JPH06106803A - Recording device - Google Patents

Abstract

PURPOSE:To realize a recording device which is free from generation of a striped pattern due to the transport of a recording medium. CONSTITUTION:The peripheral length of a downstream drive roller 41 is equal to the total length of an arrayed recording element 11 direction on a recording head 1. The peripheral length of an upstream drive roller 31 is slightly shorter. Both drive rollers can move a recording medium 8 by a micro length. A distance between both drive rollers is set to an integral multiple of the entire length of the recording head 1. Under this constitution, the periodic error of both drive rollers due to eccentricity which affects the transport amount of the recording medium 8 is offset. Further, the absolute deviation of both drive rollers due to the irregularities of an external diameter can be corrected individually. No deviation occurs in delivery between both drive rollers, so that a constant delivery state is ensured. Therefore, this recording device is almost free from the generation of a striped pattern in print with high printing accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus for recording a character or an image by a recording head having a plurality of recording elements arranged side by side.
In particular, the present invention relates to a recording apparatus that conveys a recording medium linearly on the front surface of a recording head and records characters or images.

[0002]

2. Description of the Related Art Conventionally, in a recording apparatus, as a method of conveying a recording medium, a method whose sectional view is shown in FIG. 6 has been generally used. That is, the drive roller 38 is arranged in front of the recording head 1, and the drive roller 38 is sandwiched by the recording medium 8.
The recording medium 8 is wound around the driving roller 38 by the driven rollers 39 and 49 that are pressed against each other, and the recording medium 8 is conveyed by the rotation of the driving roller 38.

However, in this method, since the recording medium 8 has a curved surface along the drive roller 38 on the front surface of the recording head 1, the recording medium 8 is formed at the central portion and the end portion of the recording element array 11 of the recording head 1. It has drawbacks that it is difficult to obtain high recording accuracy due to the change of the distance, and it is difficult to cope with recording media such as cardboard and envelopes that are difficult to bend.

As a method of conveying a recording medium that solves these problems, a method disclosed in, for example, Japanese Patent Laid-Open No. 1-258974 has been proposed. FIG. 7 shows an outline of the recording device.

In FIG. 7a, reference numeral 31 is an upstream drive roller provided on the upstream side of the recording head 1, and an upstream driven roller 32 is pressed. Reference numeral 41 denotes a downstream drive roller provided on the downstream side of the recording head 1, and the downstream driven roller 42 is pressed. The recording medium 8 is sandwiched between the upstream drive roller 31 and the upstream driven roller 32, and also sandwiched between the downstream drive roller 41 and the downstream driven roller 42, and is linear on the front surface of the recording head 1. Has become. The peripheral speed of the downstream drive roller 41 is set to be higher than the peripheral speed of the upstream drive roller 31, and the pressing force of the upstream driven roller 32 is set to be larger than the pressing force of the downstream driven roller 42. There is. The recording medium conveying operation of the recording apparatus having such a configuration is as follows.

The recording medium 8 is conveyed in the column direction of the recording heads 1 by the rotation of the upstream drive roller 31 and the downstream drive roller 41. At this time, since the pressing force of the upstream driven roller 32 is set to be larger than the pressing force of the downstream driven roller 42, the downstream drive roller 41 whose peripheral speed is set faster than that of the upstream drive roller 31 is recorded. Slip occurs with the medium 8. Therefore, the conveyance amount of the recording medium 8 is determined by the rotation amount of the upstream drive roller 31. Also,
A tension is applied to the recording medium 8 by the conveying force of the downstream drive roller 41, so that the recording medium 8 is kept flat on the front surface of the recording head 1 and a stable conveying operation is obtained.

The operation of the printing apparatus for printing a continuous pattern such as an image will be described in more detail below.

By moving the recording head 1 in which n recording elements 11 are arranged in the column direction in the row direction and during this movement, the recording elements 11 are selectively driven according to print data,
A first recorded area (hereinafter referred to as a band) is formed on the recording medium 8.

The upstream drive roller 31 and the downstream drive roller 41 are rotationally driven to move the recording medium 8 in the column direction of the recording head 1 by the total length of the print head 1 in the column direction (the number of recording elements is n, recording in the column direction). P × when the element pitch is p
Carry only n). In this carrying operation, the rotation amount of the upstream drive roller 31 that determines the carry amount is set to the upstream drive roller 3
It is obtained by setting a constant angle θ such that the arc length on the outer circumference of 1 is equal to the total length of the recording head 1 in the column direction.

The recording head 1 is again moved in the row direction and the recording element 11 is selectively driven to form a second band adjacent to the first band on the recording medium 8. Hereinafter, rotation of the first drive roller 31 by a constant angle θ,
Repeat recording for one band.

In the vicinity of the trailing edge of the recording medium 8, for printing one to several bands after the trailing edge of the recording medium 8 has left the upstream drive roller 31, the transport of the recording medium 8 is performed at a constant angle of the downstream drive roller 41. It is performed only by the rotation of.

Then, the recording for one page was completed.

[0013]

However, in this case, the upstream drive roller 31 or the downstream drive roller 4 is used.
Due to the inevitable manufacturing error, the arc length (circumferential length) on the outer circumference of the drive roller corresponding to the rotation at a constant angle is not constant. As shown in FIGS. 7b and 7c, this is due to, for example, periodic deviation due to eccentricity between the drive center of the upstream drive roller 31 and the outer diameter center (difference between the peripheral length a and the peripheral length b in FIG. 7b),
This is because the upstream drive roller 31 may be out of alignment due to the variation in the outer diameter of each roller (difference between the peripheral length C and the peripheral length D in FIG. 7C). Therefore, the conveyance amount of the recording medium 8 conveyed by the rotation of the upstream drive roller 31 (or the rotation of the downstream drive roller 41 near the trailing end) is also not constant. As a result, the pitch between the bands is too narrower than the specified amount, depending on the position within one page of the recording medium 8 or for each recording device.
It is too wide, and it can be identified as a striped pattern of recording (hereinafter referred to as banding) in the band and characters and images across the band, which is a major factor that deteriorates the recording quality. Further, this error occurs more often during the transfer from the rotation due to the rotation of the upstream drive roller 31 to the transfer due to only the downstream drive roller 41.

The present invention has been made in order to solve such a problem. Even if a drive roller having an error such as eccentricity or variation in outer diameter dimension is used, the pitch between the bands is made constant. An object of the present invention is to obtain a recording apparatus in which a recording stripe pattern (banding) due to the conveyance of the recording medium is less likely to occur from the front end to the rear end of the recording medium.

[0015]

A recording apparatus according to the present invention is provided with a recording head in which a plurality of recording elements are arranged in a column direction, and is provided on a downstream side of a recording medium path with respect to the recording head, and has a circumference of the recording head. A downstream drive roller that is equal to or a whole fraction of the total length in the column direction of the recording head (p × n when the number of recording elements is n and the pitch between recording elements in the column direction is p) and the downstream drive A downstream side recording medium conveying means for conveying a recording medium in the column direction of the recording head, which comprises a downstream driven roller having an arbitrary circumference pressed by a roller, and an upstream side of the recording medium path with respect to the recording head. And an upstream driven roller having a peripheral length slightly smaller than that of the downstream drive roller and an upstream driven roller having an arbitrary peripheral length pressed by the upstream drive roller. The downstream side in the row direction Characterized by comprising an upstream side recording medium conveying means for conveying a weak conveying force from the medium conveying means. Further, the recording head and the recording medium are characterized in that they can be relatively moved by a minute amount smaller than a pitch p between recording elements of the recording head. Further, the distance between the downstream side recording medium conveying means and the upstream side recording medium conveying means on the recording medium path is an integral multiple of 2 or more of the total length of the recording head in the column direction. Characterize.

[0016]

According to the above-mentioned structure of the present invention, since the circumference of the driving roller is substantially equal to the total length p × n of the recording head in the column direction or is a fraction of an integer, the recording medium is separated from the recording head. The eccentricity between the drive roller drive center and the outer diameter center is that the drive roller makes one rotation or an integer rotation at all times when it is conveyed by the total length p × n (that is, when moving from one band to the next band). The periodic deviation of the carry amount of the recording medium due to is canceled out, and the carry amount is always constant.
Further, since the recording head and the recording medium can be moved by a small amount relative to each other, it is possible to individually correct the difference in the conveyance amount of the recording medium due to the variation in the outer diameter of the driving roller (due to individual difference). Therefore, by sufficiently increasing the resolution of the minute amount movement, the conveyance amount of the recording medium by the driving roller can be made as close as possible to the total length p × n of the recording head. Further, since the mutual distance between the two driving rollers is arranged to be an integral multiple of the total length p × n of the recording head, the recording medium is transferred between the two driving rollers at an almost integral rotation. As a result, there is no deviation in the transport amount. As a result, it is possible to realize a recording device in which banding is less likely to occur from the leading edge to the trailing edge of the recording medium.

[0017]

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, 1 is a recording head, and a plurality of recording elements 11 from # 1 to #n in the column direction A.
Are arranged at a constant inter-element pitch p. Hereinafter, for the purpose of description using specific numerical values, for example, it is assumed that recording elements having the number of elements n = 192 are arranged at an element pitch p = 1/360 inches in the column direction.

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

Reference numeral 41 denotes a downstream drive roller, which is arranged downstream of the recording head 1 in the path of the recording medium 8.
The downstream drive roller 41 has a value such that the outermost circumference is equal to the total length in the column direction of the recording head 1 (p × n when the number of recording elements is n and the pitch between recording elements in the column direction is p). It is manufactured with the aim of measuring. In the above specific example, for example, the perimeter L = p × n = 1/360 × 192 =
192/360 inch, that is, diameter d = L / π = 192 / (360π) inch = 4.31 in terms of diameter.
2 mm. The downstream drive roller 41 is supported by a plurality of downstream bearings 43 provided on the support plate 91, and one or a plurality of arbitrary ones that press the downstream drive roller 41 from the opposite side of the downstream bearing 43 by a spring (not shown). The recording medium 8 is conveyed in the column direction A by engaging with the downstream driven roller 42 of the circumference and forming a downstream recording medium conveying means and rotating the recording medium 8 with the recording medium 8 interposed therebetween. A downstream drive gear 411 is directly connected to the downstream drive roller 41.

An upstream drive roller 31 is arranged upstream of the recording head 1 in the path of the recording medium 8.
The upstream drive roller 31 has at least the downstream drive roller 41 whose outermost circumference has taken into consideration the manufacturing error.
In order not to overlap with, the target size is manufactured with a value slightly smaller than the peripheral length of the downstream drive roller 41.

In the above-mentioned specific example, for example, the manufacturing error of the diameter is set to ± 0.03 mm, and the diameter of the upstream drive roller 31 is set to d ′ = 4.25 mm. The circumference of the driving roller 31 does not exceed the circumference of the downstream driving roller 41. The upstream drive roller 31 is supported by a plurality of upstream bearings 33 provided on the support plate 91, and one or more arbitrary ones that press the upstream drive roller 31 from the opposite side of the upstream bearing 33 by a spring (not shown). The recording medium 8 is formed by engaging the upstream driven roller 32 of the circumferential length to form an upstream recording medium conveying means and rotating the recording medium 8 with the recording medium 8 interposed therebetween.
Are conveyed in the column direction A. The pressing force of the upstream driven roller 32 against the upstream driving roller 31 is equal to that of the downstream driven roller 4
2 is set to be weaker than the pressing force applied to the downstream side drive roller 41, and therefore, the conveying force of the recording medium 8 by the upstream side recording medium conveying means is set to be weaker than the conveying force of the recording medium 8 by the downstream side recording medium conveying means. ing. An upstream drive gear 311 is directly connected to the upstream drive roller 31.

The downstream drive roller 41 and the upstream drive roller 31 are required to have a high bending strength, a low friction coefficient with respect to the bearings 43 and 33, and a high friction coefficient with respect to the recording medium 8. It is desirable to partially coat the shaft with a thin coating of ceramic or rubber.

The distance between the downstream side recording medium conveying means and the upstream side recording medium conveying means is the mutual distance, that is, the engagement point between the downstream side driving roller 41 and the downstream side driven roller 42, and the upstream side driving roller 31. The distance from the engagement point with the upstream driven roller 32 is arranged to be an integer multiple of 2 or more of the total length (p × n) of the recording head 1 in the column direction. In this specific example, they are arranged at a double distance.

Reference numeral 51 designates a paper feed roller, which has a built-in one-way clutch (not shown) and is rotationally driven in only one direction by a paper feed roller shaft 52 so that the recording medium 8 stored in a paper feed tray 53 is used as a recording device. Send in. A paper feed gear 511 is directly connected to the paper feed roller shaft 52.

Reference numeral 65 is a paper feed motor, which is a paper feed gear 511.
The paper feed motor pinion 66 that engages with is fixed, and drives the paper feed roller 51.

A conveying motor 6 is provided on the downstream side drive gear 4
11 and the transport motor pinion 61 engaging with the upstream drive gear 311 are fixed, and drive the downstream drive roller 41 and the upstream drive roller 31. The gear ratio (reduction ratio) between the downstream drive gear 411, the upstream drive gear 311, and the transport motor pinion 61 is an integer. Therefore, the downstream drive gear 411 and the upstream drive gear 311 make one rotation by the integral rotation of the transport motor pinion 61, that is, the transport motor 6
The downstream side driving roller 41 and the upstream side driving roller 31 are rotated once by an integral number of rotations. Also, deceleration is
In the illustrated example, the single-stage deceleration is used, but it is also possible to perform the multi-stage deceleration by setting the reduction ratio between the respective stages to an integer. Further, a power switching mechanism is provided to engage the transport motor pinion 61 depending on the rotation direction of the transport motor 6.
It is also possible to eliminate the paper feed motor 65 by switching between 1 and the downstream drive gear 411 and the upstream drive gear 311.

The carry motor 6 is of a general type, for example, four-phase.
A step motor having 48 poles, 96 poles, 200 poles or the like can be applied. Below, using a 96-pole step motor, reduce the gear ratio to 5
As an example, a case of combining with the above-described specific example will be illustrated. Four
The carrier motor 6, which is a phase 96-pole step motor, can be driven with a resolution of 192 steps per revolution by alternately repeating 1-phase excitation and 2-phase excitation. In this case, the unit movement amount of the downstream drive roller 41 driven through the engagement of the transport motor pinion 61 and the downstream drive gear 411 at a reduction ratio of 5 (the downstream drive roller per step of the transport motor 6). The rotation amount of 41, that is, the conveyance amount of the recording medium 8 per one step of the conveyance motor 6) is 1 / (19) of the circumferential length L of the downstream drive roller 41.
2 x 5). Similarly, the unit movement amount of the upstream drive roller 31 is slightly smaller than the unit movement amount of the downstream drive roller 41. In the specific example, the unit movement amount of the downstream drive roller 41 is 192/360 inches × 1/960 = 1/1800 inches≈14 microns, and the unit movement amount of the upstream drive roller 31 is slightly smaller than this value. Become. That is,
In each case, the pitch p between the elements of the recording head 1 in the column direction is p = 1 /
The configuration is such that the recording medium 8 can be moved by a minute amount smaller than 360 inches≈71 microns.

As is clear from the above description, in the specific example, the number of driving steps of the carry motor 6 corresponding to one rotation of the downstream driving roller 41 and the upstream driving roller 31 is 192 × 5 = 960 steps. It is configured to be.

Reference numeral 7 is a paper edge sensor.

Next, the operation of the recording apparatus having the above structure will be described.

At the time of non-recording, the carriage 2 carrying the recording head 1 is in a standby state at the home position.

When the print data is received from the host computer or the like, the paper feed motor 65 starts rotating for paper feed.
The rotation of the sheet feeding motor 65 drives the sheet feeding roller 51, and one recording medium 8 stored in the sheet feeding tray 53 is selected and sent to the upstream side recording medium conveying means. For the selected recording medium 8, when the leading edge of the recording medium 8 is detected by the paper edge sensor 7 located between the paper feed roller 65 and the upstream recording medium conveying means, the leading edge of the recording medium 8 moves upstream from that position. It is fed by a predetermined amount that sufficiently reaches the side recording medium conveying means. The leading end of the recording medium 8 is an upstream drive roller 31 and an upstream driven roller 32 of the upstream recording medium conveying means.
The sheet feeding motor 65 is pressed against the tangent to the sheet and the rotation of the sheet feeding motor 65 is stopped in a state where the skew is corrected and the sheet feeding operation ends.

Next, the conveyance motor 6 starts to rotate so as to locate the recording medium 8. The upstream drive roller 31 and the downstream drive roller 41 are driven by the rotation of the carry motor 6. The recording medium 8 is sent while being sandwiched between the upstream drive roller 31 and the upstream driven roller 32, faces the recording head 1, and the cueing operation is completed. The paper feed roller 51
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 53 with a small load. The driving amount at the time of cueing is set to the amount of feeding the recording medium 8 by the same amount as the total length (p × n) of the recording head 1 in the column direction. That is, the upstream drive roller 31 whose peripheral length is slightly smaller than the total length of the recording head 1 is driven by one revolution.

After the feeding and the cueing operation of the recording medium 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 the recording medium An arbitrary character or image for one band is recorded in the row direction recording area of 8.

After the recording of the first band is completed, the driving of the carriage motor 2 is stopped, the conveying motor 6 is driven, and the recording medium 8 is recorded on the recording medium 1 by the upstream drive roller 31 in the same manner as described above. Carry only the full length of. After that, the carriage motor 2 is reversely driven to move the recording head 1 in the opposite direction, and the second band adjacent to the first band is recorded. At this point, the front end of the recording medium 8 is the total length (p ×
It reaches the downstream side recording medium conveying means arranged at a distance twice as large as that in n). That is, the leading end of the recording medium 8 is located at the engagement point between the downstream drive roller 41 and the downstream driven roller 42.

The conveyance of the recording medium 8 for recording the third and subsequent bands is performed by one rotation of the downstream drive roller 41. By the rotation of the downstream drive roller 41, the recording medium 8 is conveyed while being sandwiched between the downstream drive roller 41 and the downstream driven roller 42. Aiming circumference is recording head 1
One rotation of the downstream drive roller 41 equal to the total length of
The recording medium 8 is conveyed by the entire length (p × n) of the recording head 1 in the column direction, and the bands are adjacent to each other. At this time, the upstream drive roller 31 is also driven for one rotation. The peripheral length of the aim is slightly smaller than the peripheral length of the downstream drive roller 41. The transport amount of the recording medium 8 by the upstream drive roller 31 is smaller than the transport amount by the downstream drive roller 41, but upstream of the upstream driven roller 32. The pressing force on the side drive roller 31 is set to be weaker than the pressing force of the downstream driven roller 42 on the downstream drive roller 41. Therefore, the conveying force of the recording medium 8 by the upstream side recording medium conveying means is the downstream side recording medium conveyance. Since it is set to be weaker than the conveyance force of the recording medium 8 by the means, the conveyance amount of the recording medium 8 is set to the downstream drive roller 41.
It is determined by the carry amount. That is, the recording medium 8
Is pulled by the downstream side recording medium conveying means, and while being slightly slipped in the upstream side recording medium conveying means, it is stably conveyed between the upstream side driving roller 31 and the downstream side driving roller 41 without slack.

After that, the moving operation of the carriage 2 and the conveying operation of the recording medium 8 are repeated until the final band allocated by the end of the recording medium 8 recognized by the paper edge sensor 7 is recorded, and one page worth of paper is repeated. Stop recording (hereafter
The recording medium 8 in which the leading end of the recording medium 8 reaches the downstream recording medium conveying means and the conveyance by the downstream drive roller 41 becomes dominant
Of the transport state of the upstream drive roller 3 before the steady transport
The conveyance state of the recording medium 8 by only 1 is referred to as a cue conveyance.

Here, the conveying operation of the recording medium 8 by the rotation of the downstream drive roller 41 or the upstream drive roller 31 will be described in more detail.

The conveyance amount of the recording medium 8 conveyed by the rotation of the downstream side drive roller 41 or the upstream side drive roller 31 causes an error due to the variability of the parts precision which cannot be avoided in manufacturing.

The errors are roughly classified into the drive roller 41 on the downstream side.
(Upstream side drive roller 31), downstream side drive gear 411 (upstream side drive gear 311), conveyance motor pinion 61 and other rotational system parts due to deviation (eccentricity) between the center of drive and the center of outer diameter of cyclic conveyance amount error And the individual outer diameter dimensions of the downstream drive roller 41 (upstream drive roller 31)
It can be divided into an absolute transport amount error due to variations.

The first error of the periodic carry amount due to eccentricity is
This is caused when the outer peripheral lengths corresponding to the respective angles θ differ when they are rotated by an arbitrary constant angle θ about a certain point deviated from the center of the outer diameter. An outline will be given with reference to FIG. In FIG. 3, the drive center is P, the outer diameter center is O, and the eccentricity amount is OP = e, and the outer diameter is a perfect circle. The difference between the circumferential length AB when rotated about the drive center P by an arbitrary angle θ and the circumferential length CD corresponding to the angle θ (centering around the outer diameter center O) of the perfect circle is the circumferential length due to eccentricity. There will be an error. The maximum circumference error occurs due to the positional relationship in which OP divides the arbitrary angle θ (the position shown in the figure or the position shifted in phase by π by the radian method). Here, if the true circle radius is r, an arbitrary angle is θ, and the true circle center angle ∠AOB corresponding to the arc AB is α, the maximum circumference error ε is ε = arc AB−arc CD = rα−rθ .

From the positional relationship shown in FIG. 3, a relationship of e.sin (.theta. / 2) = r.sin ((. Alpha .-. Theta.) / 2) is obtained, e is small, and sin ( In the range where (α−θ) / 2) ≈ (α−θ) / 2 holds, ε = r (α−θ) = 2e · sin (θ / 2) is obtained as an approximate solution.

That is, the outer peripheral length error ε due to the eccentricity can be expressed in the form of ε = 2e · sin (θ / 2) ... (1).

According to the structure of the present embodiment, during steady conveyance, the peripheral length of the downstream drive roller 41, which determines the conveyance amount of the recording medium 8, is the total length of the recording head 1 in the column direction (p ×).
Since the target size is set to a value equal to n), the target conveying operation of the recording medium 8 for arranging the recording bands and the recording bands at an equal pitch is completed by one rotation of the downstream drive roller 41. To do. Therefore, the circumference error due to eccentricity is ε = 2e · sin (2π / 2) =
It becomes 0, and the periodic carry amount error due to the eccentricity of the downstream drive roller 41 does not occur. Similarly, the downstream drive roller 41
The downstream drive gear 411, which is directly connected to the drive gear 411, completes its operation in one rotation, and no cyclic conveyance amount error due to the eccentricity of the downstream drive gear 411 occurs. Further, the carry motor pinion 61 engaged with the downstream drive gear 411 at an integer reduction ratio ends its operation at an integer rotation, and the circumferential length error due to the eccentricity of the carry motor pinion 61 is ε = 2e · from the equation (1). sin (2mπ / 2)
= 0 (m is an integer), and no periodic error occurs. Therefore, the intended carrying operation of the recording medium 8 for arranging the recording bands at equal pitches can be realized by suppressing the periodic carry amount error due to the eccentricity of the rotary system to zero.

The periodic carry amount error at the time of cueing and carrying will be described later.

Next, the second, mainly downstream drive roller 41
An absolute conveyance amount error due to the variation in the outer diameter dimension of the (upstream drive roller 31) will be described.

The outer diameter dimension of the downstream drive roller 41 (upstream drive roller 31) has an unavoidable error in manufacturing. As a specific example, assuming that there is an error of about ± 30 microns, which is a reasonable manufacturing error, with respect to the above-mentioned diameter d = 4.312 mm of the downstream drive roller 41, the circumference of the downstream drive roller 41 is assumed. The length will have an error of ± 30 microns × π≈ ± 94 microns with respect to the desired dimension. That is, when the downstream side drive roller 41 is rotated once to obtain the conveyance amount of the recording medium 8 which is equal to the total length (p × n) of the recording head 1 in the column direction, the maximum is about 94 μm. There is a possibility of over-feeding or under-feeding.

According to the configuration of this embodiment, this error can be corrected by adjusting the number of driving steps of the carry motor 6. That is, with respect to the number of drive steps of the carry motor 6 corresponding to one rotation of the downstream drive roller 41 (one transport operation of the recording medium 8), the shortage of the downstream drive roller that causes insufficient feeding in one rotation. The correction can be performed by adding the number of drive steps corresponding to the amount and reducing the number of drive steps corresponding to the excessive amount for the downstream drive roller that causes excessive feeding in one rotation. The correction is performed for each recording device, and the unit movement amount of the downstream drive roller 41 (conveyance amount of the recording medium 8 per step of the conveyance motor 6) is small, and the recording medium 8 can be moved by a minute amount. Accurate correction is possible from a possible configuration.

Further detailed description will be given based on the above-mentioned specific example. For example, the outer diameter of the downstream drive roller 41 used is
It is assumed that it is manufactured to be 30 microns smaller than the target size, and the transport amount of the recording medium 8 by one rotation of the downstream drive roller 41 is about 94 microns short of the target. Since the unit movement amount of the downstream drive roller 41 per step of the carry motor 6 is about 14 microns as described above, the correction amount is 94 microns / 14 (microns / step) ≈6.7 steps in this case. , Takes a close integer, and becomes 7 steps. That is, the number of driving steps of the carry motor 6 corresponding to one carrying operation of the print medium 8 in this printing apparatus corresponds to one rotation of the downstream drive roller 41.
By setting a value of 967 steps, which is obtained by adding 7 steps to 0 steps, the absolute carry amount error can be reduced to, for example, 14 (microns / step) × 7 steps−94 microns = 4 microns. . The above-mentioned correction can be performed with an accuracy of 1/2 of the unit movement amount of the downstream drive roller 41 by selecting either of the integer step numbers sandwiching the correction amount. If is 14 microns, an accuracy in the range of ± 7 microns can be obtained. In the actual recording apparatus, the total length (p × n) of the recording head 1 in the column direction has a slight error, and other drive systems also have an error. By carrying out the process in the final step, the total absolute carry amount error including these errors can be reduced to, for example, ± 7 microns or less. According to our experiments, 360 inches per inch
In a printing device with a density of about a dot, it has been found that the banding of the print is inconspicuous if the bands are arranged with an accuracy of about ± 15 microns or less. Can be said. Further, by making the unit movement amount of the downstream drive roller 41 per step of the carry motor 6 smaller, it is possible to further improve the correction accuracy.

Although the above-mentioned correction slightly induces an eccentricity error, the amount thereof is sufficiently small and does not spoil the purpose. For example, in the case of setting 967 steps obtained by adding 7 steps as a correction amount to 960 steps corresponding to one rotation of the downstream side drive roller 41 in the above specific example, as the number of conveyance drive steps of the downstream side drive roller 41 in the recording apparatus. The rotation angle of the downstream drive roller 41 for one transport operation of the recording medium 8 is θ = 2π ×
(967/960). The eccentricity of the downstream drive roller 41 is set to, for example, e = 30 microns, which is a reasonable manufacturing error. Even in this case, the peripheral length error of the downstream drive roller 41 due to the eccentricity is ε =
2e · sin (θ / 2) ≈1.4 microns, which is sufficiently small. Next, the carry amount error at the time of cueing and carrying will be described. During the cue conveyance, the conveyance amount of the recording medium 8 is determined by the upstream drive roller 31. As described above, the upstream drive roller 31 has a circumferential length slightly smaller than the circumferential length of the downstream drive roller 41 so as not to overlap at least the downstream drive roller 41 in consideration of manufacturing error. Manufactured as dimensions. Therefore, the aiming conveyance operation of the recording medium 8 for arranging the recording bands and the recording bands at an equal pitch is completed with one rotation of the upstream drive roller 31. Although this motion slightly induces an eccentricity error, its amount is sufficiently small that it does not hurt the purpose. In the above-mentioned specific example, for example, the diameter d of the aim of the downstream drive roller 41 is
Upstream drive roller 31 against 4.312 mm
It is assumed that the target is manufactured with a diameter d '= 4.25 mm. In this case, the rotation angle of the upstream drive roller 31 with respect to one cue conveyance operation of the recording medium 8 is θ.
= 2π × (4.312 / 4.25). If the eccentricity of the upstream drive roller 31 is set to about e = 30 microns,
The conveyance amount error due to the eccentricity of the upstream drive roller 31 at the time of cueing conveyance is ε = 2e · sin (θ / 2) from the equation (1).
≈ 2.7 microns, which is sufficiently small.

Further, the correction of the absolute carry amount error due to the variation of the outer diameter of the upstream drive roller 31 can be performed in the same manner as in the case of the downstream drive roller 41 described above.

As described above in detail, according to the configuration of this embodiment, the recording medium 8 is conveyed by substantially one rotation of the upstream drive roller 31 at the time of cue conveyance, and at the downstream side at the time of normal conveyance. Since the driving roller 41 is rotated once, the cyclic deviation of the conveyance amount of the recording medium 8 due to the eccentricity of the both driving rollers is offset, and the conveyance amount is always constant.

Further, since the recording medium 8 can be moved by a minute amount smaller than the pitch p between recording elements of the recording head 1, the outer diameter of the downstream drive roller 41 or the upstream drive roller 31 varies (due to individual differences). It becomes possible to correct the difference in the amount of conveyance of the recording medium 8, and by making the unit movement amount sufficiently small, the downstream drive roller 41
Also, the transport amount of the recording medium 8 by the upstream drive roller 31 can be made as close as possible to the total length (p × n) of the recording head 1 in the column direction.

Further, since the recording medium 8 can be conveyed with high accuracy even at the time of cueing and conveying, recording can be started from the time when the first cueing and conveying is completed, and the recording area in the column direction is extended to the leading end of the recording medium 8. It can be expanded.

In addition, since the mutual distance between the upstream side recording medium conveying means and the downstream side recording medium conveying means is arranged at an integer multiple of 2 or more of the total length (p × n) of the recording head 1 in the column direction, The cueing conveyance is ended by the rotation of the upstream drive roller 31 by an almost integral number of revolutions, and shifts to the normal conveyance, and the conveyance amount cycle due to the eccentricity of the upstream drive roller 31 or the downstream drive roller 41 when the recording medium 8 is delivered. There will be no madness.

As described above, the recording medium 8 can be conveyed with high accuracy from the front end to the rear end, and recording can be performed from the front end to the rear end of the recording medium 8 and banding hardly occurs. It can be realized without raising.

Since the driving roller has a small diameter,
The effect that the recording device can be made small and lightweight can be obtained.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

The recording head 1 is fixed to the slider 255. The slider 255 is supported by a bearing 257 that engages with a slide shaft 256 fixed to the carriage 2, and a drive plate 258 that engages with a screw rod 254, and is held by the spring 259 in a state without rattling with respect to the carriage 2. ing. Screw rod 25
Reference numeral 4 denotes a drive plate 2 which is rotatably supported by the carriage 2 and has a male screw or the like on its outer periphery, which engages by rotating.
58, the drive plate 258, a pair of sliders 255, and the recording head 1 fixed to the sliders 255 can be moved in the column direction. Screw rod 2
54 is directly connected to the rod gear 253, and is driven by the fine movement motor 251 through the engagement of the rod gear 253 and the fine movement motor pinion 252. A step motor or the like can be applied to the fine movement motor 251, and the recording head 1 can be moved by a minute amount of about 5 microns per driving step by selecting the reduction ratio and the screw of the screw rod 254.

With this configuration, in the present embodiment, correction of an absolute carry amount error due to individual variation in outer diameter dimension of the downstream drive roller 41 or the upstream drive roller 31 shown in the first embodiment is performed. This is performed by fine movement of the recording head 1 in the column direction. The transport operation of the recording medium 8 is as follows.

At the time of cue conveyance, the number of drive steps of the conveyance motor 6 is set on the assumption that the upstream drive roller 31 has a desired outer diameter. Therefore, the recording medium 8 is transported by the entire length (p × n) of the recording head 1 in the column direction if the upstream drive roller 31 is formed with the intended outer diameter. However, at this time, there is a possibility that the transport amount of the recording medium 8 may be over-sent or insufficient due to individual variations in the outer diameter of the upstream drive roller 31. This correction is performed by finely moving the recording head 1 by driving the fine movement motor 251. The fine movement motor 251 is driven by a preset number of drive steps corresponding to the individual overfeed amount or underfeed amount of the recording apparatus, and the recording head 1 is moved in a direction to correct the overfeed amount or underfeed amount. Move slightly. Similarly, during steady conveyance, the number of drive steps of the conveyance motor 6 is set assuming that the downstream drive roller 41 is made to have an outer diameter dimension aimed at, and the recording medium due to variation in outer diameter dimension of the downstream drive roller 41 is set. The deviation of the carry amount of 8 is performed by driving the fine movement motor 251. The drive of the transport motor 6 and the drive of the fine movement motor 251 can be performed simultaneously, and the transport time of the recording medium 8 is not impaired. By repeating the carrying operation and the printing operation and resetting the fine movement motor 251 when the printing of one page is completed, the printing head 1 returns to the initial position.

According to this embodiment, since the absolute carry amount error can be corrected independently of the carrying operation of the recording medium 8, the eccentricity error caused by the correction does not occur. Further, since the unit movement amount of the recording medium 8 by the downstream drive roller 41 or the upstream drive roller 31 can be freely set, the characteristics of the carry motor 6 can be maximized and the carry speed can be further increased. . Further, the unit movement amount of the recording head 1 for correction can be reduced, and more accurate correction can be performed.

As a third embodiment, in the first and second embodiments, the downstream drive gear 411 and the upstream drive gear 3
11 shows an example in which the reduction ratio between 11 and the conveyance motor pinion 61 is not an integer.

The outer diameter of the downstream side driving roller 41 or the upstream side driving roller 31 which is the final stage of the recording medium conveying system is such that the circumference is matched with the total length (p × n) of the recording head 1 in the column direction. For example, in the above-mentioned specific example, the diameter is very small, about 4.3 mm. The periodic error of the amount of rotation due to the eccentricity of the rotating system is half rotation or integer rotation +
Since it can take the maximum value in half a rotation, as a specific example,
The reduction ratio between the downstream drive gear 411 and the upstream drive gear 311 and the carry motor pinion 61 is 4.5, the carry motor pinion 61 has a pitch circle diameter of 12 mm, and the downstream drive gear 411 and the upstream drive gear 311 have a pitch. The operation will be described by taking as an example the case where the diameter of the circle is 54 mm, and the downstream drive roller 41 and the upstream drive roller 31 have an outer diameter of about 4.3 mm.

In this case, the recording medium 8 is conveyed once,
That is, the downstream drive gear 411 and the upstream drive gear 31
1 (downstream drive roller 41 and upstream drive roller 31)
The conveyance motor pinion 61 rotates 4.5 times for each rotation. Assuming that the eccentricity of the carry motor pinion 61 is, for example, a reasonable manufacturing error of about e = 30 μm, the maximum error of the outer circumference of the carry motor pinion 61 due to eccentricity is ε = 2e · sin (θ / 2) from the equation (1). ) = 2
It can be × 30 × sin ((4.5 × 2π) / 2) = 60 microns. That is, the conveyance motor pinion 61 has a possibility of causing over-feeding or under-feeding of up to 60 microns on the pitch circumference with respect to the target rotation amount, and the downstream drive gear 411 and the upstream drive gear which engage with this may occur. The gear 311 also causes over-feeding or under-feeding of up to 60 microns on the pitch circumference. However, in this embodiment, the outer diameters of the downstream drive roller 41 and the upstream drive roller 31 are sufficiently (one digit or more) smaller than the outer diameters (pitch circle diameters) of the downstream drive gear 411 and the upstream drive gear 311. Therefore, as shown in FIG. 5, an excessive feed amount or an insufficient feed amount 82 on the outer circumference of the downstream drive roller 41 and the upstream drive roller 31, which are directly connected to the downstream drive gear 411 and the upstream drive gear 311, is It can be made sufficiently small (one digit or more) for the excessive feed or the insufficient feed 81 on the pitch circumference of the side drive gear 411 and the upstream drive gear 311. In the above-described specific example, the outer diameters of the downstream drive roller 41 and the upstream drive roller 31 are about 4.3 mm, and the outer diameters (pitch circle diameters) of the downstream drive gear 411 and the upstream drive gear 311 are Since it is 54 millimeters, an excessive feed amount or an insufficient feed amount 81 on the pitch circumference of the downstream drive gear 411 and the upstream drive gear 311 that can be generated up to about 60 microns is caused by the downstream drive roller 41 and the upstream drive roller 31. On the outer periphery of the downstream side drive roller 41 due to the eccentricity of the transport motor pinion 61
And the excessive feed amount 82 or the insufficient feed amount 82 on the outer circumference of the upstream drive roller 31 is at most 60 μm × 4.3 / 54.
Approximately 5 microns, recording medium 8 with sufficiently high accuracy
Can be realized.

Although each of the above-described embodiments has been described by way of specific examples for the purpose of explanation, the dimensions and numerical values are not limited to these in applying the present invention.

[0069]

As is apparent from the above description, according to the present invention, the peripheral length of the driving roller is approximately equal to the total length p × n of the recording head in the column direction or is a fraction of an integer. When the medium is conveyed by the total length p × n of the recording head (that is, when moving from one band to the next band), the drive roller makes one rotation or an integer rotation, and the drive roller drive center and the outside The periodic deviation of the transport amount of the recording medium due to the eccentricity from the radial center is canceled out, and the transport amount is always constant.

Further, since the recording head and the recording medium can be moved relative to each other by a minute amount, it is possible to individually correct the difference in the conveying amount of the recording medium due to the variation of the outer diameter of the driving roller (due to individual difference). By sufficiently increasing the resolution of the minute amount movement, it is possible to make the amount of conveyance of the recording medium by the driving roller as close as possible to the total length p × n of the recording head.

Further, since the distance between the two driving rollers is arranged to be an integral multiple of the total length p × n of the recording head,
Even when the recording medium is delivered between the two driving rollers, it is delivered in an almost integral rotation, so that the carry amount does not vary.

As a result, it is possible to realize a recording apparatus in which banding due to conveyance of the recording medium does not easily occur from the front end to the rear end of the recording medium without increasing the precision of parts.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a recording apparatus of the present invention.

FIG. 2 is a perspective view of the recording apparatus shown in FIG.

FIG. 3 is a principle explanatory diagram of an embodiment of a recording apparatus of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of another embodiment of the recording apparatus of the present invention.

FIG. 5 is an explanatory diagram of a third embodiment of the present invention.

FIG. 6 is a diagram showing a conventional example.

FIG. 7 is a diagram showing a conventional example.

[Explanation of symbols]

 1: Recording head 11: Recording element 2: Carriage 31: Upstream drive roller 311: Upstream drive gear 32: Upstream driven roller 41: Downstream drive roller 411: Downstream drive gear 42: Downstream driven roller 6: Conveyance Motor 61: Conveyor motor pinion 8: Recording medium

Claims (3)

[Claims] 1. A recording head in which a plurality of recording elements are arranged in a column direction, and a perimeter is provided on a downstream side of a recording medium path with respect to the recording head and has a perimeter of the total length in the column direction (the number of recording elements). Is n and p is the pitch between the recording elements in the column direction, p ×
n), which comprises a downstream drive roller which is equal to or a fraction of an integer, and a downstream driven roller which has an arbitrary circumference and is pressed by the downstream drive roller, and conveys the recording medium in the column direction of the recording head. Downstream recording medium conveying means, which is provided upstream of the recording medium path with respect to the recording head, and is pressed by the upstream driving roller having a circumference slightly smaller than that of the downstream driving roller and the upstream driving roller. An upstream driven roller having an arbitrary circumference, and an upstream recording medium conveying means for conveying the recording medium in the column direction of the recording head with a weaker conveying force than the downstream recording medium conveying means. A recording device characterized by. 2. The recording apparatus according to claim 1, wherein the recording head and the recording medium are configured to be relatively movable by a minute amount smaller than a pitch p between recording elements of the recording head. 3. The distance between the downstream side recording medium conveying means and the upstream side recording medium conveying means on the recording medium path is an integral multiple of 2 or more of the total length of the recording head in the column direction. The recording apparatus according to claim 1, wherein: