JP2002248822A - Sheet transfer device and recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet transfer device capable of detecting rotation of a transfer roller 3 without decreasing the accuracy, and a recorder with the same. SOLUTION: The sheet transfer device transfers a sheet by the transfer roller 3 to which a driving force is transmitted via a wound and stretched timing belt 12. The sheet transfer device has a code wheel 15 set to a transfer roller shaft, and an encoder sensor 16 for detecting a slit 15a formed to the code wheel 15. A read direction of the sensor 16 is made perpendicular to a direction of a tensile force received by the transfer roller 3 from the timing belt 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a sheet conveying apparatus capable of conveying a sheet with high accuracy and a recording apparatus having the same.

[0002]

2. Description of the Related Art A recording apparatus having functions such as a printer, a copying machine, and a facsimile is configured to record an image on a recording sheet based on recording information. , An ink jet type, a wire dot type, a thermal type, a laser beam type, and the like.

[0003] In a serial type recording apparatus employing a serial scanning system in which scanning is performed in a direction (main scanning direction) crossing a recording sheet conveyance direction (sub-scanning direction), after a recording sheet is guided to a predetermined recording position, Recording means (recording head) mounted on a carriage that moves along the recording sheet
Is scanned in the main scanning direction to record an image. After printing by one line of scanning is completed, a predetermined amount of sheet feeding is performed, and then the next row of image is printed on the stopped recording sheet. By repeating the operation of recording, recording of the entire recording sheet is performed.

On the other hand, in a line type recording apparatus that performs recording only by sub-scanning in the transport direction of a recording sheet, the recording sheet is set at a predetermined recording position, and recording for one line is performed collectively. By repeating the operation of feeding a fixed amount of sheets and collectively recording the next line, the recording of the entire recording sheet is performed.

[0005] A sheet conveying configuration of the recording apparatus will be exemplified. FIG. 5 is an explanatory view of a sheet conveying configuration in the ink jet printer. The conveying roller pair 50, upstream of the recording area in the sheet conveying direction (hereinafter, simply referred to as “upstream side”).
A discharge roller pair 52, 53 is disposed on the downstream side in the sheet conveying direction (hereinafter, simply referred to as “downstream side”).

Drive is transmitted from the motor gear 55, which is press-fitted to the shaft of the motor 54 as a drive source, to both the transport roller gear 57 and the discharge roller gear 58 via the intermediate two-stage gear 56, and the transport roller 50 and the discharge roller 52 are driven. It is configured to be driven.
The transmission of the drive to the discharge roller 52 is performed by providing a gear train at an end of the roller opposite to the end of the transfer roller to which the transfer gear to which the drive is transmitted from the motor is attached. There is also a configuration in which drive is transmitted to 52.

The rotation of the motor 54 causes the conveying roller 50 and the discharge roller 52 to rotate in the same direction, and conveys the sheet in the recording area with the rotation of the pinch roller 51 and the spur 53 as driven rollers. In the recording area, the pinch roller 51 is offset by a predetermined amount toward the platen with respect to the conveyance roller 50, thereby pressing the recording sheet against the platen 59 disposed between the pair of rollers, and positioning the recording sheet and the recording head 60. While recording.

In the above recording apparatus, the rotation of the transport roller 50 is detected, and the motor for driving the transport roller 50 is controlled to control the sheet transport speed and the transport amount. As a detection configuration for this, the transport roller 50
An encoder plate (not shown) is attached to the shaft, and a slit formed in the encoder plate is detected by a photo sensor.

[0009]

However, in the above-described roller rotation detecting structure, when a load is applied to the transport roller due to drive transmission or the like, and the slit of the encoder plate attached to the roller shaft is displaced. In some cases, the detection accuracy of the slit by the sensor may decrease, and the conveyance accuracy may decrease due to the inability to perform stable roller rotation detection.

[0010] The present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a sheet conveying device capable of detecting the rotation of a rotating body without lowering the accuracy and a recording device having the same.

[0011]

In order to achieve the above object, a typical configuration according to the present invention is to transport a sheet by a transport rotating body to which a driving force is transmitted via a belt member stretched and suspended. In the sheet conveying device, a detection member attached to the conveyance rotating body, and a sensor for detecting a detection unit formed on the detected member, and the reading direction of the sensor is such that the conveyance rotating body is the It is characterized in that it is configured to be perpendicular to the direction of the tension received from the belt member.

In the above configuration, even if the detection portion formed on the detected member attached to the transport rotary member is displaced by the tension of the belt member, the deviation is in a direction perpendicular to the detection direction of the sensor. Therefore, the sensing is prevented from lowering without affecting the slit detection by the sensor, and stable sheet conveyance is performed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a recording apparatus provided with a sheet conveying apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a sheet conveying apparatus according to an embodiment of the present invention. FIG. 2 is a schematic side view of a transfer device,
FIG. 3 is an explanatory view of mounting the encoder sensor, and FIG.
FIG. 2 is an explanatory diagram of a configuration of a recording apparatus.

{Recording Apparatus} First, the overall configuration of the recording apparatus will be briefly described with reference to FIG. The recording apparatus according to the present embodiment is a serial type ink jet printer, which is a feeding device 31 that separates and feeds stacked sheets, and a transport rotator that feeds separated and sent sheets to a recording area. A transport roller 3 (see FIG. 1);
Conveying means constituted by the pinch roller 4 as a driven roller, a carriage 33 which can reciprocate in the main scanning direction (longitudinal direction of the apparatus), and perform recording while reciprocating by a recording head 34 mounted on the carriage. Recording means,
It comprises a discharging means for discharging the recorded sheet.

The sheet fed onto the platen 2 in the recording area by a pair of rollers including the transport roller 3 and the pinch roller 4 is held by the platen 2 having a flat transport surface in the recording area, and the set recording is performed. The area is sent by the transport roller 3. The recording is performed by the recording head 34 by the reciprocating movement of the carriage 33, and the printer repeats sheet conveyance and recording until a predetermined amount of data sent from the host is completed, and is driven by the discharge roller 5 provided on the downstream side in the conveyance direction. It is discharged by a spur 7 which is a roller. Here, the spur 7 is a rotating body that has a small contact area with the sheet and does not disturb the ink image even when the sheet contacts the sheet surface on which the ink image is recorded by ink ejection.

Further, the recording head 34 according to the present embodiment
As an ink ejection configuration, a current is supplied to the electrothermal transducer in accordance with a recording signal, and the ink is ejected from an ejection port by ink bubble growth and shrinkage utilizing film boiling caused by the thermal energy of the ink, thereby recording. It is configured to perform. As a result, compactness is facilitated, and high-density mounting is easy, and a high-precision image is obtained.

{Sheet Conveying Apparatus} FIG.
This will be described with reference to FIGS.

As described above, the sheet transporting device includes a transporting roller 3 that is driven and rotated to transport a recording sheet to a recording area, a transporting unit that has a pinch roller 4 that presses the sheet against the roller and is driven to rotate. It comprises a discharge roller which is driven and rotated to convey and discharge the subsequent recording sheet, and a discharging means which is constituted by a spur which presses the sheet against the roller and is driven to rotate.

The recording sheet separated and sent from the feeding device 31 is sent to the conveying roller 3 and the pinch roller 4 engaged with the pinch roller holder 1 while being guided by the pinch roller holder 1. The pinch roller holder 1 is urged by a pinch roller spring 1a, and urges the pinch roller 4 toward the transport roller 3.

The recording sheet is conveyed to the printing area on the platen 2 by the conveying roller 3, recorded by the recording head 34 mounted on the carriage 33, and discharged by the spur 7 held by the discharge roller 5 and the spur holder 6.

The transport roller 3 and the discharge roller 5 are driven by DC.
The motor 8 is driven by a motor pulley 9 pressed into the shaft of the DC motor, a toothed transport pulley 10 pressed into the shaft of the transport roller 3, and a toothed discharge pulley 11 pressed into the shaft of the discharge roller 5. The driving force of the DC motor 8 is transmitted to the transport pulley 10 and the discharge pulley 11 to drive the respective rollers 3 and 5 by suspending the timing belt 12 which is the same toothed belt member. Convey the recording sheet. In addition, a tension pulley 14 is provided between the motor pulley 9 and the transport pulley 10 in order to guarantee the winding angle of the timing belt 12 around the motor pulley 9 by being pressed into the pulley holder 13.

Further, a code wheel 15 (member to be detected) is attached to the transport pulley 10 for driving the DC motor. Then, the code wheel guide 17 holding the encoder sensor 16 is attached to a main body chassis (not shown),
This restricts the deflection of the code wheel 15 in the main scanning direction by sandwiching the end portion of the code wheel, and reads the rotation state of the code wheel 15 by the encoder sensor 16 so that the drive control of the transport unit is controlled based on the read pulse. Do it.

That is, as shown in FIG. 3, the code wheel 15 is provided with a slit (detection portion) having a resolution required for the conveyance in the sub-scanning direction by etching, and the slit is detected by an encoder sensor 16 (detection sensor). To control the sheet conveyance speed and the conveyance amount. Code wheel 15
The slit 15a is formed radially from the rotation center C1 of the code wheel. By detecting the slit 15a of the rotating code wheel 15 with an encoder sensor 16 such as a photo sensor, the rotation amount of the transport roller 3 is determined. Detect the rotation speed. And, as shown in FIG.
The encoder sensor 16 has a sensing center C2, and makes a straight line connecting the center C2 and the rotation center C1 of the code wheel 15 perpendicular to the reading direction R of the sensor, thereby detecting the slit 15a to ensure the slit 15a. Can be detected.

Further, in this embodiment, the encoder held by the code wheel guide 17 so that the reading direction R of the encoder sensor 16 is perpendicular to the direction P of the force due to the tension applied to the transport pulley 10 from the timing belt 12. The sensor 16 is attached. Thereby, even if the transport pulley 10 is drawn in the tension direction of the timing belt 12 stretched and stretched, the slit 15 a formed in the code wheel 15 moves vertically with respect to the center of sensing of the encoder sensor 16. , And a decrease in sensing due to displacement of the slit 15a of the code wheel 15 is prevented. Therefore, the rotation of the transport roller 3 can be detected stably.

In the configuration according to the present embodiment, since the transport pulley 10 and the discharge pulley 11 are driven by the same timing belt 12, the backlash between the gears and the gears generated when the drive train is transmitted by the gear train. There is no difference in conveyance accuracy caused by the difference in gear trains to the conveyance roller 3 and the discharge roller 5 due to a decrease in conveyance accuracy due to accuracy, and stable conveyance can be performed with high accuracy. In particular, when the trailing edge of the recording sheet comes out of the nip between the conveying roller 3 and the pinch roller 4, the force generated by the pinch roller 4 in the conveying direction causes the recording sheet to be extruded in the conveying direction more than a predetermined conveying amount, and the accuracy is deteriorated. The effect of gear train backlash, which is one of the causes, can be eliminated.

Further, since the transport pulley 10 and the discharge pulley 11 are driven by the same timing belt 12, there is no time lag between the rotation of the transport roller 3 and the start and stop of the rotation of the discharge roller 5. For this reason, in the recording area, the rotation of the transport roller 3 and the discharge roller 5 synchronize with each other, so that the recording sheet pressed and held on the transport surface of the platen 2 moves with respect to the transport roller 3 at the rotation start timing of the discharge roller 5. It is possible to prevent floating on the platen 2 due to a slight displacement.

In this embodiment, the number of teeth of the transport pulley 10 and the number of teeth of the discharge pulley 11 are the same, and the diameter of the transport roller 3 and the diameter of the discharge roller 5 are the same. As a result, the sheet conveying speed by the conveying roller 3 and the discharge roller 5 becomes constant, and the trailing end of the recording sheet is
Since the sheet conveying speed by the discharge roller 5 does not change even after the sheet is removed from the nip, more stable conveying accuracy can be obtained.

As described above, it is desirable that the diameters of the transport roller 3 and the discharge roller 5 are the same. However, in consideration of the processing tolerance, the diameter of the discharge roller
So that it becomes the minimum diameter at the maximum diameter including the outer diameter tolerance of
By setting the outer diameter and its tolerance, the difference in the transport amount generated between the transport roller 3 and the discharge roller 5 may be minimized. In this dimensional relationship, the sheet conveyance amount by the discharge roller 5 does not become smaller than the sheet conveyance amount by the conveyance roller 3, so that the state of the recording sheet on the platen can be stabilized.

In this embodiment, the motor pulley 9, the transport pulley 10, and the discharge pulley 11 are connected to the same timing belt 12.
The drive is transmitted by
The number of teeth of the discharge pulley 11 is n times the number of teeth of the motor pulley 9 (n
Is an integer). As a result, the conveyance amount of the recording sheet can be controlled on the basis of one rotation of the motor, so that the influence of the eccentricity of the DC motor shaft and the influence of the deterioration of the stop accuracy due to the polarity are eliminated, and the stop accuracy at the time of positioning can be improved.

In the above-described embodiment, an example is shown in which the direction of reading by the sensor and the direction of the tension applied to the wheel by the belt member are perpendicular to each other. Is set in the direction of the tension received from the belt member, it is possible to prevent a decrease in detection accuracy due to the influence of the belt tension.

In the above-described embodiment, an ink jet recording apparatus has been exemplified as a recording apparatus. However, the recording apparatus having the sheet conveying apparatus is not limited to this.
The present invention can be suitably used even in a recording apparatus using a method such as electrophotographic recording or thermal transfer recording.

[0032]

The present invention is constructed as described above.
Even if the detection part formed on the detected member attached to the conveyance rotating body is displaced by the tension of the belt member, the deviation is in the direction perpendicular to the detection direction of the sensor, so it does not affect the slit detection by the sensor. In addition, it is possible to prevent a decrease in sensing, and to perform stable sheet conveyance detection. For this reason, when this is provided in the recording apparatus, the sheet conveyance can be controlled with high accuracy, and a high-quality recorded image can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic perspective explanatory view of a sheet conveying apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic side view illustrating a transfer device.

FIG. 3 is an explanatory view of mounting an encoder sensor.

FIG. 4 is a diagram illustrating the configuration of a recording apparatus.

FIG. 5 is an explanatory diagram of a conventional sheet conveyance configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pinch roller holder 1a ... Pinch roller spring 2 ... Platen 3 ... Transport roller 4 ... Pinch roller 5 ... Discharge roller 6 ... Spur holder 7 ... Spur 8 ... DC motor 9 ... Motor pulley 10 ... Transport pulley 11 ... Discharge pulley 12 ... Timing Belt 13 Pulley holder 14 Tension pulley 15 Code wheel 15a Slit 16 Encoder sensor 17 Code wheel guide 18 Transport rollers 18a, 19a Axis 19 Discharge roller 31 Feeder 32 Pinch roller 33 Carriage 34 … Recording head

Claims (6)

[Claims] 1. A sheet conveying apparatus for conveying a sheet by a conveying rotating body to which a driving force is transmitted via a belt member stretched and stretched, wherein: a detected member attached to the conveying rotating body; And a sensor for detecting a detection unit formed on the member, wherein a reading direction of the sensor is configured to be perpendicular to a direction of a tension applied to the transport rotator from the belt member. Transport device. 2. The sheet conveying apparatus according to claim 1, wherein the detecting section is a slit formed radially from a rotation center of the detected member. 3. A sheet conveying apparatus for conveying a sheet by a conveying rotating body to which a driving force is transmitted via a belt member stretched and stretched, wherein: a detected member attached to the conveying rotating body; A sensor for detecting a radial slit formed in the member, wherein a longitudinal direction of the slit at a position detected by the sensor is a direction of tension applied to the rotating body from the belt member. Sheet transport device. 4. A recording apparatus for recording an image on a conveyed sheet by a recording unit, comprising: the sheet conveying apparatus according to claim 1, wherein the sheet is conveyed by the sheet conveying apparatus. A recording device, comprising: 5. The recording apparatus according to claim 4, wherein the recording means performs recording by discharging ink according to a signal.
The recording device according to claim 1. 6. The recording apparatus according to claim 1, wherein the recording means supplies a current to the electrothermal transducer in response to the signal, and discharges the ink by utilizing film boiling generated in the ink by thermal energy generated by the electrothermal transducer. The recording device according to claim 5, wherein