Patent Publication Number: US-9889688-B2

Title: Printing unit and printer

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2015-170360 filed on Aug. 31, 2015, the entire content of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a printing unit and a printer. 
     2. Description of the Related Art 
     A printer of a dot impact type is known as a printer used for a timestamp or the like. The printer of this type includes a carriage that reciprocatingly moves in a row direction, a printing head mounted on the carriage, and a cartridge mounted on the carriage and having an ink ribbon housed therein (see, for example, Japanese Patent No. 2791350 (Patent Literature 1)). 
     The printer performs printing on a recording medium by hitting head pins of the printing head against the recording medium via the ink ribbon in a process in which the carriage reciprocatingly moves in the row direction on the recording medium. 
     However, the printer described in Patent Literature 1 performs the printing only while the carriage moves on a forward path. Therefore, an information amount that can be printed in one reciprocating movement is limited. In general, in the printer used for the timestamp or the like, printing is performed in a state in which a recording medium is fixed. Therefore, the recording medium cannot be conveyed in a column direction orthogonal to the row direction. 
     Therefore, there is still room of improvement of marketability. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention has been devised in view of the circumstances and an object of the present invention is to provide a printing unit and a printer that can improve marketability. 
     In order to solve the problem, a printing unit of the present invention includes: a carriage; a printing head mounted on the carriage; a guide pillar configured to support the carriage to be reciprocatingly movable in a row direction; a unit frame configured to support the guide pillar to be movable in a column direction orthogonal to the row direction; and a line-feed mechanism configured to move the carriage in the column direction. The line-feed mechanism includes: a line-feed plate supported by the guide pillar to be movable in the row direction; and a guide member configured to engage with the line-feed plate and guide the line-feed plate in the column direction together with the guide pillar according to the movement in the row direction of the line-feed plate. The line-feed plate includes: a forward-path engaging section with which the carriage engages in a process from a forward-path start point to a forward-path end point in the row direction; and a backward-path engaging section with which the carriage engages in a process from a backward-path start point to a backward-path end point in the row direction. 
     With this configuration, the carriage engages with the forward-path engaging section of the line-feed plate during the movement on the forward path. Therefore, when the carriage moves to the forward-path end point thereafter, the carriage moves to one side in the column direction together with the line-feed plate. On the other hand, the carriage engages with the backward-path engaging section of the line-feed plate during the movement on the backward path. Therefore, when the carriage moves to the backward-path end point thereafter, the carriage moves to the other side in the column direction together with the line-feed plate. That is, the carriage moves in different positions in the column direction between the forward path and the backward path. In this case, for example, by performing printing by the printing head in both of the forward path and the backward path, it is possible to perform printing in different printing regions in two columns in the column direction on a recording medium. As a result, it is possible to improve an information amount that can be printed at a time and improve marketability. 
     In particular, since the carriage is moved in the column direction according to the movement in the row direction, it is possible to perform a line-feed operation of the carriage with one driving source. Therefore, it is possible to realize simplification and a reduction in costs compared with, for example, when the line-feed operation of the carriage is performed by two driving sources, that is, a driving source for performing the movement in the row direction and a driving source for performing the movement in the column direction. 
     In the printing unit according to the present invention, in one member of the line-feed plate and the guide member, an engaging projecting section projecting toward the other member may be formed, an engaging recessed section, with which the engaging projecting section engages, may be formed in the other member, and the engaging recessed section may extend to the one side in the column direction toward one side in the row direction. 
     With this configuration, the engaging recessed section extends to the one side in the column direction toward the one side in the row direction. Therefore, it is possible to smoothly move the carriage in the column direction according to the movement in the row direction of the carriage. 
     In the printing unit according to the present invention, a locking section, which the engaging projecting section can climb over, may be formed in the center in an extending direction in the engaging recessed section on the inner surface of the engaging recessed section. 
     With this configuration, in a state in which the engaging projecting section is located at both end portions in the extending direction in the engaging recessed section, the movement of the engaging projecting section to the center in the extending direction is regulated by the locking section. Consequently, for example, when a shock acts on the printing unit from the outside, it is possible to suppress the line-feed plate from suddenly moving. Note that, during line-feed of the carriage to the backward-path start point (the forward-path end point) and during return of the carriage to the backward-path end point (the forward-path start point), the line-feed plate moves together with the carriage in a state in which the carriage engages with the forward-path engaging section or the backward-path engaging section. Therefore, the engaging projecting section climbs over the locking section. 
     In the printing unit according to the present invention, the guide member may include a cam member configured to be rotatable on the unit frame around an axis orthogonal to the row direction and the column direction, and the cam member may engage with the line-feed plate in a position eccentric with respect to the axis and move the line-feed plate in the column direction together with the guide pillar according to the movement in the row direction of the line-feed plate. 
     With this configuration, when the cam member rotates according to the movement in the row direction of the carriage, the line-feed plate moves in the column direction. Consequently, it is possible to smoothly move the carriage in the column direction. 
     In the printing unit according to the present invention, the cam member may include a cam gear formed in a position eccentric with respect to the axis, and the line-feed plate may include a line-feed rack configured to mesh with the cam gear. 
     With this configuration, the cam member and the line-feed plate are engaged by the cam gear and the line-feed rack. Therefore, it is possible to reduce a load acting on an engaging portion while achieving simplification. 
     In the printing unit according to the present invention, the printing unit may further include: a driving source configured to move the carriage in the row direction; a printing frame mounted with the driving source and configured to support the guide pillar; and a bearing section provided in the unit frame, configured to support the guide pillar to be reciprocatingly movable in the column direction, and coupled to the printing frame to regulate a swing of the printing frame around the guide pillar. 
     With this configuration, the bearing section regulates the swing of the printing frame around the guide pillar while supporting the guide pillar to be movable in the column direction. Therefore, it is possible to achieve a reduction in the number of components, a reduction in costs, and improvement of assemblability compared with when the support of the guide plate and the regulation of the swing of the printing frame are performed by separate components. 
     In the printing unit according to the present invention, the printing head may be an impact type and include a winding mechanism connected to a cartridge detachably attached to the carriage and configured to wind an ink ribbon in the cartridge, the winding mechanism may include: a winding gear disposed in the carriage; and a rack plate including a winding rack that meshes with the winding gear, and, the winding gear may rotate according to the movement in the row direction of the carriage and the winding mechanism may perform the winding of the ink ribbon. 
     With this configuration, the ink ribbon is wound according to the movement of the carriage. Therefore, it is possible to suppress occurrence of a change in printing concentration, printing blur, and the like and keep printing quality satisfactorily. 
     In the printing unit according to the present invention, the rack plate may include chipped tooth regions for releasing the meshing of the winding gear and the winding rack at both end portions in the row direction. 
     With this configuration, the chipped tooth regions for releasing the meshing of the winding gear and the winding rack are formed. Therefore, during line-feed of the carriage to the backward-path start point (the forward-path end point) and during return of the carriage to the backward-path end point (the forward-path start point), when the carriage passes both the end portions in the row direction of the rack plate, the winding gear does not rotate according to the movement of the carriage. That is, while the carriage is moving in the chipped tooth regions, the winding of the ink ribbon is not performed. Therefore, it is possible to suppress load torque required for the winding during the line-feed and during the return from acting on the driving source and smoothly perform the line-feed operation. Since it is possible to suppress the ink ribbon from being uselessly wound during the line-feed, it is possible to effectively use the ink ribbon. 
     A printer according to the present invention includes: the printing unit of the present invention; and a casing configured to house the printing unit and including a slot into which a recording medium is inserted. 
     With this configuration, since the printer includes the printing unit of the present invention, it is possible to improve marketability. 
     According to the present invention, it is possible to provide the printing unit and the printer that can improve marketability. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a printer according to a first embodiment viewed from the left side; 
         FIG. 2  is a perspective view of a printing unit according to the first embodiment viewed from the left side; 
         FIG. 3  is an exploded perspective view of the printing unit shown in  FIG. 2 ; 
         FIG. 4  is a side view of a printing block in a detached state of a cartridge according to the first embodiment viewed from the left side; 
         FIG. 5  is a sectional view corresponding to line V-V in  FIG. 4 ; 
         FIG. 6  is a plan view of a carriage and a line-feed mechanism according to the first embodiment; 
         FIG. 7  is an explanatory diagram for explaining an operation method for the printer according to the first embodiment and is a side view equivalent to  FIG. 4 ; 
         FIG. 8  is an explanatory diagram for explaining an operation method for the printer according to the first embodiment and is a side view equivalent to  FIG. 4 ; 
         FIG. 9  is an explanatory diagram for explaining the operation method for the printer according to the first embodiment and is a plan view of the carriage and the line-feed mechanism; 
         FIG. 10  is an explanatory diagram for explaining the operation method for the printer according to the first embodiment and is a sectional view equivalent to  FIG. 5 ; 
         FIG. 11  is a sectional view corresponding to line XII-XII in  FIG. 6 ; 
         FIG. 12  is a plan view of a line-feed mechanism according to a second embodiment viewed from above; 
         FIG. 13  is a side view of a printing block according to the second embodiment viewed from the right side; and 
         FIG. 14  is an explanatory diagram for explaining an operation method for a printer according to the second embodiment and is a plan view equivalent to  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention are explained with reference to the drawings. 
     First Embodiment 
     Printer 
       FIG. 1  is an exterior perspective view of a printer  1  viewed from the left side. 
     As shown in  FIG. 1 , the printer  1  in this embodiment is used for a timestamp or the like. The printer  1  prints information concerning time such as a date and time of day in a printing region of card-like recording paper P (a recording medium). Specifically, the printer  1  includes a casing  2  and a printing unit  3  (see  FIG. 2 ) housed in the casing  2 . Note that, in the following explanation, the lower left side of the paper surface in  FIG. 1  is referred to as front (arrow FR direction), the upper right side is referred to as back, the upper side is referred to upward (arrow UP direction), and the lower side is referred to as downward. In  FIG. 1 , the lower right side with respect to the paper surface is referred to as left side (arrow LH direction) when viewed from the printer  1  and the upper left side is referred to as right side when viewed from the printer  1 . 
     The casing  2  is configured by a resin material or the like. The casing  2  is formed in a rectangular parallelepiped shape. On a front wall  2   a  of the casing  2 , a slot  5  recessed backward is formed in the center in the up-down direction. Recording paper P is removably inserted into the slot  5  from the front. Note that the slot  5  pierces through the casing  2  in the left-right direction. The thickness of the recording paper P can be changed as appropriate as long as the recording paper P can be removably inserted into the slot  5 . 
     On an upper wall  2   b  of the casing  2 , a keyhole  6 , operation buttons  7  for performing various kinds of operation, and a display section  8  that displays time of day and the like are disposed. Note that, in the example shown in  FIG. 1 , the front part of the upper wall  2   b  inclines downward toward the front. 
     Printing Unit 
       FIG. 2  is a perspective view of the printing unit  3  viewed from the left side. 
       FIG. 3  is an exploded perspective view of the printing unit  3  shown in  FIG. 2 . 
     As shown in  FIGS. 2 and 3 , the printing unit  3  mainly includes a unit frame  11  and a printing block  12  and a platen block  13  mounted on the unit frame  11 . 
     The unit frame  11  is configured by bending metal or the like. Specifically, the unit frame  11  includes a frame base  15 , printing-block supporting sections  17  that support the printing block  12 , and a platen supporting section  18  that supports the platen block  13 . 
     The frame base  15  is formed in a rectangular shape in plan view from above. At the left side end portion in the frame base  15 , an opening for printing  21  piercing through the frame base  15  in the up-down direction is formed. Not-shown stopper rubber is attached to an opening edge of the opening for printing  21  in the frame base  15  from below. Note that the frame base  15  is located above the slot  5 . 
     The printing-block supporting sections  17  include supporting walls  17   a  and  17   b  erected to be directed upward from the front and rear both end portions of the frame base  15 . 
     The platen supporting section  18  is located below the frame base  15 . The platen supporting section  18  is formed in a rectangular frame shape in plan view from above. Note that the platen supporting section  18  is located below the slot  5 . That is, the recording paper P inserted into the slot  5  enters between the frame base  15  and the platen supporting section  18  from the front. 
     The platen block  13  includes a platen main body  22  and a platen driving mechanism  23  that drives the platen main body  22 . 
     The platen main body  22  is formed in a tabular shape in plan view from above. The platen main body  22  is supported to be movable up and down by the platen supporting section  18 . Specifically, the platen main body  22  moves up and down between a holding position where the platen main body  22  comes into contact with the frame base  15  from below and a retracting position where the platen main body  22  separates from the frame base  15  downward. Note that, in the holding position, the platen main body  22  comes into contact with the frame base  15  via the stopper rubber attached to the frame base  15 . In the retracting position, the platen main body  22  retracts further downward than the slot  5 . 
     The platen driving mechanism  23  includes a platen motor  24  and a platen wheel train  25  that connects the platen motor  24  and the platen main body  22 . 
     The printing block  12  mainly includes a printing frame  31 , a guide pillar  32 , a carriage  33 , a printing head  34 , a winding mechanism  35 , and a driving mechanism for printing  36 . 
     The printing frame  31  is formed in a box shape opened upward and on the left side. As shown in  FIG. 3 , in lower parts of a front wall  31   a  and a rear wall  31   b  in the printing frame  31 , through-holes  41  (in  FIG. 3 , only the through-hole  41  of the front wall  31   a  is shown) respectively piercing through the front wall  31   a  and the rear wall  31   b  in the front-back direction (the row direction) are formed. 
     On the front wall  31   a  and the rear wall  31   b , regulating recessed sections  42  (in  FIG. 3 , only the regulating recessed section  42  of the front wall  31   a  is shown) recessed toward the inner side in the front-back direction are formed in portions located on the right side with respect to the through-holes  41 . The regulating recessed section  42  is formed in an elliptical shape having a longitudinal direction in the left-right direction (the column direction) in front view from the front-back direction. 
     The guide pillar  32  is formed in a columnar shape having an axial direction in the front-back direction. Front and rear both end portions of the guide pillar  32  are particularly supported in the through-holes  41  formed in the lower parts of the front wall  31   a  and the rear wall  31   b . In the guide pillar  32 , portions located on the outer side in the front-back direction with respect to the front wall  31   a  and the rear wall  31   b  are supported by the supporting walls  17   a  and  17   b  of the printing-block supporting sections  17 . Specifically, in the supporting walls  17   a  and  17   b , shaft supporting holes  45  piercing through the supporting walls  17   a  and  17   b  in the front-back direction are formed. The front and rear both end portions of the guide pillar  32  are respectively supported in the shaft supporting holes  45  via bearing sections  46 . 
     The shaft supporting holes  45  are long holes having a longitudinal direction in the left-right direction. Therefore, the guide pillar  32  is configured to be movable in the left-right direction in the shaft supporting holes  45 . 
     The bearing sections  46  include collar sections  47  inserted into the shaft supporting holes  45 , flange sections  48  protruding from outer side end portions in the front-back direction in the collar sections  47 , and protrusion sections  49  projecting to the inner side in the front-back direction from the flange sections  48 . 
     The collar sections  47  are formed in a cylindrical shape formed along the inner surfaces of the shaft supporting holes  45 . The collar sections  47  cover the inner circumferential surfaces of the shaft supporting holes  45 . Therefore, the guide pillar  32  is supported in the shaft supporting holes  45  via the collar sections  47 . 
     The flange sections  48  are formed in an elliptical shape having a longitudinal direction in the left-right direction in plan view from the front-back direction. The collar sections  47  are consecutively connected to the left side end portions in the flange sections  48 . 
     The protrusion sections  49  are disposed at the right side end portions in the flange sections  48 . The protrusion sections  49  pierce through the supporting walls  17   a  and  17   b  of the printing-block supporting sections  17  and project to the inner side in the front-back direction with respect to the supporting walls  17   a  and  17   b . Inner side end portions in the front-back direction in the protrusion sections  49  are respectively housed in the regulating recessed sections  42 . When the protrusion sections  49  come into contact with the inner surfaces of the regulating recessed sections  42 , the regulating recessed sections  42  regulate a swing of the printing block  12  around the guide pillar  32 . 
     The carriage  33  is formed in a rectangular parallelepiped shape. The guide pillar  32  pierces through a lower part of the carriage  33  in the front-back direction. Consequently, the carriage  33  is supported by the guide pillar  32  to be reciprocatingly movable in the front-back direction. 
     A cartridge  51 , in which a not-shown ink ribbon is housed, is detachably mounted on the carriage  33  from the left side. 
     A scanning rack  52  projecting toward the right side is formed in the carriage  33 . The scanning rack  52  extends along the front-back direction. 
       FIG. 4  is a side view of the printing block  12  in a detached state of the cartridge  51  viewed from the left side. 
     As shown in  FIG. 4 , a wheel-train housing section  54  is formed in an upper part of the carriage  33 . The wheel-train housing section  54  includes a housing recessed section  55  opening toward the left side and a cover  56  that covers the housing recessed section  55  from the left side. 
     As shown in  FIGS. 2 and 3 , the printing head  34  is attached to a lower part of the carriage  33  from the left side. The printing head  34  faces the opening for printing  21  of the frame base  15  from above. A not-shown plurality of head pins movable up and down are incorporated in the printing head  34 . The ink ribbon let out from the cartridge  51  is capable of traveling in the front-back direction below the printing head  34 . 
       FIG. 5  is a sectional view corresponding to line V-V in  FIG. 4 . 
     As shown in  FIGS. 4 and 5 , the winding mechanism  35  includes winding wheel trains  61  to  65  housed in the gear-train housing section  54  and a rack plate  67  disposed above the carriage  33 . 
     The winding wheel trains  61  to  65  include a winding shaft  61 , a first moving gear  62  and a second moving gear  63 , and an intermediate gear  64  and a reverse gear  65  disposed between the first moving gear (winding gear)  62  and the second moving gear (winding gear)  63 . 
     The winding shaft  61  is disposed in a portion located on the front side in the wheel-train housing section  54 . The winding shaft  61  is supported in the wheel-train housing section  54  to be rotatable around an axis extending along the left-right direction. The left side end portion of the winding shaft  61  pierces through the cover  56  and projects to the outside of the wheel-train housing section  54 . The left side end portion of the winding gear  61  is coupled to a not-shown bobbin of the cartridge  51 . A transmission gear  71  protruding to the outer circumference side of the winding shaft  61  is formed at the right side end portion of the winding shaft  61 . 
     The winding shaft  61  is inserted through the first moving gear  62  from the right side. The first moving gear  62  is supported in a portion located further on the left side than the transmission gear  71  in the winding shaft  61  to be rotatable around an axis extending along the left-right direction and movable in the front-back direction. The first moving gear  62  includes a first large gear  72  located on the left side, a first small gear  73  located on the right side, and a first flange section  74  located between the first large gear  72  and the first small gear  73  and larger in diameter than the first large gear  72 . The upper end portions of the first large gear  72  and the first flange section  74  project upward from the wheel-train housing section  54 . 
     The second moving gear  63  is disposed behind the first moving gear  62  in the wheel-train housing section  54 . The second moving gear  63  is supported in the wheel-train housing section  54  to be rotatable around an axis extending along the left-right direction and movable in the front-back direction. The second moving gear  63  includes a second large gear  77  located on the left side, a second small gear  78  located on the right side, and a second flange section  79  located between the second large gear  77  and the second small gear  78  and larger in diameter than the second large gear  77 . The large gears  72  and  77 , the small gears  73  and  78 , and the flange sections  74  and  79  of the moving gears  62  and  63  are respectively disposed in equivalent positions in the left-right direction. The upper end portions of the second large gear  77  and the second flange section  79  project upward from the wheel-train housing section  54 . 
     In the wheel-train housing section  54 , a spacer  81  is disposed in a position located between the moving gears  62  and  63 . The spacer  81  is formed in a disk shape. The spacer  81  is supported in the wheel-train housing section  54  to be movable in the front-back direction. The flange sections  74  and  79  of the moving gears  62  and  63  come into contact with the spacer  81  from the outer side in the front-back direction. Consequently, a minimum inter-axis distance in the front-back direction between the moving gears  62  and  63  is maintained. 
     As shown in  FIG. 5 , the intermediate gear  64  is supported to be rotatable around an axis extending in the left-right direction in a portion located further on the right side than the spacer  81  in the wheel-train housing section  54 . The intermediate gear  64  includes an intermediate large gear  83  located on the left side and an intermediate small gear  84  located on the right side. 
     Meshing and release of the meshing of the intermediate large gear  83  with the first small gear  73  are switched according to the movement in the front-back direction of the first moving gear  62 . 
     The intermediate small gear  84  is in mesh with the transmission gear  71  of the winding shaft  61 . 
     The reverse gear  65  is disposed behind the intermediate gear  64  in the wheel-train housing section  54 . The reverse gear  65  is configured to be rotatable around an axis extending in the left-right direction. The reverse gear  65  meshes with the intermediate large gear  83 . Meshing and release of the meshing of the reverse gear  65  with the second small gear  78  are switched according to the movement in the front-back direction of the second moving gear  63 . 
     As shown in  FIGS. 3 and 4 , the rack plate  67  bridges the upper end portions of the front wall  31   a  and the rear wall  31   b  of the printing frame  31  explained above. At least a part of the rack plate  67  is disposed in a position overlapping the carriage  33  in plan view from the up-down direction. In the rack plate  67 , a winding rack  87  projecting downward is extended in the front-back direction. The winding rack  87  is configured to be capable of meshing with the upper end portions (portions projecting from the wheel-train housing section  54 ) of the large gears  72  and  77  in the moving gears  62  and  63  from above. Note that the winding rack  87  is formed in a portion avoiding both the end portions in the front-back direction in the rack plate  67 . That is, both the end portions in the front-back direction in the rack plate  67  are chipped tooth regions K 1  and K 2  (see  FIG. 4 ) where the winding rack  87  is not formed. 
     The driving mechanism for printing  36  includes a printing motor (a driving source)  91  capable of regularly and reversely rotating and a scanning gear  92  that connects the printing motor  91  and the carriage  33 . 
     The printing motor  91  is disposed in a portion located further on the right side than the carriage  33  in the printing frame  31 . 
     The scanning gear  92  connects the printing motor  91  and the carriage  33  in the printing frame  31 . The scanning gear  92  meshes with a not-shown output gear coupled to an output shaft of the printing motor  91  and meshes with the scanning rack  52  of the carriage  33 . A driving force of the printing motor  91  is transmitted to the carriage  33  via the scanning gear  92  and the scanning rack  52 . Therefore, the carriage  33  reciprocatingly moves in the front-back direction along the guide pillar  32 . 
     As shown in  FIG. 3 , the printing unit  3  in this embodiment includes a line-feed mechanism  100  that moves the carriage  33  in the left-right direction. The line-feed mechanism  100  includes a line-feed plate  101  supported by the guide pillar  32  to be movable in the front-back direction and guide members  102  that guide the line-feed plate  101  in the left-right direction according to the movement in the front-back direction of the line-feed plate  101 . 
       FIG. 6  is a plan view of the carriage  33  and the line-feed mechanism  100 . 
     As shown in  FIG. 6 , the line-feed plate  101  is formed in a C-shape that opens to the left side in plan view from the up-down direction. Specifically, the line-feed plate  101  includes a forward-path engaging section  110  located in front of the carriage  33 , a backward-path engaging section  111  located behind the carriage  33 , and a line-feed base  112  that bridges the engaging sections  110  and  111 . 
     The guide pillar  32  pierces through the left side end portion of the forward-path engaging section  110 . The forward-path engaging section  110  is opposed to the carriage  33  in the front-back direction. Consequently, the carriage  33  engages (comes into contact) with the forward-path engaging section  110  from the back according to forward movement (a forward path) of the carriage  33 . Note that the forward-path engaging section  110  is located in front of the winding rack  87 . 
     The guide pillar  32  pieces through the left side end portion of the backward-path engaging section  111 . The backward-path engaging section  111  is opposed to the carriage  33  in the front-back direction. Consequently, the carriage  33  engages (comes into contact) with the backward-path engaging section  111  from the front according to backward movement (a backward path) of the carriage  33 . Note that the backward-path engaging section  111  is located behind the winding rack  87 . In the example shown in  FIG. 4 , the distance between the inner side end faces in the front-back direction in the engaging sections  110  and  111  is longer than the distance between the outer side end edges in the front-back direction in the chipped tooth regions K 1  and K 2 . 
     As shown in  FIG. 6 , the line-feed base  112  is formed in a tabular shape extending in parallel to the guide pillar  32  along the front-back direction. The line-feed base  112  connects the right side end portions of the engaging sections  110  and  111 . A pair of engaging projecting sections  113  projecting downward is formed at both the end portions in the front-back direction in the line-feed base  112 . 
     The guide members  102  are respectively disposed in positions overlapping the line-feed plate  101  in the up-down direction at both the end portions in the front-back direction of the frame base  15 . In the guide members  102 , engaging recessed sections  115 , in which the engaging projecting sections  113  are housed from above, are formed in positions overlapping the engaging projecting sections  113  in the up-down direction. The engaging recessed sections  115  incline toward the right side (one side in the column direction) toward the front (one side in the row direction). Note that an inclination angle, dimensions, and the like of the engaging recessed sections  115  can be changed as appropriate. 
     Operation Method for the Printer 
     An operation method for the printer  1  is explained. 
     First, as shown in  FIG. 1 , the recording paper P is inserted into the slot  5  from the front side. The recording paper P entered the slot  5  is disposed between the frame base  15  and the platen supporting section  18  shown in  FIG. 2  in the casing  2 . When the recording paper P reaches a predetermined position in the slot  5 , the platen block  13  is actuated. Specifically, when the platen motor  24  is actuated, a driving force of the platen motor  24  is transmitted to the platen main body  22  via the platen wheel train  25 . Then, since the platen main body  22  rises, the recording paper P is held between the platen main body  22  and the frame base  15 . 
     Subsequently, the printing block  12  is actuated. In the printer  1  in this embodiment, when the carriage  33  reciprocatingly moves in the front-back direction, the carriage  33  passes different positions in the left-right direction in the forward path and the backward path. The printer  1  performs printing in both of the forward path and the backward path. Therefore, the printer  1  can perform printing for two rows on the recording paper P. 
     Specifically, the printer  1  in this embodiment includes a forward-path printing step, a line-feed step, a backward-path printing step, and a carriage-return step. 
     In the forward-path printing step, the printer  1  performs printing for a first row on the recording paper P in a process in which the carriage  33  moves forward from a forward-path start point. 
     In the line-feed step, after the printing for the first low is performed on the recording paper P, the carriage  33  moves to the right side (a second row) while moving forward in a process for moving to a forward-path end point. 
     In the backward-path printing step, the printer  1  performs printing for the second row on the recording paper P in a process in which the carriage  33  moves backward from a backward-path start point (the forward-path end point). 
     In the carriage-return step, after the printing for the second row is performed on the recording paper P, the carriage  33  moves to the left side while moving backward in a process in which the carriage  33  moves to a backward-path end point (the forward-path start point). Note that, in the following explanation, a point where the carriage  33  is located on the rear side in the printing frame  31  is the forward-path start point (the backward-path end point). At the forward-path start point, the second moving gear  63  is located in the chipped tooth region K 1  (see  FIG. 4 ) on the rear side in the rack plate  67 . The meshing of the winding rack  87  and the second large gear  77  is released. At the forward-path start point, the carriage  33  is separated from at least the forward-path engaging section  110  backward. 
     Forward-path Printing Step 
     As shown in  FIGS. 2, 4, and 6 , in the forward-path printing step, when the printing motor  91  regularly rotates, a driving force of the printing motor  91  is transmitted to the scanning rack  52  via the scanning gear  92 . Then, the carriage  33  moves forward from the forward-path start point. At this point, as shown in  FIGS. 4 and 5 , since the first large gear  72  is in mesh with the winding rack  87 , the first moving gear  62  moves backward relatively to the carriage  33  according to the forward movement of the carriage  33 . Consequently, as shown in  FIG. 5 , the first small gear  73  of the first moving gear  62  meshes with the intermediate large gear  83 . 
       FIGS. 7 and 8  are explanatory diagrams for explaining the operation method for the printer  1  and are side views equivalent to  FIG. 4 . Note that, in  FIGS. 7 and 8 , the cartridge  51 , the cover  56 , and the like are not shown. 
     Thereafter, as shown in  FIGS. 5 and 7 , when the carriage  33  further moves forward, the first moving gear  62  rotates to one side around an axis. When the first moving gear  62  rotates to the one side, the intermediate gear  64  rotates in the opposite direction of the rotation of the first moving gear  62  (the other side). When the intermediate gear  64  rotates, the reverse gear  65  and the winding shaft  61  rotate in the opposite direction of the rotation of the intermediate gear  64  (the one side). When the winding shaft  61  rotates, a bobbin of the cartridge  51  rotates. Consequently, the carriage  33  moves forward while the ink ribbon of the cartridge  51  is wound. Note that, in the forward-path printing step, when the second moving gear  63  slips out of the chipped tooth region K 1  on the rear side and meshes with the winding rack  87 , the second moving gear  63  moves backward with respect to the carriage  33 . Consequently, as shown in  FIG. 5 , the meshing of the second small gear  78  of the second moving gear  63  and the reverse gear  65  is released. That is, in the forward-path printing step, in a state in which the second large gear  77  is in mesh with the winding rack  87 , when the second small gear  78  separates from the reverse gear  65 , the second moving gear  63  idles. 
     As shown in  FIG. 2 , in the forward-printing step, when the recording paper P is hit by the head pins of the printing head  34  via the ink ribbon, printing in a first row is performed on the recording paper P. Thereafter, when the printing head  34  passes a printing region of the first row of the recording paper P, the forward-path printing step ends. 
     Line-feed Step 
       FIG. 9  is an explanatory diagram for explaining the operation method for the printer  1  and is a plan view of the carriage  33  and the line-feed mechanism  100 . 
     As shown in  FIGS. 8 and 9 , in the line-feed step, after the printing head  34  passes the printing region of the first row of the recording paper P, the carriage  33  comes into contact with the forward-path engaging section  110  of the line-feed plate  101  from the back. When the carriage  33  further moves forward in this state, the line-feed plate  101  moves forward together with the carriage  33 . Since the engaging projecting sections  113  are engaged in the engaging recessed sections  115 , the line-feed plate  101  moves to the right side toward the front. Consequently, the entire printing block  12  moves to the right side toward the front. 
     At a point in time when the engaging projecting sections  113  approach or come into contact with the front end portions of the engaging recessed sections  115 , the carriage  33  reaches the forward-path start point (the backward-path end point). At this point in time, the driving in the regular rotation direction of the printing motor  91  is once stopped. Note that, after the carriage  33  passes the printing region of the first row in the recording paper P and before or after the carriage  33  comes into contact with the forward-path engaging section  110 , the first moving gear  62  enters the chipped tooth region K 2  on the front side in the rack plate  67 . Therefore, before or after approach to the line-feed step, the first moving gear  62  does not rotate and the winding of the ink ribbon is not performed. Note that timing when the first moving gear  62  enters the chipped tooth region K 2  can be changed as appropriate. 
     Backward-path Printing Step 
     In the backward-path printing step, when the printing motor  91  is reversely rotated in a state in which the carriage  33  is located at the backward-path start point (the forward-path end point), the carriage  33  moves backward. At this point, the carriage  33  moves backward in a portion (the backward path) located on the right side with respect to the forward path. 
       FIG. 10  is an explanatory diagram for explaining the operation method for the printer  1  and is a sectional view equivalent to  FIG. 5 . 
     As shown in  FIGS. 8 and 10 , in the backward-path printing step, since the second large gear  77  is in mesh with the winding rack  87 , the second moving gear  63  moves forward relatively to the carriage  33  according to the backward movement of the carriage  33 . Consequently, the second small gear  78  of the second moving gear  63  meshes with the reverse gear  65 . 
     In this state, when the carriage  33  further moves backward, the second moving gear  63  rotates to the other side around the axis. When the second moving gear  63  rotates to the other side, the reverse gear  65  rotates in the opposite direction of the rotation of the second moving gear  63  (one side). When the reverse gear  65  rotates, the intermediate gear  64  rotates in the opposite direction of the rotation of the reverse gear  65  (the other side). When the intermediate gear  64  rotates to the other side, the winding shaft  61  rotates in the opposite direction of the rotation of the intermediate gear  64  (the one side) via the intermediate small gear  84 . When the winding shaft  61  rotates to the one side, the bobbin of the cartridge  51  rotates. Consequently, as shown in  FIG. 7 , the carriage  33  moves backward while the ink ribbon of the cartridge  51  is wound. That is, in this embodiment, in both of the forward-path printing step and the backward-path printing step, when the winding shaft  61  rotates to the one side, the ink ribbon is wound in the same direction. Note that, in the backward-path printing step, when the first moving gear  62  slips out of the chipped tooth region K 2  on the front side and meshes with the winding rack  87 , the first moving gear  62  moves forward with respect to the carriage  33 . Consequently, the meshing of the first small gear  73  of the first moving gear  62  and the reverse gear  65  is released. That is, in the backward-path printing step, in a state in which the first large gear  72  is in mesh with the winding rack  87 , when the first small gear  73  separates from the reverse gear  65 , the first moving gear  62  idles. 
     In the backward-path printing step, when the recording paper P is hit by the head pins of the printing head  34  via the ink ribbon, printing in a second row is performed on the recording paper P. Thereafter, when the printing head  34  passes a printing region of the second row of the recording paper P, the backward-path printing step ends. 
     Carriage-return Step 
     As shown in  FIGS. 4 and 6 , in the carriage-return step, after the printing head  34  passes the printing region of the second row of the recording paper P, the carriage  33  comes into contact with the backward-path engaging section  111  of the line-feed plate  101  from the front. When the carriage  33  further moves backward in this state, the line-feed plate  101  moves backward together with the carriage  33 . Since the engaging projecting sections  113  are engaged in the engaging recessed sections  115 , the line-feed plate  101  moves to the left side toward the back. Consequently, the entire printing block  12  moves to the left side toward the back. 
     At a point in time when the engaging projecting sections  113  approach or come into contact with the rear end portions of the engaging recessed sections  115 , the carriage  33  reaches the backward-path end point (the forward-path start point). At this point in time, the driving in the reverse rotation direction of the printing motor  91  is stopped. Note that, after the carriage  33  passes the printing region of the second row in the recording paper P and before or after the carriage  33  comes into contact with the backward-path engaging section  111 , the second moving gear  63  enters the chipped tooth region K 1  on the rear side in the rack plate  67 . Therefore, before or after approach to the carriage-return step, the second moving gear  63  does not rotate and the winding of the rink ribbon is not performed. Note that timing when the second moving gear  63  enters the chipped tooth region K 1  can be changed as appropriate. 
     As shown in  FIG. 2 , when the carriage  33  returns to the forward-path start point, the platen motor  24  is actuated. Then, since a driving force of the platen motor  24  is transmitted to the platen main body  22  via the platen wheel train  25 , the platen main body  22  lowers. Consequently, the holding of the recording paper P by the frame base  15  and the platen main body  22  is released. Thereafter, when the recording paper P is removed from the slot  5 , the printing operation ends. 
     In this way, in this embodiment, the line-feed mechanism  100  includes the line-feed plate  101  supported to be movable in the front-back direction and the guide members  102  that guide the line-feed plate  101  in the left-right direction according to the movement in the front-back direction of the line-feed plate  101 . 
     With this configuration, the carriage  33  engages with the forward-path engaging section  110  of the line-feed plate  101  while moving on the forward path. Therefore, when moving toward the forward-path end point thereafter, the carriage  33  moves to the right side together with the line-feed plate  101 . On the other hand, the carriage  33  engages with the backward-path engaging section  111  of the line-feed plate  101  during the movement on the backward path. Therefore, when the carriage  33  moves toward the backward-path end point thereafter, the carriage  33  moves to the left side together with the line-feed plate  101 . That is, the carriage  33  moves in different positions in the left-right direction between the forward path and the backward path. In this case, for example, by performing printing by the printing head  34  in both of the forward path and the backward path, it is possible to perform printing in printing regions in different two columns in the left-right direction of the recording paper P. As a result, it is possible to improve an information amount that can be printed at a time and improve marketability. 
     In particular, in this embodiment, since the carriage  33  is moved in the left-right direction according to the movement in the front-back direction, it is possible to perform a line-feed operation of the carriage  33  with one printing motor  91 . Therefore, it is possible to realize simplification and a reduction in costs compared with, for example, when the line-feed operation of the carriage is performed by two printing motors, that is, a motor for performing the movement in the front-back direction and a motor for performing the movement in the left-right direction. 
     In this embodiment, since the engaging recessed sections  115  incline to the right side toward the front, it is possible to smoothly move the carriage  33  in the left-right direction according to the movement in the front-back direction of the carriage  33 . 
     Moreover, in this embodiment, the bearing sections  46  regulate the swing of the printing frame  31  around the guide pillar  32  while supporting the guide pillar  32  to be movable in the left-right direction. Therefore, it is possible to achieve a reduction in the number of components, a reduction in costs, and improvement of assemblability compared with when the support of the guide plate  32  and the regulation of the swing of the printing frame  31  are performed by separate components. 
     In this embodiment, the ink ribbon is wound according to the movement of the carriage  33 . Therefore, it is possible to suppress occurrence of a change in printing concentration, printing blur, and the like and keep printing quality satisfactorily. 
     In this embodiment, in the line-feed step and the carriage-return step of the carriage  33 , the chipped tooth regions K 1  and K 2  for releasing the meshing of the large gears  72  and  77  on a winding side (a side on which the winding shaft  61  is rotated) in the moving gears  62  and  63  and the winding rack  87  are formed on the rack plate  67 . 
     With this configuration, when the carriage  33  passes both the end portions in the front-back direction of the rack plate  67 , the moving gears  62  and  63  on the winding side do not rotate according to the movement of the carriage  33 . That is, the winding of the ink ribbon is not performed during the movement in the chipped tooth regions K 1  and K 2 . Therefore, it is possible to suppress load torque required for the winding in the line-feed step and the carriage-return step from acting on the printing motor  91  and smoothly perform the line-feed operation. Since it is possible to suppress the ink ribbon from being uselessly wound in the line-feed step and the carriage-return step, it is possible to effectively use the ink ribbon. 
     Since the printer  1  in this embodiment includes the printing unit  3 , it is possible to improve marketability. 
     Modification 
     A modification of the first embodiment is explained. 
     Note that, in the embodiment explained above, the engaging projecting sections  113  are formed in the line-feed plate  101  and the engaging recessed sections  115  are formed in the guide members  102 . However, conversely, the engaging recessed sections  115  may be formed in the line-feed plate  101  and the engaging projecting sections  113  may be formed in the guide members  102 . 
     In the embodiment explained above, the two engaging projecting sections  113  and the two engaging recessed sections  115  are provided. However, the number of the engaging projecting sections  113  and the engaging recessed sections  115  is not limited to two and may be one or three or more. If one engaging projecting section  113  and one engaging recessed section  115  are provided, rails and the like for guiding the movement in the left-right direction of the printing block  12  may be separately provided. 
     Note that, engaging timing and an engaging method for the carriage  33  and the engaging sections  110  and  111  can be designed and changed as appropriate. 
       FIG. 11  is a sectional view corresponding to line XII-XII in  FIG. 6 . Note that, in the following explanation, components same as the components in the first embodiment are denoted by the same reference numerals and signs and explanation of the components is omitted. 
     In a line-feed mechanism  150  shown in  FIG. 11 , a locking section  153  locked in the engaging projecting section  113  is formed in an engaging recessed section  152  of a guide member  151 . Specifically, the locking section  153  swells upward from the center in an extending direction of the engaging recessed section  152  in the bottom of the engaging recessed section  152 . A cross section along the extending direction of the locking section  153  is formed in a trapezoidal shape. Specifically, both end portions in the extending direction of the locking section  153  are formed as inclined surfaces extending upward toward the center of the locking section  153 . The center in the extending direction in the locking section  153  is formed as a flat surface. 
     With this configuration, in a state in which the engaging projecting sections  113  are located at both end portions in the extending direction in the engaging recessed section  152 , movement of the engaging projecting section  113  to the center in the extending direction is regulated by the locking section  153 . Consequently, for example, when a shock acts on the printer  1  from the outside, it is possible to suppress the line-feed plate  101  from suddenly moving. Note that, in the line-feed step and the carriage-return step explained above, the line-feed plate  101  moves together with the carriage  33  in a state in which the carriage  33  engages with the forward-path engaging section  110  or the backward-path engaging section  111 . Therefore, the engaging projecting sections  113  climb over the locking section  153 . Consequently, the line-feed step and the carriage-return step are performed according to action same as the action in the embodiment explained above. 
     Note that, in the explanation in the modification, the locking section  153  is formed in the bottom of the engaging recessed section  152 . However, not only this, but a locking section may be formed on the inner side surface of the engaging recessed section  152 . 
     In the modification explained above, one locking section  153  is formed in the center in the extending direction in the engaging recessed section  152 . However, not only this, but locking sections may be formed respectively at both the end portions in the extending direction in the engaging recessed section  152 . 
     Second Embodiment 
     A second embodiment of the present invention is explained. The second embodiment is different from the first embodiment in that cam members  201  are adopted in a line-feed mechanism  200 . Note that, in the following explanation, components same as the components in the first embodiment explained above are denoted by the same reference numerals and signs and explanation of the components is omitted. 
       FIG. 12  is a plan view of the line-feed mechanism  200  according to the second embodiment viewed from above. 
     As shown in  FIG. 12 , in the line-feed mechanism  200  in the second embodiment, line-feed racks  220  are formed on a line-feed plate  211 . The line-feed racks  220  project from both end portions in the front-back direction in the line-feed plate  211  toward the right side and extend in the front-back direction. 
       FIG. 13  is a side view of a printing block  210  according to the second embodiment viewed from the right side. 
     As shown in  FIGS. 12 and 13 , guide members  230  of the line-feed mechanism  200  include slope guides  231  and the cam members  201 . 
     As shown in  FIG. 12 , the slope guides  231  are respectively disposed in positions overlapping the line-feed plate  211  in up-down direction at both the end portions in the front-back direction in the frame base  15  (see  FIG. 3 ) explained above. The slope guides  231  include guide walls  232  surrounding the bottoms of the slope guides  231 . The guide walls  232  are formed in a rectangular frame shape in plan view from above. 
     The cam members  201  include base plates  235  and cam gears  236 . 
     The base plates  235  are formed in circular shapes centering on axes O 1  extending in the up-down direction. The base plates  235  are housed in the slope guides  231  (on the inner sides of the guide walls  232 ) to be rotatable around the axes O 1  and movable mainly in the front-back direction. Note that, in the guide walls  232 , the distance between inner side surfaces opposed to each other in the left-right direction is set equal to the outer diameter of the base plates  235 . Therefore, the outer circumferential surfaces of the base plates  235  are close to or in contact with the inner side surfaces opposed to each other in the left-right direction in the guide walls  232 . 
     The cam gears  236  are formed in cylindrical shapes extending upward along eccentric axes O 2  eccentric in the radial direction with respect to the axes O 1 . Support pins  240  projecting downward from the printing frame  31  are respectively inserted through the cam gears  236 . That is, the cam members  201  are supported by the printing frame  31  to be rotatable around the eccentric axes O 2 . 
     On the outer circumferential surfaces of the cam gears  236 , tooth sections  236   a  projecting to the outer side in the radial direction in the eccentric axes O 2  are formed over the entire circumferences. The tooth sections  236   a  of the cam gears  236  are in mesh with the line-feed racks  220  corresponding thereto. 
       FIG. 14  is an explanatory diagram for explaining an operation method for the printer  1  and is a plan view equivalent to  FIG. 12 . 
     With this configuration, in the line-feed step, as shown in  FIG. 14 , in a state in which the carriage  33  is in contact with the forward-path engaging section  110  of the line-feed plate  211  from the back, when the carriage  33  moves further forward, the line-feed plate  211  moves forward together with the carriage  33 . Then, since a forward driving force of the line-feed plate  211  is transmitted to the cam members  201  via the cam gears  236 , the cam gears  236  (and the support pins  240 ) are about to rotate around the axes O 1 . At this point, the cam members  201  (the base plates  235 ) are housed in the slope guides  231  to be movable in the front-back direction. Therefore, the cam members  201  move backward in the slope guides  231  (in the guide walls  232 ) while rotating to one side around the axes O 1 . Consequently, the cam gears  236  (and the support pins  240 ) linearly move to the right side. As a result, the entire printing block  12  moves to the right side toward the front. 
     On the other hand, in the carriage-return step, as shown in  FIG. 12 , in a state in which the carriage  33  is in contact with the backward-path engaging section  111  of the line-feed plate  211  from the front, when the carriage  33  further moves backward, the line-feed plate  211  moves backward together with the carriage  33 . Then, since a backward driving force of the line-feed plate  211  is transmitted to the cam members  201  via the cam gears  236 , the cam members  201  move forward in the slope guides  231  (in the guide walls  232 ) while rotating to the other side around the axes O 1 . Consequently, the cam gears  236  (and the support pins  240 ) linearly move to the left side. As a result, the entire printing block  12  moves to the left toward the back. 
     In this way, in this embodiment, the cam members  201  rotate according to the movement in the front-back direction of the carriage  33 . Therefore, it is possible to smoothly move the printing block  12  in the left-right direction according to the rotation of the cam members  201 . 
     In this embodiment, the cam members  201  and the line-feed plate  211  are engaged by the cam gears  236  and the line-feed racks  220 . Therefore, it is possible to achieve simplification. Compared with when the cam members  201  and the line-feed plate  211  are engaged by pins, through-holes, and the like, it is possible to reduce a load acting on engaging portions. 
     In the above explanation in the second embodiment, the cam members  201  and the line-feed plate  211  are engaged by the cam gears  236  and the line-feed racks  220 . However, the present invention is not limited to this. For example, it is also possible that the cam members  201  and the line-feed plate  211  are engaged by a link mechanism and the cam members  201  are moved in the front-back direction in the slope guide  231 . 
     Note that, in the above explanation in the second embodiment, the entire cam members  201  move in the front-back direction in the slope guides  231 . However, the present invention is not limited to this. The cam members  201  may only rotate around the axes O 1  in the slope guides  231  (movement in the front-back direction is regulated). 
     Guide grooves or the like for supporting the support pins  240  to be movable in the left-right direction may be provided in the slope guide  231 . 
     Further, the line-feed plate  211  and the cam members  201  may be engaged by pins, through-holes, and the like. 
     Note that the technical scope of the present invention is not limited to the embodiments explained above. It is possible to add various changes to the technical scope without departing from the spirit of the present invention. 
     For example, in the explanation in the embodiments, the printer  1  of the present invention is applied to the printer  1  of the dot impact type. However, the present invention is not limited to this. For example, the printer  1  may be applied to, for example, an inkjet printer and a thermal printer. The use of the printer  1  is not limited to the timestamp. 
     In the explanation in the embodiments, the printing is performed in both of the forward path and the backward path. However, the printing may be performed in at least one of the forward path and the backward path (e.g., only the first row may be printed or only the second row may be printed). 
     An engaging method for the line-feed plate and the guide members can be changed as appropriate. For example, the line-feed plate and the guide members may be engaged by a worm gear mechanism or a link mechanism. 
     The chipped tooth regions K 1  and K 2  of the rack plate  67  may be absent. 
     Besides, the components in the embodiments explained above can be replaced with well-known components as appropriate without departing from the spirit of the present invention. The embodiments may be combined as appropriate.