than the reference paper length, after starting the paper feed at the paper feed interval based on the paper length information sent from the host device, The proper sheet feeding interval suitable for the recording sheet that has started feeding is obtained based on the detection signal from the conveyance path sheet length detection sensor, and the appropriate sheet feeding interval is compared with the shortest sheet feeding interval to obtain the proper sheet feeding. An image forming apparatus having a function of changing a subsequent sheet feeding interval to the appropriate sheet feeding interval when the interval is a large value. 4. When the paper feed control unit recognizes that the detection signal from the paper feed unit paper length detection sensor is a signal indicating that it is longer than the reference paper length, the paper feed control unit feeds paper at the shortest paper feed interval. 4. The image according to claim 3, wherein the image forming apparatus has a function of starting the paper feeding operation at a paper feeding interval matching the longest paper feeding interval of the recording paper that can be fed by the image forming apparatus. Forming equipment. 5. The paper feed control unit, after starting a paper feed operation at a paper feed interval matched with the longest recording paper feed interval,
Based on the detection signal from the conveyance path sheet length detection sensor, an appropriate sheet feeding interval suitable for the recording sheet that has started feeding is obtained, and the appropriate sheet feeding interval is set in the sheet information sent from the host device. 5. A function for changing a subsequent sheet feeding interval to the appropriate sheet feeding interval when the appropriate sheet feeding interval has a larger value compared to the corresponding designated sheet feeding interval. Image forming device. 6. A recording sheet sent from a paper feed unit, in which the recording sheet is set, to a conveyance path without sheet length information indicating the length of the recording sheet to be used for image formation being sent from a host device. In an image forming apparatus equipped with a paper feed control unit that enables continuous paper feeding by adjusting the paper feed interval, the paper length of the recording paper set in the paper feed unit is the shortest in the image forming apparatus. A paper length detection sensor that detects whether the paper length is longer or shorter than the standard paper length that can be fed at the paper feed interval, and the recording paper sent from the paper feed unit into the transport path. And a conveyance path sheet length detection sensor for detecting the sheet length of the recording sheet by measuring the time of passage through the conveyance path. The detection signal from the sensor is less than the standard paper length If it is recognized that the signal indicates that the sheet is long, it is determined that the sheet cannot be fed at the shortest sheet feeding interval described above, and the sheet feeding interval adjusted to the longest sheet feeding interval that the image forming apparatus can feed. When the paper feed operation is performed at the paper interval, and when it is recognized that the detection signal from the paper length detection sensor of the paper feed unit is a signal indicating that the reference paper length is shorter than the reference paper length, the shortest paper feed interval is set. Determine that it is possible to feed paper, start the paper feed operation at the paper feed interval that matches the shortest paper feed interval that the image forming apparatus can feed, and then select the recording paper that started feeding An image forming apparatus having a function of obtaining a suitable appropriate sheet feeding interval based on a detection signal from the sheet length detection sensor for the transport path and changing the sheet feeding interval thereafter to the appropriate sheet feeding interval.