JPH0948540A - Sheet carrier and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a carried manuscript from going obliquely, controlling the rotational speed of a pair of rollers worn away, by controlling the rotational speed of each drive means, based on the direction of oblique displacement and the quantity of displacement of sheet material at the time of carriage, from the direction of oblique motion and the quantity of oblique motion accumulated. SOLUTION: To begin with, the angle α of oblique motion on upstream side and the angle β of oblique motion on downstream side are computed from the quantity of oblique motion measured by the detection signals of upstream and downstream manuscript detection sensors 125-18 on a carry path. The quantity S of oblique motion is the length of a manuscript being displaced by an angle θ(=β-α) by the difference of roller diameter between right and left active rollers 6 and 7. Moreover, to obtain the direction of oblique displacement, the directions of the oblique motions expressed by the binary of '1' and '0' are integrated to begin with, and the average value is taken, and it is deduced in which direction they are severally moving obliquely on the upstream side and downstream side of the carry path, and the direction of oblique displacement is obtained from the direction of oblique motion. And, based on the direction of oblique displacement and the quantity of oblique displacement, the rotational speeds of pulse motors 13 and 14 are controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet material conveying device for conveying a sheet material, and for example, in an image forming apparatus such as a copying machine, a sheet for feeding a sheet material such as a document or a recording medium to an image reading means or an image forming means. The present invention relates to a material conveying device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a feeding means for feeding an original to an image reading unit for reading an image of the original has a function of correcting skew of the original. The conveyance unit having the skew feeding correction function includes a pair of conveyance rollers that rotate independently on the left and right in the width direction orthogonal to the conveyance direction, and the pair of conveyance rollers is driven to rotate according to the skew of the document. The skew feeding of the original is corrected by changing the rotation speed of each motor.

[0003]

However, in the above-mentioned conventional example, the left and right conveyance roller pairs in the width direction have different usage frequencies depending on the skew of the document, so that they may be used for a long time or many times. When the rollers are worn due to use and the roller diameters of the left and right conveying roller pairs are different from each other, the document conveyed by the conveying roller pairs may be skewed, which may affect the image read by the image reading unit. It was

The present invention has been made to solve the above problems, and an object thereof is to control the rotational speed of a worn pair of conveying rollers to prevent a conveyed document from skewing. is there.

[0005]

A typical constitution of the present invention for achieving the above object is a conveying means that rotates independently on both sides on the same axis in the width direction orthogonal to the conveying direction of a sheet material. A detecting means for detecting the sheet material conveyed by the conveying means; a first calculating means for calculating a skew direction and a skew amount of the sheet material from detection information by the detecting means; and calculating by the first calculating means And a skew displacement direction and skew displacement amount of the sheet material at the time of transport of the transport means based on the skew direction and skew amount accumulated in the storage means. And a control means for controlling the rotation speed of each drive means for rotationally driving the conveying means based on the skew displacement direction and the skew displacement amount calculated by the second calculation means. To have It features.

According to the above construction, the sheet material conveyed by the independently rotating conveying means is detected by the detecting means, and the skew direction and skew amount of the sheet material are calculated from the detection information and accumulated. A skew displacement direction and a skew displacement amount of the sheet material at the time of transport of the transport means are calculated from the accumulated skew direction and skew amount, and the skew displacement direction and the skew displacement amount are calculated based on the skew displacement direction and skew displacement amount. Since the rotation speed of each drive means that drives the conveyor is controlled, the conveyor speed of the sheet material worn by the conveyor due to long-term use is constant on both sides of the sheet width direction, preventing skew of the sheet material. can do.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] An embodiment of a sheet material conveying apparatus to which the present invention is applied will be specifically described below with reference to the drawings. In the present embodiment, as the sheet material conveying device to which the present invention is applied, a document feeding device including a reading mechanism for reading an image of a conveyed document is illustrated.

As the order of the description, the schematic structure of the document feeding apparatus will be described first with reference to FIG. 1, and then the structure of the sheet material conveying system for feeding the document to the reading position will be described with reference to the drawings.

In the document feeding apparatus shown in FIG. 1, the document placed on the document stacking tray 1 has its leading end abutted against a document stopper 2 and is fed from the lowest side by a substantially half-moon type feeding roller 3. And sent to the separating unit 5. Here, when it is difficult for the document to enter the separating section 5 on the downstream side,
The document pressing plate 4 is dropped and pressed from above the feeding roller 3 to assist the document feeding by the feeding roller 3. The originals sent to the separating unit 5 are separated and fed one by one from the bottom.

The originals separated and fed as described above are corrected for skew by the active rollers 6 and 7 which are respectively rotated by two independent driving means on the left and right in the width direction orthogonal to the conveying direction. , And is conveyed onto the platen glass 8 which is the reading position. And at the reading position,
The exposure lamp 9 exposes the image of the document being conveyed, and the reflected light (image light) is condensed on a photoelectric conversion element (not shown) such as CCD, and the image light is converted into an electric signal to obtain image information. To be The exposed document is discharged and conveyed by the discharge rollers 10 to 12 and returned to the document stacking tray 1 again.

Next, the structure of the sheet material conveying system for feeding the original to the reading position in the above-mentioned original feeding apparatus will be described with reference to FIGS. As shown in FIG. 2, the active rollers 6 and 7 that rotate independently in the left and right directions in the width direction orthogonal to the document conveying direction are rotationally driven by pulse motors 13 and 14 as drive means, respectively. Document detection sensors 15 to 18 as detection means are provided on the conveyance path of the document conveyed by the active rollers 6 and 7.
The document detection sensors 15 to 18 are arranged two each on the upstream side and the downstream side in the transport direction, and in order to measure the skew direction and skew amount of the document, the distances from the center of the transport path to the left and right are equal in the document width direction. Are located in each.

It should be noted that here, two document detection sensors 15 to 18 are arranged as detection means for detecting the document conveyed by the active rollers 6 and 7, respectively, on the upstream side and the downstream side in the conveyance direction. The present invention is not limited to this. For example, instead of the sensor, a CCD or the like may be used to detect the document. Further, although a pulse motor is illustrated as a driving means for rotationally driving the active rollers 6 and 7, the present invention is not limited to this.

As shown in FIG. 3, the document detecting sensor 15
Information detected by .about.18 is transferred to a counter unit 19 as a first calculating means for calculating the skew direction and skew amount of the document from the detected information. In the counter unit 19, the skew direction of the document is a binary value of "1" or "0" and is used as information indicating whether the document is skewed to the left or right. The time until the sensor detects the document is counted at a certain clock frequency f, and this count value is set as the skew amount of the document. Then, the skew direction and skew amount of the document calculated here are transmitted to the CPU 20 which is the control means of the present apparatus.

The CPU 20 stores the information on the skew direction and skew amount of the original document calculated as described above in the memory unit 21 which is a storage unit, and the skew direction and the skew direction accumulated in the memory unit 21. The skew displacement direction and skew displacement amount are calculated from the skew amount. Then, based on the skew displacement direction and the skew displacement amount, the motor drive pulse (driving frequency) is varied so that the document transport speed of the active rollers 6 and 7 is constant on both sides in the width direction. It controls 14 drives.

A method of calculating the skew displacement direction and the skew displacement amount from the skew direction and the skew amount of the original when the active rollers 6 and 7 are conveyed will be described with reference to FIG. First, the upstream skew angle α and the downstream skew angle β are calculated from the skew amount (count value) measured by the detection signals of the upstream and downstream document detection sensors 15 to 18 on the transport path. . The skew angles α, β are yu, y obtained from the product of the clock frequency f, the document conveyance speed v, and the skew amount.
d, calculated using the distance x between the left and right sensors. Therefore,
The skew displacement amount S is a length in which the document is displaced by an angle θ (= β−α) due to the difference between the roller diameters of the left and right active rollers.
It is obtained from the following formula (1).

S = (2πa / x) × (x ² + yu ² ) ^1/2 × (θ / 360) (1)

Further, in order to obtain the skew displacement direction, first, the skew directions represented by the binary values of "1" and "0" are integrated and the average value is obtained, and the upstream side and the downstream side on the conveying path, respectively. Use to find out which direction you are skewing. Then, the skew displacement direction indicating which direction the displacement is from the calculated skew direction is obtained. This makes it possible to know which of the left and right active rollers is worn. And
Assuming that the distance D between the sensors on the upstream side and the downstream side is substantially equal to the circumference of the active roller, the roller diameter Rn on the worn side
Is obtained from the following equation (2) using the roller diameter Ro before wear and the skew displacement amount S calculated using the above equation (1).

Rn = (Ro / 2) −S / 2π (2)

Also, in order to prevent the original from skewing,
The drive frequency fn newly given to the motor by the CPU is
It can be obtained from the following equation (3) using the drive frequency fo given before the abrasion.

Fn = Ro × fo / Rn (3)

Next, drive control of the sheet conveying system having the above configuration will be described with reference to FIG. The original conveyed by the active rollers 6 and 7 is first detected by the sensor whose leading end is on the leading side (step S1).
1), as described above, the skew direction Dn of "1" or "0"
Is obtained (step S12). The counter section 19 starts counting at the same time when the leading edge of the leading side of the document is detected, and counting is performed until the trailing side sensor detects the leading edge of the trailing side of the document. The counting ends at the same time as the detection of the row side tip (step S13). As a result, the skew amount Sn, which is the count value, is obtained (step S14). This operation is performed by the document detecting sensors 15 to 18 on the upstream side and the downstream side, and the obtained skew direction Dn is obtained.
And the skew feed amount Sn are transmitted to the CPU 20.

The CPU 20 controls the skew direction Dn and the skew amount Sn.
When receiving, the integrated value D in the skew direction and the integrated value S of the skew amount up to the previous time are read from the memory unit 21, and the skew direction Dn and the skew amount Sn of this time are respectively set to the integrated values D and S. The added value is added to the memory unit 19 as new integrated values D and S.
To be stored. At the same time, 1 is added to the number N of originals up to the previous time, the number of data of the integrated values D and S is stored, and the above-described skew direction is reached until the preset number U of originals is reached.
The skew amount and the number of originals are integrated (step S1)
Five). When the number N of originals reaches the preset number U of originals (step S16), the skew direction, the skew amount, and the number of originals accumulated from the memory unit 21 are read out. Then, the skew displacement direction and the skew displacement amount are calculated (step S17).

A worn active roller is detected from the calculated skew displacement direction, and a drive frequency (motor drive pulse) given to a pulse motor for rotationally driving the worn active roller is detected based on the skew displacement amount. Is changed (step S18). In FIG. 5, the roller diameter Ro before wear is about 20 mm and the driving frequency f
The roller diameter Rn and the driving frequency fn with respect to the skew displacement amount when o is about 5000 pps are shown. In this apparatus, several tables shown in FIG. 5 are set, the driving frequency of the pulse motor is changed according to the skew displacement amount, and the document conveyance speed by the active rollers 6 and 7 is changed in the left and right direction in the width direction. It is controlled to be constant.

As described above, each pulse motor that rotationally drives the left and right active rollers 6 and 7 that independently rotate.
Since the rotational speeds of 13 and 14 are controlled, the document conveyance speed by the active roller worn by long-term use becomes constant on both sides in the width direction, and the document skew can be prevented. Therefore, a stable read image can always be obtained without affecting the image read by the image reading unit.

[Other Embodiments] In the above-described embodiment,
Change the drive frequency of the pulse motor that drives the worn-side active roller based on the calculated skew displacement amount,
Although the document conveyance speed by the left and right active rollers is configured to be constant, in addition to this configuration, for example, when the calculated skew displacement amount is larger than a preset value (skew displacement amount), the operator May be configured to issue a warning. This allows the operator to be notified of the time to replace the active roller.

Further, in the above-mentioned embodiment, the document feeding apparatus provided with the reading mechanism for reading the image of the conveyed original document is exemplified as the sheet material conveying apparatus to which the present invention is applied, but the present invention is not limited to this. Instead, in an image forming apparatus such as a copying machine or a facsimile machine, a sheet material conveying means for feeding a document as a sheet material to the image reading section or a sheet material conveying means for feeding a recording medium as a sheet material to the image forming section is provided. Even if the invention is applied, the same effects as the above effects can be obtained.

[0027]

As described above, the skew displacement direction and the skew displacement amount of the sheet material conveyed by the independently rotating conveying means are calculated, and based on the skew displacement direction and the skew displacement amount. By controlling the rotation speed of each drive means for rotationally driving the conveying means, the conveying speed of the sheet material by the conveying means that is worn due to long-term use becomes constant on both sides of the sheet material in the width direction, and the sheet material is skewed. Can be prevented.

When the calculated skew displacement amount is larger than the preset skew displacement amount, a warning is given to the operator so that the conveying means (roller) worn by the operator can be prevented. You can tell when to replace.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a document feeding device including a document flow reading mechanism.

FIG. 2 is a schematic configuration diagram of a document feeder according to the present invention.

FIG. 3 is a block diagram showing a configuration of a control system of the document feeding apparatus according to the present invention.

FIG. 4 is a flowchart showing a control operation of the document feeding apparatus according to the present invention.

FIG. 5 is a chart showing a roller diameter of an active roller and a driving frequency of a pulse motor with respect to a skew displacement amount.

[Explanation of symbols]

 1 ... Original Loading Tray 2 ... Original Stopper 3 ... Feeding Roller 4 ... Original Pressing Plate 5 ... Separation Part 6, 7 ... Active Roller 8 ... Platen Glass (Reading Position) 9 ... Exposure Lamp 10-12 ... Ejection Roller 13, 14 ... Pulse motors 15 to 18 ... Document detection sensor 19 ... Counter unit 20 ... CPU 21 ... Memory unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatoshi Yaginuma 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A conveyance unit that independently rotates on both sides on the same axis in the width direction orthogonal to the conveyance direction of the sheet material, a detection unit that detects the sheet material conveyed by the conveyance unit, and the detection unit. The first calculation means for calculating the skew direction and the skew amount of the sheet material from the detection information by the storage means, the storage means for storing the skew direction and the skew amount calculated by the first calculation means, and the storage means. Second calculation means for calculating the skew displacement direction and skew displacement amount of the sheet material during transportation of the transport means from the accumulated skew direction and skew amount, and the skew calculated by the second calculation means. A sheet material conveying device comprising: a control unit that controls the rotational speed of each drive unit that rotationally drives the conveying unit based on the displacement direction and the skew displacement amount. 2. The sheet material conveyance according to claim 1, wherein a warning is issued when the skew displacement amount calculated by the second calculating means is larger than a preset skew displacement amount. apparatus. 3. An image forming apparatus having image reading means for reading an image of a conveyed original, wherein the sheet material conveying device according to claim 1 or 2 is used as a conveying means for feeding the original to the image reading means. An image forming apparatus characterized by being provided. 4. The sheet material according to claim 1, which is an image forming apparatus having an image forming unit for recording and forming an image on a recording medium, and which serves as a conveying unit for feeding the recording medium to the image forming unit. An image forming apparatus comprising a conveying device.