JP4117783B2 - Image forming apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an image forming apparatus.
[0002]
[Prior art]
[Patent Document 1]
JP-A-9-212242 [Patent Document 2]
Japanese Patent Laid-Open No. 8-295438
As an image forming apparatus (or an image recording apparatus) such as a printer or a copying machine, for example, an ink jet recording apparatus or an image forming apparatus using an electrophotographic system is known. In such an image forming apparatus, paper (not limited to paper but includes OHP or the like, which means that an image can be formed and is also called a recording medium, a recording medium, or recording paper). In order to convey the sheet with high accuracy, as described in [Patent Document 1] and [Patent Document 2], the sheet is electrostatically attracted to the charged conveying belt and conveyed to maintain the flatness of the sheet. What is known to be able to be conveyed is known.
[0004]
In addition, as described in [Patent Document 1] and [Patent Document 2], there is a paper feeding method for the conveyance belt that enables so-called manual feeding.
[0005]
[Problems to be solved by the invention]
By the way, in the image forming apparatuses described in the above [Patent Document 1] and [Patent Document 2], the manual sheet feeding is not sufficiently accurate because the user manually inserts the sheet, and the sheet is slanted. There is a problem that it is difficult to accurately feed a sheet by feeding it accurately, such as being fed.
[0006]
The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus capable of performing accurate sheet conveyance during manual sheet feeding.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, an image forming apparatus according to the present invention includes a conveyance belt that conveys a sheet, a charging unit that charges the conveyance belt, and a manual sheet feeding unit that manually feeds the sheet. In the image forming apparatus, when the manual feeding is instructed, the conveying belt is rotated and charging of the conveying belt by the charging unit is started, and a charging area by the charging unit is transferred from the manual feeding unit to the sheet. The conveyance belt is stopped after the paper feeding position at which paper is fed .
[0008]
Here, it is possible to detect the sheet of the manual sheet feeding unit when manual sheet feeding is instructed, and to start charging the conveyance belt by the charging unit when no sheet is detected . Also, performs detection of a sheet of the manual sheet feeding means after stopping of the conveyor belt, when detecting the paper sheet to be manual paper feed rotates the conveyor belt after a predetermined after the detection time to the conveyor belt by the charging means It can be configured to start charging and sheet conveyance . Further, it is possible to wait until the start of image formation is instructed in a state where feeding of manually fed paper is stopped. Further, when manual paper feeding is instructed, it is possible to provide a means for displaying when a paper is detected by the manual paper feeding means. Furthermore, it can be configured such that charging can be performed both during forward rotation and reverse rotation of the conveyor belt.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory side view for explaining the overall configuration of an ink jet recording apparatus showing an example of an image forming apparatus according to the present invention, FIG. 2 is an explanatory plan view of the main part of the recording apparatus, and FIG. It is explanatory drawing.
[0010]
In this ink jet recording apparatus, a carriage 3 is slidably held in a main scanning direction by a guide rod 1 and a guide rail 2, which are guide members horizontally mounted on left and right side plates (not shown), and a timing belt 5 is held by a main scanning motor 4. 2 is moved and scanned in the direction indicated by the arrow (main scanning direction) in FIG.
[0011]
The carriage 3 includes a plurality of recording heads 7 that are image forming means including four inkjet heads that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward.
[0012]
As an ink jet head constituting the recording head 7, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like as an energy generating means for discharging ink can be used.
[0013]
The carriage 3 is also equipped with sub-tanks 8 for each color for supplying ink of each color to the recording head 7. Ink is supplied to the sub tank 8 from a main tank (ink cartridge) via an ink supply tube (not shown).
[0014]
On the other hand, as a paper feeding unit for feeding the paper 12 stacked on the paper stacking unit (pressure plate) 11 such as the paper feeding cassette 10, a half-moon roller (separately feeding the paper 12 one by one from the paper stacking unit 11) A separation pad 14 made of a material having a large friction coefficient is provided facing the sheet feeding roller 13 and the sheet feeding roller 13, and the separation pad 14 is urged toward the sheet feeding roller 13 side.
[0015]
As a transport unit for transporting the paper 12 fed from the paper feed unit on the lower side of the recording head 7, a transport belt 21 for transporting the paper 12 by electrostatic adsorption, and a paper feed unit A counter roller 22 for transporting the paper 12 fed through the guide 15 between the transport belt 21 and the paper 12 fed substantially vertically upward is turned approximately 90 ° and copied onto the transport belt 21. A conveying guide 23 for adjusting the pressure and a tip pressing roller 25 urged toward the conveying belt 21 by a pressing member 24. In addition, a charging roller 26 as a charging unit for charging the surface of the transport belt 21 is provided.
[0016]
Here, the conveyance belt 21 is an endless belt, is stretched between the conveyance roller 27 and the tension roller 28, and the conveyance roller 27 rotates from the sub-scanning motor 31 via the timing belt 32 and the timing roller 33. By doing so, it is configured to circulate in the direction indicated by the arrow in FIG. 2 (belt conveyance direction).
[0017]
This transport belt 21 is a surface layer that is a sheet adsorbing surface formed of a resin material having a pure thickness of about 40 μm that is not subjected to resistance control, for example, ETFE pure material, and resistance control by carbon is performed using the same material as the surface layer. It has a back layer (medium resistance layer, ground layer).
[0018]
Further, the conveyance roller nip portion 18 is formed by the conveyance roller 27 and the counter roller 22, and the sheet detection sensor 16 that detects the sheet 12 is disposed at a predetermined position upstream of the conveyance roller nip portion 18 in the sheet conveyance direction. . The paper detection sensor 16 detects the paper 12 by displacing the detection lever 17 by the paper 12 (the position indicated by the broken line in FIG. 1 is the ON position). The paper detection sensor 16 is for detecting paper feed.
[0019]
The charging roller 26 is disposed so as to contact the surface layer of the conveyor belt 21 and rotate following the rotation of the conveyor belt 21, and applies 2.5N to both ends of the shaft as a pressing force. Further, the transport roller 27 also serves as an earth roller, and is placed in contact with the middle resistance layer (back layer) of the transport belt 21 and is grounded.
[0020]
Further, a guide member 36 is disposed on the back side of the conveyance belt 21 so as to correspond to a printing area by the recording head 4. The upper surface of the guide member 36 protrudes toward the recording head 7 from the tangent line of the two rollers (the conveyance roller 27 and the tension roller 28) that support the conveyance belt 21. As a result, the conveying belt 21 is pushed up and guided on the upper surface of the guide member 36 in the printing region.
[0021]
In order to detect the leading edge of the paper 12 conveyed by the conveying belt 21, the carriage 3 is provided with a paper sensor 41 made up of a reflective photosensor as detection means, as shown in FIG. The paper sensor 41 is provided at a position where the paper 12 can be detected upstream of the recording position (printing area) by the recording head 7 in the paper transport direction. Further, the sheet sensor 41 is provided on the side positioned on the recording area side (conveying belt 21 side) when the carriage 3 is at the home position (the position indicated by the solid line in FIG. 3).
[0022]
Further, as shown in FIGS. 1 and 3, an encoder scale 42 having slits is provided on the front side of the carriage 3, and a transmission type photosensor that detects the slits of the encoder scale 42 is provided on the front side of the carriage 3. An encoder 44 for detecting the position of the carriage 3 in the main scanning direction (position with respect to the home position) is configured.
[0023]
Further, as a paper discharge unit for discharging the paper 12 recorded by the recording head 7, a separation unit for separating the paper 12 from the conveyance belt 21, a paper discharge roller 52 and a paper discharge roller 53, and paper discharge And a paper discharge tray 54 for stocking the paper 12 to be stored.
[0024]
A double-sided paper feeding unit 61 is detachably mounted on the back. The double-sided paper feeding unit 61 takes in the paper 12 returned by the reverse rotation of the transport belt 21, reverses it, and feeds it again between the counter roller 22 and the transport belt 21.
[0025]
Further, the upper surface of the double-sided paper feeding unit 61 is a manual paper feeding unit 62, and a manual feed sensor 63 that is a manual feed detecting unit for detecting paper manually fed is disposed on the manual paper feeding unit 62. ing.
[0026]
In the ink jet recording apparatus configured as described above, the paper 12 is separated and fed one by one from the paper feed unit, and the paper 12 fed substantially vertically upward is guided by the guide 15, and includes the transport belt 21 and the counter roller 22. The leading end is guided by the conveying guide 23 and pressed against the conveying belt 21 by the leading end pressing roller 25, and the conveying direction is changed by approximately 90 °.
[0027]
At this time, a positive output and a negative output are alternately repeated from the high voltage power source to the charging roller 26 by a control circuit (not shown), that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 21 is alternating, that is, In the sub-scanning direction, which is the circumferential direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 12 is fed onto the conveyance belt 21 charged alternately with plus and minus, the charge is polarized in the opposite direction to the charge pattern in the paper 12, so that a capacitor connected in parallel is formed. 12 is adsorbed by the conveyance belt 21, and the paper 12 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 21.
[0028]
Therefore, by driving the recording head 7 according to the image signal while moving the carriage 3, the ink droplets are ejected onto the stopped paper 12 to record one line, and after the paper 12 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 12 has reached the recording area, the recording operation is finished and the paper 12 is discharged onto the paper discharge tray 44.
[0029]
In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 12 is fed into the double-sided paper feeding unit 61 by rotating the conveyor belt 21 in the reverse direction. The paper 12 is reversed (with the back surface being the printing surface), fed again between the counter roller 22 and the transport belt 21, controlled in timing, and transported onto the transport bell 21 as described above. Then, after recording on the back surface, the paper is discharged onto the paper discharge tray 44.
[0030]
Next, an outline of the control unit of the ink jet recording apparatus will be described with reference to FIG. FIG. 4 is an overall block diagram of the control unit.
The control unit includes a printer controller 70, a motor driver 81 for driving the main scanning motor 4 and the sub-scanning motor 31, and a driver 82 for driving a high-voltage circuit 82 that applies a charging high voltage to the charging roller 26. Although not shown, a driver for driving a paper feed clutch for transmitting the rotation of the sub-scanning motor 31 to the paper feed roller 13 and a head driver (head drive circuit) for driving the recording head 7 (inkjet head). , Composed of a driver IC) 84 and an operation panel 85 for performing various instructions and display.
[0031]
The printer controller 70 is an interface (hereinafter referred to as “I”) that receives print data and the like from a host side such as an information processing device such as a personal computer, an image reading device such as an image scanner, and an imaging device such as a digital camera. / F ") 72, a main control unit 73 including a CPU, a RAM 74 for storing various data, a ROM 75 for storing various data processing routines, and the drive waveform for the recording head 7. A drive signal generation circuit 77 to be generated, an I / F 78 for transmitting print data and drive waveforms developed in dot pattern data (bitmap data) to the head driver 84, and motor drive data to the motor driver 81 In addition, on / off and polarity of the high-voltage output from the high-voltage circuit 82 I / F 79 for transmitting control data for control to the high-voltage circuit 82, transmission / reception of information to / from the operation panel 85, and input of detection signals from the encoder 44 and various sensors 16, 41, 63 / F80 etc.
[0032]
The RAM 74 is used as various buffers and work memory. The ROM 75 stores various control routines executed by the main control unit 73, font data, graphic functions, various procedures, and the like.
[0033]
The main control unit 73 performs paper feed control based on the detection signal from the paper detection sensor 16. The main control unit 73 detects the position of the carriage 3 in the main scanning direction based on the output signal of the encoder 44 and controls the stop position of the carriage 3, and the leading end position of the paper 12 based on the detection signal of the paper sensor 41. Detection and detection of the presence or absence of the paper 12 on the conveyor belt 21 are performed. Further, the main control unit 73 controls manual sheet feeding based on a detection signal of the manual sensor 63 and a manual instruction given from the host side or the operation panel 85.
[0034]
The main control unit 73 reads and analyzes the print data in the reception buffer included in the I / F 72, stores the analysis result (intermediate code data) in a predetermined area of the RAM 74, and stores the analysis result in the ROM 75. Using the stored font data, dot pattern data for outputting an image is generated and stored again in a different predetermined area of the RAM 74. Note that when image data is expanded into bitmap data and transferred to the recording apparatus by the printer driver on the host side, the received bitmap image data is simply stored in the RAM 74.
[0035]
Then, when the dot pattern data corresponding to one row of the recording head 7 is obtained, the main control unit 73 synchronizes the dot pattern data for one row with the clock signal CLK from the oscillation circuit 76 in order to obtain I Serial data is sent to the head driver 82 via / F78, and a latch signal is sent to the head driver 82 at a predetermined timing.
[0036]
The drive signal generation circuit 77 is a ROM (can also be configured by the ROM 75) storing pattern data of a drive waveform (drive signal), and a D / A for D / A converting the drive waveform data read from the ROM. It consists of a waveform generation circuit including a converter, an amplifier, and the like.
[0037]
The head driver 82 is a shift register that receives a clock signal from the main control unit 73 and serial data that is a print signal, a latch circuit that latches a register value of the shift register using a latch signal from the main control unit 73, and a latch circuit A level conversion circuit (level shifter) that changes the output value of the signal and an analog switch array (switch means) whose on / off is controlled by this level shifter, and driving waveform by controlling on / off of the analog switch array Are selectively applied to the head 7.
[0038]
Next, an outline of sheet feeding control by the main control unit 73 will be described with reference to FIGS.
First, processing in the case of paper feeding from the paper feed tray 10 will be described with reference to FIG. 5. The main control unit 73 rotationally drives the main scanning motor 4 prior to paper feeding to move the carriage 3 to the transport belt 21. Is moved to approximately the center of the sheet (or approximately the center of the sheet having the sheet size to be fed), and a sheet feeding clutch (not shown) is turned on to rotate the sub-scanning motor 31 to the sheet feeding roller 13. As a result, the paper feed roller 13 rotates once in the clockwise direction, and the paper 12 is separated from the paper feed tray 10 into one sheet by the friction pad 14 and sent out.
[0039]
Then, the detection signal of the paper sensor 41 is checked to determine whether or not the leading edge of the paper 12 has been detected, and the paper 12 is conveyed (fed) to a predetermined printing start position after the leading edge of the paper 12 is detected. Stop. At this time, the paper sensor 41 detects the leading edge of the paper 12 upstream of the printing area by the recording head 7 in the paper conveyance direction. Therefore, even if the detection position shift of the leading edge of the paper 12 occurs, the paper 12 is set to the printing start position. Therefore, even if printing is started from the leading edge of the paper 12, no erroneous printing is performed on the conveyance belt 21.
[0040]
Thereafter, the carriage 3 is temporarily returned to the home position, and the movement of the carriage 3 to the recording area side is started based on the output of the encoder 44 with reference to the home position. At this time, the detection signal of the paper sensor 41 is checked to check the paper. When the paper 12 is present, the required printing (recording operation) is performed. When the paper 12 is not detected, the recording operation is not performed. Thereby, since printing (ink droplet ejection) is not performed at a place where the paper 12 is not present, ink droplets are not ejected onto the transport belt 21, and contamination of the transport belt 21 and the paper 12 can be prevented.
[0041]
Next, the processing at the time of manual sheet feeding will be described with reference to FIG. 6. When the main controller 73 is instructed to manually feed paper from the host side or the operation panel 85, the manual sensor 63 is turned on (paper detection). If the manual feed sensor 63 is in the on state, an error is displayed on the host side through the printer driver on the host side, or an error is displayed on the display of the operation panel 65.
[0042]
As a result, when manual paper feeding is performed, it is possible to prevent a problem such as recording of the set paper when another paper (media) is already set in the manual paper feeding unit 62.
[0043]
Then, if the manual feed sensor 63 is turned on, by driving the charging roller 26 in together when starting the rotation of the conveyor belt 21 starts charging for the conveyor belt 21, charging area manual sheet feeder of the conveyor belt 21 62 The conveyance belt 21 is stopped when the paper feeding position is passed.
[0044]
In this way, by starting charging of the conveyor belt 21 in advance when manual feed is instructed, the manually fed sheet can be reliably adsorbed to the conveyor belt 21, and the paper at the time of manual feeding High-precision conveyance is possible.
[0045]
Then, it waits until the manual feed sensor 63 is turned on, and when the user inserts a sheet into the manual feed unit 62 and the manual feed sensor 63 is turned on, the setting is made within a predetermined time, for example, within a range of 1 to 3 seconds. It is determined whether or not the time has elapsed. When a predetermined time has elapsed, the conveyance belt 21 starts to rotate, and the manually fed paper is adsorbed to the conveyance belt 21 and conveyed. At this time, the conveying belt 21 is also charged by the charging roller 26.
[0046]
At this time, in the same manner as the normal paper feed control process described above (FIG. 5), the front end of the paper can be detected. When the front end of the manually fed paper is detected by the paper sensor 41, the transport belt 21 is moved. Stop.
[0047]
Then, it is determined whether or not the manual feed sensor 63 is in an on state. If the manual feed sensor 63 is in an on state, whether or not the start of printing is instructed through a printer driver on the host side or by an instruction means such as a switch on the operation panel 65. And waits until an instruction to start printing is given. At this time, if the manual feed sensor 63 is turned off, the sheet has been pulled out from the manual feed unit 62, and therefore the process returns to the determination process whether or not the manual feed sensor 63 is turned on again (manually fed). .
[0048]
As a result, when the paper is bent or not fed, the user can pull out the paper and retry the manual feeding again (retry) unless instructing to start printing. You will be able to do paper. Note that it is preferable to set the number of retries possible in advance.
[0049]
When the start of printing is instructed, the printing process is performed in the same manner as in the above-described normal paper feed control, and the paper is discharged.
[0050]
When such manual feed control is performed, the layout of the charging unit is not limited to the above embodiment, and the charging of the conveyor belt can be performed at the time of forward rotation and reverse rotation. The rotation direction of the conveyor belt can be freely determined.
[0051]
In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to a shuttle type ink jet recording apparatus using a carriage. However, the present invention can also be applied to a line type ink jet recording apparatus using a line type head. The present invention is not limited to this, and can also be applied to an image forming apparatus such as a copying machine, a facsimile machine, a copying machine / printer / facsimile machine composite machine, an image forming apparatus using an electrophotographic system, and the like.
[0052]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, when manual feeding is instructed, the conveying belt is rotated and charging of the conveying belt by the charging unit is started, and the charging area by the charging unit is manually inserted. Since the conveyor belt is stopped after the paper feeding position where the paper is fed from the paper feeding means to the conveyor belt , the paper can be accurately conveyed during manual feeding. ]
FIG. 1 is an explanatory side view showing an example of an image forming apparatus according to the present invention. FIG. 2 is an explanatory plan view of essential parts of the apparatus. FIG. 3 is an explanatory perspective view of essential parts of the apparatus. FIG. 5 is a flowchart for explaining an example of control in the case of normal paper feeding by the control unit. FIG. 6 is an example of control in the case of manual paper feeding by the control unit. Flow chart for explanation of [Description of sign]
DESCRIPTION OF SYMBOLS 3 ... Carriage, 7 ... Recording head, 10 ... Paper feed tray, 12 ... Paper, 13 ... Paper feed roller, 15 ... Guide, 16 ... Paper detection sensor, 21 ... Conveyor belt, 22 ... Counter roller, 26 ... Charging roller ( Charging means), 27 ... conveying roller, 28 ... tension roller, 41 ... paper sensor, 44 ... encoder, 62 ... manual paper feeder, 63 ... manual sensor.

Claims (6)

In an image forming apparatus comprising a conveyance belt for conveying a sheet, a charging unit for charging the conveyance belt, and a manual sheet feeding unit for manually feeding the sheet,
When manual feeding is instructed, the conveying belt is rotated and charging of the conveying belt by the charging unit is started .
The image forming apparatus , wherein the conveying belt is stopped when a charging area by the charging unit has passed a sheet feeding position where the sheet is fed from the manual sheet feeding unit to the conveying belt .   2. The image forming apparatus according to claim 1, wherein when the manual paper feeding is instructed, the paper of the manual paper feeding unit is detected, and when the paper is not detected, charging of the conveying belt by the charging unit is started. An image forming apparatus. 3. The image forming apparatus according to claim 1, wherein when the sheet of the manual sheet feeding unit is detected after the conveyance belt is stopped and the sheet manually fed is detected, a predetermined time elapses after the detection. An image forming apparatus, wherein the conveying belt is rotated and charging to the conveying belt by the charging unit and conveyance of a sheet are started . The image forming apparatus according to claim 1 , wherein the image forming apparatus waits until an instruction to start image formation is issued in a state where feeding of the manually fed paper is stopped. The image forming apparatus according to any one of claims 2 to 4, in that it comprises means for displaying to that effect when it detects a sheet on the manual sheet feeding means when the manual feed is instructed An image forming apparatus. The image forming apparatus according to any one of claims 1 to 5, the image forming apparatus characterized by capable of performing charging in either the forward rotation time and reverse rotation of the conveyor belt.

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