JP5198233B2 - Printer - Google Patents

Description

  The present invention relates to a printer that performs desired color printing by superimposing ink color images while conveying recording paper in forward and reverse directions.

  Conventionally, as a printer that performs color printing, a printer that performs desired color printing by superimposing ink colors while conveying recording paper in the forward and reverse directions has been used. The general configuration of this printer will be described. A first paper feed roller and a second paper feed roller that are driven to rotate by a stepping motor as a drive source on the upstream side and the downstream side of the platen roller in the recording paper conveyance direction, respectively. Is arranged. Above the first paper feed roller and the second paper feed roller, there are a first pressure contact roller and a second pressure contact roller, respectively, which are in pressure contact with the first paper feed roller and the second paper feed roller and can be driven to rotate. It is arranged.

  These plantain rollers, the first paper feed roller, and the second paper feed roller are rotatably supported on both side surfaces of the printer frame at both ends of the respective support shafts.

  In addition, helical gears are attached to one end portions of the plantain roller, the first paper feed roller, and the second paper feed roller, and mesh with each other. By engaging these helical gears with gears mounted on the motor shaft of the stepping motor, the rotational driving force of the stepping motor is transmitted to the platen roller, the first paper feed roller, and the second paper feed roller. It is configured.

  Above the platen roller, there is disposed a thermal head that can be brought into contact with and separated from the platen roller via a recording sheet (head down / head up), and the thermal head and the platen roller are opposed to each other. The position is the printing section. An ink ribbon is routed between the thermal head and the recording paper. In a thermal transfer printer capable of color printing, for example, four ink layers of yellow, magenta, cyan, and overcoat are continuously formed on the surface of the ink ribbon.

  Here, the operation of the first paper feed roller and the second paper feed roller when performing color recording in the printer having such a configuration will be described.

  First, a recording sheet is sandwiched between a first paper feed roller and a first pressure roller that is driven to rotate in contact with the first paper feed roller. In this state, the first paper feed roller is rotated forward by a predetermined amount to move in the transport direction ( Transport to the downstream side) and perform first cueing.

  Subsequently, with the thermal head in the head down state, the recording paper is sandwiched between the platen roller, and in this state, the first paper feed roller is further rotated forward by a predetermined amount to convey the recording paper, and the thermal head The plurality of heat generating elements formed in the first is selectively energized to thermally transfer the ink of the first color ink layer to form an image using the first color ink.

  When the leading edge of the recording paper that is conveyed to the downstream side while an image is formed reaches between the second paper feed roller and the second pressure roller that rotates following this, the second paper feed roller and the second pressure roller Until the trailing edge of the recording paper is released from the nipping by the first paper feed roller and the first pressure roller and is released by a predetermined amount. The recording paper is rotated and conveyed downstream. In addition, after the trailing edge of the recording paper is released from the nipping by the first paper feed roller and the first pressure roller, only the second paper feed roller is used until the thermal transfer of the ink of the first color ink layer is completed. By rotating forward, the recording paper is conveyed downstream.

  When the thermal transfer of the ink of the first color ink layer is completed and an image of the first color of ink is formed, the thermal head is in a head-up state and the recording paper is sandwiched between the second pressure roller. The recording paper is conveyed in the reverse conveyance direction (upstream side) by rotating the second paper feed roller reversely by a predetermined amount (feedback).

The reversely transported recording paper is nipped between the rear end of the recording paper when it reaches between the first paper feed roller and the first pressure contact roller. Then, the first paper feed roller and the second paper feed roller are reversely rotated by a predetermined amount to the upstream side until the leading edge of the recording paper is released from the nipping by the second paper feed roller and the second pressure roller. Transport. After the leading edge of the recording paper is released from the nipping by the second paper feed roller and the second pressure contact roller, only the first paper feed roller is reversely rotated until the recording paper returns to the cueing position. The recording paper is conveyed upstream .

  Thereafter, in the same manner, while carrying forward and reverse conveyance of the recording paper, the ink of the second to fourth color ink layers is thermally transferred so as to be superimposed on the already formed image, and desired color printing is performed. (For example, refer to Patent Document 1).

  Conventionally, a printer having a configuration in which a free end of a thrust plate is slidably contacted with one end of a first paper feed roller and a second paper feed roller to apply a side pressure as an earth function and a thrust operation function has been developed (for example, a patent Reference 2).

JP 2007-45577 A JP 2004-191526 A

  However, in the printer disclosed in Patent Document 1, when the rotational load torque becomes high, a sudden torque increase occurs in a low temperature environment, and the rotation start delay of the first paper feed roller and the second paper feed roller is delayed. May occur.

  If the load torques of the first paper feed roller and the second paper feed roller are different from each other, the amount of recording paper transported is controlled by the number of steps of the stepping motor. There was an error between the transport amount when transported in the transport direction by the roller and the transport amount when fed back in the reverse transport direction mainly by the second paper feed roller. In this case, if the image of each ink layer is sequentially thermally transferred while the recording paper is conveyed four times, a positional deviation of the image of each ink layer, that is, a so-called color shift occurs in the printed image. There was a problem.

  In the printer disclosed in Patent Document 2, no consideration is given to controlling the rotational load torques of the first paper feed roller and the second paper feed roller by the thrust plate.

  Accordingly, an object of the present invention is to provide a printer capable of conveying recording paper with high accuracy and capable of printing high-quality images.

In order to achieve the above-described object, the printer according to claim 1 includes a first paper feed roller and a second paper which are rotatably disposed on the upstream side and the downstream side of the platen roller in the recording paper conveyance direction, respectively. A rotation roller that rotationally drives the first paper feed roller and the second paper feed roller via the gear, and a gear coupled to one end of each of the first paper feed roller and the second paper feed roller; A mechanism for performing multicolor printing by repeatedly transporting the recording paper in forward and reverse directions by forward and reverse rotation of the first paper feed roller and the second paper feed roller. against the other end of the roller and the second sheet feed roller, while applying an axial lateral pressure as the rotation load torque is equal of the first sheet feed roller and the second sheet feed roller Characterized in that it comprises a thrust plate in contact.

  According to the printer of the first aspect, by making the rotational load torques of the first paper feed roller and the second paper feed roller equal, the first paper feed during the conveyance of the recording paper in the opposite direction and the opposite direction. An error in the conveyance amount of the recording paper by the roller and the second paper feed roller can be reduced. Thereby, it is possible to prevent printing defects such as a shift in the position of an image formed by each ink layer of the ink ribbon, a so-called color shift.

Further, the printer according to claim 2 is the printer according to claim 1, wherein both the rotational load torques of the first paper feed roller and the second paper feed roller are 0.6 Ncm or less in the front thrust plate. characterized in applying a lateral pressure in the axial direction to.

  According to the printer of the second aspect, the load torques of the first paper feed roller and the second paper feed roller are set within a range where a good image can be obtained based on the experimental results (FIGS. 4 and 5) described later. By setting the numerical value as small as possible, that is, 0.6 Ncm or less, the first paper feed roller and the first paper feed roller and the first paper feed roller and the first paper feed roller are prevented from being delayed at the start of conveyance and reverse conveyance. The recording paper can be conveyed with high accuracy by the two paper feed rollers.

The printer according to claim 3 is the printer according to claim 1 or 2, wherein the thrust plate includes a difference in rotational load torque between the first paper feed roller and the second paper feed roller. the characterized in that applying a lateral pressure in the axial direction than 0.2Ncm.

  According to the printer of the third aspect, the difference between the load torques of the first paper feed roller and the second paper feed roller is reduced based on the experimental results (FIGS. 4 and 5) described later. By setting the difference to be 0.2 Ncm or less, it is possible to reduce errors in the transport amount by the first paper feed roller and the second paper feed roller when transporting the recording paper in the transport direction and the opposite direction, and color misregistration, etc. Printing failure can be prevented.

  As described above, according to the printer of the present invention, the thrust plate has the first paper feed roller and the second paper feed roller so that the rotational load torques of the first paper feed roller and the second paper feed roller are equal. Since the lateral pressure applied to the recording paper is adjusted, it is possible to reduce errors in the transport amounts of the first paper feed roller and the second paper feed roller when transporting the recording paper in the transport direction and in the opposite direction. Thereby, it is possible to perform high-precision conveyance by the first paper feed roller and the second paper feed roller, prevent printing defects such as so-called color misregistration, and print a high-quality print image.

  Hereinafter, the printer of the present invention will be described with reference to FIG. 1 to FIG.

  FIG. 1 is a perspective view of an essential part of the printer of the present invention, and FIG. 2 is a side view of FIG. 1 viewed from the thrust plate side. FIG. 3 is an explanatory view showing an arrangement state of a thrust plate arranged in sliding contact with the first paper feed roller. Note that the printer of this embodiment has a basic configuration as a thermal transfer printer capable of printing a color image, and details thereof are omitted.

  The printer according to the present embodiment can be rotated (a head down / head up) with a platen roller 1 rotatably arranged and a platen roller 1 disposed above the platen roller 1 and via a recording sheet conveyed. And a thermal head (not shown).

  An ink ribbon (not shown) is routed between the recording paper conveyed on the platen roller 1 and the thermal head. Four ink layers of yellow, magenta, cyan, and overcoat are continuously formed on the surface of the ink ribbon of this embodiment.

  As shown in FIG. 1, on the upstream side and the downstream side of the platen roller 1 in the recording sheet conveyance direction (the direction of the arrow T in FIGS. 1 and 2), a rotational drive mechanism 11 described later is rotationally driven. A one paper feed roller 2 and a second paper feed roller 3 are rotatably arranged.

  The first paper feed roller 2 and the second paper feed roller 3 are rotatably supported on both sides of the frame 5 via bearings 4 (see FIG. 3 for the first paper feed roller 2). .

  A helical gear as a first paper feed gear 6, a second paper feed gear 7 and a platen gear 8 is connected to one end of the first paper feed roller 2, the second paper feed roller 3 and the platen roller 1, respectively. . A first intermediate gear 9 and a second intermediate gear 10 are disposed between the first paper feed gear 6 and the second paper feed gear 7. As shown in FIG. 1, the first intermediate gear 9 and the second intermediate gear 10 are two-stage gears that are integrally formed by concentrically arranging two large-diameter and small-diameter gear bodies. The large diameter gear bodies mesh with the first paper feed gear 6 and the second paper feed gear 7, respectively, and the small diameter gear bodies mesh with the platen gear 8.

  As shown in FIGS. 1 and 2, the rotation drive mechanism 11 is disposed in the vicinity of the first intermediate gear 9 and the second intermediate gear 10. The rotation drive mechanism 11 has a stepping motor 12 as a drive source, and a pinion gear 13 is connected to a shaft of the stepping motor 12. Further, the platen gear 8 meshes with the pinion gear 13 through a gear 14 and a gear 15 as power transmission gears. Specifically, the gear 14 and the gear 15 are two-stage gears formed integrally by arranging two large-diameter and small-diameter gear bodies concentrically. The pinion gear 13 meshes with the large-diameter gear body of the gear 14, the small-diameter gear body of the gear 14 meshes with the large-diameter gear body of the gear 15, and the small-diameter gear body of the gear 15. Is engaged with the platen gear 8.

  The rotational driving force of the stepping motor 12 is sequentially transmitted to the platen gear 8 through the pinion gear 13, the gear 14, and the gear 15, and further through the platen gear 8, the first intermediate gear 9, and the second intermediate gear 10. The first paper feed gear 6 and the second paper feed gear 7 are transmitted. Therefore, when the stepping motor 12 rotates forward and backward, the first paper feed roller 2, the second paper feed roller 3 and the platen roller 1 rotate forward and backward in the same direction via a plurality of gears. By controlling the number of steps of the stepping motor 12, the conveyance amount of the recording paper in the forward and reverse directions is controlled.

  Further, at the other ends of the first paper feed roller 2 and the second paper feed roller 3, the tips of the free pieces 16a and 17a of the first thrust plate 16 and the second thrust plate 17 for adjusting the lateral pressure are slid. It is touched.

  The first thrust plate 16 and the second thrust plate 17 have the function of suppressing the thrust load described above, and the friction of the first paper feed roller 2 and the second paper feed roller 3 by friction with the recording paper during conveyance. It also functions as a ground for discharging static electricity charged on the peripheral side surface to the frame 5.

  In the present embodiment, the first thrust plate 16 is made of a conductive member, and as shown in FIG. 3, is a flat plate spring, and the lower fixing piece 16 b is fixed to the frame 5 by screws 18. It is fixed to. The upper side of the first thrust plate 16 is a free piece 16a, and the tip of the first thrust plate 16 is at the end of the first paper feed roller 2 in the direction opposite to the thrust direction (the direction of arrow A in FIGS. 1 and 3). 1 and in the direction of arrow B in FIG. 3, and is in sliding contact, and functions to suppress the thrust load generated by the first paper feed gear 6.

  In the present embodiment, the second thrust plate 17 is made of a conductive member. As shown in FIG. 3, the overall shape is Y-shaped, and one fixed piece 17 b is attached by a screw 18. It is fixed to the frame 5. Further, the tips of the two free pieces 17a bifurcated from the fixed piece 17b are opposite to the thrust direction (the direction of arrow A in FIG. 1) at the ends of the second paper feed roller 3 and the platen roller 1, respectively. It is slidably contacted so as to apply a lateral pressure in the direction (direction of arrow B in FIG. 1). These free pieces 17a function to suppress the thrust load generated by the second paper feed gear 7 and the platen gear 8, respectively. Further, the lengths of the two free pieces 17 b of the second thrust plate 17 in the longitudinal direction are the same length as the free pieces 16 b of the first thrust plate 16. In the present embodiment, as the thrust plate for sliding contact with the end portions of the second paper feed roller 3 and the platen roller 1, one Y-shaped leaf spring is provided, and two free branches branched in two. By bringing the pieces 17a into sliding contact with each other, the number of parts is reduced.

  The shapes of the first thrust plate 16 and the second thrust plate 17 are not limited to the above shapes. For example, a stepped portion may be formed between the longitudinal intermediate portion of the first thrust plate 16 and one fixed piece 17a and two free pieces 17b of the second thrust plate 17.

  Further, in the present embodiment, the first thrust plate 16 and the second thrust plate 17 have the rotational load torques of the first paper feed roller 2 and the second paper feed roller 3, respectively, as will be described later (FIG. 4). And the load torque of the first paper feed roller 2 and the second paper feed roller 3 are both 0.6 Ncm or less, and the first paper feed roller 2 and the second paper feed roller 3 The lateral pressure applied to the first paper feed roller 2 and the second paper feed roller 3 is adjusted so that the load torque difference is 0.2 Ncm or less. Specifically, the first thrust plate 16 is adjusted by adjusting the screwing amount of the screw 18 fixing the fixing pieces 16b, 17b, or by using a leaf spring designed by adjusting the side pressure according to the plate thickness or the like. And the side pressure applied to the second thrust plate 17 is adjusted. In addition, as described above, when the first thrust plate 16 and the second thrust plate 17 are formed with stepped portions, it is relatively easy to adjust the bending angle on the free pieces 16a, 17a side to make the first relatively easy. The lateral pressure applied to the thrust plate 16 and the second thrust plate 17 is adjusted.

  Here, FIG. 4 is a graph showing the relationship between the measurement results of the load torque of the first paper feed roller 2 and the second paper feed roller 3 and the quality of the printed image printed under the respective conditions. FIG. 5 is a table showing the measured values of the load torque of the first paper feed roller 2 and the second paper feed roller 3, the difference between the two load torques, and the evaluation result of the print image printed under each condition. is there.

  In this experiment, the first paper feed roller 2 and the second paper feed roller 3 are adjusted by adjusting the bending angle and thickness of the free pieces 16a and 17a of the leaf springs as the first thrust plate 16 and the second thrust plate 17. 24 samples with different lateral pressures are prepared, and the rotational load torque is measured when printing is performed under the same other conditions, and the quality of the printed image actually printed at that time is determined. With the goal. In this experiment, the quality of the printed image was evaluated by visually checking whether so-called color misregistration occurred, and evaluated in three stages: good (◯ in the figure), acceptable (Δ in the figure), and defective (× in the figure). did.

  According to this measurement result, the load torques of the first paper feed roller 2 and the second paper feed roller 3 are both 0.6 Ncm or less, and the load torques of the first paper feed roller 2 and the second paper feed roller 3 are It was found that a good printed image can be obtained when the difference is 0.2 Ncm or less.

  Based on this result, in the printer of the present embodiment, the first thrust plate 16 and the second thrust plate 17 are set so that the rotational load torques of the first paper feed roller 2 and the second paper feed roller 3 are equal, that is, Both the first paper feed roller 2 and the second paper feed roller 3 have a rotational load torque of 0.6 Ncm or less, and the difference between them is 0.2 Ncm or less, respectively. The lateral pressure applied to the paper feed roller 3 is adjusted. As a result, an error between the transport amount when transported mainly in the transport direction by the first paper feed roller 2 and the transport amount when transported mainly in the reverse transport direction by the second paper feed roller 3 is reduced. The sheet can be conveyed with high accuracy, print defects such as so-called color misregistration caused by each ink layer of the ink ribbon can be prevented, and a high quality print image can be printed.

  Further, in the printer of this embodiment, the first thrust plate 16 and the second thrust plate 17 are made as small as possible within a range where a good image can be obtained, that is, the first paper feed roller 2 and the second paper feed roller 3. The lateral pressures applied to the first paper feed roller 2 and the second paper feed roller 3 are adjusted so that both of the rotational load torques of the first paper feed roller 2 and the second paper feed roller 3 become 0.6 Ncm or less. This prevents a delay in the start of rotation of the first paper feed roller 2 and the second paper feed roller 3 at the start of conveyance and reverse conveyance, and highly accurate conveyance by the first paper feed roller 2 and the second paper feed roller 3. The high-quality print image can be printed.

  In addition, this invention is not limited to the said embodiment, It shall change variously as needed.

  For example, the lateral pressure applied to the platen roller 1 from one free piece 17a of the second thrust plate 17 slidably in contact with the end of the platen roller 1 may be adjusted to control the rotational load torque of the platen roller 1. . For example, one free piece 17a of the second thrust plate 17 is set so that the rotational load torque of the platen roller 1 is equal to that of the first paper feed roller 2 and the second paper feed roller 3, that is, 0.6 Ncm or less. By adjusting the lateral pressure applied to the platen roller 1 from the above, more accurate conveyance may be performed. Further, an appropriate value of the rotational load torque of the platen roller 1 is obtained by performing an experiment similar to the measurement in the above embodiment, and the lateral pressure of the free piece 17a of the second thrust plate 17 is adjusted so as to be the load torque. May be.

The perspective view of the principal part of the printer of this invention Side view of Fig. 1 viewed from the thrust plate side Explanatory drawing which shows the arrangement | positioning state of the thrust plate arrange | positioned in sliding contact with the 1st paper feed roller The graph which shows the relationship between the measurement result of the load torque of a 1st paper feed roller and a 2nd paper feed roller, and the quality of a printed image Table showing the measured values of the load torque of the first paper feed roller and the second paper feed roller, the difference between both load torques, and the evaluation result of the printed image printed under each condition

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Platen roller 2 1st paper feed roller 3 2nd paper feed roller 6 1st paper feed gear 7 2nd paper feed gear 11 Rotation drive mechanism 12 Stepping motor 13 Pinion gear 14 Gear 15 Gear 16 1st thrust plate 16a Free piece 16b Fixed piece 17 Second thrust plate 17a Free piece 17b Fixed piece

Claims (3)

A first paper feed roller and a second paper feed roller rotatably arranged on the upstream side and the downstream side of the platen roller in the recording paper conveyance direction,
Gears respectively connected to one ends of the first paper feed roller and the second paper feed roller;
A rotational drive mechanism that rotationally drives the first paper feed roller and the second paper feed roller via the gear ,
In a printer that performs multicolor printing by repeatedly conveying the recording paper in the forward and reverse directions by forward and reverse rotation of the first paper feed roller and the second paper feed roller,
The relative other end portions of the first sheet feed roller and a second paper feed roller, the first paper feed roller and the second sliding while applying an axial lateral pressure as the rotation load torque is equal of the paper feed roller A printer comprising a thrust plate in contact therewith. 2. The printer according to claim 1, wherein the thrust plate applies an axial side pressure in which rotational torques of the first paper feed roller and the second paper feed roller are both 0.6 Ncm or less. 3. The thrust plate according to claim 1, wherein an axial side pressure is applied to the thrust plate so that a difference in rotational load torque between the first paper feed roller and the second paper feed roller is 0.2 Ncm or less. The printer described.

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