JP2007326257A - Image forming apparatus and position detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that when mist, dust or the like is adhered to a linear scale to result in erroneous detection, controlling of a carriage in a main scanning direction is disturbed, thereby lowering quality of an image. <P>SOLUTION: A linear encoder unit 200 is provided along the main scanning direction of the carriage 23. In the linear scale encoder 200, a linear scale 202 having a scale formed by printing thereon and an encoder sensor 203 constituted of a photosensor for reading the linear scale 202 are placed in a sealed space constituted of a cylindrical sealed vessel 201. The encoder sensor 203 is provided to be movable along with the movement of the carriage 23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a position detection apparatus.

  2. Related Art As an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, and a composite machine of these, for example, an ink jet recording apparatus is known as an image forming apparatus of a liquid discharge recording method using a recording head that discharges a recording liquid droplet. . This ink jet recording apparatus means a recording liquid (for example, ink droplets) conveyed from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). And recording medium or recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). There is a serial type in which the recording head moves in the main scanning direction.

In such an image forming apparatus, a linear scale stretched along the main scanning area of the carriage and an encoder for detecting the scale of the linear scale in order to control the moving amount and moving speed of the carriage as a moving body. A linear encoder configured with a sensor is provided, and drive control of a motor that drives the carriage is performed based on a signal output from the linear encoder in accordance with the movement of the carriage.
JP 2005-349799 A

  By the way, in the image forming apparatus of the serial type ink jet recording system as described above, a mist or the like may adhere to the linear scale to form an image by ejecting the recording liquid, and the carriage moves. If the linear scale for detecting is contaminated, the detection signal is disturbed and the movement (position and speed) control of the carriage is disturbed, so that the droplet landing accuracy is lowered and the image quality is lowered.

  Therefore, in the image forming apparatus described in Patent Document 1, a dust collecting electrode for collecting mist is provided, but the mist is completely collected so as not to adhere to the linear scale. There is a problem that is difficult.

  The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus and a position detection apparatus that prevent mist, dust, and the like from adhering to components of a linear encoder.

  In order to solve the above problems, the image forming apparatus according to the present invention includes a sealed container in which a linear scale and a sensor constituting an encoder are arranged in a sealed space.

  Here, the sealed container is a cylindrical member, the sealed container has a configuration in which a portion along the longitudinal direction can be opened and closed, the sealed container has positioning means for positioning both ends of the linear scale, and the sealed container The end portion may be provided with an opening / closing means for opening and closing the sealed state, and the closed container may be provided with a guide means for guiding the movement of the sensor.

  In addition, it can be configured to include a means for transmitting and receiving the sensor detection signal by electromagnetic waves, and a structure to include a means for transmitting and receiving the sensor detection signal by infrared. In these cases, the sealed container is formed of a non-metallic member. Preferably it is.

  Moreover, it can be set as the structure provided with the means which transmits / receives the detection signal of a sensor by wire, and it is preferable in this case that the space which a wire can move is formed in the airtight container.

  Further, the carriage and the sensor in the sealed container can be coupled by magnetic force, and the carriage and the sensor can be moved simultaneously by the same driving means. Further, the position of the carriage home position and the sensor home position can be confirmed every predetermined number of reciprocating movements. Further, the linear scale, the sensor, and the sealed container can be configured as a unit.

  The position detection device according to the present invention is configured to include a sealed container in which a linear scale and a sensor are arranged in a sealed space.

  According to the image forming apparatus according to the present invention and the position detection apparatus according to the present invention, the linear scale and the sensor in which the mist and dust constitute the encoder are provided with the sealed container in which the linear scale and the sensor are arranged in the sealed space. Can be reliably prevented from adhering to the surface.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus according to the present invention will be described with reference to FIGS. 1 is a schematic configuration diagram showing the overall configuration of the image forming apparatus, FIG. 2 is an explanatory plan view of an image forming unit and a sub-scanning conveying unit of the apparatus, and FIG. 3 is a perspective view of a carriage moving scanning mechanism portion of the apparatus. It is explanatory drawing.

  This image forming apparatus has an image forming part (means) 2 for forming an image, a sub-scanning conveying part (means) 3, etc. in the inside (enclosure) of the apparatus main body 1. A recording medium (hereinafter referred to as “paper”, but the material is not limited to paper) 5 serving as a transported member is separated and fed one by one from a paper feeding unit (means) 4 serving as a housing unit. Paper is formed and the sub-scanning conveyance unit 3 intermittently conveys the paper 5 at a position facing the image forming unit 2 while the image forming unit 2 ejects droplets onto the paper 5 to form (record) a desired image. After that, the paper 5 is discharged onto a paper discharge tray 7 formed on the upper surface of the apparatus main body 1 through the paper discharge conveyance unit 6. The image forming unit 2 and the sub-scanning conveyance unit 3 are unitized to form an engine unit 100 that is detachably attached to the apparatus main body 1.

  The image forming apparatus also has an image reading unit (scanner) for reading an image above the discharge tray 7 above the apparatus main body 1 as an input system for image data (print data) formed by the image forming unit 2. Part) 11. The image reading unit 11 includes a scanning optical system 15 including an illumination light source 13 and a mirror 14 and a scanning optical system 18 including mirrors 16 and 17. The scanned document image is read as an image signal by the image reading element 20 disposed behind the lens 19, and the read image signal is digitized and subjected to image processing, and the image-processed print data is printed. be able to. A pressure plate 10 is provided on the contact glass 12 for pressing the document.

  Here, as shown in FIG. 2, the image forming section 2 of the image forming apparatus is provided on a carriage guide (guide rod) 21 and a rear stay 101B which are horizontally mounted between the front plate 101F and the rear plate 101R. A guide stay (not shown) holds the carriage 23 movably in the main scanning direction, and the main scanning motor 27 moves and scans in the main scanning direction via a timing belt 29 spanned between the driving pulley 28A and the driven pulley 28B.

  On the carriage 23, recording heads 24k1 and 24k2 each composed of two droplet discharge heads for discharging black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y). A total of five droplet ejection heads, recording heads 24c, 24m, and 24y each composed of one droplet ejection head that ejects ink (when not distinguishing colors and collectively referred to as “recording head 24”), are included. A shuttle type is mounted, in which the carriage 23 is moved in the main scanning direction, and droplets are ejected from the recording head 24 while the paper 5 is fed in the paper transporting direction (sub-scanning direction) by the sub-scanning transport unit 3. Yes.

  In addition, a sub tank 25 is mounted on the carriage 23 in order to supply a recording liquid of a required color to each recording head 24. On the other hand, as shown in FIG. 1, recording liquid containing black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink from the front of the apparatus main body 1 to the cartridge mounting portion 26A. Each color ink cartridge 26 can be detachably mounted, and ink (recording liquid) is supplied from each color ink cartridge 26 to each color sub-tank 25 via a tube (not shown). The black ink is supplied from one ink cartridge 26 to the two sub tanks 25.

  The recording head 24 uses a piezoelectric element as a pressure generating means (actuator means) for pressurizing the ink in the ink flow path (pressure generation chamber) to deform the vibration plate that forms the wall surface of the ink flow path. A so-called piezo type that discharges ink droplets by changing the volume in the flow channel, or discharges ink droplets with a pressure generated by heating the ink in the ink flow channel using a heating resistor to generate bubbles. The so-called thermal type, the diaphragm that forms the wall surface of the ink flow path and the electrode are placed opposite to each other, and the diaphragm is deformed by the electrostatic force generated between the vibration plate and the electrode, thereby the ink flow path inner volume It is possible to use an electrostatic type or the like that discharges ink droplets by changing the above.

  Also, as shown in FIG. 3, a linear encoder unit 200 that is a position detection device according to the present invention is disposed between the front plate 101F and the rear plate 101R along the main scanning direction of the carriage 23. Based on a signal output from the linear encoder unit 200 according to the movement of the carriage 23, the main scanning motor 27 is driven and controlled, and the main scanning control of the carriage 23 is performed at a required speed and with a required moving amount.

  Further, as shown in FIG. 2, a maintenance / recovery mechanism (device) 121 for maintaining and recovering the nozzle state of the recording head 24 is disposed in the non-printing area on one side of the carriage 23 in the scanning direction. . The maintenance / recovery mechanism 121 is a cap member for capping each nozzle surface 24a of the five recording heads 24, and includes one suction cap 122a that also serves as a moisture retention, and four moisture retention caps 122b to 122e. A wiper blade 124, which is a wiping member for wiping the nozzle surface 24a of the recording head 24, and an idle ejection receiver 125 for performing idle ejection are disposed.

  Further, an idle ejection receptacle 126 for performing idle ejection is disposed in the non-printing area on the other side of the carriage 23 in the scanning direction. Openings 127 a to 127 e are formed in the idle discharge receptacle 126.

  The sub-scanning conveyance unit 3 includes a conveyance roller 32 and a tension roller that are driving rollers for conveying the paper 5 fed from below by facing the image forming unit 2 by changing the conveyance direction by approximately 90 degrees. An endless conveyance belt 31 that is stretched between the driven rollers 33, a charging roller 34 that is a charging unit to which an AC bias voltage that is an alternating voltage is applied to charge the surface of the conveyance belt 31, and a conveyance belt 31 The image is formed by the guide member 35 that guides the sheet 5 in the opposite region of the image forming unit 2, the pressing roller 36 that presses the paper 5 against the conveying belt 31 at the position facing the conveying roller 32, and the image forming unit 2. A separation claw 37 for separating the formed paper 5 from the transport belt 31 and a transport roller 38 for feeding the separated paper 5 to the paper discharge transport unit 6 are provided.

  The transport belt 31 of the sub-scan transport unit 3 is rotated in the paper transport direction (sub-scan direction) in FIG. 2 by rotating the transport roller 32 from the sub-scan motor 131 through the timing belt 132 and the timing roller 133. It is configured to do.

  The paper feeding unit 4 is detachable from the apparatus main body 1 and separates the paper 5 in the paper feeding cassette 41 one by one from the paper feeding cassette 41 which is a storing means for stacking and storing a large number of papers 5. A sheet feeding roller 42 and a friction pad 43 for feeding out, and a registration roller pair 44 for conveying the fed sheet 5 to the sub-scanning conveying unit 3 are provided. The sheet feeding roller 42 is rotated by a sheet feeding motor (drive source) 45 including an HB type stepping motor via a sheet feeding clutch (not shown), and the registration roller pair 44 is also rotated by the sheet feeding motor 45.

  The paper discharge conveyance unit 6 includes a pair of paper discharge conveyance rollers 61 and 62 for conveying the paper 5 on which image formation has been performed, a paper discharge conveyance roller pair 63 and a paper discharge roller 64 for sending the paper 5 to the paper discharge tray 7. And.

  In the image forming apparatus configured as described above, the rotation amount of the conveyance roller 32 that drives the conveyance belt 31 is detected, and the sub-scanning motor 131 is driven and controlled according to the detected rotation amount, and an AC (not shown) is also illustrated. A positive and negative rectangular wave high voltage, which is an alternating voltage, is applied from the bias supply unit to the charging roller 34, whereby positive and negative charges are alternately band-shaped in the conveying direction of the conveying belt 31. And is charged with a predetermined charging width on the conveying belt 31 to generate an unequal electric field.

  Therefore, the conveyance belt in which an unequal electric field is generated by the sheet 5 being fed from the sheet feeding unit 4 and fed between the conveyance roller 32 and the pressing roller 36 to form positive and negative charges. When fed onto the paper 31, the paper 5 is instantly polarized according to the direction of the electric field, and is attracted onto the transport belt 31 by the electrostatic attraction force, and is transported as the transport belt 31 moves.

  Then, while the paper 5 is intermittently transported by the transport belt 31, recording liquid droplets are ejected from the recording head 24 onto the paper 5 to record (print) an image, and the front end of the paper 5 on which printing is performed The side is separated from the conveyance belt 31 by the separation claw 37 and sent to the paper discharge conveyance unit 6 by the conveyance roller 38.

  During printing (recording) standby, the carriage 23 is moved to the maintenance / recovery mechanism 121 side, and the nozzle surface of the recording head 24 is capped by the cap 122, and the nozzles are kept in a wet state. To prevent. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 24 is capped by the suction and moisture retention cap 122a (referred to as “nozzle suction” or “head suction”), and the recovered recording liquid and bubbles are discharged. Wiping is performed by the wiper blade 124 in order to clean and remove ink adhering to the nozzle surface of the recording head 24 by this recovery operation. In addition, a blank ejection operation is performed in which ink that is not related to printing is ejected toward the blank ejection receiver 125 before recording is started or during recording. Thereby, the stable ejection performance of the recording head 24 is maintained.

Next, a first embodiment of the present invention applied as a linear encoder unit in this image forming apparatus will be described with reference to FIG. FIG. 4 is a partially broken perspective view of the linear encoder unit according to the embodiment.
The linear encoder unit 200 includes a linear scale 202 on which a scale is printed and an encoder sensor 203 including a photosensor that reads the linear scale 202 in a sealed space formed by a cylindrical sealed container 201. It is a thing. Here, both end portions 202 a of the linear scale 202 are held by both end portions 201 of the sealed container 201. Further, the encoder sensor 203 is arranged to be movable in accordance with the movement of the carriage 23 as will be described later.

  In this way, by providing a sealed container in which a linear scale and a sensor constituting an encoder that generates a signal in response to movement of a moving body, for example, a carriage, is arranged in a sealed space, mist scattered in the image forming apparatus, Dust and the like are prevented from adhering to the linear scale and sensor, and stable and accurate position detection can be performed. Thereby, a high quality image can be stably formed.

  In addition, since the sealed container is cylindrical, a sealed space can be formed with a single component, thereby reducing costs and improving assembly.

  Further, by unitizing the encoder sensor unit 200, parts can be easily replaced.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 is a partially broken perspective explanatory view of the linear encoder unit according to the embodiment, and FIG. 6 is a side explanatory view of the unit.
In the linear encoder unit 200, a portion 201b along the longitudinal direction, which is a part of the sealed container 201, can be opened and closed.

  As described above, since the portion along the longitudinal direction of the sealed container can be opened and closed, it is possible to prevent the linear scale from touching the container and becoming dirty when the linear scale is assembled.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a view for explaining the end portion of the linear encoder unit according to the embodiment.
In this linear encoder unit 200, locking pieces 201 c as positioning means for locking holes 202 b formed in the ends 202 a of the linear scale 202 are formed at both ends of the sealed container 201, and the holes of the linear scale 202 are formed. The linear scale 202 is positioned by locking 202b to the locking piece 201c. Although the end of the sealed container 201 is shown as being open in the figure, the end opening is finally sealed after the linear scale 202 is locked to the locking piece 201c.

  Thus, since the sealed container is provided with positioning means for positioning both ends of the linear scale, the positional relationship with the sensor can be accurately determined when the linear scale is placed in the sealed container. It is possible to prevent the false detection by the sensor by eliminating the slack of the linear scale.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 8 is an explanatory perspective view of an end portion of the linear encoder unit according to the embodiment, and FIG. 9 is an explanatory plan view of a cross section of the end portion.
The linear encoder unit 200 is provided with lid members 211 and 211 that can be opened and closed at both ends of the hermetic container 201 as an opening / closing means that opens and closes in a double-folded manner with hinges 113 and the like. Is provided with an elastic member 212.

  In the unit 200, when the lid members 211 and 211 are closed, the end portion 202a of the linear scale 202 is sandwiched and held between the elastic members 212 and 212 of the lid members 211 and 211. Only one lid member 211 can be opened and closed, and it is preferable to provide stopper means for restricting the lid member 211 from entering the sealed container 201.

  As described above, the opening and closing means for opening and closing the sealed state is provided at the end of the sealed container, thereby facilitating replacement of parts such as a linear scale while preventing intrusion of mist and the like.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a partially broken perspective view of the linear encoder unit according to the embodiment.
In this linear encoder unit 200, a guide member 204, which is a guide means for guiding the movement of the encoder sensor 203, is arranged along the linear scale 201.

  Thus, by providing the guide means (guide member) for guiding the sensor, the movement of the sensor can be performed smoothly and stably, and the positional relationship between the linear scale and the sensor can be accurately maintained. it can.

Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a perspective view of a main part of the linear encoder unit according to the embodiment.
In this linear encoder unit 200, the encoder sensor 203 is provided with transmission means 205 for transmitting a sensor detection signal to the apparatus main body side (preferably the carriage 23) by electromagnetic waves, and the apparatus main body side receives the electromagnetic waves from the transmission means 205. A receiving means is provided.

  In this way, by providing means for transmitting and receiving the detection signal of the sensor with electromagnetic waves, the sensor can be made independent from the carriage, and the linear scale and the sensor can be completely isolated from the print unit and the head maintenance and recovery mechanism. And false detection can be prevented.

Next, a seventh embodiment of the present invention will be described with reference to FIG. FIG. 12 is an explanatory perspective view of a main part of the linear encoder unit according to the embodiment.
In this linear encoder unit 200, the encoder sensor 203 is provided with a transmission means 206 for transmitting a sensor detection signal to the apparatus main body side (preferably the carriage 23) by infrared rays, and the apparatus main body side receives infrared rays from the transmission means 206. A receiving means is provided.

  Thus, by providing means for transmitting and receiving the detection signal of the sensor with infrared rays, the sensor can be made independent of the carriage, and the linear scale and the sensor can be completely isolated from the printing unit and the head maintenance and recovery mechanism. And false detection can be prevented.

  When the transmission means using these electromagnetic waves and infrared rays is provided, the sealed container is preferably formed of a non-metallic member. By forming the sealed container with a non-metallic member, for example, a resin member, transmission and reception of sensor detection signals by electromagnetic waves and infrared rays can be performed without hindering.

Next, an eighth embodiment of the present invention will be described with reference to FIG. FIG. 13 is an explanatory perspective view of the linear encoder unit according to the embodiment.
The linear encoder unit 200 includes a cable (harness) 207 that transmits a sensor detection signal from the encoder sensor 203 to the apparatus main body in a wired manner. A space 215 along the longitudinal direction in which the cable 207 is movable is formed when the cable 207 moves following the movement of the encoder sensor 203 in the part 214 of the sealed container 201.

  Thus, by providing a means for transmitting and receiving the detection signal of the sensor by wire, the influence of noise can be suppressed and erroneous detection can be prevented. And since the space where the wire can move is formed in the sealed container, the cable and the harness can be prevented from getting entangled, and the movable harness and the cable are put in the same sealed space as the linear scale and the sensor. It is possible to widen the movement area of the material and prevent entry of dirt substances (mist, dust, etc.).

Next, a ninth embodiment of the present invention will be described with reference to FIG. FIG. 14 is an explanatory side view for explaining the coupling relationship between the linear encoder unit and the carriage according to the embodiment.
A magnet 221 is provided on the side of the carriage 23 of the encoder sensor 203 on the linear encoder unit 200 side, and a magnet 222 that is magnetically coupled to the magnet 221 is provided on the carriage 23 side, so that the encoder sensor 203 and the carriage 23 are magnetically connected. The encoder sensor 203 is moved as the carriage 23 moves.

  As described above, since the carriage and the sensor in the sealed container are coupled by magnetic force, the sensor can be moved as the carriage moves without being physically coupled to the carriage. The sensor is linearly separated from the carriage. The scale and the sensor can be completely isolated from the printing unit and the head maintenance / recovery mechanism, and erroneous detection can be prevented.

Next, a tenth embodiment of the present invention will be described with reference to FIG. FIG. 15 is an explanatory side view for explaining the coupling relationship between the linear encoder unit and the carriage according to the embodiment.
The encoder unit 200 is disposed by extending a part of the driving roller 28A in one end portion of the sealed container 201 (can be sealed by providing a member that can be rotatably sealed), and a driven roller (not shown) in the other end portion. The belt 223 is wound around the drive roller 28A and the driven roller, and the encoder sensor 203 of the belt 223 is coupled. Thus, the encoder sensor 203 is moved in the main scanning direction via the belt 223 when the main scanning motor 27 is driven to move the carriage 23 in the main scanning direction.

  In this way, the carriage and the sensor are moved simultaneously by the same driving means, so that the sensor can be moved as the carriage moves without being physically coupled directly to the carriage. And the sensor can be completely isolated from the print unit and the head maintenance / recovery mechanism, and erroneous detection can be prevented.

Next, an eleventh embodiment of the present invention will be described with reference to FIG. FIG. 16 is a block diagram of a portion related to the main scanning control of the carriage.
The main control unit 301 controls the entire image forming apparatus and includes a microcomputer. The main control unit 301 receives a detection signal from a carriage position detection circuit 302 that detects the position of the carriage 23, and the main control unit 301 controls the movement position and movement speed of the carriage 23 based on the detection signal. . The carriage position detection circuit 302 counts the number of slits based on the sensor detection signal output from the encoder sensor 203 corresponding to the slits of the linear scale 202 arranged in the scanning direction of the carriage 23 as described above. The position of the carriage 23 is detected. The main control unit 301 rotates the main scanning motor 27 via the motor driver 303 based on the deviation between the detection result of the carriage position and the target value, and moves the carriage 23 to a predetermined position at a predetermined speed.

  Further, the main control unit 301 moves the carriage 23 in the home position direction at a required timing, and the carriage home detection unit 304 detects the carriage 23 so that the home position of the carriage 23 is determined. Confirmation is made as to whether the home position of the carriage 23 and the home position of the encoder sensor 203 are aligned, and alignment operation is performed.

  For example, as shown in FIG. 17, when the number of main scans of the carriage 23 reaches a predetermined number, the carriage 23 is moved in the home position direction, and it is determined whether or not the carriage home detection unit 304 has detected the carriage 23. . When the carriage home detection unit 304 detects the carriage 23, it is checked whether the detection signal of the encoder sensor 203 is the home position. At this time, when the detection signal of the encoder sensor 203 is not at the home position even though the carriage home detection unit 304 detects the carriage 23, it is assumed that the positions of the carriage 23 and the encoder sensor 203 are misaligned. Perform the action.

  In other words, for example, as described in the ninth embodiment, when the carriage 23 and the encoder sensor 203 are magnetically coupled, if the magnetic coupling state is lost, the carriage 23 is moved. A detection signal is not output from the encoder sensor 203, and control cannot be performed.

  Therefore, it is confirmed at a predetermined timing whether or not the home positions of the carriage 23 and the encoder sensor 203 are aligned. When the home position is not correct, for example, the carriage 23 is moved at a relatively slow speed in the direction opposite to the home position and returned to the home position side again to check whether the home position is correct. . Since the magnetic coupling with the encoder sensor 203 can be recovered by moving the carriage 23 at a relatively slow speed, alignment can be performed.

  For the home position of the encoder sensor 203, for example, a slit for generating a home position signal is formed in the linear scale 202, and the width of the detection signal of the encoder sensor 203 is the slit width for the home position. Whether or not the vehicle is at the home position can be determined based on whether or not there is. The number of times of main scanning of the carriage may be every one reciprocating scan, or two or more reciprocating scans. Further, the predetermined timing is not limited to the timing at which a predetermined number of main scans are completed, and may be, for example, a timing for performing an idle discharge operation for discharging droplets that do not contribute to image formation in order to maintain and recover the recording head 24.

  In each of the above embodiments, the present invention has been described as an example in which the present invention is applied to an image forming apparatus as a multi-function machine having a plurality of functions. For example, a printer, a facsimile, a printing apparatus, a plotter, a copying apparatus, etc. The present invention can be similarly applied to a single-function image forming apparatus.

1 is a schematic configuration diagram for explaining an image forming apparatus according to the present invention. FIG. 6 is an explanatory plan view of the image forming unit and the sub-scanning conveyance unit. It is a perspective explanatory view of a portion related to the carriage movement scanning mechanism. It is a partial fracture perspective explanatory view of the linear encoder unit concerning a 1st embodiment of the present invention. It is a partial fracture perspective explanatory view of a linear encoder unit concerning a 2nd embodiment of the present invention. It is side surface explanatory drawing of the unit. It is a view explanatory drawing of the edge part part of the linear encoder unit which concerns on 3rd Embodiment of this invention. It is a perspective explanatory view of the end part of the linear encoder unit concerning a 4th embodiment of the present invention. It is a plane cross-section explanatory drawing of the end part. It is a partial fracture perspective explanatory view of a linear encoder unit concerning a 5th embodiment of the present invention. It is principal part perspective explanatory drawing of the linear encoder unit which concerns on 6th Embodiment of this invention. It is principal part perspective explanatory drawing of the linear encoder unit which concerns on 7th Embodiment of this invention. It is a perspective explanatory view of a linear encoder unit according to an eighth embodiment of the present invention. It is side surface explanatory drawing with which it uses for description of the coupling relationship of the linear encoder unit and carriage which concern on 9th Embodiment of this invention. It is side surface explanatory drawing used for description of the coupling relationship of the linear encoder unit and carriage which concern on 10th Embodiment of this invention. It is a block explanatory drawing of the part in connection with the main scanning control of the carriage in 11th Embodiment of this invention. It is a flowchart with which it uses for description of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 2 ... Image formation part 3 ... Sub-scanning conveyance part 4 ... Paper feed part 5 ... Paper (recording medium)
6 ... Paper discharge conveyance unit 7 ... Paper discharge tray (paper discharge unit)
DESCRIPTION OF SYMBOLS 11 ... Image reading part 23 ... Carriage 24 ... Recording head 27 ... Main scanning motor 28A ... Drive pulley 28B ... Drive pulley 29 ... Timing belt 200 ... Linear encoder unit 201 ... Sealed container 202 ... Linear scale (encoder scale)
203 ... Encoder sensor

Claims (16)

  An image forming apparatus including a linear scale and a sensor constituting an encoder that generates a signal in response to movement of a carriage mounted with a recording head, and including a sealed container in which the linear scale and the sensor are arranged in a sealed space. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the sealed container is a cylindrical member.   3. The image forming apparatus according to claim 1, wherein a part along the longitudinal direction of the sealed container can be opened and closed.   4. The image forming apparatus according to claim 1, wherein the sealed container includes positioning means for positioning both ends of the linear scale.   5. The image forming apparatus according to claim 1, further comprising an opening / closing means for opening / closing a sealed state at an end of the sealed container.   6. The image forming apparatus according to claim 1, further comprising guide means for guiding movement of the sensor in the sealed container.   7. The image forming apparatus according to claim 1, further comprising means for transmitting and receiving a detection signal of the sensor by electromagnetic waves.   7. The image forming apparatus according to claim 1, further comprising means for transmitting and receiving a detection signal of the sensor by infrared rays.   9. The image forming apparatus according to claim 7, wherein the sealed container is formed of a non-metallic member.   7. The image forming apparatus according to claim 1, further comprising means for transmitting and receiving a detection signal of the sensor by wire.   The image forming apparatus according to claim 10, wherein a space in which the wire is movable is formed in the sealed container.   12. The image forming apparatus according to claim 1, wherein the carriage and a sensor in the sealed container are coupled by a magnetic force.   12. The image forming apparatus according to claim 1, wherein the carriage and the sensor are simultaneously moved by the same driving unit.   14. The image forming apparatus according to claim 1, wherein the home position of the carriage and the home position of the sensor are confirmed every predetermined number of reciprocating movements.   15. The image forming apparatus according to claim 1, wherein the linear scale, the sensor, and the sealed container are unitized. A position detection device including a linear scale and a sensor constituting an encoder that generates a signal in accordance with movement of a moving body, comprising a sealed container in which the linear scale and the sensor are arranged in a sealed space. Position detection device.

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