JPH02158543A - Paper conveyance control method for picture forming device - Google Patents

Abstract

PURPOSE:To prevent a paper jam obtaining a paper space in the time of normal conveyance even when a slip rate of paper conveyance is increased by averaging detecting timing of a paper detecting sensor, comparing this averaged value with the reference timing and performing a feedback of the change amount to the time of repeating paper conveyance space. CONSTITUTION:In the case of a continuous copy mode with the first point of paper passing, a CPU 40 detects the paper passing through each sensor from the rear end of the paper to the point end of the next paper in continuous paper passing time, that is, between-paper data in actual conveyance time stored in a non-volatile RAM 44. Simultaneously with the above, updated several data are averaged and similarly memorized in the RAM 44. And the CPU 40 compares a value of normal time paper space data, stored in a ROM 42, with a value of the RAM 44. Only by a number of pulses of this increases, repeat timing is delayed. As the result, even when a slip rate of paper conveyance is increased, a paper jam is prevented by obtaining a paper space in normal conveyance time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention compares the timing of paper passage detected by a paper detection sensor installed in a paper conveyance path with a reference value to determine whether or not conveyance is normal. The present invention relates to a paper conveyance control method for an image forming apparatus such as a copying machine, a printer, or a printer.

[Conventional technology]

In an image forming apparatus, a plurality of sensors for detecting paper passage are provided at a plurality of predetermined positions on a paper conveyance path from a paper feeding section to a paper discharging section, and jam detection is performed using these sensors.

Conventionally, the timing at which the edge of the transfer sheet passes through each sensor is compared with a reference value to determine whether or not conveyance is normal.

Therefore, the timing deviations in each detection sensor are accumulated, and as a result, the detection sensor located downstream includes all the timing deviations on the upstream conveyance path, resulting in a control method that is prone to jams. It had become.

For this reason, as shown in Japanese Patent Application Laid-open No. 63-92553, by feeding back the increase/decrease of the paper edge passing data from the reference value in each sensor to the reference value of each subsequent sensor, the transfer paper Techniques have been proposed to prevent timing deviations in sensors located upstream in the passageway from accumulating and affecting sensors located downstream.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, if the timing exceeds a certain level, a jam will definitely occur. In other words, when the slip in the paper conveyance system becomes large and the paper is conveyed continuously, when the paper distance between the previous paper and the paper following that paper becomes 0, it becomes impossible to detect the low edge, and the paper Conveyance control becomes impossible. In this case, there is a problem in that the main body control section has no choice but to determine that there is a jam even though there is actually no jam.

It is an object of the present invention to eliminate the drawbacks of the above-mentioned prior art and to prevent detection of M in a paper passing state that is not a jam.

[Means to solve the problem]

In order to achieve this objective, the present invention compares the timing of paper passage detected by a paper detection sensor installed in the paper conveyance path with a reference value, and determines whether the paper is being conveyed normally. In a paper conveyance control method of an image forming apparatus, the detection timings of at least one paper detection sensor are memorized, the detection timings are averaged, and this averaged value is compared with a reference timing to determine whether there is a change. The present invention is characterized in that when the change occurs, the amount of change is fed back to the paper conveyance interval of repeated paper conveyance.

[Effect]

In the present invention, even if the slip rate of the conveyance system becomes large and the detection timing is significantly different from the reference timing and there is no paper gap, the paper feed repeat (1?) is created so that the paper gap is created in advance. By varying the j'l interval, jams are prevented as much as possible.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

First, an outline of a copying machine/apparatus to which the present invention is applied will be explained with reference to FIG. Inside the copying machine body 1, a belt-shaped photoconductive illuminant 3 is provided which is supported by a plurality of rollers 2 and rotates. A charging charger 4 for uniformly charging the surface of the photoreceptor 3 is disposed oppositely to the photoreceptor 3, and an optical system is provided to expose and scan an original set on the contact glass 5 and form an optical image on the photoreceptor 3. A system 6 is provided.

Furthermore, an eraser 7. which erases unnecessary static '71t'/JI images is provided at the rear stage in the rotational direction. Developing device for developing the static 'O1 latent image into a visible image8. Transfer chargers 10 for transferring this developed image onto transfer paper 9 are sequentially provided. Due to the action of the transfer charger 10, the transfer paper 9 on which the image has been transferred is sent from the conveyance path 11 to the fixing roller 12, where it is fixed, and then ejected onto the paper ejection tray 13. Here, a transfer paper cassette 14 containing transfer paper 9 of different sizes is detachably set in the copying machine main body 1.
Paper is selectively fed by each paper feed roller 15, and is fed to the transfer section by the transfer charger IO at a predetermined timing by a common conveyance path 16 and registration rollers 17.

The common conveyance path 16 and l! Along the transfer paper cassette 14, there is a paper feed sensor 30. Registration roller 1
There is a resist sensor 31 near 7. A separate sensor 32 is located near the transfer charger 10. A fixing sensor 33 is located near the fixing roller 12. A paper ejection sensor 34 is located near the paper ejection tray 13.
are respectively installed to perform paper detection of the transfer paper from when it is fed from the transfer paper force sensor 1-14 until it is ejected to the paper ejection tray 13 after the copying operation.

FIG. 6 is a schematic diagram of the control section.

40 is micro CPLJ, 41 is microphone CJ CP t
J address, data and control bus, 42°4
3.44.45 are ROM, RAM, and non-volatile RA each connected to the micro CPU 40 through the bus 41.
M and a human output boat. This human output boat accommodates the paper detection sensors shown in FIG. 1, the operation switch groups 46, and the like.

Paper detection is generally performed in the following manner.

An encoder (not shown) is installed in the same place as the roller 2 that rotates the photoreceptor 3, and a counter that counts clock pulses generated from this encoder is stored in the RAM 43 in FIG.
Provided inside. The counter starts counting at the timing when the transfer paper 9 is fed from the cassette I4, and the counter value at the time when the edge of the transfer paper 9 passes through each of the paper detection sensors 30 to 34 is checked.

The present invention will now be described in detail.

In the present invention as well, it is necessary to make the jam detection timing variable by changing the detection timing of the paper (transfer paper). The following description will be limited to the registration sensor 31.

As with conventional paper conveyance methods, if the paper being conveyed is subjected to the scheduled driving force and conveyed by the conveyance system, the conveyed paper is controlled so that it is repeatedly conveyed at the optimum paper interval. be. In general, the conveyance speed of the paper feed roller 15 is faster than the conveyance speed of other conveyance systems (for example, the conveyance system of the conveyance path 16 shown in the figure). If the paper slips before reaching the paper, the next paper fed will catch up with the previous paper.

Furthermore, the slip rate in the conveyance system increases little by little depending on the frequency of use.

Therefore, in the present invention, the timing of the sensor OFF edge of the trailing edge of the paper and the timing of the sensor ON edge of the leading edge of the paper by the registration sensor 31 are constantly monitored.
Averaging multiple latest counter values.

If the conveyance is normal, as shown in Fig. 3, the ON edge of the first sheet of paper at the registration sensor 31 will have a pulse number of 58 after the first sheet is fed, and the pulse number will be 58 when passing. OF
The F edge timing is 88 pulses. Further, the leading edge ON edge of the second sheet of paper is 118 pulses after the first sheet is fed. This value is the sum of the detection pulse for the first sheet of paper and the repeated paper feeding interval (repeat interval) of 60 pulses. Also, the paper interval between the first and second sheets is 118 pulses - 88 pulses and 30 pulses.

As mentioned above, if normal conveyance is no longer possible due to some external factor (such as changes over time), the timing of reaching the registration sensor and completing the passage will be delayed and the paper spacing will change as shown in Figure 4. However, in the present invention, when a discrepancy occurs between the value during normal conveyance and the averaged value when paper is actually conveyed, the values are compared and the repeat timing is changed. control so that the paper spacing is constant.

The above is not limited to the registration sensor 31,
The same can be said of other sensors.

The control method according to the present invention will be specifically described below.

FIG. 1 is a flowchart illustrating a paper conveyance control method according to an embodiment of the present invention in which repeat is variable.

First, when the leading edge of the first paper passes in continuous copy mode (Y in steps l-1 and 1-2), the CPU 40 causes the paper to pass through each sensor, and the next paper in continuous copying starts from the trailing edge of the paper. (Steps I-3, 1-4), that is, the sheet spacing data during actual conveyance is detected and stored in the non-volatile RAM 44 (Step 1-5.1-6). data is averaged and similarly 1'? AM44
(steps 1-7, 1-8), and
The CPU 40 compares the normal paper spacing data stored in the ROM with the value in the RAM 44, and delays the repeat timing by the incremented number of pulses (step 1-9).

For example, as shown in Figure 4, if the paper interval is now 20 pulses compared to the standard paper interval of 30 pulses, calculate the new repeat timing using the following formula based on the standard 60 pulses. do.

-60+(30-20)=70 or more.For ease of understanding, calculations were made without averaging, but in reality, the value corresponding to 20 pulses is an averaged value.

FIG. 2 is a flowchart of repeat paper conveyance, in which the print switch is pressed (step 2-1), the paper feed roller 15 is turned ON (step 2-2), and the roller group of the paper feed conveyance system is turned ON (step 2-1). 3) After sending out the paper,
At the OFF timing of the paper feed roller 15 (step 2-4)
(Y), and turn off the paper feed roller 15 (step 2-5).
), after this cycle, the repeat timing is determined (step 2-6).

In machines with multiple sensors, each conveyance system has a different slip rate, so by selecting the maximum repeat timing calculation value for each sensor, the paper interval during normal conveyance can be adjusted even in the conveyance section with the highest slip rate. can get.

〔Effect of the invention〕

The present invention has been described above, and according to the present invention, even if the slip rate in paper conveyance increases, the paper interval during normal conveyance can be obtained, and jams can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a paper conveyance control method according to an embodiment of the present invention, FIG. 2 is a flowchart when paper is repeatedly conveyed, and FIGS. Detection timing diagram, FIG. 5 is a schematic configuration diagram of a copying machine to which the present invention is applied, and FIG. 6 is a control block diagram of the same. No.! Figure 2 Paper feeding sequence Figure 5 Figure 6 Figure z qri

Claims (1)

[Claims] In a paper conveyance control method for an image forming apparatus capable of repeatedly conveying paper, the paper passage timing detected by a paper detection sensor installed in a paper conveyance path is compared with a reference value to determine whether or not conveyance is normal. The detection timings of at least one paper detection sensor are memorized, the detection timings are averaged, and this averaged value is compared with the reference timing, and if there is a change, the change is repeated to detect the paper conveyance. A method for controlling paper conveyance in an image forming apparatus, characterized in that the time of the conveyance interval is fed back.