JP2016117193A - Head gap adjustment mechanism and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head gap adjustment mechanism capable of reducing cost for an image forming device and preventing fluctuation of a head gap, and provide the image forming device.SOLUTION: The head gap adjustment mechanism includes a print head 13 for protruding a printing wire to carry out printing, a carriage 24 which is made of a resin material and on which the print head 13 is mounted, a carriage shaft 26 for movably supporting the carriage 24, and a platen 14 disposed to face the print head 13. At a predetermined part, a gap fluctuation preventing member 45 made of a predetermined material and configured to prevent fluctuation of a head gap between the print head 13 and the platen 14 with a temperature change is provided. As the carriage 24 is made of a resin material, the cost of the image forming device can be low. As the gap fluctuation prevention member 45 is provided, printing can be stably carried out.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a head gap adjusting mechanism and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine, for example, a printer, a carriage shaft is installed between left and right side frames, and a carriage with a print head mounted along the carriage shaft. Guided.

  The print head is provided with an electromagnetic coil, a print wire that protrudes from the nose of the print head by exciting the electromagnetic coil, and the print head is selectively protruded according to print data. And printing is performed on the sheet conveyed between the platen and the platen.

  By the way, in the print head, since heat is generated by exciting the electromagnetic coil, in order to prevent the temperature of the print head from becoming excessively high, the casing of the print head is formed of a metal material, The generated heat is released to the outside of the casing through fins formed to protrude from the outer peripheral surface of the casing.

  In addition, in order to release the heat generated in the print head to the outside of the housing, the carriage and the carriage shaft are formed of a metal material, and the heat generated in the print head is transmitted to the carriage shaft via the carriage. It is possible to release from the shaft or through the side frame. However, if the carriage is made of a metal material, the cost of the printer increases.

  Therefore, a printer provided with a carriage formed of a resin material is provided (for example, see Patent Document 1).

JP 2003-251834 A

  However, in the conventional printer, since the carriage is formed of a resin material, the gap between the nose of the print head and the platen, that is, the head gap, varies as the temperature in the printer casing changes. It is impossible to print stably.

  The present invention provides a head gap adjusting mechanism and an image forming apparatus capable of solving the problems of the conventional printer, reducing the cost of the image forming apparatus, and preventing the head gap from fluctuating. The purpose is to do.

  Therefore, in the head gap adjusting mechanism of the present invention, a print head that performs printing by protruding a print wire, a carriage that is formed of a resin material, and on which the print head is mounted, and the carriage is movably supported. A carriage shaft, and a platen disposed to face the print head.

  A gap fluctuation preventing member that is made of a predetermined material and prevents the head gap between the print head and the platen from fluctuating with a change in temperature is disposed at a predetermined portion.

  According to the present invention, in the head gap adjusting mechanism, a print head that performs printing by protruding a print wire, a carriage that is formed of a resin material, and on which the print head is mounted, and the carriage is movably supported. A carriage shaft, and a platen disposed to face the print head.

  A gap fluctuation preventing member that is made of a predetermined material and prevents the head gap between the print head and the platen from fluctuating with a change in temperature is disposed at a predetermined portion.

  In this case, since the carriage is formed of a resin material, the cost of the image forming apparatus can be reduced.

  In addition, since the gap fluctuation preventing member is disposed at a predetermined portion, it is possible to prevent the head gap from fluctuating with a change in temperature, and to perform printing stably.

It is a perspective view of the scanning unit in the 1st Embodiment of this invention. 1 is a schematic diagram of a printer according to a first embodiment of the present invention. 1 is a first perspective view showing a state in which a scanning unit according to a first embodiment of the present invention is mounted on a printer. FIG. It is a 2nd perspective view which shows the state which mounted the scanning unit in the 1st Embodiment of this invention in the printer. It is sectional drawing of the scanning unit in the 1st Embodiment of this invention. It is a figure for demonstrating the fluctuation | variation of a head gap. It is a figure for demonstrating the arrangement | positioning position of the slider in the 1st Embodiment of this invention. It is a 1st figure for demonstrating operation | movement of the slider in the 1st Embodiment of this invention. It is a 2nd figure for demonstrating operation | movement of the slider in the 1st Embodiment of this invention. It is a perspective view which shows the state which mounted the scanning unit in the 2nd Embodiment of this invention in the printer. It is principal part sectional drawing which shows the state which mounted the scanning unit in the 2nd Embodiment of this invention in the printer. It is a 1st figure for demonstrating operation | movement of the platen in the 2nd Embodiment of this invention. It is a 2nd figure for demonstrating operation | movement of the platen in the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a serial printer as an image forming apparatus will be described.

  FIG. 2 is a schematic view of the printer according to the first embodiment of the present invention.

  In the figure, 10 is a printer, 12 is disposed on the front side of the printer 10, a table for setting paper P as a medium, 13 is a print head, and 14 is disposed to face the print head 13. A printing portion Ar that performs printing on the paper P is formed between the print head 13 and the platen 14.

  The print head 13 is provided with an electromagnetic coil (not shown), a print wire (not shown) protruding from the nose 13a of the print head 13 by exciting the electromagnetic coil. An ink ribbon (not shown) is disposed between the nose 13a and the paper P, and a print wire is selectively protruded according to the print data and is struck against the paper P via the ink ribbon. Is transferred to the paper P and printing is performed.

  16 is arranged on the front side from the printing unit Ar, and a pair of front feed rollers as a first conveying roller for conveying the paper P in the direction of the arrow, 17 is arranged on the rear side from the printing unit Ar, It is a rear feed roller pair as a second transport roller that transports the paper P in the direction of the arrow. The front feed roller pair 16 includes an upper roller 16U disposed above the sheet P to be conveyed, and a lower roller 16L disposed below the sheet P and in contact with the upper roller 16U. The lower roller 16L A first transport gear g1 is attached on the same axis at one end. The rear feed roller pair 17 includes an upper roller 17U disposed above the sheet P to be conveyed, and a lower roller 17L disposed below the sheet P in contact with the upper roller 17U. A second transport gear g2 is attached on the same axis as one end of the lower roller 17L.

  Reference numeral 18 denotes a first sheet that is disposed adjacent to the front feed roller pair 16 on the upstream side of the front feed roller pair 16 in the conveyance direction of the sheet P and detects the sheet P placed on the table 12. A table sensor 19 serving as a medium detection unit is adjacent to the front feed roller pair 16 between the front feed roller pair 16 and the platen 14 on the downstream side of the front feed roller pair 16 in the conveyance direction of the paper P. This is a cueing sensor as a second medium detecting unit that is disposed and detects the paper P conveyed by the front feed roller pair 16.

  Reference numeral M denotes a line feed motor as a transport drive unit for transporting the paper P. By driving the line feed motor M, the front feed roller pair 16 and the rear feed roller pair 17 are rotated. The paper P is conveyed.

  For this purpose, the output gear g4 of the line feed motor M and the first idle gear g5 are meshed, and the first idle gear g5 and the small gear g7 of the second idle gear g6 comprising a two-stage gear. And the large gear g8 of the second idle gear g6 and the third and fourth idle gears g9 and g10 are meshed. Then, the third idle gear g9 and the first transport gear g1 are meshed, and the fourth idle gear g10 and the second transport gear g2 are meshed.

  Reference numeral 24 denotes a carriage for mounting the print head 13, and 26 denotes a bridge extending between the left and right side frames (not shown) of the printer 10 in the scanning direction of the print head 13 to support the carriage 24 movably. A carriage shaft as a first guide member for guiding the print head 13 in the scanning direction. The print head 13 and the carriage 24 constitute a scanning unit u1.

  Reference numeral 29 denotes an adjustment device for adjusting the gap between the nose 13a of the print head 13 and the platen 14, that is, the head gap, in accordance with the thickness of the paper P. The adjusting device 29 is formed at both ends of the carriage shaft 26 so as to be eccentric with respect to the carriage shaft 26, and has an eccentric shaft sh1 and an arc shape that are arranged to be rotatable with respect to the side frames. In addition, an adjustment lever 29a that is rotated in the circumferential direction by an operation of an operator (operator) and a connecting portion 29b that connects the eccentric shaft sh1 and the adjustment lever 29a are provided. When the operator operates the adjustment lever 29a to rotate in the circumferential direction, the eccentric shaft sh1 is rotated with respect to each side frame, and the carriage shaft 26 is moved in the height direction of the printer 10. As a result, the carriage 24 is moved with respect to the platen 14, and the head gap is adjusted. The carriage shaft 26 is supported so as to be allowed to move only in the height direction.

  Next, the operation of the printer 10 will be described.

  First, when the operator sets the paper P on the table 12, the table sensor 18 detects the front end of the paper P and sends the sensor output to a control unit (not shown). The control unit receives the sensor output, determines that the sheet P is set on the table 12, and drives the line feed motor M in the forward direction.

  The line feed motor M rotates through the output gear g4, the first idle gear g5, the small gear g7 of the second idle gear g6, the large gear g8 of the second idle gear g6, and the third idle gear g9. As a result, the front feed roller pair 16 is rotated at a reduced rotational speed.

  The line feed motor M is rotated by the output gear g4, the first idle gear g5, the small gear g7 of the second idle gear g6, the large gear g8 of the second idle gear g6, and the fourth idle gear g10. As a result, the rear feed roller pair 17 is rotated at a reduced rotational speed.

  As a result, the paper P is conveyed in the direction of the arrow, and then the cueing sensor 19 detects the front end of the paper P and sends the sensor output to the control unit. The control unit receives the sensor output, determines that the paper P has reached the front feed roller pair 16, and stops the line feed motor M at a predetermined timing. As a result, the paper P is stopped at a predetermined printing position.

  Subsequently, the control unit drives a space motor (not shown) as a scanning drive unit, moves the carriage 24 in the scanning direction along the carriage shaft 26, and performs a space operation.

  At this time, the control unit excites the electromagnetic coil of the print head 13, protrudes the print wire from the nose 13 a, and prints on the paper P.

  Subsequently, the control unit drives the line feed motor M in the forward direction, conveys the paper P by a predetermined amount in the sub-scanning direction, and performs a line feed operation. The controller performs a printing operation by alternately repeating a space operation and a line feed operation.

  When the printing operation is completed, the control unit further drives the line feed motor M in the forward direction to discharge the paper P to a stacker formed on the back side of the printer 10, or moves the line feed motor M in the reverse direction. Driven to discharge the paper P onto the table 12.

  The head gap is adjusted in advance before the printing operation is performed.

  Next, the main part of the printer 10 will be described.

  FIG. 1 is a perspective view of a scanning unit according to the first embodiment of the present invention. FIG. 3 is a first perspective view showing a state in which the scanning unit according to the first embodiment of the present invention is mounted on a printer. FIG. 5 is a second perspective view showing a state in which the scanning unit according to the first embodiment of the present invention is mounted on a printer, FIG. 5 is a sectional view of the scanning unit according to the first embodiment of the present invention, and FIG. FIG. 7 is a diagram for explaining the variation of the gap, FIG. 7 is a diagram for explaining the arrangement position of the slider in the first embodiment of the present invention, and FIG. 8 is a diagram of the slider in the first embodiment of the present invention. FIG. 9 is a first diagram for explaining the operation, and FIG. 9 is a second diagram for explaining the operation of the slider according to the first embodiment of the present invention.

  In the drawing, u1 is a scanning unit, 13 is a print head, 14 is a platen, 24 is a carriage, 26 is a carriage shaft, and 32 is installed between side frames of the printer 10 so as to extend in the scanning direction of the print head 13. , A guide frame as a second guide member that supports the carriage 24 movably and guides the print head 13 in the scanning direction.

  The guide frame 32 has a “U” -shaped cross section, and is formed of a processed plate material including a top portion 32a and hanging portions 32b and 32c that are suspended downward from both edges of the top portion 32a. A groove m1 is formed between the hanging portions 32b and 32c. The guide frame 32 is disposed above the carriage shaft 26 so as to extend in parallel with the carriage shaft 26. In the present embodiment, iron or stainless steel is used as a material for forming the processed plate material.

  The platen 14 has a “U” -shaped cross section, a flat portion 14a to which a printing wire is struck via the paper P, and a hanging portion that is suspended downward from both edges of the flat portion 14a. It consists of a processed plate material provided with 14b and 14c. The platen 14 can reduce the cost, has a low coefficient of linear expansion, is not easily deformed with changes in temperature, and has high durability. In this embodiment, iron, stainless steel, or the like is used. It is formed of a metal material.

  The platen 14 is disposed to extend in parallel with the carriage shaft 26 at an obliquely lower position on the front side than the carriage shaft 26.

  The carriage 24 is formed by a main body 71 having a through-hole h1 in which a carriage shaft 26 is slidably fitted, and is projected from the lower end of the main body 71 toward the front side of the printer 10 for printing. A head mounting portion 72 for mounting the head 13; a sliding contact portion 73 which is formed to protrude upward from the upper end of the main body portion 71 and is slidably contacted with the guide frame 32; and A slide piece 74 is provided so as to be swingable with respect to the sliding contact portion 73 and holds the guide frame 32 together with the sliding contact portion 73.

  The main body 71 includes a cylindrical bearing 76 having a predetermined length in the axial direction of the carriage shaft 26, and the through hole h 1 is formed in the bearing 76. The carriage shaft 26 and the through hole h1 have a circular cross section.

  The head mounting portion 72 is longer than the bearing portion 76 in the axial direction of the carriage shaft 26 and extends along the platen 14. When the print head 13 is mounted, the nose 13 a is connected to the platen 14. An opening h <b> 2 is provided at the center in the moving direction of the print head 13 so as to face each other.

  The sliding contact portion 73 includes a sliding surface Sa formed at the upper end so as to be opposed to the guide frame 32 and brought into contact with the outer peripheral surface of the hanging portion 32 c of the guide frame 32.

  The slide piece 74 is disposed so as to extend in parallel with the sliding contact portion 73 in the height direction of the printer 10, and is slid by the support portion 83 at substantially the center in the height direction of the printer 10. The movable contact portion 73 is supported so as to be swingable. The slide piece 74 includes, at the upper end, a sliding portion 80 formed in contact with the inner peripheral surface of the hanging portion 32c in the groove m1 of the guide frame 32. A spring 85 as a biasing member is disposed between the lower end of the slide piece 74 and the sliding contact portion 73, and the slide piece 74 is biased by the biasing force of the spring 85, and the sliding portion 80. Is pressed against the guide frame 32.

  Therefore, in a state where the guide frame 32 is sandwiched between the sliding contact portion 73 and the slide piece 74, the sliding surface Sa and the outer peripheral surface of the hanging portion 32c are slid, and the sliding portion 80 and the hanging portion 32c The carriage 24 is moved by sliding with the inner peripheral surface.

  The carriage 24 is positioned at two points: a fitting portion of the carriage shaft 26 into the bearing portion 76 and a holding portion of the guide frame 32 by the sliding contact portion 73 and the slide piece 74.

  In the present embodiment, in order to reduce the cost of the printer 10, a predetermined material, for example, a resin material such as polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), or polycarbonate (PC) is injection molded. The formed carriage 24 is used. And in order to make a linear expansion coefficient small and to make durability high, glass fiber or carbon fiber is contained in the resin material. In addition, a plurality of reinforcing ribs 81 are formed in a connecting portion between the main body 71 and the head mounting portion 72 so as to protrude in parallel with each other.

  By the way, in the printer 10, as printing is performed, heat is generated in the electronic components constituting the control unit, or in the print head 13, heat is generated by exciting the electromagnetic coil. The temperature inside the housing of the printer 10 changes.

  As described above, since the carriage 24 is formed of a resin material, the carriage 24 expands as the temperature in the casing of the printer 10 increases, and the temperature in the casing of the printer 10 decreases. Shrink.

  Further, as a characteristic of the resin material, the linear expansion coefficient in the direction perpendicular to the flow direction tends to be higher than the linear expansion coefficient in the flow direction of the resin at the time of injection molding. Therefore, in the rib 81, since the resin enters the narrow gap of the mold in the direction perpendicular to the resin flow direction at the time of injection molding, the linear expansion coefficient is increased and the carriage 24 is warped. End up.

  As a result, as the temperature in the housing of the printer 10 changes, the carriage 24 expands and contracts, and the carriage 24 warps, as shown in FIG. When the unit u1 is rotated about the carriage shaft 26 in the direction of the arrow A, the head gap δ fluctuates, the striking force by the printing wire changes, and it becomes impossible to print on the paper P stably. .

  That is, as the temperature in the housing of the printer 10 increases, the head gap δ increases. When the temperature in the housing of the printer 10 decreases, the head gap δ decreases, so the print density changes and the print quality decreases. End up.

  Therefore, in this embodiment, in order to prevent the head gap δ from fluctuating as the temperature in the housing of the printer 10 changes, a predetermined part of the carriage 24, in this embodiment, A slider 45 as a gap fluctuation preventing member is disposed in contact with the guide frame 32 on the sliding surface Sa of the sliding contact portion 73.

  The slider 45 expands when the temperature in the casing of the printer 10 increases, and contracts when the temperature in the casing of the printer 10 decreases, thereby changing the head gap δ accompanying the change in temperature in the casing of the printer 10. This cancels out and prevents the head gap δ from fluctuating.

  In the present embodiment, the slider 45 is made of a predetermined material, in the present embodiment, a resin material having a high slidability, in order to increase the slidability with respect to the guide frame 32. In the present embodiment, “Derlin 500AF” (manufactured by DuPont) made of polyacetal (POM) is used as the resin material.

  Since the head gap δ fluctuates in the range of 0.0008 to 0.0012 [mm / ° C.] without the slider 45 being disposed, the size of the slider 45, in the present embodiment, the front of the slider 45 is changed. The distance between the end on the side and the end on the rear side, that is, the thickness W of the slider 45 is set so that the head gap δ varies in the range of 0.0012 to 0.0008 [mm / ° C.]. . As a result, fluctuations in the head gap δ are offset by expansion and contraction of the slider 45, and fluctuations in the head gap δ can be prevented.

  That is, in the present embodiment, when the temperature in the housing of the printer 10 becomes high, the scanning unit u1 is rotated in the direction of arrow B about the carriage shaft 26 as shown in FIG. Then, the slider 45 expands in the direction of the arrow C and rotates the scanning unit u1 in the direction of the arrow D. Further, when the temperature in the housing of the printer 10 is lowered, as shown in FIG. 9, when the scanning unit u1 is rotated in the direction of the arrow B ′ about the carriage shaft 26, the slider 45 is moved. By contracting in the direction of arrow C ′, the scanning unit u1 is rotated in the direction of arrow D ′.

In this embodiment, when the distance between the center of the carriage shaft 26 and the center of the rear end surface of the slider 45 is L1, and the distance between the center of the carriage shaft 26 and the center of the nose 13a of the print head 13 is L2. , Distances L1 and L2 are
L1: L2 = 1.5: 1
Therefore, the ratio η of the distance L1 to the distance L2 is
η = 1.5
become. Since the linear expansion coefficient of the polyacetal is 0.0001 [/ ° C.], the thickness W of the slider 45 is 12 to 18 [mm] as the temperature in the housing of the printer 10 changes. It is set to vary with the range.

  Actually, the direction in which the slider 45 expands and contracts is not perpendicular to the line connecting the center of the carriage shaft 26 and the center of the rear end surface of the slider 45, and the direction in which the head gap δ fluctuates. Although not perpendicular to the line connecting the center of the carriage shaft 26 and the center of the nose 13a, in the present embodiment, the thickness W of the slider 45 is approximated by a value calculated based on the ratio η. .

  Then, the thickness W of the slider 45 is adjusted in accordance with the structure of the rib 81 of the carriage 24 and the positions of the slider 45, the carriage shaft 26, and the nose 13a.

  The print head 13, the platen 14, the carriage 24, the carriage shaft 26, the slider 45, and the like constitute a head gap adjusting mechanism.

  Thus, in this embodiment, since the carriage 24 is formed of a resin material, the cost of the printer 10 can be reduced.

  Further, since the slider 45 is disposed in contact with the guide frame 32, even if the head gap δ fluctuates as the temperature in the housing of the printer 10 changes, the head gap δ is expanded by the expansion and contraction of the slider 45. Fluctuations are offset. Therefore, it is possible to prevent the head gap δ from fluctuating, so that printing can be performed stably, and the print quality can be improved.

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 10 is a perspective view showing a state in which the scanning unit according to the second embodiment of the present invention is mounted on the printer, and FIG. 11 is a diagram showing a state in which the scanning unit according to the second embodiment of the present invention is mounted on the printer. FIG. 12 is a partial sectional view, FIG. 12 is a first diagram for explaining the operation of the platen in the second embodiment of the present invention, and FIG. 13 is a diagram for explaining the operation of the platen in the second embodiment of the present invention. FIG.

  In the drawing, u1 is a scanning unit, 13 is a print head, 84 is a platen, 24 is a carriage, 26 is a carriage shaft as a first guide member, and 32 is between the left and right side frames of the printer 10 (FIG. 2). It is a guide frame that extends in the scanning direction of the print head 13 and serves as a second guide member that guides the print head 13 in the scanning direction.

  The platen 84 has a circular cross section and functions as a third transport roller for transporting the paper P as a medium. The platen 84 is rotated together with the front feed roller pair 16 and the rear feed roller pair 17 by driving a line feed motor M as a driving unit for conveyance.

  In addition, the platen 84 is disposed as a metal cored bar 84a as a core member and a predetermined portion of the platen 84, in the present embodiment, radially outward of the cored bar 84a. It consists of a coating layer 84b as a gap fluctuation preventing member covering the outer peripheral surface. The coating layer 84b generates a frictional force for transporting the paper P, and is resistant to deterioration even when struck by a printing wire, and has a sufficient durability. It is made of a rubber material among high resin materials. In this embodiment, styrene-butadiene rubber (SBR) is used as the rubber material. However, since styrene-butadiene rubber is easily affected by changes in temperature, it is molded into a thin cylindrical shape. The covering layer 84b is formed by fitting the cored bar 84a by press fitting.

  The covering layer 84b expands as the temperature in the casing of the printer 10 increases, and contracts as the temperature in the casing of the printer 10 decreases, thereby changing the head gap δ. This cancels out and prevents the head gap δ from fluctuating.

  That is, in the present embodiment, when the temperature inside the housing of the printer 10 becomes high, as shown in FIG. 12, the scanning unit u1 is rotated in the direction of arrow E about the carriage shaft 26. The covering layer 84b expands, and the portion of the platen 84 facing the nose 13a is moved in the direction of arrow F. Further, when the temperature inside the housing of the printer 10 is lowered, as shown in FIG. 13, when the scanning unit u1 is rotated about the carriage shaft 26 in the direction of the arrow E ′, the covering layer 84b contracts. Then, the portion of the platen 84 that faces the nose 13a is moved in the direction of the arrow F ′.

  In this case, since the linear expansion coefficient of the styrene-butadiene rubber is 0.00023 [/ ° C.], in order to offset the head gap δ that fluctuates in the range of 0.0008 to 0.0012 [mm / ° C.], The dimension of the coating layer 84b, in the present embodiment, the thickness q of the coating layer 84b is set so as to change in the range of about 3.5 to 5.2 [mm].

  The thickness q of the coating layer 84b is adjusted in accordance with the structure of the rib 81 of the carriage 24, the positions of the carriage shaft 26 and the nose 13a, and the like.

  In the present embodiment, the print head 13, the platen 84, the carriage 24, the carriage shaft 26, the coating layer 84b, and the like constitute a head gap adjustment mechanism.

  Thus, in the present embodiment, since the coating layer 84b is disposed on the platen 84, the coating layer 84b expands even if the head gap δ fluctuates as the temperature in the housing of the printer 10 changes. And by contracting, the fluctuation of the head gap δ is canceled out. Therefore, it is possible to prevent the head gap δ from fluctuating, so that printing can be performed stably, and the print quality can be improved.

  In the first and second embodiments, the case where a serial printer is used as the printer 10 has been described. However, the present invention can be applied to various printers in which a print head is mounted on a carriage. .

  The present invention is not limited to the above embodiments, and various modifications can be made based on the gist of the present invention, and they are not excluded from the scope of the present invention.

13 Print head 14, 84 Platen 24 Carriage 26 Carriage shaft 45 Slider 84b Cover layer

Claims (5)

(A) a print head that performs printing by protruding a printing wire;
(B) a carriage formed of a resin material for mounting the print head;
(C) a carriage shaft that movably supports the carriage;
(D) having a platen disposed opposite to the print head;
(E) A gap fluctuation preventing member is provided at a predetermined part, which is made of a predetermined material and prevents a head gap between the print head and the platen from fluctuating with a change in temperature. Head gap adjustment mechanism.   The head gap adjusting mechanism according to claim 1, wherein the gap fluctuation preventing member is dimensioned based on a linear expansion coefficient of the predetermined material and a range of fluctuation of the head gap. (A) having a guide frame that is arranged in parallel with the carriage shaft and movably supports the carriage;
(B) The head gap adjusting mechanism according to claim 1 or 2, wherein the gap fluctuation preventing member is disposed in contact with the guide frame.   The head gap adjusting mechanism according to claim 1, wherein the gap fluctuation preventing member is a coating layer that covers the core member of the platen.   An image forming apparatus on which the head gap adjusting mechanism according to claim 1 is mounted.

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