JP2597308Y2 - Recording paper feeder - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a recording paper feeder (hereinafter referred to as a recording paper feeder).
In particular, the present invention relates to a bearing structure of a recording paper feeding device in a serial recording device that performs high-density recording.

[0002]

2. Description of the Related Art Conventionally, as a paper feeder of a serial recording apparatus, a method shown in a sectional view in FIG. 6 is generally used. FIG.
In the drawing, reference numeral 3 denotes a paper feed drive roller (hereinafter, also referred to as a drive roller), which is disposed on the front surface of the recording head 1. Reference numerals 321 and 322 denote paper feed driven rollers (hereinafter also referred to as driven rollers), which are pressed by the paper feed drive roller 3 with a recording medium (hereinafter also referred to as recording paper) 8 interposed therebetween. The recording medium 8 is wound around the paper feed drive roller 3 by the paper feed driven rollers 321 and 322. The paper feed drive roller 3 has a shaft portion 34 at the center, and is rotatably supported by two bearings 33 rotatably engaged with the shaft portion 34 and fixed to frames 41 and 42 at both ends. One end of the shaft portion 34 of the paper feed drive roller 3 is provided with a drive roller gear 31.
Are combined. The drive roller gear 31 is directly engaged with a paper feed motor gear 51 serving as a transmission means, or is engaged with an intermediate reduction gear (not shown) which is engaged with the paper feed motor gear 51 and serves as a transmission means for multi-stage reduction. I agree. The paper feed motor gear 51 is connected to the paper feed motor 5.

[0003] The operation of the paper feeder having the above configuration is as follows. That is, by rotating the paper feed motor 5 by a predetermined amount, the rotational driving force of the paper feed motor 5 is transmitted to the drive roller gear 31 via the transmission means composed of gears, and the paper feed drive roller coupled to the drive roller gear 31 3 rotates by a predetermined amount supported by the bearing 33, and the recording medium 8 is conveyed by a predetermined amount.

[0004]

In recent years, there has been a strong demand for smaller, thinner, and lighter recording apparatuses of this type, and for this purpose, the outer diameter of the paper feed drive roller 3 in the paper feeder has been required. It is a very effective means to reduce the diameter of.

However, in the above conventional example,
Since both ends of the paper feed drive roller 3 are supported by the bearings 33, if the outer diameter of the paper feed drive roller 3 is reduced, the axial strength of the paper feed drive roller 3 in the longitudinal direction is weakened.
Due to the pressing force of the paper feed driven roller 321 or 322, deflection that cannot be ignored in the paper feed drive roller 3 occurs, and the conveyance accuracy of the recording medium 8 decreases. Therefore, there is a great limitation in reducing the diameter of the paper feed driving roller 3.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a bearing structure of a paper feeder capable of reducing the size, thickness, and weight of a recording apparatus.

[0007]

The recording paper feeder according to the present invention is disposed immediately upstream of the recording head in the paper transport direction and does not exceed the paper transport surface of the drive roller whose upper part is pivotally supported. A small-diameter bearing member, a small-diameter drive roller whose entirety in the axial direction except for a bearing portion serves as a recording paper conveyance surface, and a bearing arranged across the bearing member, and the bearing of the drive roller In the vicinity of the member, a small-diameter roller is provided at both ends to press the recording paper, and a driven roller urged toward the driving roller by an elastic member is provided.

[0008]

The paper feed drive roller is supported, has a release portion in a side view shape, and has a shape in which the open end face of the release portion does not intersect with one of the contact surfaces with the outer periphery of the paper feed drive roller. By providing a plurality of paper feed drive rollers in the vicinity of the feed driven roller pressing portion, the deflection of the paper feed drive roller due to the pressing force of the paper feed driven roller is reduced, and a small-diameter paper feed drive roller can be used.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a perspective view thereof.

In these figures, reference numeral 1 denotes a recording head, and a plurality of recording elements 11 from # 1 to #n in the column direction A.
Are arranged at a constant element pitch p. The array of the recording elements 11 may be arranged in a row to obtain a pitch p between the elements,
The element pitch may be obtained by arranging the elements in a plurality of rows.

Reference numeral 2 denotes a carriage on which the recording head 1 is mounted, which is driven by a carriage motor 21 via a timing belt 24, and is moved in a row direction B (width direction of the recording paper 8) along guide shafts 22 and 23. Moving.

Reference numeral 3 denotes a paper feed drive roller, which is arranged on the upstream side of the recording medium 8 with respect to the recording head 1. For the following description of the operation, the outer diameter (outermost diameter) of the paper feed drive roller 3 is described as d. The paper feed drive roller 3 has a shaft portion 34 smaller than the outermost diameter, and the shaft portion 34 is rotatably supported by a plurality of bearings 33 provided on a support plate 43. The paper feed drive roller 3 is engaged with one or a plurality of paper feed driven rollers 32 pressing the outermost diameter portion of the paper feed drive roller 3 by a spring (not shown) from the opposite side of the bearing 33, and holds the recording medium 8 therebetween. By rotating between
The recording medium 8 is transported in the column direction A.

The driving roller 3 has a high bending strength and the bearing 3
It is necessary that the friction coefficient of the recording paper 8 be low while the friction coefficient of the recording paper 8 is low. For example, a metal shaft partially coated with a thin ceramic or the like is suitable.

A plurality of bearings 33 are provided near the pressing portion of the paper feed driven roller 32 in the row direction recording area, and are provided with an opening 331 in a side view shape shown in a sectional view of FIG. The open end surface 332 of the open portion 331 has a shape that does not project with respect to the outer diameter of the paper feed drive roller 3, that is, a shape that does not intersect with at least one contact surface with the outer periphery of the paper feed drive roller 3. Therefore, by arranging the recording medium 8 so as to be a non-intersecting contact surface, the recording medium 8 can pass between the paper feed drive roller 3 and the paper feed driven roller 32 without being interfered by the bearing 33. Becomes possible.

A drive roller gear 31 is connected to one end of the paper feed drive roller 3. For the operation explanation to be described later,
The pitch circle diameter of the drive roller gear 31 is described as D.

Reference numeral 5 denotes a paper feed motor. A paper feed motor gear 51 which is engaged with the drive roller gear 31 and forms a transmission means is fixed.
Then, the paper feed drive roller 3 combined with the drive is driven. Gear ratio of drive roller gear 31 and paper feed motor gear 51 (reduction ratio)
Is optional. In the illustrated example, the speed is reduced by one step. However, the paper feed motor gear 51 and the drive roller gear 31
It is also possible to insert an intermediate reduction gear (not shown) serving as a transmission means for multi-stage reduction between the two stages to realize multi-stage reduction.

As the paper feed motor 5, a general step motor having, for example, four-phase 48 poles, 96 poles, and 200 poles can be applied. The transport amount of the recording medium 8 per one step of the paper feed motor 5 (paper feed resolution) is determined by the number of poles of the paper feed motor 5, the driving method of the paper feed motor 5, and the speed reduction from the paper feed motor 5 to the drive roller gear 31. The ratio is determined by a combination of the ratio and the outer diameter of the paper feed drive roller 3. In the present embodiment, the paper feed resolution was set to about 10 microns.

Reference numeral 45 denotes a platen, which has a flat surface and is arranged on the entire surface of the recording element 11 of the recording head 1. 6
Is a paper feed roller, which has a built-in one-way clutch (not shown) and is driven to rotate only in one direction by a paper feed roller shaft 64 to separate the recording medium 8 stored in the paper feed tray 65 while separating the recording device 8 for each leaf. Into the paper feeder. The feed gear 63 is connected to the feed roller shaft 64.

Reference numeral 61 denotes a paper feed motor. A paper feed motor gear 62 engaged with a paper feed gear 63 is fixed.
Drive. The paper feed motor 61 is eliminated by providing a power switching mechanism and switching the engagement of the paper feed motor gear 51 between the paper feed gear 63 and the drive roller gear 31 according to the rotation direction of the paper feed motor 5. It is also possible.

Reference numeral 7 denotes a paper end sensor, which is disposed between the paper feed roller 6 and the paper feed drive roller 3, and detects the position of the end surface of the recording medium 8.

For discharging the recording medium 8 after recording, a pair of discharge rollers (not shown) may be provided on the recording head 1 on the downstream side of the path of the recording medium 8.

Next, the operation of the paper feeder having the above configuration will be described.

When the recording data is received, the paper feeding motor 61 starts rotating for paper feeding. The paper feed roller 6 is driven by the rotation of the paper feed motor 61, one of the recording media 8 stored in the paper feed tray 65 is selected, and is sent to the engaging portion between the paper feed drive roller 3 and the paper feed driven roller 32. It is. The selected recording medium 8 includes a paper feed roller 6 and a paper feed drive roller 3.
When the leading end of the recording medium 8 is detected by the paper end sensor 7 located between them, the recording medium 8 is fed from that position by a predetermined amount necessary for the leading end of the recording medium 8 to reach the paper feed drive roller 3 sufficiently. It is. The leading end of the recording medium 8 is the paper feed drive roller 3
The paper feed motor 61 is pressed against the tangential portion between the paper feed driven roller 32 and the skew and the like, and the rotation of the paper feed motor 61 is stopped, and the paper feed operation ends.

Next, the paper feed motor 5 starts rotating for cueing the recording medium 8. The paper feed drive roller 3 is driven by the rotation of the paper feed motor 5. The recording medium 8 is sent out while being sandwiched between the paper feed drive roller 3 and the paper feed driven roller 32, faces the recording head 1 along the platen 45, and the cueing operation ends. The paper feed roller 6 is idled in the pull-out direction of the recording medium 8 by a built-in one-way clutch, and the recording medium 8 is pulled out from the paper feed tray 65 with a small load.

After the feeding and cueing of the recording paper 8 are completed as described above, the carriage motor 2 is driven.
After the carriage 2 moves in the row direction and the recording element 11 of the recording head 1 mounted on the carriage 2 reaches the recording area in the row direction, the recording element 11 is selectively energized according to the recording data, and 8, an arbitrary character or image for one band is recorded in the recording area in the row direction B.

For recording a continuous pattern such as an image, for example, after the recording of the first band is completed,
The driving of the carriage motor 2 is stopped, the paper feed motor 5 is driven, and the recording medium 8 is rotated by the rotation of the paper feed drive roller 3.
Is conveyed by the entire length of the recording element 11 in the column direction. Thereafter, the carriage motor 2 is driven in reverse to move the print head 1 in the reverse direction, and print a second band adjacent to the first band. Hereinafter, the movement operation of the carriage 2 and the conveyance operation of the recording medium 8 are repeated.

When the recording approaches the end of the recording medium 8, the end of the recording medium 8 passes by the paper edge sensor 7 and the paper edge sensor 7
, The end of the recording medium 8 is detected. Thereafter, the movement operation of the carriage 2 and the conveyance operation of the recording medium 8 are repeated until the last band allocated to the end of the recording medium 8 is recorded, and the recording of one page is completed.

Here, the operation of transporting the recording medium 8 by the rotation of the paper feed drive roller 3 will be described in further detail.

A major factor that hinders the transport accuracy in the transport operation of the recording medium 8 by the paper feeder is the engagement between the drive roller gear 31 coupled to the paper feed drive roller 3 and the transmission means.

Normally, a pair of gears meshing with each other needs a play on the pitch circumference of the gears called backlash. Due to this backlash, it is possible to avoid problems in meshing caused by errors in gear pitch, tooth profile, tooth traces, tooth thickness, etc., tooth groove runout, expansion due to temperature rise, and the like.

Assuming that the transmission means is a paper feed motor gear 51 (one-step reduction), the total amount of backlash provided between the drive roller gear 31 and the paper feed motor gear 51 is f. An example of the numerical value of f is shown below for the description with specific numerical values.

The magnitude of the backlash in the circumferential direction of a single gear is specified for each accuracy class in JIS B 1703 (backlash of spur gear and helical gear). As for the accuracy class of the gear, in a paper feeder or the like, a class of 3 to 5 is appropriate in consideration of economy, and in the present embodiment, a class of 4 is used.
Use grade gears. When the amount of backlash according to the above-mentioned JIS rules is obtained, the drive roller gear 31 (φ25 to 50) has a size of 150 μm and a module of 0.5 or less.
The paper feed motor gear 51 (φ6 to 12) has a size of 100 microns. Therefore, the total amount of backlash f in the engagement between the drive roller gear 31 and the paper feed motor gear 51 is f
Is f = 150 + 100 = 250 microns.

In the above engaged state, the paper feed motor 5
When the drive roller gear 31 stops after rotating by a predetermined amount, the drive roller gear 31 driven via the transmission means has an area where the stop position is not determined by the total amount f of backlash in the rotation direction, and the drive roller gear 31 Error occurs in the transport amount of the recording medium 8 due to the rotation of the paper feed drive roller 3 combined with
The recorded image quality is degraded.

The relationship between the outer diameter d of the paper feed drive roller 3 and the pitch diameter D of the drive roller gear 31 will be described with reference to FIG.

As shown in FIG. 3, the stop position uncertainty area 82 on the outer periphery of the paper feed drive roller 3 is
In comparison with the uncertainty area 81 of the stop position on the circumference of one pitch, the diameter becomes smaller by the ratio of the diameter. That is, the uncertain region of the stop position on the pitch circumference of the drive roller gear 31 which is generated by f due to the total amount of backlash between the drive roller gear 31 and the transmission means is the drive roller gear on the outer periphery of the paper feed drive roller 3. 31 and the diameter ratio D / d of the outer diameter d of the paper feed drive roller 3 to the outside diameter d of the paper feed drive roller 3, and f /
(D / d).

Accordingly, the outer diameter d of the paper feed drive roller 3
Is a very effective means for improving the conveyance accuracy of the recording medium 8.

However, when the outer diameter d of the paper feed drive roller 3 is reduced, the axial strength of the paper feed drive roller 3 in the longitudinal direction is weakened, and the deflection of the paper feed drive roller 3 due to the pressing force of the paper feed driven roller 32. Becomes a new factor that hinders the conveyance accuracy of the recording medium 8.

According to the structure of the present embodiment, it is possible to reduce the deflection. Hereinafter, a specific example will be described in detail with reference to FIG.

FIG. 4A is a front view showing the bearing structure of the paper feeder of the present invention.

In FIG. 4a, five bearings 33a, 33b, 3 are mounted on a support plate 43 extending between the frames 41, 42.
3c, 33d, and 33e were provided.

The paper feed drive roller 3 having the shaft portion 34 is
The steel shaft portion 34 is disposed on the bearing 33 so as to be supported by the bearings 33a to 33e.

Three paper feed driven roller pairs 3 for pressing the paper feed drive roller 3 above the bearings 33b, 33c, 33d
2b, 32c and 32d were provided.

Paper feed driven roller pair 32b, 32c, 32
The pressing force W of d was 0.5 kg weight.

The outer diameter d of the paper feed drive roller 3 was 3.5 mm, and the diameter d 'of the shaft portion 34 was 3.4 mm.

Between the bearings 33b and 33c and the bearing 33
The distance L between c and 33d was 60 mm, and the distance L1 between the point of action of the paper feed driven roller 32 and the bearing 33 was 8 mm each.

The distance between the frames 41 and 42 was 280 mm.

With the above configuration, the amount of deflection of the paper feed drive roller 3 was measured. As a result, the maximum deflection amount generated in the paper feed drive roller 3 was 10 μm or less, and hardly affected the conveyance accuracy of the recording medium 8. This is mainly because the distance between the bearings 33a to 33e can be reduced and the bearing 33 can be disposed near the paper feed driven roller 32, that is, the axial span of the paper feed drive roller 3 and the paper feed driven roller This is because the distance between the point of action 32 and the bearing 33 can be reduced.

FIG. 4B is a front view showing a bearing structure of a prototype paper feeder as a comparative example.

In FIG. 4b, frames 410, 420
Are provided with two bearings 330f and 330g.

The steel shaft 340 of the paper feed drive roller 30
Was disposed between the bearings 330f and 330g.

The paper feed drive roller 30 is pressed onto the paper feed drive roller 30 (or the shaft 340 as a substitute).
Two paper feed driven rollers 320f and 320g are provided.

The pressing force W of the paper feed driven rollers 320f and 320g was 0.5 kg weight.

Between the bearings 330f and 330g (the frame 41
0 and 420) is 280 mm, and the distance L between the point of action of the paper feed driven roller 320 and the bearing 330 is L.
1 was 90 mm each.

The paper feed drive roller 30 was replaced with a large diameter one having only the shaft portion 340, and various diameters d 'of the shaft portion 340 were manufactured.

With the above configuration, the paper feed drive roller 30
(Or the shaft portion 340) was measured for the amount of deflection. As a result, the outer diameter d = φ3.5 mm and the shaft diameter d ′ = φ, the same as the paper feed drive roller 3 used in the above-described embodiment.
When the 3.4 mm paper feed drive roller 30 was used, the maximum amount of deflection that occurred was about 300 times that of the above-described embodiment, reaching 2.8 mm, and the conveyance of the recording medium 8 was impossible. .

The same level of deflection as that of the above-described embodiment fits into the shaft portion 34 having a shaft diameter d '= 15 mm.
0 was used. This is approximately 17 times the weight of the paper feed drive roller 3 in the above-described embodiment,
This was equivalent to about 300 times the moment of inertia.

The above is one specific example, and by considering the arrangement of the bearings 33 and other parameters, it is possible to use the paper feed drive roller 3 having a smaller diameter, to reduce the number of the bearings 33, and the like. It goes without saying.

As described in detail above, according to the present embodiment,
A low-height bearing member 33 that is disposed immediately upstream of the recording head in the paper transport direction and that does not exceed the paper transport surface of the drive roller 3 whose upper portion is pivotally supported, and substantially the entire axial direction except for the bearing portion. Is disposed so as to straddle the small-diameter drive roller 3 serving as a recording paper conveyance surface and the bearing member 33,
And in the vicinity of the bearing member 33 of the drive roller 3,
In order to press the recording paper, a driven roller 32 having a small diameter roller at both ends and being urged toward the driving roller 3 by an elastic member is provided. As a result, the recording paper can be conveyed accurately regardless of the presence or absence of backlash, and the bearing member is positioned close to the upper side of the recording head in the paper conveyance direction, and its height is lower than the paper conveyance surface. As a result, the top margin can be reduced in addition to hindering the paper conveyance, and furthermore, the driven roller comes into pressure contact with the driving roller near the bearing member, even if the pressing force of the elastic means is set large. Accurate recording paper feeding can be realized without bending the driving roller.

As a result, it is possible to obtain a paper feeder with high transport accuracy even if a transmission means having an unstable factor such as backlash is used.

Further, it is possible to obtain a small, thin and lightweight paper feeder and a recording apparatus including the paper feeder.

In the present embodiment, the paper feed drive roller 3 is disposed upstream of the recording medium 1 with respect to the recording head 1, but can be freely laid out, for example, disposed downstream. It is.

FIG. 5 is a perspective view showing another embodiment of the present invention. The bearing 33 is formed integrally with a platen 45 arranged on the front surface of the recording head 1. According to this configuration, the flat surface of the platen 45 and the outer peripheral position of the paper feed driving roller 3 can be more accurately matched, so that the interval between the recording medium 8 and the recording head 1 is more correctly maintained, and Good recording quality is obtained.

Also, since the assembly of the device is facilitated,
The paper feeder can be provided at a lower cost.

[0065]

As is apparent from the above description, the recording paper feeder according to the present invention is provided in the vicinity of the upper side of the recording head in the paper transport direction, and the upper portion of the drive roller 3 for supporting the paper transports. Low-height bearing member 33 that does not cross the surface
A small-diameter drive roller 3 having a substantially entire recording sheet conveying surface except for a bearing portion, and a small-diameter drive roller 3 disposed so as to straddle the bearing member 33, and the bearing member 33 of the drive roller 3. The driven roller 32 has small-diameter rollers at both ends in order to press the recording paper in the vicinity of the driven roller 32 and is urged toward the driving roller 3 by an elastic member.
First, the driving roller 3 having a very small diameter can be used. As a result, the recording paper can be accurately conveyed regardless of the presence or absence of the backlash. As a result of being provided immediately below the paper conveyance surface in the conveyance direction and having a lower height than the paper conveyance surface, the paper conveyance is not hindered and the top margin can be reduced.
As a result of the driven roller coming into pressure contact with the drive roller in the vicinity of the bearing member, even if the pressing force of the elastic means is set to be large, there is an effect that accurate recording paper feeding can be realized without bending the drive roller. .

As a result, a small, thin, and lightweight paper feeder and a recording apparatus including the paper feeder can be realized.

Further, even if a transmission means having an unstable factor such as backlash is used, a paper feeder with high conveyance accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a bearing structure of a paper feeder device of the present invention.

FIG. 2 is a perspective view of a bearing structure of the paper feeding device shown in FIG.

FIG. 3 is a diagram illustrating a transport error in one embodiment of the present invention.

FIG. 4 is a front view showing the configuration of an embodiment of the bearing structure of the paper feeder of the present invention.

FIG. 5 is a partial view showing a configuration of another embodiment of the present invention.

FIG. 6 is a diagram showing a conventional example.

[Explanation of symbols]

 1: Recording head 11: Recording element 2: Carriage 3: Paper feed drive roller 31: Drive roller gear 32: Paper feed driven roller 33: Bearing 331: Open part (of bearing) 332: Open end face (of bearing) 34: ( Shafts 41, 42: frame 43: support plate 45: platen 5: paper feed motor 51: paper feed motor gear 6: paper feed roller 7: paper end sensor 8: recording medium

Claims (1)

(57) [Scope of request for utility model registration] 1. A low-height bearing member that is disposed immediately upstream of a recording head in the paper transport direction and that does not exceed a paper transport surface of a drive roller whose upper part is supported by a shaft. A driving roller having a small diameter, which is formed almost entirely in the axial direction as a conveying surface of the recording paper, and is disposed so as to straddle the bearing member, and presses the recording paper in the vicinity of the bearing member of the driving roller. And a driven roller having small-diameter rollers at both ends and being urged toward the driving roller by an elastic member.