JP2012030465A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer that effectively eliminates dirt of a heating part of a thermal head and between before and behind the part when a cleaning sheet is used.SOLUTION: A top 5a and slopes 5b and 5c between before and behind that are formed in a thermal head 5. A cleaning sheet Sc is held only by a platen roller 1 and the top 5a of the thermal head 5, and is conveyed by the turning force of the platen roller 1. Further, the surface of the platen roller 1 is formed by an elastic body 3. In a cleaning mode, both-way transfer of the cleaning sheet Sc is carried out frontward and backward. At this time, the cleaning sheet Sc becomes easy to hit the top 5a of the thermal head 5 and also the slopes 5b and 5c between before and behind that, thereby dirt is eliminated in the large range of the thermal head 5.

Description

  The present invention relates to a printer including a thermal head, and more particularly to a printer that can clean a thermal head with a cleaning sheet.

  A printer equipped with a thermal head melts the ink layer with heat generated by the heat generating part of the thermal head, and therefore, dirt is likely to adhere to the head surface.

  In the recording paper used in the color printer described in Patent Document 2, cyan, magenta, and yellow heat-sensitive coloring layers are stacked in three layers, and the outermost surface is covered with a protective layer made of an organic material. When the heat generating portion of the thermal head that is in close contact with the recording paper is heated, the protective layer is melted and the thermosensitive coloring layer is colored, and a full-color image is recorded on the recording paper.

  In this printer, the organic compound formed by melting the protective layer tends to adhere to the surface of the thermal head as dirt. When the amount of the adhered dirt increases, it becomes difficult to provide a sufficient amount of heat necessary to dissolve the protective layer of the recording paper and to develop the pressure-sensitive color developing layer.

  Therefore, a cleaning sheet is used to clean the thermal head. In the cleaning sheet described in the cited document 1, a large number of abrasive grains formed of inorganic fine particles are adhered to the cleaning surface. The cleaning surface is slid on the surface of the thermal head to scrape off and remove the dirt adhering to the head surface.

  Further, Patent Document 2 describes that the cleaning sheet is reciprocated in the forward direction and the reverse direction to enhance the effect of scraping off dirt adhering to the heating element of the cleaning head.

Japanese Patent Laid-Open No. 5-138992 JP 2004-9455 A

  However, by simply sliding the cleaning surface of the cleaning sheet on the thermal head, it is difficult to completely remove the dirt on the head surface. In particular, the organic layer formed by melting the protective layer of the recording paper for color printing It is difficult to completely remove compound contamination.

  The printer described in Patent Document 2 is in contact with the thermal head in a state where the cleaning sheet is sandwiched between rollers provided at a plurality of locations. The contact point with the head is always the same. Therefore, it is difficult to sufficiently remove the heat generating element and the dirt adhering to the front and back thereof in a wide area.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and provides a printer having a structure capable of effectively removing dirt adhered to a thermal head in a wide area by reciprocating a cleaning sheet. It is aimed.

The present invention has a platen roller having an elastic body at least on the surface, and a thermal head facing the platen roller,
The thermal head has a top portion that protrudes toward the platen roller, and an inclined portion that inclines in a direction away from the platen roller as it moves away from the top in the front and rear in the transport direction,
The cleaning sheet is sandwiched between the platen roller and the thermal head and is reciprocally conveyed forward and backward, and the top portion and the conveyance direction both in the case of being forwardly conveyed and the case of being conveyed backward. The inclined portion located on the upstream side is rubbed with a cleaning sheet.

  In the printer of the present invention, the cleaning sheet is reciprocally conveyed in the cleaning mode using the cleaning sheet. The thermal head has a top portion and inclined portions before and after the top portion, and the platen roller that presses the recording paper against the thermal head has an elastic body on the surface. Due to the shape of the thermal head and the elastic deformation of the surface of the platen roller, the cleaning sheet transported reciprocally can slide on the top of the thermal head and the inclined portion on the upstream side in the transport direction. As a result, dirt is effectively removed in a wide area from the top of the thermal head to the inclined portion.

  In the present invention, it is preferable that the cleaning sheet is supported by only the platen roller and the thermal head and is reciprocated forward and backward.

  At least when the cleaning sheet is transported back and forth to clean the thermal head, if the cleaning sheet is supported only by the platen roller and the thermal head, the transported cleaning sheet is held between the platen roller and the thermal head. The cleaning sheet can easily come into contact with not only the top of the thermal head but also the inclined portion, and the top of the thermal head and dirt around it can be easily removed.

  The present invention provides a sheet loading unit in which a plurality of recording sheets are stacked behind the platen roller and the thermal head, and sends out the recording sheets one by one from the sheet loading unit to the platen roller. A feeding roller is provided, and the cleaning sheet is reciprocated forward and backward at a position where it does not contact the recording paper located in the paper loading section.

  In the above configuration, since the cleaning sheet is reciprocated and conveyed at a position where it does not contact the recording paper in the paper loading section, the cleaning sheet becomes free, and the cleaning surface of the cleaning sheet easily comes into contact with the top and inclined portions of the thermal head. Become.

  Further, it is preferable that the cleaning sheet is reciprocated forward and backward at a position away from the feeding roller.

  In the above configuration, the head surface can be cleaned by sandwiching and moving the cleaning sheet between the platen roller and the thermal head alone.

  In the present invention, the cleaning sheet may be reciprocated forward and backward at locations where the forward traveling positions are different. This operation allows the thermal head to be cleaned using a large area of the cleaning surface of the cleaning sheet.

  Furthermore, in the present invention, when the cleaning sheet is reciprocally conveyed forward and backward, the heat generation part of the thermal head may generate heat so that organic substances on the head surface can be easily removed.

  The printer of the present invention can effectively remove the heat generating portion of the thermal head and its surroundings in a wide range when the cleaning sheet is used.

Sectional drawing which shows the whole structure of the printer of the 1st Embodiment of this invention, The side view which expands and shows the opposing part of the platen roller and thermal head of the printer shown in FIG. (A) (B) is an enlarged side view showing the operation of cleaning the thermal head using a cleaning sheet; The side view which expands and shows the opposing part of the platen roller and thermal head in the printer of the 2nd Embodiment of this invention,

  The printer shown in FIG. 1 is a line printer that performs full-color printing and recording on the recording paper Sp.

  The platen roller 1 is composed of a metal roller shaft 2 and an elastic body 3 covering the surface thereof. The platen roller 1 is rotationally driven by a control motor M1.

  A head base 4 having a heat dissipation function is provided above the platen roller 1, and a thermal head 5 is supported below the head base 4. As shown in an enlarged view in FIG. 3, the thermal head 5 has a substrate 6 having a heat dissipation function, and this substrate 6 is fixed to the lower portion of the head base 4. On the lower surface of the substrate 6, there are provided a heat generating portion 7 composed of a heat generating element and a heat-resistant protective layer 8 covering the front and rear and the periphery of the heat generating portion 7.

  One of the platen roller 1 and the head base 4 is fixed to the casing, and the other is urged by a spring member so that the platen roller 1 and the thermal head 5 are pressed against each other. The elastic body 3 provided on the platen roller 1 has such a hardness that the surface can be slightly recessed in a state where the thermal head 5 is elastically pressed.

  The left direction in FIG. 3 is the front in the transport direction of the recording paper Sp and the cleaning sheet Sc, and the right direction in the figure is the rear in the transport direction.

  The thermal head 5 has a top 5 a that is closest to the platen roller 1. The plurality of heat generating portions 7 are provided on the top portion 5a, and a plurality of heat generating portions 7 are provided side by side in a direction perpendicular to the front-rear direction (a direction perpendicular to the paper surface).

  The thermal head 5 has a rear inclined portion 5b that gradually separates from the platen roller 1 as it goes rearward from the top portion 5a, and has a front inclined portion 5c that gradually separates from the platen roller 1 as it moves forward from the top portion 5a. ing. The rear inclined portion 5 b and the front inclined portion 5 c are formed by a part of the heat generating element and a part of the protective layer 8.

  As shown in FIG. 1, a paper loading unit 10 is provided behind the platen roller 1 and the head base 4. In the paper loading unit 10, a support plate 11 and a pressure plate 12 are provided so as to face each other vertically, and a plurality of recording papers Sp and a cleaning sheet Sc are loaded between the support plate 11 and the pressure plate 12. The pressure plate 12 is urged toward the support plate 11 by the spring member 13, and the recording paper Sp and the cleaning sheet Sc are pressed toward the support plate 11.

  A feeding roller 14 is provided below the paper loading unit 10. When the feeding roller 14 is rotationally driven by the feeding motor M2, the recording paper Sp or the cleaning sheet Sc located at the lowermost part in the paper loading unit 10 is fed forward.

  A lower guide 16 and an upper guide 17 are provided in front of the paper loading unit 10, and an optical sensor 18 is provided between the lower guide 16 and the platen roller 1. The optical sensor 18 includes a light emitting element that applies light to the back surface (lower surface) of the recording paper Sp and the cleaning sheet Sc, and a light receiving element that detects light emitted from the light emitting element and reflected from the back surface.

  As shown in FIG. 1, the light reception output detected by the light receiving element of the optical sensor 18 is given to the optical reading unit 21, and is given to the control unit 20 after waveform shaping or the like. The motor driver 22 for driving the control motor M1 and the motor driver 23 for controlling the feeding motor M2 are controlled by the control unit 20. Further, a head drive unit 24 that selects and drives the heat generating elements of the plurality of thermal heads 5 is provided. The head driving unit 24 operates based on the control of the control unit 20.

  The recording paper Sp installed in the paper loading unit 10 has a recording surface on the surface directed to the thermal head 5. On the recording surface, cyan, magenta, and yellow heat-sensitive color forming layers are formed to overlap each other, and the outermost surface is covered with an organic material protective layer. The cleaning sheet Sc has a large number of abrasive grains such as fine particles of inorganic material attached to the cleaning surface facing upward.

  When a command to start a recording operation is issued from the control unit 20, the control motor M1 and the feeding motor M2 are started, and the feeding roller 14 and the platen roller 1 start to rotate. Further, the optical sensor 18 starts a detection operation.

  When the recording paper Sp or the cleaning sheet Sc is sent out by the feeding roller 14 and moves on the optical sensor 18, light is given to the back surface of the recording paper Sp or the cleaning sheet Sc from the light emitting element of the optical sensor 18, and the paper Reflected light from the back surface is detected by the light receiving element and provided to the optical reading unit 21. When detecting the reflected light, the control unit 20 recognizes that the recording paper Sp or the cleaning sheet Sc is conveyed forward.

  An identification mark is attached to the back surface of the cleaning sheet Sc, and when the optical sensor 18 detects this recording mark, the control unit 20 determines that the cleaning sheet Sc has been fed, and when the recording mark cannot be detected, It is determined that the recording paper Sp is being fed out. Alternatively, a recording mark is attached to both the back surface of the recording paper Sp and the back surface of the cleaning sheet Sc, and the recording paper Sp is conveyed by the read output from the optical sensor 18 or the cleaning sheet Sc. It may be determined whether or not there is.

  When it is determined by the control unit 20 that the conveyed sheet is not the cleaning sheet Sc but the recording sheet Sp, the control unit 20 sends the image data to the head drive unit 24 in synchronization with the rotation of the platen roller 1. Based on the control signal is sent. Control signals are processed by the head drive unit 24, and the heat generation temperatures and heat generation times of the plurality of heat generation units 7 provided in the thermal head 5 are controlled according to the density and hue of the image data.

  When the recording surface of the recording paper Sp is heated by the heat generating part 7, the protective layer of the organic material is melted, and the color development of each of the three heat-sensitive heat generating layers is controlled, and a color image is formed on the recording surface of the recording paper Sp. Printed.

  The sheet loading unit 10 is loaded with the cleaning sheet Sc at a ratio of one sheet to a predetermined number of recording sheets Sp.

  When it is determined based on the detection signal from the optical sensor 18 that the cleaning sheet Sc is fed forward by the feed roller 14, the cleaning mode is set by the control unit 20.

  In the cleaning mode, the cleaning sheet Sc is sandwiched between the platen roller 1 and the thermal head 5, and the cleaning sheet Sc is conveyed by the rotation of the platen roller 1. At this time, dirt such as an organic compound adhering to the thermal head 5 is removed by the abrasive grains on the cleaning surface of the cleaning sheet Sc so as to be removed.

  In the cleaning mode, the motor driver 22 of the platen roller 1 is controlled by the control unit 20, and as shown in FIG. 2, the conveyance direction of the cleaning sheet Sc is the forward travel of (a), and the subsequent travel of (b). Further, the rotation direction of the platen roller 1 is switched so that the forward travel stage of (c), the backward travel stage of (d), and the forward travel stage of (e) are reached.

  By reciprocating the cleaning sheet Sc, the surface of the thermal head 5 is repeatedly cleaned. At this time, the rear end of the cleaning sheet Sc is reciprocated at a position away from the front end of the recording paper Sp located in the paper loading unit 10. The reciprocating distance W shown in FIG. 2 is set so that the rear end of the cleaning sheet Sc does not hit the recording paper Sp of the paper loading unit 10 due to the reciprocating movement.

  When the cleaning sheet Sc is reciprocally conveyed, the rear end of the cleaning sheet Sc is disengaged from the feeding roller 14, and the cleaning sheet Sc is sandwiched only by the platen roller 1 and the thermal head 5, and is sandwiched at other locations. Absent. Therefore, during reciprocal conveyance, the cleaning sheet Sc tends to tilt with the pinching portion between the platen roller 1 and the thermal head 5 as a fulcrum. As shown in FIG. 3, the surface of the elastic body 3 of the platen roller 1 is easily deformed into a concave shape by the pressure of the thermal head 5, so that the cleaning sheet Sc being conveyed is more easily inclined.

  As shown in FIG. 3A, when the platen roller 1 rotates in the α1 direction in the strokes (a), (c), and (e), the cleaning sheet Sc is the nipping portion between the platen roller 1 and the thermal head 5. Is used as a fulcrum, and is conveyed forward in a state where it tends to fall in the β1 direction. Further, since the surface of the elastic body 3 is slightly recessed while the cleaning sheet Sc is slightly deformed by the pressure of the top 5a of the thermal head 5, the cleaning surface of the cleaning sheet Sc is not only in contact with the top 5a of the thermal head 5 but also transported. The rear inclined portion 5b located on the upstream side is also easily contacted, and the dirt on the top portion 5a and the rear inclined portion 5b is easily removed in a wide range.

  On the contrary, as shown in FIG. 3B, when the platen roller 1 rotates in the α2 direction in the steps (b) and (d), the cleaning sheet Sc is moved to the platen roller 1 and the thermal head 5. In the state where it is easy to fall down in the β2 direction with the holding portion of the At this time, the cleaning surface of the cleaning sheet Sc not only contacts the top portion 5a of the thermal head 5, but also easily contacts the front inclined portion 5c, and dirt on the top portion 5a and the front inclined portion 5c is easily removed in a wide range. Become.

  As described above, not only the top portion 5a where the heat generating portion 7 of the thermal head 5 is located but also the inclined portions 5b and 5c before and after that are easily removed in a wide range, and the dirt on the inclined portions 5b and 5c is easily removed. Can be prevented, and the print quality can always be kept high.

FIG. 4 shows a printer according to the second embodiment of the present invention.
In the cleaning mode, the cleaning sheet Sc moves forward in the stroke (f), moves backward in the stroke (g), moves forward in the stroke (h), and then moves backward in the stroke (i). Then, it is transported back and forth so as to move forward in the process (j). That is, the reciprocating movement of the cleaning sheet Sc is repeated a plurality of times at different locations where the cleaning sheet Sc is advanced. Therefore, the location where the cleaning sheet Sc and the thermal head 5 come in contact is different in each reciprocating operation process, and the thermal head 5 can be cleaned using a wide area of the cleaning surface of the cleaning sheet Sc.

  Also in the cleaning mode shown in FIG. 4, the rear end portion of the cleaning sheet Sc is reciprocated and conveyed in an area where the rear end portion of the cleaning sheet Sc does not come into contact with the recording paper Sp in the paper loading unit 10. As a result, as shown in FIG. 3, not only the top portion 5a of the thermal head 5, but also the inclined portions 5b and 5c before and after the thermal head 5 are effectively cleaned.

  In each of the embodiments described above, when the cleaning sheet Sc is reciprocally conveyed, each of the heat generating portions 7 is heated, and the inorganic compound adhering to the thermal head 5 is dissolved and then removed by the cleaning sheet Sc. May be.

  Further, as shown in FIG. 4, the cleaning member 31 may be pressed against the surface of the platen roller 1 by a spring member 32 so that the contamination on the surface of the platen roller 1 can always be removed. The cleaning member 31 is made of a soft material such as a felt or a non-woven fabric that can easily remove dirt.

  Furthermore, when an adhesive layer such as an acrylic rubber layer is formed on the back surface of the cleaning sheet Sc, when the cleaning sheet Sc is conveyed by the platen roller 1, the surface of the platen roller 1 can be easily removed by the adhesive layer. .

DESCRIPTION OF SYMBOLS 1 Platen roller 2 Roller shaft 3 Elastic body 4 Head base 5 Thermal head 5a Top part 5b Back inclined part 5c Front inclined part 6 Substrate 7 Heat generating part 8 Protective layer 10 Paper loading part 14 Feeding roller 18 Optical sensor 20 Control part Sp Recording paper Sc Cleaning sheet

Claims (6)

A platen roller having an elastic body at least on the surface, and a thermal head facing the platen roller,
The thermal head has a top portion that protrudes toward the platen roller, and an inclined portion that inclines in a direction away from the platen roller as it moves away from the top in the front and rear in the transport direction,
The cleaning sheet is sandwiched between the platen roller and the thermal head and is reciprocally conveyed forward and backward, and the top portion and the conveyance direction both in the case of being forwardly conveyed and the case of being conveyed backward. The printer is characterized in that the inclined portion located upstream is rubbed with a cleaning sheet.   The printer according to claim 1, wherein the cleaning sheet is supported by only the platen roller and the thermal head and is reciprocated forward and backward. A sheet loading unit in which a plurality of recording sheets are stacked and installed behind the platen roller and the thermal head, and a feeding roller for feeding the recording sheets from the sheet loading unit to the platen roller one by one. Provided,
The printer according to claim 1 or 2, wherein the cleaning sheet is reciprocated forward and backward at a position where it does not contact the recording paper located in the paper loading section.   The printer according to claim 3, wherein the cleaning sheet is reciprocated forward and backward at a position away from the feeding roller.   The printer according to any one of claims 1 to 4, wherein the cleaning sheet is reciprocated forward and backward at a location where the forward traveling position is different.   The printer according to any one of claims 1 to 5, wherein when the cleaning sheet is reciprocally conveyed forward and backward, the heat generating portion of the thermal head generates heat.

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