JP2003065798A - Encoder and recording device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the small diameter of a disk-like scale having a pattern for rotation detection without dropping the resolution of an encoder and changing a sensor. SOLUTION: The encoder 40 is constituted of a sensor holder 53, the disk-like scale 41, and a photointerrupter 44. A transportation drive roller gear 62b is attached to a transportation drive roller 62 as a detected object shaft and the disk-like scale 41 is provided on a transmission gear 52 engaging with a transportation drive roller gear 62b. A slit-like pattern for rotation detection is formed in a circumferential direction at a constant pitch on the outer circumference of the disk-like scale 41. The rotation quantity of the transportation drive roller 62 to the pitch can be maintained by adjusting the gear ratio between the transportation drive roller gear 62b and the transmission gear 52.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder for detecting the amount of rotation of a rotary shaft. Further, the present invention relates to a recording device which is provided with the encoder and performs recording on a recording material.

[0002]

2. Description of the Related Art A printer is one of recording devices,
In some printers, the feed control of the printing paper as the recording material (paper feed control) is performed by feedback control. In a printer that performs such feedback control, a disc-shaped scale provided with a rotation detection pattern in the circumferential direction and rotation of the rotation detection pattern are detected as detection means for obtaining the conveyance amount and conveyance speed of the printing paper. Then, an encoder including a sensor that converts the rotation into an electric signal is provided, and the control unit of the printer is configured to obtain the conveyance amount and the conveyance speed of the printing paper based on the signal from the encoder.

Here, the disk-shaped scale is provided with a rotation detecting pattern (radial slits) in which light-transmitting portions and light-shielding portions are alternately arranged at a constant pitch in the circumferential direction, and is printed on the outer peripheral portion. It is common to attach the shaft of a transport drive roller that extends in the main scanning direction, which transports the paper, and determine the transport amount and transport speed of the printing paper by detecting the amount of rotation of the transport drive roller.

[0004]

By the way, the encoder is provided on the shaft end side of the transport drive roller, and the shaft end side of the transport drive roller is connected to the transport drive roller from a drive motor for driving the transport drive roller. Since other components of the printer, such as a power transmission device and a frame member that pivotally supports a carriage guide shaft that guides the carriage in the main scanning direction, are arranged, it may be difficult to arrange the disk-shaped scale.

In particular, in the case of an ink jet printer as a recording apparatus, the transport driving roller is generally arranged below the carriage which reciprocates in the main scanning direction. Therefore,
For example, if the reciprocating region of the carriage becomes large due to the enlargement of the carriage while keeping the axial dimension of the transport drive roller unchanged, the reciprocating region of the carriage may interfere with the disk-shaped scale.

On the other hand, when the disc-shaped scale is made smaller (smaller) in order to deal with such a problem, the pitch in the circumferential direction of the rotation detection pattern becomes small, which causes a problem in consideration of the detection limit of the sensor. In addition, the cost is increased if the sensor is changed to a high resolution one. On the contrary,
If the circumferential pitch of the rotation detection pattern is increased in order to avoid such a problem, the resolution of the encoder decreases and the rotation amount of the transport drive roller, that is, the transport amount or transport speed of the printing paper is accurately detected. become unable.

The present invention has been made in view of the above problems, and its object is to reduce the diameter of a disk-shaped scale having a rotation detection pattern without lowering the resolution of the encoder and without changing the sensor. Is to be able to

[0008]

In order to solve the above-mentioned problems, the encoder according to the first aspect of the present invention is a rotation detecting device in which light blocking portions and light transmitting portions are alternately arranged at a constant pitch in the circumferential direction. A disk-shaped scale provided with a pattern for the outer peripheral portion, and a sensor including a light-emitting unit and a light-receiving unit, which converts a state change of the rotation detection pattern due to the rotation of the disk-shaped scale into an electric signal, An encoder for detecting a rotation amount of a detection target shaft, wherein the rotation shaft of the disk-shaped scale is engaged with the detection target shaft via a gear reduction device,
By adjusting the reduction ratio of the gear reduction device, it is possible to change the diameter of the disc-shaped scale while maintaining a constant relationship between the circumferential pitch of the rotation detection pattern and the rotation amount of the detection symmetry axis. It is characterized by being configured.

According to the first aspect of the present invention, it is possible to reduce the diameter of the disk-shaped scale having the rotation detection pattern, which constitutes the encoder, without lowering the resolution of the encoder by the gear reduction device. Become. That is, in the encoder according to the first aspect of the present application, the rotating shaft of the disk-shaped scale is engaged with the detection symmetric shaft via the gear reduction device. That is, the rotation axis of the disk-shaped scale and the rotation axis of the detection symmetry axis are separate and have different rotation centers.

Next, the disk-shaped scale is provided with a rotation detecting pattern in which light blocking portions and light transmitting portions are alternately arranged at a constant pitch in the circumferential direction, and the rotation detecting pattern of the rotation detecting pattern is provided. The sensor that detects a state change includes a light emitting unit and a light receiving unit, and detects a light receiving state and a non-light receiving state of light with the rotation of the disk-shaped scale to detect a rectangular wave signal (On / O).
ff signal) is output.

Here, the circumferential pitch of the rotation detecting pattern is the distance between two adjacent light blocking portions, that is, the width of the light transmitting portion, and therefore the pitch of the light blocking portion and the light transmitting portion arranged. If the diameter of the disk-shaped scale is reduced while maintaining the number, that is, while maintaining the resolution of the encoder, the circumferential pitch also decreases accordingly. However, in the sensor, there is a limit to reducing the diameter of the disc-shaped scale due to the balance between the spot diameter of the light emitted from the light emitting portion and the detection accuracy of the light receiving portion, and it is also necessary to reduce the circumferential pitch. If the sensor is changed to a high precision one, the cost will increase. On the other hand, if the diameter of the disk-shaped scale is reduced while keeping the circumferential pitch constant, the number of light blocking sections and light transmitting sections decreases, and the rotation amount of the detection target shaft corresponding to the circumferential pitch increases. As a result, the amount of rotation of the detection target shaft cannot be accurately detected due to the reduction in the resolution of the encoder.

However, the encoder according to claim 1 of the present application is provided with a gear reduction device in which the rotation axis of the disk-shaped scale and the detection target axis are different from each other, and which engage with each other. Therefore, even if the diameter of the disc-shaped scale is changed, the relationship between the circumferential pitch of the rotation detection pattern and the rotation amount of the detection target shaft is maintained constant by adjusting the reduction ratio of the gear reduction device. Therefore, it is possible to reduce the diameter of the disc-shaped scale in the recording apparatus without changing the sensor to a high-resolution one and without lowering the resolution of the encoder. It is possible to increase the degree of freedom of arrangement.

According to a second aspect of the present invention, there is provided a recording apparatus according to the first aspect.
In the above, the gear reduction device is configured by using a gear that constitutes a power transmission device that transmits power from a drive motor that is a drive source of the detection target shaft to the detection target shaft. According to the second aspect of the present invention, the gear reduction device is configured using a gear that constitutes a power transmission device that transmits power from a drive motor that is a drive source of the detection target shaft to the detection target shaft. Therefore, it is possible to configure the encoder at low cost without separately providing a gear reduction device for the encoder.

In the recording apparatus according to claim 3 of the present application, the apparatus main body is configured by combining a plurality of units,
A recording device for recording on a recording material, which reciprocates in a main scanning direction with a conveyance unit having a conveyance drive roller that conveys the recording material at a constant pitch by rotating, and a carriage having an inkjet recording head. Ready to move,
A carriage unit provided above the transport unit, wherein the main scan area is extended when the encoder extends the main scan area of the carriage on the side surface of the transport unit. It is characterized in that it is arranged in a place located below.

According to the invention described in claim 3 of the present application, the function and effect of the invention described in claim 1 of the present application can be more effectively exhibited. That is, in the recording apparatus, the apparatus main body is configured by combining a plurality of units, and the conveyance unit including the conveyance driving roller that conveys the recording material and the carriage including the inkjet recording head can reciprocate in the main scanning direction. And a carriage unit.

The carriage unit is provided above the transport unit. However, since the dimension of the carriage unit in the main scanning direction (width dimension) changes depending on the design of the carriage,
In some cases, it has a width dimension larger than the transport unit,
It may be provided so as to project from both sides of the transport unit. Here, since the encoder according to claim 3 of the present application is arranged on the side surface of the transport unit at a position located below the main scanning area when the main scanning area of the carriage is extended, When the scanning area is extended, the disk-shaped scale that constitutes the encoder may interfere with the carriage.

However, since the encoder is equipped with the gear reduction device as described above, by adjusting the reduction ratio,
As described above, the diameter of the disc-shaped scale can be reduced without deteriorating the resolution of the encoder, and thus the encoder can be reasonably arranged below the main scanning area of the carriage.
At the same time, since the gear reducer allows the disk-shaped scale to be arranged at a position far from the main scanning area of the carriage, this also makes it possible to arrange the encoder under the main scanning area of the carriage without difficulty. Become.

The recording apparatus according to claim 4 of the present application is the same as that of claim 3.
In the above, the disk-shaped scale is provided on a second gear that rotates by meshing with a first gear provided on the shaft end of the rotation shaft of the transport drive roller. According to the invention of claim 4 of the present application, the disk-shaped scale serves as the second gear that rotates by meshing with the first gear provided at the shaft end of the rotation shaft of the transport drive roller as the detection target shaft. Since the gear reduction device is provided with the minimum number of gears as described above, it is possible to suppress the influence of backlash and perform more accurate detection.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. <Structure of Apparatus Main Body of Inkjet Printer> The structure of the apparatus main body of the inkjet printer according to the embodiment of the present invention will be described below with reference to FIGS. 1 to 4. Here, FIG. 1 is an external perspective view of an apparatus main body of the inkjet printer (hereinafter abbreviated as “printer”) 100, FIG. 2 is the same exploded perspective view, FIG. 3 is the same side sectional view, and FIG. It is a figure.

In FIG. 1 and FIG. 2, the printer 100 is divided into a plurality of units, and the plurality of units are combined to form a main unit. In the figure, reference numeral 1 is a paper feeding unit as a paper feeding device capable of feeding a paper P (see FIG. 3) as a recording material or roll paper (not shown), and reference numeral 20 is an inkjet recording head 24 (see FIG. 3)), a carriage unit including a carriage 22 having a carriage 22 having a reference numeral 60, a conveyance unit 60 for conveying a recording material, and a reference numeral 80 an ink system unit for performing maintenance of the inkjet recording head 24. Is divided into these four units as shown in FIG.
It is constructed by combining two units as shown in FIG. Incidentally, in the present embodiment, the carriage unit 20 and the ink system unit 80 are respectively the upper side and the right side of the transport unit 60 (the right side in FIG. 4).
And the paper feeding unit 1 is connected to the carriage unit 20.
The four units are configured to be united by connecting to the back side of the.

Next, referring to FIG. 3, the printer 100
The paper transporting route will be described. In addition, in the following, FIG.
The left side (rear side of the printer 100) is referred to as “upstream side”, and the right side of FIG. 3 (front side of the printer 100) is referred to as downstream side. The printer 100 is provided with a hopper 6 on the upstream side, and the sheets P as cut sheets are accumulated and stored on the hopper 6 in an inclined posture. The hopper 6 is rotatably provided in a clockwise direction and a counterclockwise direction in FIG. It is designed to be pressed and separated. Further, the hopper 6 is provided with a movable guide 4 that can slide in the width direction of the paper P (see FIG. 1), and a fixed guide 5 (see FIG. 1).
(See reference), the side edge of the accumulated paper P is guided.
Then, the topmost one of the accumulated sheets P is the hopper 6
Performs a pressure contact operation with respect to the paper feed roller 3, and in the pressure contact state, the paper feed roller 3 rotates and is fed to the downstream side. The paper feed roller 3 has a substantially D-shape when viewed from the side, and is rotated when the rotation shaft 3a is driven to rotate. The paper feed roller 3 is controlled so that the flat portion thereof faces the paper P during the printing operation (the state of FIG. 3), thereby preventing the paper P from being conveyed.

Next, a paper guide 67 as a plate-like member is provided substantially horizontally below the paper feed roller 3, and the front end of the paper P fed out by the paper feed roller 3 is the paper guide 67.
It obliquely abuts and is smoothly guided to the downstream side. The transport drive roller 62 that is rotationally driven downstream from the paper guide 67.
And the transport driven roller 6 that is in pressure contact with the transport drive roller 62.
3 is provided, the sheet P is nipped between the conveyance driving roller 62 and the conveyance driven roller 63, and is conveyed to the downstream side at a constant pitch.

The transport driven roller 63 is axially supported on the downstream side of the transport driven roller holder 64, and the transport driven roller holder 64 rotates in the clockwise direction and the counterclockwise direction in FIG. 3 about the rotation shaft 64a. The transport driven roller 63 is rotatably biased in a direction in which the transport driven roller 63 is constantly in pressure contact with the transport drive roller 62 (clockwise direction in FIG. 3) by a torsion coil spring (not shown). The transport drive roller 62 is composed of a rotary shaft that is long in the main scanning direction. Therefore, in the present embodiment, the transport drive roller 62 and the transport drive roller 62 are provided.
Is the same as the rotation axis of.

Next, in the vicinity of the conveyance driven roller holder 64 located on the most one-digit side (on the right front side in FIG. 2), the sheet detection consisting of the sensor main body portion 36b and the detector 36a for detecting the passage of the sheet P is detected. A container 36 is provided. Detector 36a
Is formed in a substantially V shape in a side view, and is rotatably provided in a clockwise direction and a counterclockwise direction in FIG. 2 around a rotation shaft 36c near the center thereof. The sensor main body portion 36b located above the detector 36a includes a light emitting portion (not shown) and a light receiving portion (not shown) that receives light from the light emitting portion, and the sensor main portion 36b is placed above the rotating shaft 36c of the detector 36a. The rotation operation blocks and passes the light traveling from the light emitting section to the light receiving section. Therefore, as shown in FIG. 3, when the detector 36a is rotated so as to be pushed upward with the passage of the paper P, the upper side of the detector 36a is disengaged from the sensor body 36b, whereby the light receiving portion is in the light receiving state. Therefore, the passage of the paper P is detected.

Then, downstream of the transport drive roller 62,
The platen 66 and the inkjet recording head 24 are arranged so as to face each other vertically. The platen 66 is long in the main scanning direction (see FIG. 2), and the paper P conveyed below the inkjet recording head 24 by the rotation of the conveyance driving roller 62 is supported from below by the platen 66. The ink jet recording head 24 is the ink cartridge 2
The carriage 22 is provided at the bottom of the carriage 22 for mounting the carriage 3. The carriage 22 reciprocates in the main scanning direction while being guided by a carriage guide shaft 25 extending in the main scanning direction. still,
In this embodiment, the ink cartridge 23 is composed of four cartridges as shown in FIG. 4, that is, four cartridges in which four color inks (black, yellow, cyan, and magenta) are separately and independently filled. It can be exchanged separately.

Next, a sheet discharge section of the printer 100 is provided downstream from the ink jet recording head 24, and a sheet discharge drive roller 65, a sheet discharge driven roller 31, and a sheet discharge auxiliary roller 32 are arranged. . A plurality of paper ejection drive rollers 65 are attached in the axial direction of the paper ejection drive roller shaft 65a that is rotationally driven (see FIG. 4), and the paper ejection driven roller holder 3
The paper discharge driven roller 31 pivotally supported by 1a is provided so as to be driven to rotate by being lightly pressed against the paper discharge drive roller 65. Therefore, the paper P printed by the inkjet recording head 24 is rotated in a state where it is nipped by the paper ejection drive roller 65 and the paper ejection driven roller 31, so that the paper ejection direction (FIG. Three
Is discharged in the direction of arrow). The paper ejection auxiliary roller 32 pivotally supported by the paper ejection auxiliary roller holder 32a is provided on the slightly upstream side of the paper ejection driven roller 31, and presses the paper P slightly downward from the platen 66 of the paper P. Lifting is prevented and thus the distance between the paper P and the inkjet recording head 24 is regulated.

The hopper 6, the movable guide 4, the fixed guide 5, and the paper feed roller 3 described above are provided in the above-mentioned paper feed unit 1 shown in FIGS. 1 and 2. As shown in FIG. 2, the sheet feeding unit 1 includes a mounting portion right 2a and a mounting portion left 2 which are vertically arranged on both sides of a hopper 6 and have a substantially columnar shape.
The base of the paper feeding unit frame 2 is provided with a rotary shaft 3a of the hopper 6 and the paper feeding roller 3.
Etc. are provided in the paper feeding unit frame 2.
Then, the paper feeding unit 1 includes the mounting portion 2a and the mounting portion 2b.
Is connected to the back side of the carriage unit 20 at the upper part of the.

Next, the paper guide 67 and the conveyance drive roller 6
2, transport driven roller holder 64, paper ejection drive roller shaft 65
a is provided in the transport unit 60 shown in FIGS. 1 and 2. As shown in FIG. 2, the transport unit 60 includes a transport unit frame 61 having a substantially U-shaped plan view as a base body, a power supply unit 68 that is a power supply unit of the printer 100 at the rear, and a paper discharge at the front. The drive roller shaft 65a is attached to the transport drive roller 62 in the middle of the main body.
Further, a platen 66 is provided in the upper front part, and a transport driven roller holder 64 is provided in the middle upper part. In the lower left part of the transport unit 60, a drive that serves as a common drive source for the paper feed roller 3, the transport drive roller 62, the paper discharge drive roller 65, a pump device 82 described later, and the blade unit 84. A motor 69 (see FIG. 4) is provided. Power transmission from the drive motor 69 to the paper feed roller 3, the transport drive roller 64, and the paper discharge drive roller 65 is performed by a power transmission device (gear device), which will be described later, provided on the left side surface of the transport unit 60. Power transmission to the pump device 82 and the blade unit 84 provided on the right side surface of the transport unit 60 is performed via the paper ejection drive roller shaft 65a, and a power transmission device (not shown) provided at the right end of the paper ejection drive roller shaft 65a. (Gear device).

Connected to the right side of the transport unit 60,
The ink system unit 80 as a maintenance means of the inkjet recording head 24 includes a frame 81, which is connected to the right side surface of the transport unit frame 61 and serves as a base of the unit, as shown in FIG.
Further, a cap device 83, a pump device 82, and a blade unit 84 are provided. The cap device 83 protects the nozzle surface (not shown) by capping the inkjet recording head 24 when the carriage 22 moves to the home position (in the area a _{1 in} FIG. 4), and the pump device 82 is in the cap state. A negative pressure is supplied to the cap device 83 to suck ink from the nozzle openings of the inkjet recording head 24.

Further, the blade unit 84 is movable between a position that crosses the reciprocating region of the carriage 22 and a position that retracts from the reciprocating region, moves to a position that traverses the reciprocating region of the carriage 22, and the carriage 22
By moving from the print area (area a _{0 in} FIG. 4) to the home position (area a _{1 in} FIG. 4), or
By moving in the opposite direction, the nozzle surface (not shown) of the inkjet recording head 24 is wiped to perform cleaning.

The carriage guide shaft 25 and the paper detector 36 are provided in the carriage unit 20. As shown in FIG. 2, the carriage unit 20 includes a main frame 21a, a side frame right 21b and a side frame left 21c that are erected on both sides of the main frame 21a. 25 is pivotally supported.

Further, as shown in FIG. 4, the carriage unit 20 is provided with a carriage motor 27 on the left rear surface of the unit, and a drive pulley 28 is attached to the carriage motor 27. A driven pulley 29 is provided on the right side of the unit, a carriage belt 26 is hung between the drive pulley 28 and the driven pulley 29, and a part of the carriage belt 26 is fixed to the carriage 22. . Therefore, the carriage 22 reciprocates in the main scanning direction (left and right direction in FIG. 4) by the rotation of the carriage motor 27.

Although the paper discharge frame 30 is attached to the carriage unit 20 side in FIG. 2, the paper discharge frame 30 can be attached to the carriage unit 20 side or the transport unit 60 side. It is possible to belong to either side.

The above is the configuration of the main body of the printer 100, and the printer 100 becomes movable by combining and connecting the four units. The carriage unit 20 and the sheet feeding unit 1 are connected by one unit connecting device and one connecting portion described later, and the other units are connected by fixing screws not shown.

<Width Dimension of Carriage Unit> Next, the width dimension of the carriage unit 20 will be described with reference to FIG. First, the carriage 22 prints on the paper P by reciprocating in the main scanning direction as described above.
The reciprocating operation area of the carriage 22 can be divided into areas a ₀ , a ₁ and a ₂ from the viewpoint of its role, as shown in FIG. That is, the area a ₀ is a printing area, and the carriage 22 performs the main scanning at a constant speed (V ₀ ) in the area a ₀ while ejecting ink droplets onto the paper P to perform printing. The area a ₁ is an acceleration / deceleration area and a standby area, and the carriage 22
Is in a standby state at a home position (not shown) set in the area, and when the ink system unit 80 receives maintenance such as capping and ink suction as described above, when heading for the printing area a _{0. First} , the acceleration operation is performed to reach the main scanning speed (V ₀ ) in the print area a ₀ in the area a ₁ .
The area _{a 2,} like the region _{a 0,} when toward the printing area _{a 0,} the acceleration operation for reaching the main scanning speed in the printing area _{a 0 (V 0)} in the region _{a 2.}
The regions a ₀ and a ₂ also serve as deceleration regions for stopping the carriage 22 at both ends of the main scanning region.

When the printer design is changed,
In general, the number of ink colors mounted on the carriage 22 (the number of ink cartridges 23: four in this embodiment) and the capacity of the ink cartridge 23 are often changed. Therefore, the design of the carriage 22 is changed depending on the design of the printer, which causes the weight or width of the carriage 22 to be different. When the weight of the carriage 22 is different, it is necessary to change the size of the acceleration region necessary to reach the main scanning speed (V ₀ ), that is, the size of the regions a ₁ and a ₂ , and thus the region a. ₁ and components related to the size of a ₂ , specifically, the main frame 2
It is necessary to change the design of 1a and the carriage guide shaft 25.

Further, if the width of the carriage 22 is different, it is necessary to change the sizes of the areas a ₁ and a ₂ due to this, and therefore, the size of the areas a ₁ and a ₂ is related to the above. It is necessary to change the design of the components, that is, the main frame 21a and the carriage guide shaft 25. The design of the carriage 22 remains the same,
Even when the main scanning speed (V ₀ ) in the print area a ₀ is changed, the required acceleration area, that is, areas a ₁ and a ₂
It is necessary to change the size of
It will be necessary to change the design of the components related to the size of ₁ and a ₂ , that is, the main frame 21a and the carriage guide shaft 25.

As described above, in almost all cases in which the design of the printer is changed, it is necessary to change the width dimensions of the components related to the sizes of the areas a ₁ and a ₂ , and therefore, for example, the main frame 21a is installed in the apparatus. In the case of a printer in which the constituent elements of the printer are assembled into the main frame 21a as the main body of the main body to form an integral structure, the size of the regions a ₁ and a ₂ is not related to the design change of the main frame 21a. The design change of the constituent elements, for example, the conveyance drive roller 62, the paper discharge drive roller shaft 65a, etc. is required, which complicates the design change of the printer and makes it impossible to use common parts, which is a barrier to cost reduction.

However, the printer 100 according to the present embodiment.
As described above, the apparatus main body is configured by combining the paper feeding unit 1, the carriage unit 20, the transport unit 60, and the ink system unit 80 as described above, and other than the carriage unit 20 including the carriage 22. The unit is composed of components that do not require a design change even when the printer design is changed. In other words, the printer 100 includes a general-purpose unit (the paper feeding unit 1, the transport unit 60, and the ink system unit 80) that includes components whose width-direction dimensions do not change and can be shared by a plurality of printers having different designs. It consists of a dedicated unit (carriage unit 20) unique to each design, including components with varying directional dimensions. Therefore, when the design of the printer is changed, in most cases it is sufficient to change the design of only the carriage unit 20, which makes it possible to easily change the design of the printer and to reduce the cost by sharing the parts. It is possible to measure it.

When the design of the ink jet recording head 24 is changed, particularly when the number of nozzles is increased,
Since the sizes of the inkjet recording heads 24 are different, it is necessary to change the design of the unit ink system unit 80 including the cap device 83 that caps the inkjet recording heads 24.

As described above, the widthwise dimension of the carriage unit 20 changes depending on the design of the carriage 22, and in the present embodiment, the carriage unit 20 is larger than the widthwise dimension of the transport unit 60. When connected, they project outward from both sides of the transport unit 60 as shown in FIG.

<Encoder Configuration and Operational Effects> Next,
The configuration and operational effects of the encoder 40 will be described with reference to FIGS. 5 to 8 and other drawings as appropriate. Here, FIG. 5 is a partially enlarged view of the side surface of the printer 100 apparatus main body, FIG. 6 is a plan view of the encoder 40, FIG. 7 is a front view and a partially enlarged view of a disc-shaped scale 41 constituting the encoder 40, and FIG. It is explanatory drawing which shows the rotation ratio of two disk-shaped scales from which a diameter differs.

First, the structure of the power transmission device provided on the side surface of the transport unit 60 will be described with reference to FIG. In FIG. 5, the drive motor 69 is provided on the lower front side (lower right side in FIG. 5) of the left side surface (left side surface in FIG. 4) of the transfer unit frame 61 which is the base of the transfer unit 60, and will be described with reference to FIG. The transport driving roller 62,
The paper ejection drive roller shaft 65a and the paper feed roller shaft 3a (see FIG. 3) are rotationally driven.

A pinion gear 69a is attached to the rotating shaft of the drive motor 69, and the pinion gear 69a, a transmission gear 49 provided above the drive motor 69, and a transmission provided in the middle of the rear of the transport unit frame 61. Gear 5
An endless belt 51 is wound between the two. Therefore, when the drive motor 69 rotates, the transmission gears 49 and 52 simultaneously rotate via the endless belt 51.

The transmission gear 49 has a discharge driving roller shaft 65.
The paper ejection drive roller gear 65b attached to the shaft end of a is meshed, so that the paper ejection drive roller shaft 6
5a rotates. The transmission gear 52 is configured by a two-stage gear, and a gear 52a engaged with the endless belt 51 and a gear 52b engaged with a transport drive roller gear 62b attached to the shaft end of the transport drive roller 62 are integrally formed. It is provided so as to be rotatable around the rotation shaft 48.
Therefore, this causes the transport drive roller 62 to rotate.

A transmission gear 50 that meshes with the conveyance drive roller gear 62b is provided behind the conveyance drive roller gear 62b (on the left side in FIG. 5).
The transmission gear 59 provided on the side of the sheet feeding unit 1 meshes when the sheet feeding unit 1 is connected to the carriage unit 20. Accordingly, this causes the paper feed roller shaft 3a (see FIG. 3) to rotate.

The above is the configuration of the power transmission device provided on the left side surface of the transport unit 60. Next, the encoder 40
The configuration of will be described. First, the encoder 40 is the carriage unit 20 that is on the left side surface of the transport unit 60 and further projects from the transport unit 60 on both sides.
(See FIG. 4).

In FIG. 5 and FIG. 6, the encoder 40
Is composed of a sensor holder 53 attached to the transport unit frame 61, a photo interrupter (optical sensor) 44 attached to the sensor holder 53, and the disc-shaped scale 41 attached to the transmission gear 52 described above. Here, the disc-shaped scale 41 is attached to the shaft end of the transport drive roller 62 as the “detection target shaft”, and is the transport drive roller gear 62 as the “first gear”.
Since it is attached to the transmission gear 52 as the "second gear" that meshes with b, the transport drive roller 62 and the transmission gear 52 form the "gear speed reducer" of the encoder 40. That is, the gear reduction device of the encoder 40 is
The encoder 40 is inexpensive because it is composed of the two gears that compose the power transmission device described above.

The photo interrupter 44 is attached to the sensor holder 53 with the printed circuit board 45 attached. The printed board 45 is provided with a connector 46 having a terminal for transmitting an electric signal to the outside and a terminal for supplying power from the outside, and is connected to a control device (not shown) via the connector 46. The photo interrupter 44 has a light emitting portion 44a that emits light as shown in FIG.
(The side far from the transport unit frame 61) and the light emitting section 4
4a (the side close to the transport unit frame 61) for receiving the radiated light of 4a, and a space 44c is formed between them. And the interval 4
The outer peripheral portion of the disk-shaped scale 41 provided in parallel with the left side surface of the transport unit frame 61 is inserted into 4c, and the optical axis of the light emitted from the light emitting portion 44a to the light receiving portion 44b is The light emitting portion 44a and the light receiving portion 44b are arranged so as to vertically penetrate the outer peripheral portion of the disk-shaped scale 41.

More specifically, as shown in FIG. 7, the disc-shaped scale 41 has a light-transmitting portion 43a and a light-shielding portion 43b, which have substantially the same width, on the outer peripheral portion thereof alternately arranged at a constant pitch L in the circumferential direction. It has a slit-shaped rotation detection pattern 42 that is repeatedly formed. And the disc-shaped scale 41
Is the light emitting unit 4 of the photo interrupter 44 as shown in FIG.
4a and the light receiving portion 44b, and a light emitting surface (a surface of the light emitting portion 44a that faces the disc-shaped scale 41: hereinafter referred to as a "light emitting surface") and a light receiving surface (a disc-shaped scale of the light receiving portion 44b). A surface facing 41: hereinafter, referred to as a "light receiving surface") and in a state of being substantially parallel to the outer surface, the outer peripheral portion is adjusted so as to be sandwiched at a gap 44c.

On the other hand, as shown in FIGS. 5 and 6, the sensor holder 53 extends vertically on the front side (right side in FIG. 5: lower side in FIG. 6) of the light emitting section 44a, and then the light emitting section 44a. An outer regulation portion 54 having an arm shape that reaches the vicinity of the upper portion, and inner regulation portions 55 and 56 provided so as to sandwich the light receiving portion 44b are formed. Then, the disc-shaped scale 4 is provided at the tip of the outer restricting portion 54.
1 surface (surface far from the transport unit frame 61)
A protrusion 54 a that protrudes toward the disc-shaped scale 41 is formed on the side opposite to. Further, in the inner side regulation portions 55 and 56, on the side facing the back surface (the surface facing the transport unit frame 61) of the disc-shaped scale 41, the protrusion portions 55 a and 56 protruding toward the disc-shaped scale 41.
a is formed.

Here, the protrusion 54a slightly protrudes from the light emitting surface of the light emitting portion 44a toward the disc-shaped scale 41 in FIG. 6, and forms a slight gap with the surface of the disc-shaped scale 41. The disc-shaped scale 41 is regulated so as not to bend to the front side. Also, the protrusions 55a, 56a
6 slightly protrudes from the light receiving surface of the light receiving portion 44b toward the disc-shaped scale 41 in FIG. 6, and forms a minute gap with the back surface of the disc-shaped scale 41, so that the disc-shaped scale 41 bends to the back side. We have regulations to prevent it.

As described above, the rotation detecting pattern 42 is provided on the outer peripheral portion of the disc-shaped scale 41 which is inserted at the interval 44c.
The mounting position of the sensor holder 53 is adjusted so that is positioned on the optical axis of the photo interrupter 44. Therefore, when the disc-shaped scale 41 rotates, the rotation detection pattern 42 is moved from the light emitting portion 44a to the light receiving portion 44b.
The transmission and the blocking of the light traveling toward are repeated.

The disc-shaped scale 41 is attached to the transmission gear 52 as described above, and the transmission gear 52 is meshed with the conveyance drive roller gear 62b attached to the shaft end of the conveyance drive roller 62. Therefore, when the transport drive roller 62 is rotationally driven to transport the paper P while the printer 100 is performing printing, the disc-shaped scale 41 rotates accordingly. As a result, the transmission and blocking of the light traveling from the light emitting portion 44a to the light receiving portion 44b by the rotation detection pattern 42 is repeated, and the photointerrupter 44 outputs a rectangular wave signal that alternately turns ON and OFF to control the printer 100. Provided to a device (not shown). A control device (not shown) obtains the carry amount of the paper P from the number of the rectangular waves, and determines the paper P from the repetition period of the rectangular waves.
The transport speed of is calculated. The above is the configuration of the encoder 40.

Next, referring to FIG. 8, the encoder 40
The rotation amount of the transport drive roller 62 as the detection target axis of
The relationship between the circumferential pitch of the rotation detection pattern 42 and the diameter of the disc-shaped scale 41 will be described.

First, the rotation detection pattern 4 shown in FIG.
The light transmitting portions 43a and the light blocking portions 43b in 2 are alternately formed at a constant pitch L in the circumferential direction. The pitch L corresponds to the rotation amount of the transport drive roller 62 as the detection target axis, and the rotation angle α of the transport drive roller 62 is
The pitch L is detected. Therefore, as the pitch L is smaller, the rotation detecting pattern 42 has a larger number of light transmitting portions 43.
a and the light blocking portion 43b, the rotation angle α of the transport driving roller 62 corresponding to the pitch L is reduced, so that the detection accuracy of the rotation amount of the transport driving roller 62, in other words, of the encoder 40. The resolution is high. However, there is a limit in terms of the spot radius of the light emitted from the light emitting portion 44a and the light receiving sensitivity of the light receiving portion 44b,
Therefore, the minimum value of the pitch L depends on the performance of the photo interrupter 44.

Here, consider the case where the disk-shaped scale 41 is reduced in diameter for reasons of the installation space for disposing the encoder 40. In FIG. 8, reference numeral 41 'is a disc-shaped scale with a reduced diameter. In FIG. 8, for convenience of explanation, the rotation detection pattern formed on the disc-shaped scale 41 is formed by a pitch L obtained by dividing the outer peripheral length of the disc-shaped scale 41 into eight, and the disc-shaped scale is reduced in diameter. The rotation detection pattern formed on the scale 41 ′ has a pitch L / which is obtained by dividing the outer peripheral length of the disc-shaped scale 41 ′ into eight.
2 (FIG. 8A).

FIG. 8B is an explanatory view in the case where the disk scale 41 in the encoder 40 is simply replaced with the disk scale 41 '. In the case of the disc-shaped scale 41, assuming that the pitch L corresponds to the rotation angle α of the transport driving roller 62, if the transport driving roller 62 rotates by the angle α, the disc-shaped scale 41 and the disc-shaped scale 41 ′. Both of them rotate in the direction of the arrow by the angle β (45 ° because of 8 divisions). Therefore, the photo interrupter 44 detects a state change from the light transmitting portion 43a to the light blocking portion 43b or vice versa according to the pitch L in the case of the disc-shaped scale 41, and the pitch L in the case of the disc-shaped scale 41 '. A similar state change is detected by / 2.

However, if the detection limit of the photo interrupter 44 is the pitch L, the photo interrupter 44 in the disc-shaped scale 41 'shown in FIG. 8B is used.
Even if the light transmissive portion 43a or the light blocking portion 43b crosses the optical axis of the photo interrupter 44 only by changing the pitch L / 2 in the optical axis of the photo interrupter 44, the photo interrupter 44 cannot detect this (detect it. Therefore, the rotation indicated by the wavy line is required). On the other hand, in order to solve such a problem, if the formation pitch of the rotation detection pattern in the disc-shaped scale 41 'is simply set to L, the optical axis of the photo interrupter 44 is set to the light transmission part 43a or the light blocking part 43b.
The rotation angle of the transport drive roller 62 required for the
The angle α is doubled to 2α, which allows the encoder 4
This means that the resolution of 0 is reduced (decreased to 1/2).

Here, in FIG. 8C, reference numeral 41 "
Is a disk-shaped scale having the same diameter as the disk-shaped scale 41 ', and is formed by a pitch L obtained by dividing the outer peripheral length of the disk-shaped scale 41 "into four.
By setting the pitch L in this way, the state change of the rotation detection pattern by the photo interrupter 44 can be detected, but if it is applied to the encoder 40 having the same configuration as in FIG. 8B, as described above. The resolution of the encoder 40 decreases.

However, the encoder 40 according to the present invention is
It is not directly attached to the conveyance drive roller 62 as the detection target shaft, but is attached via the gear reduction device including the conveyance drive roller gear 62b and the transmission gear 52 (52b) as described above. Therefore, it is possible to adjust the gear ratio (reduction ratio) of the two gears, and by adjusting the gear ratio (reduction ratio) of the two gears,
When the transport drive roller 62 is rotated by an angle α,
The pitch L can be secured by rotating the disc-shaped scale 41 ″ by an angle 2β as shown in (c).

That is, in the encoder 40, the rotation axis of the disk-shaped scale 41 (rotation axis 48: see FIG. 5) and the transport drive roller 62 as the detection target axis are different from each other, and the gear deceleration for engaging them is performed. It is equipped with a device. Therefore, even if the diameter of the disc-shaped scale 41 is changed, the pitch in the circumferential direction (pitch L) of the rotation detection pattern 41 and the conveyance drive roller 6 can be adjusted by adjusting the reduction ratio of the gear reduction device.
It is possible to maintain a constant relationship with the rotation amount of 2 (angle α). Therefore, this allows the photo interrupter 4
4 without changing to expensive high resolution one, and
It is possible to reduce the diameter of the disc-shaped scale 41 without lowering the resolution of the encoder 40.
It is possible to increase the degree of freedom in arranging the disk-shaped scale 41 at 00.

In particular, in the present embodiment, the encoder 40 is provided on the side surface of the transport unit 40, and is positioned so as to interfere with the main scanning area when the main scanning area of the carriage 22 becomes large. Therefore, the design of the carriage 22 can be freely changed by the encoder 40 capable of reducing the diameter of the disk-shaped scale 41 without lowering the resolution, without considering the interference with the main scanning area of the carriage 22. ing. Further, since the encoder 40 has the gear reduction device as described above, the transport drive roller 62 as the detection target shaft, which is located below the main scanning region of the carriage 22, and the disc-shaped scale 41 are thereby arranged. It is possible to move away from the
The degree of interference with the second main scanning area is reduced, and thus the design of the carriage 22 can be freely changed.

[0064]

As described above, according to the present invention, the rotary axis of the disk-shaped scale constituting the encoder is different from the detection target axis, and the gear reduction device for engaging them is provided. Therefore, even if the diameter of the disc-shaped scale is changed, by adjusting the reduction ratio of the gear reduction device, while maintaining the circumferential pitch of the rotation detection pattern constant, It is possible to maintain a constant relationship with the rotation amount of the detection symmetry axis, and thus it is possible to reduce the diameter of the disc-shaped scale without lowering the resolution of the encoder.

[Brief description of drawings]

FIG. 1 is an external perspective view of an apparatus main body of an inkjet printer according to the present invention.

FIG. 2 is an exploded perspective view of the apparatus body of the inkjet printer according to the present invention.

FIG. 3 is a side sectional view of the inkjet printer according to the present invention.

FIG. 4 is a front view of the apparatus main body of the inkjet printer according to the present invention.

FIG. 5 is a partially enlarged view of the side surface of the apparatus main body of the inkjet printer according to the present invention.

FIG. 6 is a plan view of an encoder according to the present invention.

7A and 7B are a front view and a partially enlarged view of a disk-shaped scale that constitutes an encoder.

FIG. 8 is an explanatory diagram showing rotation ratios of two disc-shaped scales having different diameters.

[Explanation of symbols]

1 Paper feeding unit 20 Carriage unit 22 carriage 24 inkjet recording head 40 encoder 41 disk scale 42 Rotation detection pattern 44 Photointerrupter 44a light emitting unit 44b Light receiving part 51 endless belt 52 transmission gear 53 sensor holder 54 Outside regulation section 55, 56 Inner regulation part 60 transport units 61 Transport unit frame 62 Transport drive roller 69 drive motor 100 inkjet printer

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) // B65H 7/14 B41J 3/04 101Z 3F048 (72) Inventor Keitomo Tanaka 3-5 Yamato, Suwa City, Nagano Prefecture No. Seiko over Epson Corporation in the F-term (reference) 2C056 EA23 EB12 EB35 EB36 FA10 HA28 HA29 HA37 KD06 2C058 AB02 AC07 AC11 AD01 AE02 AE09 AF23 GA02 GA06 GB05 GB07 GB19 GB20 GB43 GB48 GB53 GE01 2C480 CA44 CB02 CB31 CB34 EA22 2F063 AA35 BA30 CA34 DA05 DC03 EA03 KA02 2F077 AA25 CC02 DD05 NN02 NN23 NN30 PP19 VV01 3F048 AA05 AB01 BB02 BB05 CC13 DA06 DC06 DC13 EB29

Claims (4)

[Claims] 1. A disk-shaped scale having a rotation detecting pattern, which is formed by alternately arranging light-shielding portions and light-transmitting portions in a circumferential direction at a constant pitch, on the outer peripheral portion, and said disk-shaped scale according to the rotation of the disk-shaped scale. An encoder for detecting a rotation amount of a detection target shaft, comprising: a sensor including a light emitting part and a light receiving part, which converts a state change of a rotation detection pattern into an electric signal, wherein the rotary shaft of the disk-shaped scale is provided. Is engaged with the detection target shaft via a gear reduction device, and by adjusting the reduction ratio of the gear reduction device, the relationship between the circumferential pitch of the rotation detection pattern and the rotation amount of the detection symmetric shaft. An encoder characterized in that the diameter of the disk-shaped scale can be changed while maintaining a constant value. 2. The gear reduction device according to claim 1, wherein the gear reduction device uses a gear that constitutes a power transmission device that transmits power from a drive motor that is a drive source of the detection target shaft to the detection target shaft. An encoder that is characterized by: 3. A recording device for recording on a recording material, comprising an apparatus main body formed by combining a plurality of units, wherein the recording material is conveyed by a rotation drive roller at a constant pitch. 3. The encoder according to claim 1, further comprising: a transport unit that includes the carriage unit; and a carriage unit that is provided on an upper portion of the transport unit that includes a carriage that includes an inkjet recording head so as to reciprocate in a main scanning direction. The recording apparatus is disposed on a side surface of the transport unit at a position located below the main scanning area of the carriage when the main scanning area of the carriage is extended. 4. The disk-shaped scale according to claim 3, wherein the disc-shaped scale is provided on a second gear that rotates by meshing with a first gear provided on the shaft end of the rotation shaft of the transport drive roller. A recording device characterized by the above.