JP3927665B2 - Sheet transport device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus used in an image processing apparatus such as a copying machine, a laser beam printer, and a facsimile machine.
[0002]
[Prior art]
Conventionally, as a sheet conveying device in an image processing apparatus such as a copying machine, a laser beam printer, a facsimile machine, a scanner, etc., a separation belt that separates a feeding roller and a sheet, which prevents double feeding of a conveyed sheet, has a comb-like shape. In general, a comb-separated sheet conveying apparatus is generally used.
[0003]
The driving structure of the comb separation type sheet separating and conveying unit is such that the driving force from the driving mechanism is input to the driving shaft of the separation belt, and the driving force is transmitted to the feeding roller through one idler gear. The separation belt and the feeding roller rotate in the same direction to prevent double feeding of sheets. Further, the rotation speed of the feeding roller for separating and conveying is set so that the peripheral speed matches the sheet conveying speed.
[0004]
However, in the sheet separating / conveying section of the image processing apparatus as described above, the feeding roller and the sheet slip due to the difference in the thickness of the sheet to be conveyed, the friction coefficient between the front and back surfaces, and the like. May change and become slow, and the sheet may not arrive at the reading position or the recording position at a regular time.
[0005]
For the conventional example as described above, the conveyance speed of the sheet separation and conveyance unit is measured using a conveyance speed measurement sensor, and when the speed is lower than a predetermined speed, the drive mechanism of the sheet separation and conveyance unit is controlled to increase in speed. Accordingly, the conveyance delay due to the slip as described above is reduced, and the sheet can be conveyed to the reading position and the recording position at a regular time.
[0006]
[Problems to be solved by the invention]
However, in the sheet separating and conveying unit having the above-described configuration, when the friction coefficient on the surface of the rotation roller of the conveyance speed measurement sensor decreases due to problems such as durability, the rotation roller and the sheet slip, and the conveyance speed measurement sensor described above is In some cases, the conveyance speed could not be measured correctly.
[0007]
That is, when the rotation roller slips with respect to the sheet, the conveyance speed measurement sensor may determine that the actual conveyance speed is slow. At this time, since the drive mechanism of the sheet separation / conveyance unit is controlled to increase in speed, the sheet arrives at the reading position earlier than the normal time, or an excessive load is applied to the sheet separation / conveyance unit, and the life of the sheet separation / conveyance unit is reduced. It was also a cause of shortening.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a sheet conveying apparatus having a sheet conveying unit that conveys a sheet and a conveyance speed measuring unit that measures a conveyance speed of a sheet conveyed by the sheet conveying unit. a life judging means for judging the life of the speed measuring means, the transport speed measuring means is determined as the life by the life determination means, it has a display means for displaying that it should replace it, the conveying speed measuring means The light emitting means for emitting light, the light receiving means for receiving the light from the light emitting means, and rotating according to the movement of the sheet in contact with the sheet, and shielding the light from the light emitting means toward the light receiving means in a predetermined cycle consists rollers member, the life determination means, the number of the light on-off signals emitted by the rotation between the roller member advances a predetermined distance and tolerance By predetermined number of times is determined whether there is, there is provided a sheet conveying device, characterized in that the means for determining that it should be replaced the conveying speed measuring means, thereby, the conveying speed It is possible to accurately determine the life of the measuring means and replace it, and to prevent the occurrence of poor measurement of the sheet conveyance speed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
[0011]
FIG. 1 is a schematic sectional view of an entire image reading apparatus according to the present invention. The operations of the image reading unit 1 and the document conveying unit 2 of the image reading apparatus will be described with reference to this drawing.
[0012]
Reference numeral 3 denotes a stacking tray on which the document sheets S are stacked. When an instruction to start image reading is given, the exposure lamp 4 of the image reading unit 1 is turned on, the image reading preparation is started, and the paper feeding operation of the document conveying unit 2 is started. Is done.
[0013]
Then, the stacking tray 3 moves upward from the standby position where the lower limit sensor 5 detects the uppermost document sheet S until the uppermost original sheet S is detected to come into contact with the paper surface height sensor 6, and then stops.
[0014]
Then, when the pickup roller 7 comes into contact with the uppermost document sheet S and rotates, the document sheet S is sent out.
[0015]
The document sheet S sent out from the stacking tray 3 is separated from unnecessary document sheets S by the separation unit 8, and only one document sheet S is read by the drawing roller 9 and the transport rollers 10, 11, 12. It will be transported to.
[0016]
The image reading unit 1 is provided with a mechanism for reading an image on the document sheet S. That is, at the image reading point 13, the exposure lamp 4 is turned on to irradiate the original sheet S, and the reflected light is guided to the lens 18 by the mirrors 15, 16 and 17 through the contact lens 14, and the CCD sensor 19. The information is converted into an electrical signal and subjected to image processing through a known amplifier circuit or the like.
[0017]
Thereafter, the document sheet S is further conveyed downstream by the conveyance rollers 20, 21, and 22 and is discharged to the discharge tray 23.
[0018]
The above series of operations is repeated until all the original sheets S are exhausted. When all the original sheets S are exhausted, the stacking tray 3 is lowered to the standby position, the reading operation is finished, and the exposure lamp 4 is turned off.
[0019]
Here, reference numeral 24 denotes a leading edge detection sensor that detects that the leading edge of the original sheet has reached the transport position, and is provided at a position separated from the stacking tray by a predetermined distance.
[0020]
During the conveying operation of the original sheets S, the uppermost height of the original sheets on the stacking tray 3 is always kept constant.
[0021]
The uppermost document sheet S on the stacking tray 3 is provided with a conveyance speed measurement sensor 25 for measuring the conveyance speed. The configuration of the sensor 25 will be described below with reference to FIGS.
[0022]
2 to 4 are diagrams illustrating a configuration of the conveyance speed measurement sensor.
[0023]
In FIG. 2, reference numeral 251 denotes a rotating roller, which is composed of a core portion 251a, a roller portion 251b made of a rubber material, a disc portion 251c, and a hole portion 251d. Hole portions 251d are opened at predetermined intervals in the disc portion 251c. It is what.
[0024]
Reference numeral 252 denotes a rotating shaft of the rotating roller 251 and is rotatably supported by the holder 253 by the details 252b and the convex portion 252c shown in FIG.
[0025]
The holder 253 has a hole 253b in which the rotary shaft 252 is rotatably supported, and a slit is formed in the hole 253b so that the rotary shaft 252 can be fitted. ing.
[0026]
As a result, the rotating roller 251 can be removed from the holder 253 and can be replaced.
[0027]
A photosensor 254 is fixed to the holder 253 and detects the rotation of the disk portion 251c.
[0028]
Then, the disk portion 251c is driven to rotate in response to the conveying operation of the document sheet S, so that an on / off signal is output to the CPU 26 by the photo sensor 254, whereby the conveying speed of the document sheet S is measured. .
[0029]
FIG. 5 is a perspective view showing the configuration of the paper feed unit around the pickup roller 7.
[0030]
Based on FIG. 5, the configuration around the pickup roller 7 will be described.
[0031]
The pickup roller 7 is rotatably attached to an arm 27, and this arm 27 is rotatably attached to a shaft 28.
[0032]
In addition, the driving force of the paper feed driving motor 31 is transmitted to the pickup roller 7 via the driving belts 29 and 30.
[0033]
Reference numeral 32 denotes a rotation support lever, which is rotatable about a shaft 33. The power of the vertical drive motor 35 is transmitted by the drive belt 34, and the pickup roller 7 is driven up and down in the direction of arrow L. Has been. That is, when not feeding paper, the rotation support lever 32 raises the arm 27 by the vertical drive motor 35 and holds the arm 27 at the standby position. When feeding paper, the rotation support lever 32 lowers the arm 27 to the paper feeding position. The sheet is held and fed by bringing the pickup roller 7 into contact with the original sheet.
[0034]
The conveyance speed measurement sensor 25 described above is upstream of the conveyance direction (arrow B direction) of the document sheet S and prevents skew due to the load of the rotating roller 251 during conveyance of the document sheet S. It is provided substantially at the center in the vertical direction with respect to the transport direction.
[0035]
Next, based on FIG. 6 thru | or FIG. 8, the lifetime determination of the rotating roller 251 of the said conveyance speed measurement sensor 25 based on this invention is demonstrated in detail.
[0036]
FIG. 6 is a diagram illustrating a configuration of a control circuit for determining the life of the rotating roller 251.
[0037]
When the CPU 26 gives a rotation drive command to the motor driver 31a, the motor driver 31a gives a pulse signal to the paper feed drive motor 31 to drive the pickup roller 7 to rotate.
[0038]
Thereafter, the output of the conveyance speed measurement sensor 25 and the output of the leading edge detection sensor 24 are taken into the CPU 26 and stored in the RAM 36 along with the conveyance operation of the original sheet S. The ROM 37 stores a program shown in a flowchart described later.
[0039]
FIG. 7 is a diagram showing an output signal of the control circuit shown in FIG.
[0040]
First, when a paper feed start signal is output from the CPU 26, a motor driver output pulse is output from the motor driver 31a to the paper feed drive motor 31, the pickup roller 7 is rotated, and the original sheet S on the stacking tray 3 is conveyed. The
[0041]
When the leading edge of the conveyed document sheet S reaches the leading edge detection sensor 24, the signal output value changes from low to high.
[0042]
Here, for example, the distance X from the wall 3 a of the stacking tray 3 to the leading edge detection sensor 24 is 40 mm, the diameter of the pickup roller 7 is 30 mm, and there is no increase / decrease from the paper feed drive motor 31 to the pickup roller 7. Assuming that the motor 31 rotates 1.8 ° per pulse, the pickup roller 7 conveys and moves the original sheet S 0.47 mm (30 mm × π × 1.8 ° / pulse ÷ 360 °) per pulse. Thus, 85 pulses (40 mm ÷ 0.47 mm / pulse) are output to the paper feed drive motor 31 while the leading edge of the document sheet S reaches the leading edge detection sensor 24 from the stacking tray 3.
[0043]
Then, assuming that the diameter of the rotating roller 251 of the conveyance speed measuring sensor 25 is 30 mm and the disk portion 251c has 15 ° hole portions 251d at intervals of 30 °, the document sheet S is placed on the stacking tray 3. 7 is rotated by 152.8 ° (40 mm ÷ 30 mm ÷ π × 360 °) during the 40 mm conveyance from the leading edge detection sensor 24 to the leading edge detection sensor 24. Therefore, the encoder output 1 shown in FIG. Thus, during this time, high and low are repeated 5 times (152.8 ° ÷ 30 °).
[0044]
However, as described above, when the number of original sheets S to be fed increases and the service life approaches, slip occurs between the rotary roller 251 and the original sheet S due to a decrease in the friction coefficient of the rubber surface of the rotary roller 251 and the like. Will come to do. The encoder output 2 shown in FIG. 7 shows this state, and the waveform is not constant. In the normal state, the encoder output 1 is output five times during the distance of 40 mm when the document sheet S reaches the leading edge detection sensor 24. While it repeats high and low one by one, it only repeats four times.
[0045]
If it can be determined that such a phenomenon is different from a sudden one, it can be determined that the life of the rotating roller 251 is reached, and the above-described problems can be solved by replacing the rotating roller 251.
[0046]
The flowchart for that will be described below.
[0047]
FIG. 8 is a flowchart for determining the life of the rotating roller of the conveyance speed measuring sensor, and is stored in the ROM 36 of the control circuit shown in FIG.
[0048]
First, for example, assuming that the configuration of the conveyance speed measurement sensor 25 is set under the above-described conditions, the encoder output 1 repeats five highs and lows during the distance X. Is stored in the ROM 37. Although this allowable value stores the number of pulses, the pulse width may be stored and the difference may be compared.
[0049]
In consideration of the fact that the above-mentioned sudden phenomenon occurs at a probability of about 1 / 100,000, the case where the number of times that the measured value of the encoder output is different from the allowable value occurs three times or more is sudden. This is also set in the counter 38 as the number of times of life determination so as to be determined and excluded. (Note that it is sufficient to make three judgments based on the probability that a sudden phenomenon will occur.)
[0050]
When the life determination start signal is input to the CPU 26, the life determination flowchart shown in FIG. 8 is started. In step 81, the measured encoder output value is compared with the allowable value 5 stored in the ROM 37. To do.
[0051]
Next, it is determined in step 82 whether or not the actually measured value of the encoder output value is different from the allowable value. If there is a difference, the process proceeds to step 83 to perform a normal reading operation sequence and the process is terminated.
[0052]
If there is a difference from the allowable value, the counter value is incremented by 1 in step 84, and it is determined in step 85 whether or not the counter value exceeds the threshold value (3). Returning to step 81, in step 82, it is determined whether the encoder output value is different from the allowable value.
[0053]
If it is determined in step 85 that the counter value exceeds the threshold value (3), a display prompting replacement of the rotating roller 251 is displayed on the display 39 in step 86, and the apparatus main body is displayed in step 87. Stop and exit. As a result, the operator or service person can know the life of the rotating roller and can be replaced.
[0054]
By the operation described above, it is possible to accurately determine the life of the rotation roller of the conveyance speed measurement sensor, distinguishing it from a sudden phenomenon, and to prevent an excessive load on the sheet separation and conveyance unit. Can do.
[0055]
【The invention's effect】
As described above, according to the present invention, the service life of the roller member of the conveying speed measuring means to determine the constant, since it is configured to perform the display prompting the replacement, be exchanged for accurately roller member In addition to this, it is possible to prevent the occurrence of a measurement failure of the conveyance speed of the original sheet, and to prevent an excessive load on the drive mechanism of the sheet separation and conveyance unit. it can.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an entire image reading apparatus according to the present invention.
FIG. 2 is a diagram illustrating a configuration of a conveyance speed measurement sensor according to the present invention.
FIG. 3 is a diagram showing a configuration of a conveyance speed measurement sensor according to the present invention.
FIG. 4 is a diagram showing a configuration of a conveyance speed measurement sensor according to the present invention.
FIG. 5 is a diagram showing a configuration around a pickup roller of the image reading apparatus of the present invention.
FIG. 6 is a diagram showing a configuration of a control circuit for determining the life of a rotating roller of a conveyance speed measuring sensor according to the present invention.
7 is a diagram showing an output signal of the control circuit shown in FIG. 6;
FIG. 8 is a flowchart for determining the life of a rotating roller of a conveyance speed measurement sensor according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image reading part 2 Original conveyance part 3 Stack tray 4 Exposure lamp 5 Lower limit sensor 6 Paper surface height sensor 7 Pickup roller 8 Separation part 9 Pull-out roller 10 Conveyance roller 11 Conveyance roller 12 Conveyance roller 13 Image reading point 14 Contact lens 15 Mirror 16 Mirror 17 Mirror 18 Lens 19 CCD
20 Conveying roller 21 Conveying roller 22 Conveying roller 23 Discharge tray 24 Tip detection sensor 25 Conveying speed measuring sensor 251 Rotating roller 252 Rotating shaft 253 Holder 254 Photo sensor

Claims (3)

In a sheet conveying apparatus having sheet conveying means for conveying a sheet, and conveying speed measuring means for measuring the conveying speed of a sheet conveyed by the sheet conveying means,
A life determining means for determining the life of the transport speed measuring means;
The conveyance speed measuring means is determined as the life by the life determination means, it has a display means for displaying that it should replace it,
The transport speed measuring means includes: a light emitting means that emits light; a light receiving means that receives light from the light emitting means; a light that contacts the sheet and rotates according to the movement of the sheet; Consists of a roller member that shields in a predetermined cycle,
The life determination means determines the number of times that the on / off signal of light emitted by rotation while the roller member travels a predetermined distance is different from a permissible value, thereby determining the conveyance speed measurement means. A sheet conveying apparatus characterized by being a means for determining that the sheet should be replaced . 2. The sheet conveying apparatus according to claim 1 , further comprising a stacking unit for stacking sheets, wherein the transport speed measuring unit is arranged on the uppermost sheet stacked on the stacking unit. The life judgment unit, a sheet conveying apparatus according to claim 1, characterized in that it comprises means for determining that it should replacement of the conveying speed measuring means by determining the life of the roller member.

Images