JPH03243553A - Recording sheet carrying device - Google Patents

Abstract

PURPOSE:To prevent a recording sheet from slipping at the time of being carried as well as to restore the sheets back to a stable carrying condition even when it is obliquely carried by providing a switching means which can change the carrying force of a carrying roller for the sheet. CONSTITUTION:When the kind of a recording sheet is selected by an operator with an console panel operated, a drive device for rotating a cam 6 so as to be driven is actuated in response to signals so that the cam 6 is rotated by a determined angle of rotation. In this case, tension force is produced by a press spring 4, which is sufficiently enough to give an auxiliary scanning roller 1 carrying force required for carrying the recording sheet selected. In detail, when a plastic film S, for example, is selected, which requires the high carrying force of the auxiliary scanning roller because of its high absorbing force onto a platen 23 and of its low surface frictional coefficient, the cam 6 is restored so as to be suspended at a position where a spring peg 5 is lowered, that is, the spring is lengthened. This thereby causes energizing pressure to be increased, thereby producing high carrying force.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a recording sheet conveying device used in recording apparatuses such as printers and facsimiles.

(Prior Art) Conventionally, as a recording sheet conveying apparatus of this type, a recording sheet conveying apparatus applied to a recording apparatus A as shown in FIG. 6, for example, is known. In addition.

Here, the term "recording sheet" includes all sheet-like materials on which images can be recorded, such as thermal recording paper, plain paper, and thin plastic plates.

That is, the recording sheet S is stored in a predetermined storage section C as a roller-shaped recording sheet Sa wound around a core sb.

The set guide 102 is located in the recording device A and in the storage section C.
It is installed near the exit side of the The set guide 102
When the operator sets the rolled recording sheet Sa, he pulls out the leading edge of the recording sheet S and places it on the paper feed roller 1.
It is used as a guide when supplying to 04.

A drive sensor 103 detects the recording sheet S through a hole provided in the set guide 102, generates a detection signal, and drives the paper feed roller 104 based on the detection signal.

The paper feed roller 104, which is composed of a pair of rollers, is provided along the conveyance path of the recording sheet S, and is provided with a motor 10.
5. The paper feed roller 104 pinches the recording sheet S pulled out from the rolled recording sheet Sa,
The recording sheet S is driven by a motor 105 to apply tension to the recording sheet S, thereby rotating the rolled recording sheet hsa in the direction of arrow d, thereby continuously feeding the recording sheet S.

A pair of first transport kites 108 are provided between the paper feed roller 104 and the cutter mechanism 109 with the transport path in between.

A pair of second conveyance guides 110 are provided between the cutter mechanism 109 and the conveyance roller 112a with the conveyance path in between.

The above-mentioned conveyance guy I''108, 110 and conveyance roller 112
A conveying section for conveying the recording sheet to the image forming means 111 serving as a recording section is formed.

Here, the conveyance roller 112b is disposed on the opposite side of the conveyance roller 112a across the image forming means 111. This conveyance roller 112b is used to sequentially send recorded recording sheets to the discharge side, and is also called a sub-scanning roller. The conveyance roller 112a and the sub-scanning roller 1
The recording sheet 12b is driven by a motor 113a and a motor 113b, and is configured to sandwich and convey the recording sheet S.

Note that while image recording is being performed by the image forming means 111, the recording sheet S is intermittently conveyed in the direction of arrow a by a sub-scanning roller 112b by a distance corresponding to one line of recording in accordance with the progress of image recording. In this case, the conveying roller 112a is driven.

The image forming means 111 is driven in accordance with image information to form an image line by line on the recording sheet S, and during image recording, the recording sheet S is precisely positioned with respect to the image forming means. It must be. Therefore,
In the recording section, air suction means is provided on a platen 123 serving as a support member, and the recording sheet is attracted and fixed by this means. However, the platen surface needs to be positioned with high precision with respect to the image forming means.

Reference numeral 114 denotes a paper end stop sensor, which detects when the recording sheet S is conveyed within the conveyance path prior to image recording.
The paper end stop sensor 114 detects the sheet end and generates a detection signal, and the conveyance of the recording sheet S is stopped based on the detection signal.

Note that the above-mentioned storage section C is provided with a known brake means in order to send out the rolled recording sheet Sa with a constant tension, but its explanation will be omitted here.

(Problem to be Solved by the Invention) However, in such conventional technology, a coating layer for ink retention is applied to various recording sheets (for example, coated paper, thick coated paper, and plastic film) depending on the purpose of use, usage cost, etc. Despite using a set sheet, etc.),
Since the pressing force (conveying force) between the sub-scanning rollers of the recording sheet conveying device is always the same, there is a problem as detailed below.

(1) When forming a recorded image, the recording sheet is sucked and attracted through a number of small suction holes provided on the surface of the platen for positioning. This suction normally operates even during intermittent feeding of the sub-scanning roller 112b to improve positional accuracy. Therefore, the attraction force of the recording sheet to the platen acts as a resistance force when the sheet is conveyed by the sub-scanning roller 112b. Here, the above-mentioned adsorption force changes depending on the air permeability of the recording sheet. For example, coated paper has some air permeability because the base is plain paper, whereas coated paper has some air permeability because the base is plain paper. The one with the same coated paper has zero air permeability.
Even if there is one, if it is thicker, there will be a difference in that the breathability will be lower. This causes a problem in that the conveyance resistance force of the recording sheet on the platen changes.

(2) Furthermore, when the recording sheet is conveyed by the sub-scanning roller, it comes into contact with guide plates, etc. in the conveyance path, which also acts as a resistance force during conveyance, and this is due to the friction coefficient of the contact surface of the recording sheet. Since it is closely related to the strength of the paper and stiffness, the problem arises that the conveyance resistance force varies depending on the surface properties and materials of the recording sheet.

(3) Regarding the problems (1) and (2) mentioned above,
By increasing the pressing force between the sub-scanning rollers and increasing the conveying force to the extent that the conveying performance does not change due to the properties of the recording sheet,
It becomes possible to respond. However, if the pressing force between the sub-scanning rollers is increased too much in order to increase the conveying force, a new problem will occur as described below. In other words, the recording sheet may be held at an angle by the sub-scanning roller due to incorrect work when setting the recording sheet in the conveyance section of the device or due to poor installation of the device itself (the sheet orientation and sub-scanning direction are different). (the direction of conveyance of the rollers deviates from the conveyance direction of the rollers), the stronger the roller conveyance force, the longer the time required for the direction of the sheet to follow the direction of conveyance of the rollers.

This point will be specifically explained with reference to FIGS. 7 to 10. First, when the sub-scanning roller 112b conveys the recording sheet S by one line in a tilted and nipped state as shown in FIG. 7, the recording sheet is conveyed from the solid line to the dotted line. Then,
The recorded images are as shown in 130a and 130b. (
130a is the image area recorded when the recording sheet is at the position indicated by the solid line, and 130b is the image area recorded at the position indicated by the dotted line).Then, each image margin is 131a.

131b, and the difference between the two becomes the skew amount when advancing one line. If no other external force is acting on the recording sheet,
The recording sheet continues to be skewed while the skew speed is kept constant.

However, in reality, as shown in Figure 8, a tension T is applied to the recording sheet in the opposite direction to the conveyance direction by the brake mechanism of the storage section. Adjustments will be made.

FIG. 9 shows the general progression of the skew.

In the figure, when the conveying force is large (A) and when it is small (B)
It shows about. This adjustment action is performed by the sub-scanning roller 1.
1 of the conveying force of the rollers in the part sandwiched by 12b.
A direction different from the moving direction X (Y direction) or rotation direction (R)
By acting on the recording sheet as a force (see figure S9), it suppresses the skew of the recording sheet.

In other words, in the roller nipping section, the ease of movement (degree of freedom) of the recording sheet in a direction different from the conveyance direction determines the time it takes for the conveyance of the recording sheet to become stable and the degree of skew.

Therefore, if the roller conveyance force is large, the degree of freedom in other directions will be relatively reduced, and the movement and rotation of the sheet in the axial direction of the roller will be more restricted), which will reduce the skew of the sheet and converge to stable feeding. It will take time to do so (for example, like A for B in FIG. 9).

Another problem that is more likely to occur as the conveying force of the sub-scanning roller increases is a phenomenon in which the sheet feed amount distribution on the roller shaft becomes unbalanced. For example, consider a case where images with different ink densities in the roller axis direction are recorded on coated paper based on plain paper. If a lot of ink is applied, the paper will stretch. Then, if the sheet is fed by a certain amount in the elongated area and the less elongated area, the sheet feed amount in the elongated area will be reduced by the amount of elongation. −
For example, as shown in Figure 1O, if a high-density image is printed on the left half, the coated paper stretches on the left side of the figure, so the feed amount on the left side decreases, and as a result, the coated paper turns as shown in the figure. , and skew occurs. The degree of this skew increases as the roller conveyance force increases, and decreases as the roller conveyance force decreases. The reason for this is, as mentioned above, the difference in degrees of freedom.

As described above in detail about the problems of the prior art divided into (1), (2), and (3), the conveyance of the sub-scanning roller for using various recording sheets in the same sheet recording device is Determining power is extremely difficult, and no effective proposal has yet been made.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to adjust the conveyance force of the sub-scanning roller (conveyance roller) appropriately according to the properties of the recording sheet used in the recording device. It is an object of the present invention to provide a recording sheet conveying device that can always stably convey a recording sheet by switching to the following.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a recording sheet conveying device having a conveying roller for conveying a plurality of types of recording sheets. It is characterized by being provided with a switching means that allows the conveying force to be changed.

It is further preferable that the switching means is switchable depending on the type of recording sheet being conveyed.

(Function) Since the conveying force of the conveying roller changes appropriately depending on the recording sheet to be conveyed, stable conveyance of the recording sheet is always achieved regardless of the type of recording sheet. At this time, the recording sheet does not slip or skew.

(Example) The present invention will be explained below based on the illustrated example. However, since the basic configuration is the same as that of the conventional recording sheet conveying device shown in FIG. 6 described above, a redundant explanation will be omitted, and the peripheral portion of the sub-scanning roller l will be explained in an enlarged manner.

In FIG. 1, 1 is a sub-scanning roller serving as a conveying roller, which conveys a recording sheet on which a recorded image has been formed by the image forming means 11 of the recording section in the direction of the arrow.
On the opposite side of the image forming means 11 and the recording sheet, a platen 23 is arranged as a support means for positioning the recording material.

The sub-scanning roller 1 has a pressure roller 8 pressed by a pressure spring 4. The switching means for changing the conveying force employed in this embodiment will be specifically described. The pressure roller 8 is supported at one end of the arm 2 which is swingable about the support shaft 3. A pressure spring 4 is hung on the other end of the arm 2, and the other end of the pressure spring 4 is hung on a spring hook 5. The pressure spring 4 acts in a direction to pull the arm 2 downward in the figure, and the pressure roller 8 is pressed in the direction of the sub-scanning roller 1 by its acting force.

On the other hand, the spring hook 5 is supported by the main body so as to be able to swing in the direction of arrow a about a fulcrum 7, and is always urged toward the circumferential surface of the cam 6 by the tensile force of the pressure spring 4. . Therefore, when the cam 6 rotates, the spring catch 5 moves up and down along its circumferential surface. Accordingly, the length of the pressure spring 4 expands and contracts, and the pressure of the pressure roller 8 pressed against the sub-scanning roller 1 (hereinafter referred to as biasing pressure) can be changed. Here, since the conveying force of the sub-scanning roller l is proportional to the urging pressure, the sub-scanning conveying force ultimately changes with the rotation of the cam.

Note that the circumferential shape of the cam 6 needs to be determined depending on the recording sheet to be conveyed, but in the present embodiment, the circumferential shape of the cam 6 is determined so as to be applicable to three types of recording sheets. In other words, in order to accommodate the three types of recording sheets, coated paper, thick coated paper, and plastic film (each with a different conveyance resistance force, shown in descending order of resistance force), three phases as shown in Fig. 2 are used. A cam with a shape was used. In other words, the cam can be selected from three phases depending on the type of recording sheet mentioned above, and the pressure lever length is changed to fL+, 12, and fL3 to generate the optimal conveying force for each sheet. It is designed to let you do so. Here, FIG. 2(a) shows the cam state of coated paper, FIG. 2(b) shows the cam state of thick coated paper, and FIG. 2(C) shows the cam state of plastic film.

Further, a drive device (for example, a stepping motor) is provided to rotate the cam 6, and instructions can be input via an operation panel.

In the recording sheet conveying device configured as described above, when the operator selects the type of recording sheet from the operation panel, the drive device for rotationally driving the cam 6 is operated in response to the signal, and the cam 6 is rotated at a predetermined rotation speed. The cam rotates only around the corner. At this time, the pressure spring generates a tensile force sufficient to provide the sub-scanning roller l with the transport force necessary to transport the selected recording sheet. Specifically, if a recording sheet such as a plastic film that has a high adsorption force on the platen 23 and has a low surface friction coefficient and therefore requires a high conveyance force of the sub-scanning roller is selected, The cam 6 rotates and stops at a position where the spring tension is low, that is, the spring length is long (FIG. 2(C)). This increases the biasing pressure and generates a high conveying force. On the other hand, if a very high conveying force is not required, such as for single-sided coated paper, rotate the cam to shorten the wing length and reduce the biasing pressure to an extent that does not fall below the required conveying force (see Figure 2 (d). )).

When the apparatus according to the first embodiment of the present invention described above was actually used, it was found that for any type of recording sheet, the time required to stabilize the conveyance of a skewed sheet without causing any slip during conveyance. It has become possible to reduce the time and the amount of skew at that time, making it possible to achieve optimal conveyance for each. Additionally, the lifespan of the sub-scanning roller, pressure roller, etc. is longer than that of a device with a conventional configuration, which always applies a constant biasing pressure (the conveying force is always maintained to feed the sheet with the maximum conveying resistance). It also has the advantage of being elongated.

In the present embodiment, the apparatus is configured such that the operator inputs the type of recording sheet to be conveyed from the operation panel and rotates the cam 6, but there is a risk that mistakes may occur if the selection is made manually. Therefore, if a function is provided to automatically identify the type of recording sheet that is set in some way, the apparatus will become even more reliable.

An example of automatic setting is shown based on FIGS. 3(a), (b), and (c). Specifically, the difference in shape may be detected by two sensors 58a, 58a, and 58a.
58b (for example, an optical sensor may be used, or a microswitch may be used to mechanically turn ON/OFF), and the cam may be rotated by a predetermined angle based on the signal. By providing such a function, the user does not have to take the trouble to input the sheet type, and malfunctions due to input errors can be prevented.

Here 1. Although the sub-scanning roller has been described so far in a configuration in which the sub-scanning roller is disposed downstream of the recording section, the present invention is not limited to this. There is no problem even if you do.

Next, FIGS. 4 and 5 show a second embodiment of the present invention. Components that are the same as those in the first embodiment described above are given the same reference numerals and redundant explanations will be omitted.

In this embodiment, as shown in FIG.
This embodiment is different from the first embodiment described above in that the switching means is configured with a single pressure roller and no pressure roller is provided. Instead of providing a pressure roll, a winding roller 21 and a discharge roller 22 are provided downstream of the sub-scanning roll 20. Drive from a drive device (not shown) is transmitted to the paper discharge roller 22 via a torque limiter.

The reason for using the torque limiter is to keep the recording sheet tensioned at all times without sagging on the downstream side from the sub-scanning roller 20, and to keep the recording sheet tensioned at all times without sagging on the downstream side from the sub-scanning roller 20. This is to prevent the transport of

The winding roller 21 is a roller for determining the winding angle when the recording sheet is wound around the sub-scanning roller 20, and the details thereof are shown in FIG.
It is supported by a swing arm 31 that swings around a support shaft 30 fixed to the main body of the device. This swing arm 31 is always urged against the rotating cam 26 by the tension spring 24. Therefore, due to the rotation of the cam, the winding is performed on the roller 21.
swings in the direction of the arrow in the figure, thereby changing the wrapping angle α at which the sheet S wraps around the sub-scanning roller 20. 27-2
Reference numeral 9 denotes a guide member for guiding the sheet to the paper discharge roller 22 at the time of initial paper feeding.

In the device of this embodiment as well, the cam 26 is provided with a rotation drive means so that instructions can be inputted using the operation panel.

In the recording sheet conveyance device having the above configuration, it is assumed that the operator selects a sheet (for example, a plastic film) having a high conveyance resistance from the operation panel. Then, after the recording sheet is fed to the paper ejection roller, the rotary cam 26 rotates in response to the signal, and the winding roller 21 comes to the lowest position, that is, the recording sheet is wound around the sub-scanning roller 20. Stop at the position where the angle α is the largest. Then, the sub-scanning roller 20
The recording sheet is conveyed by one scan.

On the other hand, the paper discharge roller 22 is driven at least while the sub-scanning roller 20 is rotating. Therefore, the recording sheet is stretched on the downstream side of the sub-scanning roller 20, and the recording sheet is conveyed by the sub-scanning roller 20 under the tension of the negative leg and the wrapping angle. Here, if the tension is constant, the conveying force of the recording sheet depends on the wrapping angle around the sub-scanning roller 20, and the larger the one wrapping angle, the larger the conveying force. Therefore, in the case of a recording sheet with a high conveyance resistance force, it is conveyed with a high conveyance force.

On the other hand, when a recording sheet with a small conveyance resistance force, such as coated paper, is selected, the winding roller 21 is raised, and the winding angle α of the recording sheet around the sub-scanning roller 20 becomes smaller. In other words, the conveyance force of the sub-scanning roller 20 is reduced.

As a result of using the apparatus of this embodiment described above, in addition to the effects shown in the first embodiment, the configuration of the sub-scanning roller section for performing high-precision conveyance is simplified, and the durability remains constant even as the durability time progresses. It has become possible to maintain conveyance power.

(Effects of the Invention) The present invention has the above-described structure and operation, and by providing a switching means that can appropriately change the conveying force of the conveying roller according to the type of recording sheet to be conveyed, it is possible to It is possible to provide a recording sheet conveyance device that does not cause the recording sheet to slip and can quickly return to stable conveyance even when skew occurs.

Furthermore, the durability of the apparatus itself is improved compared to conventional apparatuses that are configured to always apply a constant conveying force regardless of the type of recording sheet.

By applying the recording sheet conveying device of the present invention to a recording apparatus, it is possible to provide a recording apparatus that always obtains highly accurate recorded images.

[Brief explanation of drawings]

FIG. 1 is an enlarged view of the main parts of the recording sheet conveying device according to the first embodiment of the present invention, and FIGS. 2(a), (b), (C
) are diagrams showing the rotation of the cam in the first embodiment, Figures 3 (a), (b), and (C) are diagrams each showing an example in which a roll axis detection sensor is adopted, and Figure 4 is a diagram showing the rotation of the cam in the first embodiment. A diagram showing a recording sheet conveying device according to a second embodiment of the present invention,
FIG. 5 is an enlarged view of the main part, FIG. 6 is an overall schematic diagram of a conventional recording sheet conveying device, and FIGS. 7 to 10 are diagrams showing the oblique feeding of a recording sheet. Explanation of symbols: l... Conveyance roller (sub-scanning roller) 2.3, 4, 5, 6, 7.8... Switching means (2...
Arm, 3... Support shaft, 4... Pressure spring, 5... Spring hook, 6... Cam, 7... Fulcrum, 8... Pressure roller) 11... Image formation Means (recording section) 23...Recording sheet support member (platen) Fig. 1 Fig. 3 (O) (b) <c> Fig. 4 Fig. 14

Claims (2)

[Claims] (1) A recording sheet conveying device having a conveying roller for conveying a plurality of types of recording sheets, characterized in that a switching means is provided to change the recording sheet conveying force of the conveying roller. Conveyance device. (2) The recording sheet conveying device according to claim 1, wherein the switching means is switchable depending on the type of recording sheet to be conveyed.