JPH0687543A - Paper feeding device for recording device - Google Patents

Abstract

PURPOSE:To reduce loss time to a minimum at the switching time by performing the lift-up one cassette gradually during the stop of lift-up of the other cassette selected between two paper feeding cassettes disposed in vertical stages. CONSTITUTION:A lift-up unit formed of one motor, two one-way clutches, a gear train and the like lifts up recording paper in two paper feeding cassettes 10, 20 in vertical stages so as to be feedable in compliance with the normal/ reverse rotation of the motor. When the cassettes are set and the upper stage cassette is selected, a sensor 17 is turned off, so that the motor is rotated normally to start lift-up. When the sensor 17 is turned on, the feedable state is obtained. At the ready time, the sensor 17 is left off for 20-30 seconds. The motor is therefore rotated reversely at this time to perform lift-up in the lower stage, that is, the lift-up of the other cassette 20 is performed during the stop of lift-up of the selected cassette 10. This results in eliminating the generation of loss time due to a delay in the start of copying even with a switching command given.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to a paper feeding device in a recording device such as a light printing machine, and more particularly to a paper feeding device of a recording device in which a paper feeding cassette is detachably mounted in two upper and lower stages in a paper feeding portion of the recording device.

[0002]

2. Description of the Related Art Conventionally, in a recording device such as a copying machine,
The paper feeding unit of the recording apparatus has a two-stage structure, and recording papers having different paper sizes and paper qualities are separately stored in advance in a paper feeding cassette in each paper feeding unit, and each of these paper feeding cassettes has the above two-stage structure. It is mounted in the paper feed unit, and the desired paper is fed to the recording unit by selecting and switching the desired type of paper by button operation.

Here, as a method of lifting up a sheet to a state where it can be fed, a method of using one motor and one clutch is known. That is, a push-up member that swings and raises the recording paper in the paper feed cassette to a predetermined position, and an upper and lower two series that is connected to the drive shaft of one motor to transmit power to operate the push-up member. Drive system and each one one-way clutch provided in each drive system, the normal rotation of the motor pushes up the one lifting member, and the reverse rotation of the motor drives the other lifting member. A sheet feeding device has been developed which has a configuration selectively formed by pushing up (Japanese Patent Laid-Open No. 2-276736).

[0004]

In the above system, the same size sheets are stored in the upper and lower cassettes, and when the sheets in one of the cassettes are exhausted during copying, the sheet is automatically switched from the other cassette. In switching paper feed, the recording paper in the other cassette is not lifted up and is in a standby state, so even if a selection change instruction is given by button operation, copy start is not performed for the time to lift up and switching paper feed is performed. Occurrence of lost time was unavoidable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet feeding device that minimizes loss time at the time of switching when performing the above-described switching sheet feeding.

[0006]

In order to achieve the above object, according to the present invention, recording in which a paper feed cassette containing a plurality of recording papers is detachably mounted in two upper and lower stages in a paper feed section of a recording apparatus. In the switching paper feeding in the apparatus, the recording paper in the cassette not used for paper feeding of the two-stage paper feeding cassette is gradually lifted up when other cassettes are not performing the lift up operation, and switching is performed. It is configured to eliminate time lost as much as possible.

That is, the sheet feeding device of the recording apparatus of the present invention is a switching sheet feeding apparatus in which a sheet feeding cassette containing a plurality of recording sheets is detachably mounted in two upper and lower stages in a sheet feeding section of the recording apparatus. A paper feeding device according to the method,
The motor is provided with a lift-up unit as a mechanism that lifts up the recording paper in the paper feed cassette, which is mainly composed of one motor, two one-side clutches, and a gear train, to a forward / reverse direction of the motor. Corresponding to the above, when the recording sheets in the upper and lower two-stage sheet feeding cassettes are lifted up to the respective sheet-feedable states, one of the sheet feeding cassettes selected from the upper and lower two-stage sheet feeding cassettes is selected. When the recording paper is not lifted up, the paper feed control means is provided to control the recording paper in the other paper feed cassette to be gradually lifted up.

[0008]

The sheet feeding operation of the apparatus of the present invention constructed as above will be described.

First, the upper sheet feeder 100 and the lower sheet feeder 20
Set the paper to 0. The paper in the paper feed unit selected here is immediately lifted up until the upper limit detection sensor is turned on. During paper feeding, the number of paper sheets decreases, and the lift-up is performed every time the upper limit detection sensor is turned on.

The same applies to the lower sheet feeding section 200.

However, when the paper feed cassettes 10 and 20 are mounted on the main body of the apparatus, the two paper feed units cannot be lifted up at the same time.

In the present invention, in order to eliminate time loss, the paper feed cassette which is not selected during paper feed or standby is also lifted up.

That is, the motor of the lift-up unit does not always rotate for lifting the selected paper feed cassette. Upper limit detection sensor is OFF
The motor turns on only when you do. Therefore, while the lift-up of the selected paper feed cassette is stopped, the other paper feed cassettes are lifted up.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet feeding device of the present invention will be described with reference to FIGS.

These figures show the front loading system in which the paper feed cassette is attached to and detached from the front surface of the recording apparatus main body.

The upper sheet feeding section 100 is composed of a sheet feeding cassette 10, a lift plate 14, a lift shaft 15, a rotating plate 16, a sheet feeding roller 11, a reversing roller 12, a pick roller 13, an upper limit detection sensor 17 and the like.

Similarly, the lower sheet feeding section 200 also has a sheet feeding cassette 2.
0, lift plate 24, lift shaft 25, rotary plate 26,
Paper feed roller 21, reversing roller 22, pick roller 23,
It is composed of an upper limit detection sensor 27 and the like.

As shown in FIGS. 4 and 5, the lift-up unit 3 located in the middle of the sheet feeding cassettes 10 and 20.
There is 00. Here, 31 is a lift motor, 32, 34
Is a gear train, and 33 is a lift-up coupling. Further, 35 and 36 are one-way clutches.

The operation of the paper feeding apparatus of the present invention will be described with reference to the timing example shown in FIG. In this embodiment, the sensor ON-OFF time is about 20 to 30 seconds. Therefore, the reverse rotation time is set to 10 seconds.

First, when the sheet cassette is set and the upper stage is selected, the sensor 17 is turned off, so the motor 31 rotates in the normal direction to start the lift-up. When the sensor 17 is turned on, the sheet can be fed. The sensor remains off for 20 to 30 seconds even when the immediate paper feeding is started. Therefore, at this time, the motor 31 is reversed to lift up the lower stage. However, it is necessary to lift up the upper stage, so 1
It is not possible to feed paper with a single lift-up, and multiple times are required. The number of times also changes depending on the amount of paper stored. After the upper stage becomes ready to feed, if the paper feeding operation does not start immediately, the lower stage lift-up is started (when ready).

A method of controlling the sheet feeding device according to the present invention will be described by taking the sheet feeding standby state of the lower sheet feeding cassette in the sheet feeding mode from the upper sheet feeding cassette side as an example.

Next, the method of controlling the sheet feeding device of the present invention will be described with reference to the flowchart shown in FIG. First, the state of the paper is checked from the output signal of the upper limit detection sensor 17 (step 1). If the output of the sensor 17 is off, it means that the height of the sheet with respect to the sheet feeding roller is low, so that the process proceeds to (step 2) and the motor 31 is driven in the forward direction. When the sheet is fed by the forward rotation of the motor 31 and the sheet feed timing comes (step 3), the driving of the motor 31 is temporarily stopped by (step 4). This is because if the paper is pushed up from below during the paper feeding operation, that is, while the paper feeding roller is acting on the uppermost surface of the paper stack, the paper feeding state becomes unstable and a paper feeding error occurs.

Once the paper feeding is completed (step 5), the driving of the motor 31 is started again until the next paper feeding (step 6), and the above operation is repeated until the sensor 17 is turned on. (Since the checks from (step 3) to (step 6) are not directly related to the present invention, the paper push-up plate may be raised even during paper feeding except for some devices.) When the rise to the sheet feeding position is determined by the ON signal of the upper limit switch 17 (step 7), the normal rotation drive of the motor 31 is stopped (step 8).

In the routine from (step 1) to (step 8), the paper level state of the paper feeding cassette on the paper feeding operation side, that is, the paper feeding selected side is always maintained at a constant height. It has become.

In the above routine, when the paper height of the upper paper feed cassette is pushed up to the desired position, that is, when the motor 31 is stopped, the process proceeds from (step 1) to (step 9).

In step 9, the output of the upper limit detection sensor 27 of the lower paper feed cassette is checked to determine the state of pushing up the paper in the cassette. Sensor 2
If the output of 7 is turned on, it is determined that the sheet is pushed up, and the lower sheet cassette is returned to (step 1) without doing anything. If the output of the sensor 27 is not on, it is determined that the push-up plate of the lower-stage paper feed cassette is down, and the motor 31 is driven in reverse to push up the paper to the feedable state (step 10). Next, it is checked whether the sensor 27 is turned on (step 11), and when it is turned on (step 12), the motor 3 is turned on.
1 is stopped.

The motor 31 is driven in the reverse direction until the sensor 27 is turned on. However, by the time the sensor 27 is turned on, a signal indicating a decrease in the sheet level is output from the sensor 17 on the upper sheet feeding cassette side during sheet feeding. When you come (step 13),
After shifting to (step 14) to stop the reverse rotation of the motor 31, the process returns to (step 2) and returns to the routine for controlling the sheet height of the upper end sheet feeding cassette. When the height adjustment of the paper in the upper paper feed cassette is completed, the paper height adjustment of the lower paper feed cassette is performed again.

In the mode for selecting and feeding the lower paper cassette side, the control for raising the paper push-up plate of the upper paper feed cassette is performed in the same manner as described above. Therefore, as shown in FIG. The flow of the flowchart is the same,
Only the check destination of the sensor in each step and the drive rotation direction of the motor 31 are different.

Further, a block diagram of a control system for carrying out the above control is shown in FIG. 9. Usage Example Hereinafter, a usage example of the image forming apparatus provided with the sheet feeding device of the present invention will be described.

FIG. 10 is a sectional view showing the overall construction of a digital copying machine which is an example of a double-sided image forming apparatus equipped with a paper feeding device according to the present invention.

As shown in the drawing, the digital copying machine 30 is provided with a scanner unit 31, a laser printer unit 32, a multi-stage paper feeding unit 33 and a sorter 34.

The scanner unit 31 includes a document placing table 35 made of transparent glass and a double-sided automatic document feeder (RDF) 36.
And a scanner unit 40.

The multi-stage paper feeding unit 33 includes the first cassette 5
It has a first cassette 52, a second cassette 52, and a third cassette 53.

In the multi-stage sheet feeding unit 33, the sheets are fed out one by one from the sheets stored in the cassettes of the respective stages, and are conveyed toward the laser printer section 32.

The RDF 36 sets a plurality of originals at one time, automatically feeds the originals one by one to the scanner unit 40, and one side or both sides of the original is scanned by the scanner unit 40 according to an operator's selection. It is configured to be read by.

The scanner unit 40 exposes a document to a lamp reflector assembly 41, a plurality of reflection mirrors 43 for guiding a reflected light image from the document to a photoelectric conversion element (CCD) 42, and a reflected light image from the document to the CCD 42. It includes a lens 44 for imaging.

When scanning a document placed on the document placing table, the scanner section 31 is configured to read the document image while the scanner unit 40 moves along the lower surface of the document placing table. When using the RDF 36, the scanner unit 4 is placed at a predetermined position below the RDF 36.
The document image is read while the document is conveyed with 0 being stopped.

The image data obtained by reading the original image with the scanner unit 40 is sent to an image processing unit (not shown), which will be described later, and subjected to various processing, and then temporarily stored in the memory of the image processing unit. In response to the output instruction, the image data in the memory is given to the laser printer unit 32 to form an image on the paper.

The laser printer unit 32 includes a manual document tray 45, a laser writing unit 46, and an electrophotographic process unit 47 for forming an image.

The laser writing unit 46 is a semiconductor laser that emits a laser beam according to the image data from the above-mentioned memory, a polygon mirror that deflects the laser beam at a constant angular velocity, and a laser beam that is deflected at a constant angular velocity is an electrostatic photography process section. It has an f-θ lens and the like for correcting so as to deflect at a constant velocity on the photosensitive drum 48 of 47.

The electrophotographic process section 47 comprises a charging device, a developing device, a transfer device, a peeling device, a cleaning device, a static eliminator and a fixing device 49 arranged around the photosensitive drum 48 according to a known manner. .

A transport path 50 is provided downstream of the fixing 49 in the transport direction of the sheet on which the image is to be formed. The transport path 50 communicates with the transport path 57 leading to the sorter 34 and the multi-stage sheet feeding unit 33. It is branched to the transport path 58 which is open.

The conveying path 58 is branched in the multi-stage sheet feeding unit 33, and the reversing conveying path 5 is formed as a conveying path after branching.
0a and a double-sided / composite transport path 50b are provided.

The reverse conveyance path 50a is a conveyance path for reversing the front and back sides of a sheet in a double-sided copy mode for copying both sides of a document. The double-sided / composite conveying path 50b conveys a sheet from the reverse conveying path 50a to the image forming position of the photosensitive drum 48 in the double-sided copy mode, or forms an image of different originals or images of different colors on one side of the sheet This is a conveyance path for conveying the sheet to the image forming position of the photosensitive drum 48 without reversing the sheet in the single-sided composite copying mode for copying.

The multi-stage sheet feeding unit 33 includes a common conveyance path 56, and the common conveyance path 56 includes the first cassette 51 and the second cassette 51.
The sheets from the cassette 52 and the third cassette 53 are carried out toward the electrophotographic process section 47.

The conveying path 60 merges with the conveying path 61 from the double-sided / composite conveying path 50b and the manual document tray 45 at a confluence point 62 to form an image between the photosensitive drum 48 of the electrostatic photography process section 47 and the transfer device. The confluence point 62 of these three conveyance paths is provided at a position close to the image forming position.

Therefore, in the laser writing unit 46 and the electrophotographic process section 47, the image data read from the above-mentioned memory is the laser writing unit 46.
The toner image formed as an electrostatic latent image on the surface of the photoconductor drum 48 by scanning with a laser beam is visualized with toner, and the toner image is statically formed on the surface of the sheet conveyed from the multi-stage sheet feeding unit 33. It is electrotransferred and fixed. The sheet on which the image is thus formed is sent from the fixing device 49 to the sorter 34 via the transport paths 50 and 57, or is transported to the reverse transport path 50a via the transport paths 50 and 58.

The common transport path 56 is an example of the first transport path. The reverse conveyance path 50a and the double-sided / composite conveyance path 50b are examples of the second conveyance path. The first cassette 51, the second cassette 52, and the third cassette 53 are examples of a sheet feeding unit.

Next, the structure and function of the image processing unit included in the digital copying machine 30 will be described.

FIG. 11 is a block diagram of an image processing unit included in the digital copying machine 30 shown in FIG.

The image processing unit included in the digital copying machine 30 includes an image data input unit 70, an image processing unit 71, an image data output unit 72, a memory 73 including a RAM (random access memory), and a central processing unit. An arithmetic unit (CPU) 74 is provided. The image data input unit 70 includes a CCD unit 70a, a histogram processing unit 70b, and an error diffusion processing unit 70c.

The image data input section 70 is the CCD 42 of FIG.
Binary conversion of the image data of the original read from
While taking a histogram as a binary digital amount, the image data is processed by the error diffusion method and temporarily stored in the memory 73.

That is, in the CCD unit 70a, after the analog electric signal corresponding to the pixel density of the image data is A / D converted, MTF correction, black and white correction or gamma correction is performed.
It is output to the histogram processing unit 70b as a digital signal of 256 gradations (8 bits).

In the histogram processing section 70b, the digital signal output from the CCD section 70a is added for each pixel density of 256 gradations to obtain density information (histogram data), and if necessary, the obtained histogram data is It is sent from the CPU 74 or sent to the error diffusion processing unit 70b as pixel data.

In the error diffusion processing unit 70c, the CCD unit 70a is processed by an error diffusion method, which is a kind of pseudo intermediate processing, that is, a method in which a binarization error is reflected in the binarization judgment of adjacent pixels.
The digital signal of 8 bits / pixel output from is converted into 1 bit (binary), and the redistribution operation for faithfully reproducing the local area density in the original is performed.

The image processing unit 71 includes multi-valued processing units 71a and 71b, a synthesis processing unit 71c, a density conversion processing unit 71d, a scaling processing unit 71e, an image processing unit 71f, an error diffusion processing unit 71g and a compression processing unit 71h. Contains.

The image processing section 71 is a processing section for finally converting the input image data into image data desired by the operator, and until the image data is finally stored in the memory 73 as the converted output image data. The processing unit is configured to process. However, each of the above-mentioned processing units included in the image processing unit 71 functions as necessary and may not function.

That is, in the multi-valued processing units 71a and 71b, the data binarized by the error diffusion processing unit 70a is converted again into 256 gradations.

In the synthesizing section 71a, a logical operation for each pixel, that is, a logical sum, a logical product or an exclusive logical sum is selectively performed. The data to be calculated is the pixel data stored in the memory 73 and the bit data from the pattern generator (PG).

The density conversion processing section 71d arbitrarily sets the relationship between the input density and the output density for the 256-tone digital signal based on a predetermined gradation conversion table.

In the scaling processing unit 71e, the pixel data (density value) for the scaled target pixel is obtained by performing interpolation processing based on the input known data according to the designated scaling ratio. After the scanning is scaled, the main scanning is scaled.

In the image processing section 71f, various image processings may be performed on the input pixel data, and information collection such as feature extraction may be performed on the data string.

The error diffusion processing section 71g performs the same processing as the error diffusion processing section 70c of the image data input section 70.

In the compression processing section 71h, the binary data is compressed by the encoding called run length. Regarding the compression of image data, the compression functions in the final processing loop when the final output image data is completed.

The image data output unit 72 includes a restoration unit 72a, a multi-value quantization processing unit 72b, an error diffusion processing unit 72c, and a laser output unit 72d.

The image data output unit 72 restores the image data stored in the memory 73 in a compressed state to the original 2
It is configured to convert again to 56 gradations, perform error diffusion of 4-valued data that is a smoother halftone expression than binary data, and transfer the data to the laser output unit 72d.

That is, in the decompression unit 72a, the compression processing unit 72
The image data compressed by h is restored.

In the multi-value processing section 72b, the image processing section 71
Processing similar to that of the multi-value quantization processing units 71a and 71b is performed. In the error diffusion processing unit 72c, the image data input unit 70
Processing similar to that of the error diffusion processing unit 70c is performed.

In the laser output section 72d, the digital pixel data is converted into a laser on / off signal based on a control signal from a silence controller (not shown), and the laser is turned on / off.

The data handled by the image data input section 70 and the image data output section 72 is basically in the form of binary data in order to reduce the capacity of the memory 73.
Although it is stored in 3, 4 in consideration of deterioration of image data
It is also possible to process in the form of value data.

[Brief description of drawings]

FIG. 1 is a sheet feeding device of the invention.

FIG. 2 is a schematic diagram of a paper feeding device according to the present invention;

FIG. 3 is a lower stage lift-up of the sheet feeding device of the present invention.

FIG. 4 is a drive mechanism for the upper-stage paper feeding cassette of the paper feeding device of the present invention.

FIG. 5 is a drive mechanism of a lower sheet feeding cassette of the sheet feeding device of the present invention.

FIG. 6 is a timing chart of upper and lower sheet feeding lift-ups of the sheet feeding device of the present invention.

FIG. 7 is a flowchart of a control method during the upper sheet feeding operation.

FIG. 8 is a flowchart of a control method during a lower sheet feeding operation.

FIG. 9 is a block diagram of a control system of the present invention.

FIG. 10 is an image forming apparatus including the sheet feeding device of the invention.

11 is a block configuration diagram of an image processing unit of the image forming apparatus in FIG.

[Explanation of symbols]

 10, 20 Paper feed cassette 11, 21 Paper feed roller 12, 22 Reverse roller 13, 23 Pick roller 14, 24 Lift plate 15, 25 Lift shaft 16, 26 Rotating plate 17, 27 Sensor 31 Lift motor 32-34 Gear train 33 Lift-up coupling 35, 36 One-sided clutch 100 Upper feed unit 200 Lower feed unit 300 Lift-up unit

Claims (1)

[Claims] 1. A sheet feeding device of a switching sheet feeding system in a recording device in which a sheet feeding cassette containing a plurality of recording sheets is detachably mounted in two upper and lower stages in a sheet feeding portion of the recording device. Motor, two one-side clutches, and a lift-up unit as a mechanism for lifting up the recording paper in the paper feed cassette, which is mainly composed of a gear train, to a state in which the recording paper can be fed. Then, when the recording papers in the upper and lower two-stage paper feed cassettes are lifted up so that they can be fed, respectively, the recording papers in one of the upper and lower two-stage paper feed cassettes are selected. Of the other paper feeding cassette, the paper feeding control means is provided for controlling the gradual lifting of the recording paper in the other paper feeding cassette. Place