JPH01232080A - Sheet feeder and image recorder comprising said sheet feeder - Google Patents

Abstract

PURPOSE:To obtain constantly a strictly uniform energizing force distribution irrespective of sheet size, by dividing an energizing roller according to sheet sizes, and providing an energizing force-controlling member for turning ON/OFF the energizing forces for the energizing rollers. CONSTITUTION:A sheet-shaped recording medium 11 is fed by a supplying roller 10 until the leading end thereof is clamped by a feeding roller 1, and in the condition where the medium 11 is sucked through minute holes 9 formed in a platen 8, a head unit 7 is scanningly moved to record a one-line amount of data. An energizing roller for clamping and energizing the medium 11 between it and the feeding roller 1 through the supplying roller 10 and an intermediate roller 2 is divided into three energizing rollers 3a, 3b, 3c. The energizing roller 3a is constantly energized by an energizing spring 4a fastened to a fixed plate 12, whereas the energizing rollers 3b, 3c are selectively energized according to sheet size by energizing springs 4b, 4c connected to an ON-OFF mechanism. Thus, a uniform energizing force distribution can be obtained, and sheets of small to great sizes can be fed with high accuracy without skewing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sheet conveying device for conveying a sheet in a predetermined direction, and an image recording apparatus equipped with the sheet conveying device.

Here, the sheet includes a recording sheet on which an image is recorded, a document sheet on which an image to be read is formed, and the like.

Furthermore, the image recording device includes a copying device, a printer, a word processor, an electronic typewriter, a facsimile device, and the like.

[Prior Art] FIG. 9 shows an example of a conventional sheet conveying device disposed in an image recording apparatus.

A sheet-like recording medium 11 such as paper, film, cloth, etc. is fed by a feeding roller 1O until its leading end is nipped by the conveying roller 1. After that, the recording element (or nozzle in an inkjet printer) is scanned by the head unit 7.
When one line of recording corresponding to the vertical array width is performed, the recording medium is conveyed only by the conveyance roller 1 at a feed pitch corresponding to the recording width. M is a motor that drives the conveyance roller 1 via a belt transmission mechanism T. During the conveyance, air is sucked through pores 9 provided in the platen 8 by a suction blower (not shown) to bring the recording medium 11 into close contact with the platen.

In addition, 10' is a recording medium l between the feeding roller lO.
! This is a biasing roller section that clamps the recording medium, and is divided into three rollers 10'-a to 10-c corresponding to the width of usable recording media. That is, for example, it is divided by a distance from the l side of the transport reference that is approximately equal to the length of the long side of the 4th edition and the length of the long side of the 3rd edition.

Similarly to the urging roller section 10', the urging roller section is divided into three rollers 3-a to 3-c, and the intermediate roller 2 having a uniform diameter in the axial direction is connected to the conveying roller. 1, and the recording medium 11 is sandwiched and conveyed between them. The divided rollers 3-a to 3-c are supported by arms 6-a to 6-c that are rotatable around the shaft 5, respectively. Biasing shaft 13-a provided on each arm 6-a to 6-c
13-c and fixed plates 12-a to 12-c, biasing springs 4-a to 4-c are stretched, respectively, and the springs 4-c are connected to these springs 4-a. Each of the divided rollers 3-a to 3-c urges the intermediate roller 2 by the urging force.

The intermediate roller 2 having a uniform diameter in the axial direction and the biasing roller 3 divided at predetermined portions are designed to support the recording medium 1 as disclosed in Japanese Patent Application No. 146094/1988 proposed by the applicant.
1 is provided so that it can be held with appropriate frictional force. By adjusting the biasing force of the biasing roller 3, a uniform biasing force distribution can be obtained, and when a small-sized recording medium is transported with one side along the transport path as a reference, skew can be effectively reduced. be done. In addition, if the intermediate roller matches the partition band that divides the suction area in the platen according to the width of the recording medium used, and the position where there is no urging roller (the part between the urging rollers) matches the ink, etc. The intermediate roller is also effective in preventing this floating because swelling of the divided portions of the recording medium after recording due to adhesion of the recording medium increases and causes floating on the platen.

In other words, in order to convey paper from dog-sized paper to small-sized paper with high precision without skewing, it is effective to provide an intermediate roller having a uniform diameter in the axial direction and a biasing roller that is biased separately. be.

[Problems to be Solved by the Invention] However, if the recording device is constructed so that it can cope with even large differences in the size of the recording medium, it is possible to make the biasing force distribution strictly uniform for all sizes. is desired. Furthermore, as the density of recording heads increases, the demand for higher accuracy in the paper feed amount of the recording medium also increases. For this reason, there is a strong demand for uniformity of biasing force distribution in all sizes. For example, inkjet recording heads that have been used in recent years as recording heads have a dot density of 400 dots/
Some even have 256 nozzles per inch (dpi). When this head is used, the width of the head is 16.25611 m, so the accuracy of the feeding amount of the recording medium is 16.2 mm in order to make the recording joints inconspicuous.
Approximately 256mm±0.015mm is required.

Moreover, the width of the usable recording medium is A4 (297+n
m) to A2 (594mm) and those with a large difference, the above-mentioned 16.256m
In order to pursue accuracy of m±0.0015 mm, strict uniformity of the biasing force has become essential.

However, in the configuration shown in FIG. 9, a strictly uniform pressure distribution may not be obtained. For example, in Figure 9,
By appropriately displacing and fixing the fixing plates 12-a-12-c, for example, the biasing force of the biasing springs 8-a to 8-c can be adjusted so as to obtain a uniform pressure distribution on the A2 size recording medium. Suppose you have adjusted it. Conveying roller 1, intermediate roller 2 when conveying ^4 size paper in this state. Recording medium 1
1. The relationship between the urging rollers 3-a to 3-c is shown in FIG. 10 (A).
Shown below. Since the intermediate roller 2 is not a completely rigid body,
As shown in the figure, it is conceivable that the portion without the recording medium 11 may be unable to resist the urging force of the urging rollers 3-b and 3-c and may bend. For this purpose, the edge 1 of the recording medium
1-8, stress concentration occurs. As a result, the pressure distribution becomes non-uniform as shown in Figure 1O (El). When the pressure distribution becomes like this, the recording medium becomes 10th
As shown in Figure (C), the head unit 7 moves diagonally each time it is fed after one scan, and gaps or overlaps occur at the joints between each scan by the head unit 7. . In other words, the highly accurate feeding of the recording medium that has been desired in recent years may not be achieved.

Such problems related to feeding accuracy occur not only in the sheet conveying device that conveys the sheet-shaped recording medium (recording sheet) in the image recording device described above, but also in the image reading device combined with various printers, facsimile machines, etc. A conveying device for sheet-like originals (original sheets) disposed in the device, and a device capable of recording and reading images (for example, in FIG. 9, the head unit 7 is detachable and a reading head can be attached instead). It also occurs in sheet conveyance devices that are shared for recording and reading operations. That is, if the sheet is not conveyed with high precision, the reliability of the read data will decrease.

SUMMARY OF THE INVENTION An object of the present invention is to solve this problem and provide a sheet conveying device that can always convey sheets with a uniform biasing force even when sheets of various sizes (recording sheets and original sheets) are used. shall be.

Another object of the present invention is to provide an image recording apparatus that is equipped with such a sheet conveying device and is capable of recording high-quality images.

[Means for Solving the Problems] To this end, a sheet conveyance device according to one embodiment of the present invention includes a rotatable conveyance roller and a rotatable conveyance roller in order to convey the sheet.
An intermediate roller is provided so as to be able to come into contact with the conveyance roller, and is movable between a pressing position where it comes into contact with the intermediate roller and a retreating position where it is retracted from the pressing position, and is divided according to the width of the sheet that can be conveyed. A biasing roller is provided.

Further, a sheet conveying device according to another aspect of the present invention includes a sheet conveying means for conveying the sheet, and a variable conveying force for changing the sheet conveying force by the sheet conveying means in a direction crossing the sheet conveying path. and a control means for controlling the conveying force variable means according to the width of the sheet to be conveyed.

Further, in a sheet conveying device according to still another aspect of the present invention, the recording medium is urged along the conveying member for conveying the sheet-shaped recording medium toward the conveying member. A biasing roller member is provided for transmitting a conveying force from the recording medium and has a biasing roller divided according to the width of the recording medium that can be selected by the recording device, and a biasing roller member is combined with each of the divided biasing rollers. The present invention is characterized in that it is provided with a biasing control member that turns on/off the biasing force individually.

An image recording apparatus according to still another aspect of the present invention includes a recording sheet conveying means for conveying a recording sheet, and a recording sheet conveying force for changing the recording sheet conveying force by the recording sheet conveying means in a direction transverse to the conveyance path of the recording sheet. A variable conveyance force means, a control means for controlling the variable conveyance force according to the width of the recording sheet to be conveyed, and a recording means for recording an image on the recording sheet conveyed by the recording sheet conveyance means. It is characterized by

[Function 1] According to the present invention, the biasing roller is divided according to the size of the sheet (sheet-shaped recording medium or original document), and a biasing control member for turning on/off the biasing force is provided. This makes it possible to always obtain a strictly uniform biasing force distribution regardless of the size of the sheet. Moreover, by using this, high-quality image recording becomes possible.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIGS. 1(A) and (B) show the first embodiment of the present invention.
As an example, an example of the configuration of a sheet conveying device applied to an image recording apparatus is shown, and corresponding parts are given the same reference numerals for parts that can be configured in the same way as the apparatus shown in FIG. 9.

In the figure, the smallest recording medium among recording sheets is A4 size, the largest one is A2 size, and the case where there is A3 size in between is shown by a two-dot chain line. The urging roller 3 is an A4 width urging roller 3-a.
, A3-width biasing roller 3-b, A2-width biasing roller 3
-c and is divided according to each size, and each urges the intermediate roller 2. In this example, since the minimum size of the recording medium is A4, one end of the biasing spring 4-a is fixed to the fixed plate 12-a in the same way as in FIG. 9, and the other end is fixed to the biasing shaft 13-a. This rotates the arm 6-a and applies a biasing force to the biasing roller 3-a.

Respective urging rollers 3 corresponding to A3 width and A2 width
-b and 3-c are connected to respective on/off mechanisms at one end of biasing springs 4-b and 4-c in order to turn on/off the biasing force as necessary.

That is, as shown in FIG. 1(B), the biasing spring 4-b
is fixed to the slider 14-b. Slider 14-b
The position where the biasing spring 4-b is pulled by the stop position of the cam 15-b (the position shown in FIG. 1 (B)) and the position where it is returned to its free length (the position where the cam 15-b is rotated 180 degrees from the position shown in the figure) It can be set to Each stop position is on sensor 25
-b and off sensor 26-b. An operating gear 16-b is coaxially fixed to the cam 15-b, and receives rotational force from a drive gear 18-b via an intermediate gear 17-b. The drive gear 18-b receives rotational force from the gear 22 provided on the rotating shaft of the motor 24 via the gears 20-b, 21-b and the clutch 19-'b. Further, the same transmission path is applied to the biasing spring 4-c, that is, the slider 14-c, the cam 15-c, the gears 1B-c, 17-c,
18-c.

The biasing force is turned on and off by the rotational force from the motor 24 through a mechanism consisting of 20-c, 21-c and the clutch 19-C, and the on/off is controlled by the sensor 25-C.
and 26-C.

FIG. 2 shows an embodiment of an image recording apparatus to which the above configuration is applied. Here, the control unit 100 controls the sheet conveyance device described above and the entire image recording apparatus equipped with this sheet conveyance device, and includes, for example, a CPLllooa such as a microprocessor, which corresponds to the processing procedure described later with reference to FIG. ROM100b which stores the control program of CPU100a and various fixed data, and CPU100
It is equipped with a RAM 100c, etc., which is used as a work area for A and temporarily stores various data.

In addition to manually instructing the start of recording, the control unit 100 also instructs the user to specify, for example, the sheet size, one color, and the mode (
an operation panel 100d for performing enlargement/reduction etc.), on-sensors 25-b, 25-c, and off-sensors 26-b.
It obtains information signals from 26-c and 26-c and controls the operations of each section. That is, the transport system including the motor M for transporting the recording medium is driven and controlled to perform paper feeding, line feeding, and paper ejection, and the motor M and clutches 19b and 19c are turned on/off depending on the size of the recording sheet. to set the divided roller biasing state, and after the setting, drive the head unit 7 for recording according to the image data,
This is a process of driving the main scanning unit 1008 and the like that performs scanning.

FIG. 3 shows an example of a recording processing procedure by such an image recording apparatus. When the size of the recording sheet is specified using the operation panel 100d and a recording command is input, step 51
), the driving of the recording sheet feeding or conveyance system (motor M, etc.) is started (step S3). Next, the motor 24 is turned on to set on/off of the urging rollers 3-b and 3-c according to the specified size (step S5), and it is determined whether the specified size is A4 size ( Step S7)
.

When the size of the recording medium used is A4, a spring 4-a is connected to the fixed plate 12-a and constantly generates a biasing force.
The biasing force may be applied only to the biasing roller 3-a by the biasing roller 3-a, and the biasing force of the other biasing rollers 3-b and 3-c may be turned off. That is, since the gear 22 rotates when the motor 24 rotates, when both the on-sensor 25-b and the off-sensor 26-b or the off-sensor 26-b does not detect the slider 14-b (step S9
), the clutch 19-b is turned on and the gear train 21b-18 is turned on.
-b is rotated, and the cam 15-b is rotated (step 5ll). Then, the slider moves along the cam surface until the biasing spring 4-b reaches its free length, and the on-sensor 25-b
The clutch 19-b is turned off at the position where the slider 14-b and the off sensor 26-b both detect the slider 14-b, and step 51
3,515), stop the operation. Off sensor 2 from the beginning
If the slider 14-b is detected by the on-sensor 6-b and the on-sensor 25-b, the biasing force is not acting, but the clutch 19-b is turned off to ensure reliability (step S9,
515).

This also applies to the biasing spring 4-c. That is, depending on whether or not the slider 14-C is detected by the on sensor 25-C and the off sensor 26-C, the clutch 19-0 is turned on/off, and the urging force of the urging spring 4-c is turned off (steps 517 to 523). ).

FIG. 4(A) shows a state in which only the biasing roller 3-a applies biasing force to the intermediate roller 2 as a result of the above-described operations. As is clear from the figure, there is no deflection of the intermediate roller 2 in the area where the recording medium is not present, and the biasing force distribution becomes uniform because stress concentration does not occur. In other words, it becomes possible to transport small-sized recording media with high precision without skewing, and the recording quality is also improved (see figure (B)).
).

Next, in step S7, a size other than A4 (in this example, A3
Or if A2) is specified, urging roller 3-b
The same process as above is performed for setting the energized state to the energized state. That is, the on sensor 25-b and the off sensor 26
Clutch 19-b may be turned off when both -b are turned off. Then, if the specified size is A3 size (step 527), the biasing roller 3-c
The process of turning off the (steps 517 to 523) is executed.

That is, when the recording medium is A3 size, the slider 14-C is detected by the on-sensor 25-C and the off-sensor 26-C at a position where the slider 14-b is not detected by the on-sensor 25-b and the off-sensor 26-b. The clutch 19-
c and 19-c are turned on and off, thereby applying force only to the urging rollers 3-a and 3-b. As a result, it becomes possible to obtain a uniform biasing force distribution as shown in FIG.

If a recording medium of size 2 is selected, the process advances to step S29 and the biasing roller 3-c is roughly turned on.

That is, in this case as well, as shown in FIG.
By turning on and off 9-b and 19-c, it becomes possible to obtain a uniform biasing force distribution.

It goes without saying that the biasing springs 4-a to 4-C are set to spring constants that provide a uniform biasing force per unit length in the width direction of the recording medium.

After completing the biasing roller setting process as described above, the motor 24 is turned off and the head unit 7 and main scanning unit 100e are driven to perform line feeding and image recording processing (step 531). 533)
.

FIG. 7 shows another embodiment of a mechanism for turning on/off the urging force of the urging roller. The wood layer side is shown in Figure 1 (B).
In place of the cams 15-b and 15-C and the sliders 14-b and 14-c in the embodiment shown in FIG.
and 27-C to actuating gears 16-b and 16, respectively.
-C to slide the urging rollers 4-b and 4-c.
The biasing force is turned on/off. The other mechanisms and their operations are the same as those shown in FIG. 1(B), and this example can also achieve exactly the same effects as the first example.

FIG. 8 shows still another embodiment of the present invention. In this example, one end of the biasing spring 4-b is connected to the slider 28b. This slider 28b is attached so that it can move only in the left and right directions in the figure along a guide 29b. A female thread is carved in the center of the slider 2 [1b, and is screwed into the male thread of the motor shaft 31b. That is, the motor 30
By turning on the motor shaft 31b and rotating the motor shaft 31b, the slider 28b moves in the horizontal direction.

If the motor is stopped at the position where the on-sensor 25-b detects the slider 28b, the biasing roller 3-b biases the intermediate roller. Furthermore, if the motor is stopped at the position where the off sensor 26-b detects the slider, the biasing roller 3-b
does not energize the intermediate roller. The slider 28b can be moved in the left-right direction in the figure by reversing the rotation direction of the motor fIII 31b.

A mechanism consisting of completely similar parts 29c, 28c, 26-c and 25-C is provided for the urging roller 3-c, and the mechanism is operated appropriately, that is, the urging force is turned on according to the size of the recording medium. /off, the same effect as in the two embodiments described above can be obtained.

Furthermore, in this example, instead of the motors 30c and 30b, solenoids may be coupled to the sliders 28b and 28c directly or through a mechanical amplification mechanism such as a lever, and the same effect can be obtained, as well as the sensors 25c and 26c.
There is also no need to install.

It goes without saying that the mechanism for selectively turning on the biasing force of each biasing roller is not limited to the three examples described above, and can be of various forms.

Also, on the top side, the recording medium is A4 size, A3 size and A2 size.
Although it has been explained as a plate, the type of size of the recording medium, the number of divisions of the urging roller corresponding to this, and the division position are as follows.
Of course, it can be determined as desired.

Furthermore, the form of the instruction means for selectively turning on/off each urging roller may be a selection key or switch corresponding to each size that accepts the operator's selection of the recording medium as described above, or For example, keys or switches provided for each roller, or other paper width sensors may be used.

In addition, the form of the control means that controls the upper mechanism according to the instructions may be of any type, and the function may be assigned to the CPU that controls the operation of the device as described above, or, for example, It may also be a hardware logic circuit that controls the above-mentioned operations in accordance with a key or switch manual input.

In addition, although the case where the on/off mechanism is provided for the J roller 3 associated with the conveyance roller 1 is described above, the biasing roller lO' associated with the paper feed roller 10 or other conveyance of the recording medium has been described. It goes without saying that a mechanism similar to that described above may be provided for each roller in the recording apparatus that is involved.

In addition, in the above section, we have described the case where the invention is applied to a device equipped with an intermediate roller, but even if there is no intermediate roller, depending on the width of the recording medium, the recording medium may partially fall on a certain divided roller. Therefore, the problem described in connection with FIG. 8 may occur, so the configuration of the present invention in which the biasing force is turned on and off for each divided roller is extremely effective.

In the embodiments described above, the conveyance of a recording sheet was explained as an example, but it goes without saying that the sheet conveyance of the present invention can also be applied to the conveyance of original documents, etc., as described above. Further, it goes without saying that the image recording apparatus of the present invention can apply an inkjet recording method, a thermal recording method, an electrophotographic recording method, a laser recording method, or the like. Further, the sheet conveying member is not limited to rollers, and may be, for example, a belt suspended on a pulley. Further, the means for varying the conveying force is not limited to the contact and separation of the urging rollers described in the embodiments, but may be, for example, the contact and separation of a plate spring member.

[Effects of the Invention] As explained above, according to the present invention, the urging force of the urging rollers other than the urging rollers involved in conveying the sheet to be used is released, thereby reducing stress concentration at the edge of the sheet. It has become possible to obtain a uniform biasing force distribution on sheets of all sizes. As a result, it became possible to increase the accuracy of the conveyance amount from small-sized sheets to large-sized sheets without causing skew, and in turn, it was possible to improve the recording quality of the image recording apparatus using this.

[Brief explanation of the drawing]

FIGS. 1A and 1B are a perspective view and a plan view, respectively, showing a configuration example of a sheet conveying device according to the present invention, and FIG. 2 is an image recording device to which the device shown in FIG. 1 is applied. A block diagram showing the embodiment; FIG. 3 is a flowchart showing an example of the recording processing procedure; FIGS. Explanatory diagram for, No. 7
FIG. 8 is a plan view showing still another configuration example of the sheet conveying device according to the present invention; FIG. 9 is a conventional sheet conveying device A perspective view showing an example, and FIGS. 1O (A) to (C) are explanatory diagrams for explaining the operation. DESCRIPTION OF SYMBOLS 1... Conveyance roller, 2... Intermediate roller, 3.10'... Urging roller part, 3-a, 3-b, 3-c, 10°-a, 10°-b, 1
0°-c ・"Biasing roller, 4-a, 4-b, 4-c
- Biasing spring, 5... Shaft, 6-a, 6-b, 6-c - Arm, 7... Head unit, 8... Platen, 9... Pore, 10... Supply Feed roller, 11...recording medium, 12-a, 12-b, 12-c-fixing plate, 14-b, 1
4-c, 28b, 28c - slider, 15-b,
15-c...Cam, 19-b, 19-c...Clutch, 24.30b,
30c...Motor, 25-b, 25-c...On sensor, 26-b, 26
-c...off sensor, 27-b, 27-c...rack, 100...control unit, 100a...-CPU. 100b...ROM. 100c...RAM. 100d...operation panel, 100e...main scanning unit. (A) Figure 4 Figure 5 Figure 6 Figure 7 26-C213-c Nurida

Claims (1)

[Claims] 1) A rotatable transport roller for transporting a sheet, an intermediate roller provided so as to be able to come into contact with the transport roller, a pressing position that contacts the intermediate roller, and the pressing position. What is claimed is: 1. A sheet conveying device comprising: a biasing roller that is displaceable between a retracted position and a retracted position and that is divided according to the width of a sheet that can be conveyed; 2) The sheet conveying apparatus according to claim 1, further comprising a control means for controlling the urging roller to be displaced between the pressing position and the retreating position according to the width of the sheet to be conveyed. . 3) a sheet conveying means for conveying the sheet; a conveying force variable means for changing the sheet conveying force of the sheet conveying means in a direction transverse to the conveying path of the sheet; A sheet conveyance device comprising: a control means for controlling the conveyance force variable means; 4) The sheet conveying device according to claim 3, wherein the sheet conveying means includes a pair of rollers. 5) A sheet characterized in that the conveying force variable means includes a plurality of divided rollers, and biasing springs that are combined with the plurality of rollers and can press the conveying means. Conveyance device. 6) a recording sheet conveying means for conveying a recording sheet; a conveying force variable means for changing the recording sheet conveying force of the recording sheet conveying means in a direction across the conveying path of the recording sheet; and a recording sheet to be conveyed. an image recording device comprising: a control means for controlling the conveying force variable means according to the width of the recording sheet conveying means; and a recording means for recording an image on a recording sheet conveyed by the recording sheet conveying means. Device. 7) The image recording apparatus according to claim 6, wherein the sheet conveying means includes a pair of rollers. 8) The conveyance force variable means has a plurality of divided rollers, and a biasing spring that is combined with each of the plurality of rollers and can press the conveyance means. 6. The sheet conveying device according to 6. 9) Provided along a conveying member for conveying a sheet-shaped recording medium, for transmitting a conveying force from the conveying member to the recording medium by urging the recording medium toward the conveying member. , a biasing roller member having a biasing roller divided according to the width of the recording medium that can be selected by the recording device; and a biasing roller member that is provided in combination with each of the divided biasing rollers and applies a biasing force to each of the divided biasing rollers. A sheet conveying device comprising: a biasing control member for turning off the sheet; 10) The sheet conveying device according to claim 9, wherein the biasing control member turns on/off the biasing force in accordance with the width of the selected recording medium. 11) Between the biasing roller member and the conveying member,
10. The sheet conveying device according to claim 9, wherein an intermediate roller having a uniform diameter is provided continuously in the axial direction, and a recording medium is conveyed while being held between the intermediate roller and the conveying member.