JPH04182162A - Sheet transfer mechanism - Google Patents

Abstract

PURPOSE:To make change of transfer speed unnecessary for a thermal developing machine and to make less precise, inexpensive parts usable for manufacturing the same by a method wherein the transfer of sheets is made by repeating start and stop of the driving while movement of the sheets is detected with sensors. CONSTITUTION:While a first sheet is being transferred, a sheet sensor S1 detects the rear end of said sheet. At this moment, transfer force of an entrance transfer means of an unit 1 is released. A transfer means on the upstream side of the unit 1 starts the transfer of the next sheet 2 to the unit 1. At the moment when the sheet sensor S2 of an unit 2 detects the front end of the sheet 1, the transfer force is given to the entrance transfer means Hi1 of the unit 1 and, at the same time, driving of a motor of the unit 1 is stopped while the driving of the motor M2 of the unit 2 is started. The sheet sensor S2 of the unit 2 detects the rear end of the sheet 1 while the sheet 1 is being transferred in the unit 2. At this moment, the motor M1 of the unit 1 is driven for starting of the transfer of the sheet 2, and the transfer force of the entrance transfer means Hi2 of the unit 2 is released.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a sheet conveyance mechanism, and particularly to a sheet conveyance mechanism that is divided into a plurality of units within an apparatus and that conveys sheets between each unit using the sheet conveyance mechanism. The present invention relates to a sheet conveyance mechanism suitable for application to an image forming apparatus that forms color images using a diffusion transfer type sensitive material.

(Prior art) In order to obtain a color image using a diffusion transfer type photosensitive material, a photosensitive sheet with a photosensitive layer coated with photosensitive silver salt holes on the surface of the support, and a photosensitive sheet that is developed. An image-receiving sheet is required, in which a layer for receiving the dye (hereinafter referred to as an image-receiving layer) is coated on a support.First, the photosensitive sheet is imagewise exposed, and then the image-wise exposed photosensitive sheet is The sheet and the image-receiving sheet are overlapped so that the photosensitive layer and the image-receiving layer are in contact with each other.

When these two sheets are overlapped, the temperature is high (120℃).
' ~ 160 °C) for 30 seconds to 120 seconds.

The photosensitive sheet is developed (imagewise diffusive dye is produced) by high temperature. Further, the generated diffusible dye is transferred to the image-receiving layer. In order to improve the adhesion between the photosensitive layer and the image-receiving layer and improve the transfer rate of the diffusible dye from the photosensitive layer to the image-receiving layer, pressure is often applied in addition to high temperature. Since the purpose of this pressure is to maintain the adhesion between the photosensitive layer and the image-receiving layer, it does not need to be continuous and may be applied intermittently as long as the photosensitive layer or image-receiving layer itself has adhesion.

After developing and transferring for a predetermined period of time, the photosensitive sheet is peeled off. By separating the photosensitive layer and the image-receiving layer, transfer of the diffusible dye to the image-receiving layer is prevented. In other words, the separation of the photosensitive layer and the image-receiving layer corresponds to fixing in general silver salt sensitive materials. In this way, the image-receiving sheet to which the diffusible dye has been transferred becomes the final product.

As described above, in order to record an image using a diffusion transfer type sensitive material, it is necessary to superimpose an imagewise exposed photosensitive sheet and an image receiving sheet, and perform thermal development and transfer at a predetermined temperature and time.

FIG. 13 shows an example of the configuration of such an image forming apparatus.

The photosensitive sheet picked up by the photosensitive sheet pickup unit is conveyed to the scanning exposure unit by the photosensitive sheet feeding unit.

The photosensitive sheet conveyed to the scanning exposure unit is conveyed to the scanning exposure unit by a photosensitive sheet feeding unit. The photosensitive sheet conveyed to the scanning exposure unit is scanned and exposed by a scanning optical system, and a latent image is formed in the photosensitive layer.

The photosensitive sheet on which the latent image has been formed is transported to a superimposing unit by an intermediate transport unit. The photosensitive sheet conveyed to the overlapping unit is detected by the image receiving sheet detecting means S.
If there is an image-receiving sheet in 8, it is conveyed as is, and overlapping is performed at the point where both conveyance paths meet. If there is no image-receiving sheet in the image-receiving sheet detecting means S8, the process waits until the image-receiving sheet is detected by the photosensitive sheet detecting means S5, that is, until the sheet is hidden.

The superimposed photosensitive sheet and image-receiving sheet are conveyed as they are to the heat developing machine. A heat developing machine develops a latent image on a photosensitive sheet and transfers it to an image receiving sheet. The two sheets exiting the developing machine are quickly cooled by a cooling unit to the lowest temperature among the development temperature, transfer temperature, and sheet material softening temperature.

Lowering the temperature to a level lower than the development temperature or transfer temperature is necessary to obtain the desired image quality (density).

Further, lowering the temperature to a temperature lower than the softening temperature of the sheet material is necessary in order to improve the flatness of the sheet material, and to enable peeling of the photosensitive sheet and image-receiving sheet and conveyance by a pair of rollers. The two sheets that came out of the heat developing machine are
Due to the high temperature and so-called limp state, peeling and transportation are extremely difficult. Furthermore, if the sheet is not cooled while maintaining its flatness, the surface of the sheet will become uneven or have a tendency to bend (so-called curl). A cooling unit is required to avoid such inconveniences. Since the cooled photosensitive sheet is no longer needed, it is peeled off from the image-receiving sheet by a peeling unit and discarded. As a result, only the image-receiving sheet is discharged from the discharge unit.

In this way, the conveyance path of the sheet becomes long because it goes through many steps before obtaining one final image, so this conveyance path is divided midway and divided into units.

In this case, the scanning exposure process and thermal development process require a predetermined transport speed or processing time to obtain the optimal image.
Therefore, the transport speeds of other transport units are
It is often matched to the transport speed of one unit.

Therefore, among these units, from the photosensitive sheet feeding unit to the scanning exposure unit, the photosensitive sheet is transported at the same speed as the sub-scanning speed of the scanning exposure unit, and from the intermediate transport unit to the discharge unit, the photosensitive sheet is transported by the thermal developing machine. conveyed at the same speed as the speed. On the other hand, all units of the image receiving sheet are transported at the same speed as the transport speed of the heat developing machine.

(Problems to be Solved by the Invention) In the conventional technology described above, when the conveyance speed of a unit downstream from the exposure unit is adjusted to the conveyance speed of a thermal developing machine, the developing time is changed because the type of photosensitive sheet is not changed. In this case, it is necessary to change the conveyance speed of the relevant unit to match the conveyance speed of the heat developing machine, which is time-consuming.

In addition, the conveyance speed of the relevant units must match the conveyance speed of the heat developing machine with high accuracy, so the precision of the parts used and the high quality of the motor that is the drive source are required, which causes high costs. becomes.

The present invention has been made in view of the problems of the prior art, and its purpose is to provide easy management without the need to change the conveyance speed of the heat developing machine, and to achieve accuracy and low cost. It is an object of the present invention to provide a sheet conveyance mechanism that allows the use of various parts.

(Means for Solving the Problems) A typical overview of the present invention is as follows. In other words, when conveying a sheet from one unit to the unit downstream of that unit, the downstream unit is stopped (action). Since the sheet is conveyed by repeatedly driving and stopping while checking the movement of the sheet, consistency in conveyance between units is always ensured, and good sheet conveyance is possible between units having different conveyance speeds.

(Example) Example 1 FIGS. 1(a) and 1(b) are diagrams showing the configuration of an example of the present invention, and (a) shows a state in which a conveying force is applied,
(b) shows a state in which the conveying force is released.

First, an overview of the overall configuration will be explained.

Hi is the transport means (hereinafter referred to as
(referred to as the entrance conveyance means), which is composed of a pair of rollers. The sheet detection means S is composed of a microswitch or an optical sensor. When detecting photosensitive sheets, microswitches are more suitable than optical sensors.

The most downstream conveyance means in the unit (hereinafter referred to as outlet conveyance means) HO is constituted by a pair of rollers or a belt conveyance mechanism.

When the artificial conveyance means of the next unit is conveying sheets, the exit conveyance means stops driving, so in order to convey the sheet smoothly, a one-way clutch is used for the exit conveyance means, or a one-way clutch is used for the next unit. Appropriate sliding or pressing force must be provided so that when the sheet is pulled by the inlet conveyance means of the unit, the sheet held by the outlet conveyance means can be pulled out without strain.

The means (lO) for driving the transport means is a DC motor, an AC
C motor consists of Stella pink motor.

The conveying force switching means has the function of applying or not applying the conveying force of the artificial conveyance means. Specifically, there are those in which a clutch is provided on the drive roller, those in which the driven roller is supported in a swingable manner and the pressing force is released by swinging the driven roller using a solenoid, and those in which the inlet conveyance means is driven. A motor is provided and a device for driving and stopping the motor is provided.

Another conveying means I4 is provided between the artificial conveying means Hi and the exit conveying means Ho0 as necessary, and the interval between the respective conveying means is not longer than the length of the sheet in the conveying direction. In addition, the next means of transportation after population transportation means is
It is necessary to provide an interval longer than the length of the sheet in the conveying direction from the outlet conveying means of the unit on the upstream side of this unit. If this interval is shorter than the length of the sheet, even if the conveyance force of the artificial conveyance means is released, the sheet will continue to be conveyed as is if the next conveyance means is driven.

FIG. 2 shows an example of a control means for driving one unit. The part surrounded by the two-dot chain line in FIG. 2 is a functional block (means for realizing a specific function, constructed as a result of operating according to hardware or software) possessed by the CPU.

The conveying force switching means of each unit and the means for driving the conveying means operate as shown in the third flowchart.

In other words, the conveying force switching means of each unit has a function that is set at the time of initialization after the power is turned on and when the sheet detecting means of the next unit of this unit detects the leading edge of the conveyed sheet (the sheet detecting means' At the moment when the signal changes from the state without a sheet to the state with a sheet), the inlet transport means Hi is brought into a state in which a transport force is applied. Also, when the sheet detection means of this unit detects the trailing edge of the sheet that has started conveying (
At the moment when the signal from the sheet detecting means changes from the state with a sheet to the state with no sheet, the inlet transport means Hi is brought into a state in which no transport force is applied.

In addition, the conveying means detects a sheet when there is a sheet in the sheet detecting means of this unit at the time of initialization after turning on the power, and when the sheet detecting means of the next unit detects the leading edge of the sheet conveyed from this unit (sheet detecting means). The drive is stopped at the moment when the signal from the means changes from the sheet-absent state to the sheet-present state. In addition, if there is a sheet in the sheet detection means of this unit and there is no sheet in the sheet detection means of the next unit at the time of initialization after turning on the power, and when the inlet side conveyance means H1
o is in a state where a conveying force is applied, and the moment when the sheet detecting means of the next unit detects the trailing edge of the sheet being conveyed (the signal of the sheet detecting means changes from the state with a sheet to the state with no sheet) (or the moment when the sheet detection means of this unit detects the leading edge of the conveyed sheet, whichever is later).

The operation of the apparatus having a configuration in which a plurality of units as described above are connected will be explained using FIGS. 4 and 5. FIGS. 4 and 5 show an example of a configuration in which three units are connected.

In the figure, K1. , 2, and K3 are the entrance conveyance means H, respectively.
This is a means for applying or eliminating the conveying force of il to Hi3. In this case, a solenoid is used to move one of the pair of rollers so that no pressing force is applied or applied. 81 to S4 are sheet detection means;
Hol to Ho3 are exit conveyance means. The roller pair on the right side of Ho3 is always rotating at a slower transport speed than any of the three units.

When the power is turned on, the conveying force switching means is driven to apply the conveying force of the entrance conveying means of all the conveying units (arrows i1, i2, i in Fig. 4 (a) and Fig. 5).
3). Then, the motors of the units with the same sheet conveyance conditions are driven.

In other words, this unit has a seat and drives the motor of the next unit. That is, the motor is driven when there is a seat in this unit and there is no seat in the next unit. Here, only the motor M1 of unit 1 was driven because there was a seat only in unit 1 (see Fig. 4).
b) and arrow i4 in Figure 5).

While conveying the first sheet, the sheet detection means S1 detects the trailing edge of the sheet (that is, the presence of the sheet changes to the absence of the sheet). At this moment, the conveying force of the inlet conveying means of unit 1 is released (arrow 1 in Fig. 11 (1) and Fig. 5).
1). Also, the transport means (not shown) upstream of the unit 1 starts transporting the next sheet 2 to the unit 1 .

The motor of unit 1 is driven until the next sheet detection means S2 of unit 2 detects the leading edge of sheet 1. During this time, either the next sheet 2 is conveyed to the sheet detection means S, or the sheet 2 is not conveyed any further even if the motor M1 is driven because the artificial conveyance means Hi1 has no conveying force. Driving of Ml in Fig. 4 (1) and Fig. 5)
.

At the moment when the sheet detecting means S2 of the unit 2 detects the leading edge of the sheet 1, it applies a conveying force to the entrance conveying means Hil of the unit 1, and stops driving the motor of the unit.
Start driving motor M2 of unit 2 (Fig. 4 (
e) and arrow 14 in Figure 5).

While the sheet 1 is being conveyed in the unit 2, the sheet detection means S2 detects the trailing edge of the sheet 1. At this moment, motor M1 of unit 1 is driven to begin conveying sheet 2,
Also, the conveying force of the entrance conveying means Hi2 of the unit 2 is released (arrows 15 and 12o in Fig. 4 (force) and Fig. 5).
).

While repeating such operations, the sheets are conveyed one after another from unit to unit. Then, the transport operation is performed in accordance with the slowest transport speed among the connected transport means. In this explanation, since the transport speed of unit 3 is slow, each unit operates in accordance with this speed. Judging from the driving cycle of the motor of each unit, unit 1 performs a conveyance operation matching the conveyance speed of unit 3 from the fifth sheet, and unit 2 from the fourth sheet.

Example 2 FIG. 6 is a diagram showing the configuration of a second embodiment of the present invention.

The basic configuration of this embodiment is similar to that shown in FIG. 1, and is characterized in that application and release of the conveying force are directly controlled by starting and stopping the rotation of the motor.

FIG. 9 shows an example of a control means for driving one unit. In the figure, the part surrounded by the two-dot chain line is the part that the CPU has as a functional block.

The conveying force switching means of each unit and the means for driving the conveying means operate as shown in the flowchart of FIG.

The conveying means detects the leading edge of the sheet conveyed from the sheet detecting means of the next unit or from the sheet detecting means at the time of initialization after the power is turned on and when the leading edge of the sheet conveyed from this unit is detected (signal kan-1 of the sheet detecting means).
The drive is stopped at the moment when the state changes from the state without a sheet to the state with a sheet). Further, if the sheet detection means of this unit is not detecting a sheet and the conveyance motor of the next unit is stopped, the conveyance means starts driving.

The operation when a plurality of each unit shown above is connected will be explained using FIG. 7 and FIG. 8.

FIG. 7 and FIG. 8 are explanations of the case where three units are connected. In the figure, 81 to S4 are sheet detection means. Ho1 to Ho3 are exit conveyance means. Ho
The pair of rollers on the right side of No. 3 are constantly rotating at a transport speed slower than that of the three units.

Drives the motor of the unit that meets the conditions for sheet conveyance. That is, the motor is driven when there is a seat in this unit and there is no seat in the next unit. Here, only the motor M1 of unit 1 was driven assuming that only unit 1 had a seat (arrow 1 in FIG. 7(a) and FIG. 8).

While the first sheet is being conveyed, the sheet detection means S2 of the next unit detects the leading edge of the sheet (that is, the sheet changes from no sheet to present). At this moment, the drive of the transport motor of unit 1 is stopped, and the motor of transport unit 2 is driven (arrows 2 and 3 in FIG. 7 and FIG. 8). In addition, a conveying means (not shown) upstream of the unit 1
starts conveying the next sheet 2 to unit 1.

Here, even if the sheet 2 is detected by the sheet detecting means S1, the motor of the unit 1 is operated until the sheet detecting means S3 of either the sheet 1 or the unit 3 detects the sheet, that is, while the motor of the unit 2 is being driven. It's stopped.

The moment the sheet detection means S32 of the unit 3 detects the sheet 1, the motor of the unit 3 is driven, and the driving of the motor M2 of the unit 2 is stopped. Further, if there is a sheet in the sheet detection means S1, the drive of the motor of the unit 1 is started (arrows 4 and 5 in FIG. 7 (1) and FIG. 8).
．． 6).

The sheet detection means S2 detects the sheet 2 while the sheet 1 is being conveyed by the unit 3, but since the motor of the unit 3 is being driven, the motor of the unit 2 remains stopped (see Fig. 7). e) and the period between arrows 7 and 9 in Figure 8).

By repeating this operation, the sheets are conveyed one after another from unit to unit. Then, the transport operation is performed in accordance with the slowest transport speed among the connected transport means. In this explanation, since the transport speed of unit 3 is slow, each unit performs an operation in accordance with this speed. Judging from the drive cycle of the motor of each unit, unit 1 performs a conveyance operation matching the conveyance speed of unit 3 from the fourth sheet, and unit 2 from the third sheet. This embodiment has fewer components than the previous embodiments, and can provide a device at a lower cost.

As explained above, when conveying a sheet from one unit to the next unit, the conveyance means of the next unit is in a stopped state, so there is no problem in conveying the sheet even if the conveyance speed of each unit is different. be able to.

For this reason, there is no need to adjust the transport speed of each transport unit to a predetermined value, and there is no need to manage the transport speed such as controlling the speed of the motor or controlling the dimensions of the transport rollers, so the precision of the parts used must be high. We can provide equipment at low prices.

Furthermore, since there is no need to adjust the transport speed of the assembled equipment, there is no need for adjustments or maintenance management, and productivity is improved by reducing costs associated with these operations and improving machine operating rates.

Embodiment 3 An example in which each of the units shown above is applied to a thermal development image forming apparatus is shown in FIGS. 11 and 12.

FIG. 11 is a configuration diagram of a thermal development image forming apparatus. This device will be briefly explained. This device consists of a photosensitive sheet pickup unit that picks up a photosensitive sheet cut into a predetermined size, and a photosensitive sheet feeding unit that positions the picked up photosensitive sheet at a desired position on a conveyance path and then conveys it to an exposure system. , first and second intermediate transport units that transport the scan-exposed photosensitive sheet to a superimposing unit that superimposes it on an image-receiving sheet; and a superimposing unit that superimposes the photosensitive sheet and the image-receiving sheet and transports them to a heat developing machine. , an image-receiving sheet pickup unit that picks up an image-receiving sheet cut to a predetermined size, and an image-receiving sheet feeding unit that positions the picked-up image-receiving sheet at a predetermined position on a conveyance path and then conveys it to a stacking unit. , first and second
an image-receiving sheet intermediate conveyance unit, a heat developing machine that develops the photosensitive sheet by applying high temperature while maintaining close contact between the stacked photosensitive sheets and the image-receiving sheet, and transfers the generated diffusible dye to the image-receiving sheet; A cooling unit that lowers the temperature of the high-temperature photosensitive sheet and the transfer sheet to below the softening temperature of the support after the first image transfer, a peeling unit that peels off the photosensitive sheet and the transfer sheet, and a discharge unit that discharges the transfer sheet. have.

Each unit upstream of the heat developing machine has a structure as explained in FIG. 6, except for the overlapping unit. The overlapping unit has a configuration as shown in FIG. 2
It is more convenient to stack the sheets if one of the pair of rollers of the entrance conveyance means Hj5 is retracted from the conveyance path and does not press against each other until the sheets are stacked at a predetermined position. It is difficult to overlap the sheets with pressing force constantly applied to the pair of rollers, and conveyance failures are likely to occur.

These units shown in FIG. 1 or 6 are connected as shown in FIG. 12.

Among these units, the scanning exposure unit is a scanning exposure unit that uses a D
A C motor or a stepping motor is used. Furthermore, since recording is performed while conveying the photosensitive sheet, it is necessary that the image data to be recorded be ready as a condition for starting conveyance of the photosensitive sheet. Other control signals are required for this purpose.

The overlapping unit overlays the photosensitive sheet and image receiving sheet, which are transported from separate transport paths, in a predetermined position.
The two sheets are conveyed to the entrance of the heat developing machine while maintaining this overlap. For this reason, it is necessary to control the conveyance motor of the stacking unit to start driving when the photosensitive sheet and image receiving sheet reach the entrance conveyance means Hi5 of the unit. For this reason, the superimposing unit requires two sheet detection means at the entrance, one for the photosensitive sheet 85 and one for the image receiving sheet 89.

Further, in the control circuit, it is determined that a sheet is present when two sheets are aligned. - Boat fishing requires several sheet detection means for each sheet conveyance path.

A thermal developing machine thermally develops a photosensitive sheet and maintains the two sheets at a development transfer temperature for a predetermined time (development transfer time) in order to transfer the dye produced by the development to an image receiving sheet. If the type of photosensitive sheet used changes and the development transfer time is changed, this can be done by changing the conveying speed of the developing machine.

The unit downstream of the heat developing machine does not require any other special control as long as the transport speed is higher than the transport speed of the heat developing machine.

The arrows between each unit in FIG. 12 indicate the conveyance direction of the sheet. Also, arrows between each unit and the control circuit indicate the direction of the signal. Arrows within each unit indicate the target to be driven by each drive means. The control circuit of each unit reads the signals from the sheet detection means of this unit, the sheet detection means of the next downstream unit, and the signal indicating the driving state of the motor of the next unit, and controls this unit.

Among these units, the scanning exposure unit and the thermal developing machine require varying conveyance speeds depending on the photosensitive material used. The conveyance speed of these two units may be changed to obtain an appropriate exposure amount or appropriate development time depending on the photosensitive material used. If the conveyance unit according to the present invention is used, even if the conveyance speed of some conveyance units is changed, there is no need to adjust the speed of other conveyance units, making the change work very easy and improving the machine operating rate. or improve. Further, in a heat developing machine, the development transfer temperature and time are determined so as to obtain the optimum image quality, and the temperature and time are controlled to be maintained. However,
In reality, the temperature will fluctuate slightly around the standard value. If the time remains fixed, as the temperature fluctuates and becomes higher, the overall density of the resulting image will increase, resulting in a darker image. On the other hand, if the temperature is too low, the resulting image will be low density and unclear.

Therefore, in order to reduce density fluctuations due to such temperature fluctuations, the developing time is increased or decreased in response to the temperature fluctuations. That is, the conveyance speed of the developing machine is controlled so that when the temperature is on the high side, the developing time is shortened, and when the temperature is on the low side, the developing time is made long. In this way, even if the conveying speed of the developing machine constantly fluctuates, it can automatically follow it, so processing can be continued without any problems, and images of optimal quality can be provided.

The above explanation was given using a thermal development image forming apparatus as an example.
It can also be applied to other devices. For example, in a device that performs normal development processing (liquid development) on photosensitive paper or photosensitive film that undergoes development processing after exposure, or in a device that performs heat-sensitive recording, gradation image areas are recorded by sublimation thermal transfer recording, such as characters, etc. If the line drawing part is applied to an apparatus that has two or more processes with different processing speeds, such as an apparatus that performs melt-type thermal transfer recording, the operating rate of the process with the slowest processing speed can be maximized.

(Effects of the Invention) As explained above, according to the present invention, in an apparatus in which the interior is divided into a plurality of units, such as a thermal development image forming apparatus, when conveying a sheet from one unit to the next unit, By keeping the next unit in a stopped state, good sheet conveyance between units with different conveyance speeds is automatically achieved, which simplifies maintenance management, and also eases the conditions for used parts and improves equipment performance. This has the effect of reducing costs.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are diagrams showing the configuration of an embodiment of the sheet conveying mechanism of the present invention, in which (a) shows a state in which a conveying force is applied, and (b) shows a state in which a conveying force is applied. 2 is a diagram showing the configuration of the control means in FIG. 1, FIG. 3 is a flowchart showing the control procedure of the control means, and FIGS. 5 is a timing chart for performing the operation shown in FIG. 4. FIG. 6 is a diagram showing the configuration of another embodiment of the present invention. The figures are (An) to (C) are diagrams for explaining a series of operations of the embodiment shown in Fig. 6, Fig. 8 is a timing chart when performing the operations shown in Fig. 4, and Fig. 9 is a diagram in Fig. 6. 10 is a flowchart showing the control procedure of the control means. FIG. 11 is a diagram showing an example of the structure of a thermal development image forming apparatus to which the present invention is applied. 13 is a diagram showing a general configuration example of a thermal development image forming apparatus. 10...Motor 11...Motor driving means I2
...CPU 13...Drive means 14 for the conveyance force switching means...Other conveyance means K...Conveyance force switching means S/Unit sheet detection means Hl...Entrance conveyance means HO...Exit conveyance means

Claims (3)

[Claims] (1) In an image forming apparatus composed of a plurality of transport units, each unit transports the sheet while repeatedly driving and stopping depending on the state of its own unit and the state of the next unit. Conveyance mechanism. (2) Each conveyance unit includes two or more conveyance means provided from the entrance to the exit of the unit, and the interval between each conveyance means is shorter than the length of the sheet in the conveyance direction, and
The distance from the entrance of one unit to the entrance of the next unit is longer than the length of the sheet, and in the vicinity of the most upstream conveyance means of the unit, there is a conveyor provided on the upstream side of this unit. The same number of sheet detection means as the number of sheets are provided, and the distance from this sheet detection means to the sheet detection means of the next unit is longer than the length of the sheet in the transport direction. It is configured to be driven by one driving means or a plurality of driving means that can be driven simultaneously, and the conveying means at the most upstream side of the unit is provided with a conveying force switching means for switching between applying and canceling the conveying force. In addition, the distance between the most downstream conveying means of a unit and the most upstream conveying means of the next unit is shorter than the length of the sheet in the conveying direction, and the distance between the most downstream conveying means of this unit and the most upstream conveying means of the next unit is shorter than the length of the sheet in the conveying direction. The distance from the upstream conveyance means to the next conveyance means is
Furthermore, the conveyance means and conveyance force switching means of the unit are controlled by a control means, and this control means has a sheet detection means of this unit and a sheet detection means of the next unit. , a conveyance motor drive means, a means for driving the conveyance motor, a conveyance force switching means, and a CPU having predetermined functional blocks and controlling these in an integrated manner. The conveyance force switching means sets a state in which conveyance force is applied to the most upstream conveyance means when the power is turned on and when the sheet detection means of the unit next to this unit detects the leading edge of the conveyed sheet. When the unit's sheet detection means detects the trailing edge of the sheet that has started conveyance, the conveyance force of the most upstream conveyance means is released, and when the power is turned on, the conveyance force of the most upstream conveyance means is released. If there is a sheet in the sheet detection means of the unit next to the unit, or if the sheet detection means of the next unit detects the leading edge of the sheet conveyed from this unit, the drive is stopped, and when the power is turned on, this unit If there is a sheet in the sheet detection means of the next unit and there is no sheet in the sheet detection means of the next unit, or if a conveyance force is applied to the conveyance means on the entrance side, and the sheet detection means of the next unit is being conveyed. 2. The driving according to claim 1, wherein the driving is started at the moment when the trailing edge of the sheet is detected or the moment when the sheet detecting means of the unit detects the leading edge of the conveyed sheet, whichever is later. sheet conveyance mechanism. (3) Each transport unit is provided with two or more transport means from the entrance to the exit of the unit, and the interval between these transport means is shorter than the length of the sheet in the transport direction, and the distance to the inlet of the unit is longer than the length of the sheet;
Near the most upstream conveyance means of the unit, the same number of sheet detection means as the conveyance paths provided on the upstream side of this unit are provided. The conveyance means within the unit are driven by one drive means or multiple drive means that can be driven simultaneously, and the conveyance means at the most downstream of the unit and the conveyance means at the next unit are The distance between the most upstream conveying means of a unit is shorter than the length of the sheet in the conveying direction, and the distance between the most downstream conveying means of a unit and the next conveying means of the next unit is less than the length of the sheet. The conveyance means and conveyance force switching means of this unit are controlled by a control means, and this control means includes a sheet detection means of this unit, a sheet detection means of the next unit, a conveyance motor drive means,
It is equipped with a conveyance motor and a CPU that has predetermined functional blocks and centrally controls these. As a result of control by this control means, the conveyance motor of each unit is detected,
If the sheet detection means of the next unit does not detect a sheet and the conveyance motor of the next unit is stopped, the drive starts, and the sheet detection means of the next unit changes from the state of no sheet to the state of presence of a sheet. 2. The sheet conveyance mechanism according to claim 1, wherein the sheet conveyance mechanism is configured to stop driving at the moment the state changes to.