JPH0388659A - Sheet conveyance device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sheet conveyance device used in a transfer paper conveyance system of an image forming apparatus such as a copying machine, a facsimile machine, and a printer.

(Prior Art) FIG. 6 shows a schematic configuration of a printer 101 to which this type of sheet conveying device W100 is applied.
2 is an image carrier, and around this image carrier 102 there is a charger 103 . Developing device 104, transfer charging device 105. A cleaner 106, a pre-exposure device 107, etc. are arranged.

Further, 108 is a conveyance path that guides the sheets 110 stored in the cassette 109 to the transfer section A.

This conveyance path 108 is orthogonal to the conveyance direction. A reference means 111 consisting of a pair of rollers and a loop forming means 112 consisting of a paper feed roller are provided. Note that B is a sensor provided upstream of the reference means ill.

In the printer 101 having the above configuration, when an image forming button (not shown) is pressed, a laser beam 114 emitted from a semiconductor laser 113 is transmitted to a rotating polygon mirror 115 and an optical lens 116.
The electrostatic latent image is guided onto the image carrier 102 via the two-reflection mirror 117 to form an electrostatic latent image. This electrostatic latent image is transferred to the developing unit 104.
At the same time, the image carrier 102 is rotated in the direction of the arrow to move to the transfer position.

On the other hand, the sheet 110 in the cassette 109 is carried out by the rotation of the loop forming means 112 in the direction of the arrow, and its leading end is detected by the sensor B, and then comes into contact with the contact surface between the reference means 111. At this time, the reference means i
ll is stationary, and only the loop forming means 112 rotates a predetermined amount and stops, thereby urging the sheet 11O in the conveying direction, and the sheet 110 is moved as shown by the solid line in FIG.
A loop is formed. As a result, the leading edge of the sheath 110 becomes parallel to the reference means 111, and the skew is corrected.

Then, the reference means ill starts rotating in the direction of the arrow in response to a timing signal from a control section (not shown).
110 is guided to the transfer section A.

Here, the developed image on the image carrier 102 described above is transferred onto the sheet 110 and fixed by the fixing device 118, and then
The paper is discharged to the outside by the paper discharge roller 119.

(Problem to be Solved by the Invention) By the way, the sheet 11 formed by the loop forming means 112
The degree of bias toward 0 is always constant, and the operation is often controlled so that a loop is formed in an amount that corresponds to the maximum size of the sheet 11O being conveyed.

However, the material of the sheet 110 to be fed 41,
Since the strength, thickness, size, and other characteristics of Ws are not all the same, if loops are always formed with a constant bias as described above, especially in the case of the smallest size sheet, As shown by the dashed line in Figure 7, the leading edge of the sheet 110 may come off the contact surface of the reference means ill, resulting in poor conveyance.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a sheet conveyance device that can prevent defective sheet conveyance after completion of skew correction by loop formation.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a reference means disposed perpendicularly to the conveyance direction of the sheet, and a leading end of the sheet is brought into contact with the reference means.

and a loop forming means for biasing the sheet in a contacting state in the transporting direction to form a loop, a detection means for detecting characteristics of the sheet before it contacts the reference means; A control means is provided for determining the degree of bias applied to the sheet by the loop forming means based on the detection information of the detecting means.

(Function) Based on the above configuration, first, the characteristics of the sheet are detected by the detection means, and then the leading end of the sheet is brought into contact with the reference means by the loop forming means.

On the other hand, the control means determines the degree of energization by the loop forming means based on the detection information of the detecting means, and controls the operation of the loop forming means.

(Example) Next, the present invention will be explained based on FIGS. 1 to 5.

FIG. 2 shows a sheet conveying device according to the present invention in a printer 1.
FIG. 2 is a schematic configuration diagram showing a first embodiment applied to the present invention. 411
A cassette 2 containing transfer paper (sheet) P is provided on the upstream side of the feeding path. 3 is a paper feed roller (loop forming means) that rotates in the direction of the arrow and feeds the transfer paper P in the cassette 2.
This is for transporting the materials toward the downstream side.

On the downstream side of the paper feed roller 3 in the conveyance direction, a pair of skew correction rollers (reference means) 4 are disposed vertically so as to be in contact with each other across the conveyance path so as to be orthogonal to the conveyance direction.

Further, an image carrier 5 is provided further downstream of the conveyance path, and a negative charger 6 is provided around the image carrier 5.
, developing device 7, transfer charger 8, cleaner 9, pre-exposure device 10
Image forming means such as the following are arranged. 11 is a semiconductor laser, 12 is a rotating polygon mirror, 13 is an optical lens, and 13a is a reflecting mirror. Note that on the downstream side of the transfer section E, a fixing device 14 and a paper ejection roller 15 are provided.

A leading edge detection sensor 16 is provided between the paper feed roller 3 and the skew correction roller 4 to detect the leading edge of the transferred transfer paper P. On the conveyance path, the tip detection sensor 1
On the upstream side of 6, the thickness, size, and
Type (material) 9 Detection means for detecting features such as surface shape 1
7 is provided.

FIG. 1 is a block diagram showing the main circuit configuration of the present invention.

The CPU 18 that controls the entire printer l has a built-in jam timer, and also includes a main motor drive control circuit 19, a paper feed roller drive control circuit 20 (control means),
A transport system for the transfer paper P, such as the skew correction roller drive control circuit 21, and the leading edge detection sensor 16. Detection sensors such as a paper thickness detection sensor 17a and a paper size detection sensor 17b as the detection means 17 are connected. The CPU 18 also performs serial communication with the printer controller 22 and exchanges timing signals with the image signal control circuit 23 and the laser drive circuit 24.
．． Scanner drive control circuit 25 connected to scanner motor 25a. It controls the high voltage control circuit 26 and the like.

Next, the detection means 17 in the above embodiment will be explained in detail.

(2) Detection of Thickness First, the paper thickness detection sensor 17a can be satisfied with a well-known potentiometer or the like connected to a roller (not shown), and the thickness of the transfer paper P can be detected by reading the voltage value thereof. Alternatively, a variable resistor or the like may be attached to the cassette 2 so that it can be set in advance according to the thickness of the transfer paper P used by the user, and this voltage value may be read by the CPU 18.

■Size detection The size of the transfer paper P may be configured such that the size to be used is automatically transferred to the paper size detection sensor 17b when the printer controller 22 sends a print signal, or the above-mentioned potentiometer may be used. may also be used,
In addition to the photoelectric sensor, two light sources, a lens, and an image sensor may be used in combination.

0Other DetectionAlso, using a known optical sensor, it is easy to determine whether the transfer paper P is plain paper or a transparent film-like material with different stiffness based on whether light is transmitted or not. can be detected. Furthermore, when using transfer paper P made of a different material, the printer controller 22 is provided with a material selection button or the like.

This may be configured to operate as a detection means.

Further, by providing a large number of position sensors perpendicular to the conveying direction and continuously measuring the displacement of each part, it is possible to detect wrinkles and other surface shapes of the transfer paper P.

Next, the operation of the above embodiment will be explained with reference to the flowchart shown in FIG.

First, when the print start button of the printer controller 22 is pressed, the CPU 18 receives a print request signal (
Step ■) The paper feed roller 3 starts driving, and a predetermined time To of the jam timer is set (Step ■). When characteristics such as size and thickness are detected (step ■), and when the leading edge detection sensor 16 detects the transfer paper P by the aforementioned predetermined time To (step ■), the jam timer in the CPU 1a is reset. (step ■), and after the predetermined time To has elapsed (
If the transfer paper P is not detected in step 2 (2), jam processing is performed (step (2)).

Then, when the jam timer is reset as described above, the CPU 18 reads the data detected by the detection means 17 (step ■) and forms a loop amount corresponding to the size, thickness, and other characteristics of the transfer paper P. Determine the drive timer T1 of the paper feed roller 3 to obtain by the calculation table (step 2), rotate the paper feed roller 3 in the direction of the arrow by the drive timer T1 (step o), and then the leading edge of the transfer paper P will be While coming into contact with the contact surface of the skew correction roller 4, the transfer paper P is urged in the conveying direction. Thereafter, the drive timer T1 of the paper feed roller 3 elapses (step o), the paper feed roller 3 comes to a stop (step o), and skew correction is performed by forming a loop. The loop formation of the transfer paper P performed here corresponds to the size, thickness, stiffness, etc. of the transfer paper P detected by the detection means 17, so if the loop amount is too large and the leading edge is Situations such as coming off the contact surface of the skew correction roller 4, bending, or wrinkles do not occur.

On the other hand, when the paper feed roller 3 stops, the CPU 18 sends a vertical synchronization request signal to the printer controller 22 (step o), and when there is a vertical synchronization signal from the printer controller 22 (step o), the skew correction roller 4 is rotated in the direction of the arrow (step o), and the transfer paper P is conveyed toward the transfer section E. As described above, since the leading edge of the transfer paper P is in accurate contact with the contact surface of the skew correction roller 4, no conveyance failure occurs during conveyance to the transfer section E.

By the way, the laser beam F emitted from the semiconductor laser 11 during the above operation is guided to the surface of the image carrier 5 via the rotating polygon mirror 12, the optical lens 13, and the reflecting mirror 13a, and forms an electrostatic latent image. ing. This electrostatic latent image is developed by the developing device 7, and is transferred to the transfer section E by rotation of the image carrier 5 in the direction of the arrow.

This developed image is transferred by the transfer charger 8 onto the transfer paper P conveyed as described above, and after being fixed by the fixing device 14, the transfer paper P is discharged to the outside by the paper discharge roller 15. be done.

Since the transfer paper P does not have wrinkles or folds during loop formation, the developed image on the image carrier 5 is transferred onto the transfer paper P with high precision, and a high-quality transferred image can be obtained.

FIG. 4 is a schematic configuration diagram showing a second embodiment.

In this embodiment, the upstream of the conveyance path is D l +D
It is divided into two parts, each of which is equipped with a separate cassette 2 containing transfer paper P. Detecting means 17 are arranged on each of the transport paths DI and D2.

z6 is a forward/reverse roller for double-sided printing; 27 is a flapper provided between the fixing unit 14 and the forward/reverse roller 26; this flapper 27 is for guiding the transfer paper P to the re-conveying path 28; . A positioning sensor 30 is located downstream of the paper refeeding roller (loop forming means) 29 in the reconveying path 28.
And a detection means 17 similar to the above is provided. The main circuit configuration of this second embodiment is also the same as that of the first embodiment.

Next, the operation of the second embodiment will be explained with reference to the flowchart shown in FIG.

First, the stays and steps ■ to ■ are the same as in the first embodiment, and when single-sided printing is selected in the printer controller 22 (step ■'), the same steps as in the first embodiment are performed. [Phase] - Perform the operations of ■.

Then, when the printer controller 22 selects the double-sided print mode in step (3), the transfer paper P conveyed from the cassette 2 passes through the transfer section E and the fixing device 14, and reaches the forward/reverse rotation roller z6, and the flapper 27 is activated. At the same time, the forward/reverse roller 26 rotates in the reverse direction, and the transfer paper P is conveyed to the re-conveyance path 28.

The leading edge of the transfer paper P is detected by the positioning sensor 30, and the characteristics of the transfer paper P are detected by the detection means 17 (step ■''), and based on this information, the Cr
t318 determines the driving timer T1 of the paper refeed roller 29 (step III). In this embodiment, table a is referred to in the case of a single-sided printer, and another table a is referred to in the case of a double-sided printer. The drive timer T1 is determined by referring to table b. The reason for this is that during double-sided printing, the transfer paper P is heated and pressurized by the -degree fixing device 14, and its properties change (the surface has a shift, etc.).

In this way, the paper refeed roller 29 rotated by the drive timer T1 comes into contact with the skew correction roller 4, and thereafter the operations from steps [phase] to (2) are performed in the same manner as in the first embodiment. Although the first and second embodiments are examples in which the present invention is applied to a printer, it goes without saying that the present invention may also be applied to a copying machine, a facsimile machine, etc.

(Effects of the Invention) Since the present invention is configured as described above, the degree of biasing of the sheet in the conveyance direction performed by the loop forming means with the leading edge of the sheet in contact with the reference means can be detected. This corresponds to the size, thickness, stiffness, etc. of the transfer paper detected by the means, so it is possible to prevent the loop from being too large and the tip coming off the contact surface with the reference means, or being bent. No wrinkles will occur,
Therefore, an excellent effect can be achieved in that it is possible to prevent sheet conveyance failures that occur immediately after completion of skew correction due to loop formation.

[Brief explanation of drawings]

1 to 5 show embodiments of the present invention, FIG. 1 is a block diagram showing the main circuit configuration, FIGS. 2 and 4 are schematic configuration diagrams of a printer to which this invention is applied, and FIG. 3 FIG. 5 is a flowchart showing the operation. FIG. 6 is a schematic configuration diagram of a conventional example, and FIG. 7 is an enlarged front sectional view showing a loop forming state of the conventional example. Explanation of symbols 3.29...Loop forming means 4...Oblique correction roller 17...Detection means 17a...Paper thickness detection sensor 17b...Paper size detection sensor 20...Paper feed roller drive Control circuit P...transfer paper (sheet) (reference means) (control means)

Claims (1)

[Claims] A reference means disposed perpendicularly to the conveying direction of the sheet, a leading end of the sheet abutting the reference means, and the sheet in the abutting state being urged in the conveying direction. A sheet conveying apparatus comprising: a loop forming means for forming a loop; a detecting means for detecting the characteristics of the sheet before it contacts the reference means; A sheet conveying device provided with a control means for determining the degree of bias applied to the sheet.