Printer

A printer includes a transporting block, a printing block, a positioning block, and an intermediate picking-up device. The positioning block is disposed between the transporting block and the printing block, and positions printing sheets transported by the transporting block at a predetermined location one at a time, so that they are positioned one at a time at a printing location of the printing block where printing is performed on the printing sheets. The intermediate picking-up means picks up the printing sheets positioned at the predetermined location in the positioning block one at a time in order to transport the printing sheets to the printing block.

This application claims priority to Japanese Patent Application Number JP2001-355670 filed Nov. 21, 2001, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a printer. More specifically, the present invention relates to the technological field of a printer comprising a sheet-holding block which can hold a plurality of printing sheets in a stack, a picking-up block for picking up the printing sheets held by the sheet-holding block one sheet at a time, a transporting block for transporting the printing sheets that have been picked up by the picking-up block, a printing block for performing printing on the printing sheets that have been transported by the transporting block, and a sheet-discharging block for discharging the printing sheets that have been subjected to printing at the printing block.

2. Description of the Related Art

There are printers which perform a printing operation on a printing sheet, such as printing paper or a printing film, by, for example, heat transfer or laser. Such a printer ordinarily comprises a sheet-holding block which can hold a plurality of printing sheets in a stack, a picking-up block for picking up the printing sheets held by the sheet-holding block one sheet at a time, a transporting block for transporting the printing sheets that have been picked up by the picking-up block, a printing block for performing printing on the printing sheets that have been transported by the transporting block, and a sheet-discharging block for discharging the printing sheets that have been subjected to printing by the printing block. In the printer, each of the blocks is disposed inside a housing.

There is a printer of what is called a horizontally-setting type which can be set horizontally so that a printing sheet is transported from the sheet-holding block to the sheet-discharging block with the surface of the printing sheet being faced vertically, and a printer of a horizontally-setting-and-vertically-setting type which can be set horizontally and which can be vertically so that a printing sheet is transported from the sheet-holding block to the sheet-discharging block with the surface of the printing sheet being faced horizontally.

Such a horizontally-setting-and-vertically-setting type can be set in accordance with the space of an installation place, so that it can be installed more freely at the installation place, thereby making it easier to use.

When the printer can be set vertically, installation area can be reduced. In particular, when computed tomography (CT) is carried out at a hospital, a large setting area is not required, so that the printer can be set as an accessory of a shooting device or as an accessory of a computer in a medical examination room. Therefore, this type of printer makes it possible to carry out medical work more quickly and simply.

However, in the related printer, printing sheets are successively transported by a plurality of transport rollers, etc., in the process of transporting them to the printing block by the transporting block by picking them up by the picking-up block from the sheet-holding block, so that the position of the printing sheets transported to the printing block may be shifted with respect to the position of the printing sheets picked up from the sheet-holding block.

When such a shift in position occurs, a missing image results because an image is no longer printed onto the entire sheet at the printing block, a shift in the orientation of an image with respect to the printing sheet occurs, etc.

In the sheet-holding block, a plurality of printing sheets are held in a stack. When the printing sheets are held by the sheet-holding block in a warped state, problems such as the printing sheets being improperly picked up by the picking-up block or the printing sheets being damaged when they are picked up by the picking-up block may occur.

The problems of shifts in the position of the printing sheets and warping of the printing sheets tend to occur particularly when the printer is vertically set so that the printing sheets are transported with their surfaces being faced horizontally.

In the horizontally-setting-and-vertically-setting type which performs a printing operation by scanning a printing sheet by a printing head pushed against a platen roller with the printing sheet being interposed therebetween, the pressures upon the printing sheet when the printer is set horizontally and when the printer is set vertically are different due to the effects of the weight of the printing head. Therefore, when printing is performed with the pressures being different, a printing failure may occur in either one of the horizontally set and vertically set states.

SUMMARY OF THE INVENTION

Accordingly, a printer of the present invention makes it possible to overcome the above-described problems in order to make each block operate properly and to prevent printing failure.

To this end, according to one aspect of the present invention, there is provided a printer wherein a positioning block is disposed between a transporting block and a printing block and positions printing sheets transported by the transporting block at a predetermined location of the positioning block one at a time so that they are positioned one at a time at a printing location of the printing block where each printing sheet is subjected to printing; and wherein intermediate picking-up means for picking up the printing sheets positioned at the predetermined location in the positioning block one at a time in order to transport the printing sheets to the printing block is provided.

Therefore, in the printer of the present invention, the printing sheets that have been transported by the transporting block are positioned just before they are transported into the printing block.

To this end, the sheet-holding block may comprise a sheet-receiving plate for receiving one of the surfaces of each printing sheet held in the sheet-holding block, and holding means, disposed opposing the sheet-receiving plate and moving away from the sheet-receiving plate depending upon the thickness of the printing sheets held in the sheet-holding block, for holding the other surface of each printing sheet, the other surface being opposite to the one surface.

Therefore, in the printer of the present invention, the printing sheets are held in the sheet-holding block with the printing sheets being held between the sheet-receiving plate and the holding means.

To this end, according to another aspect of the present invention, there is provided a printer further comprising state recognizing means for recognizing the vertically set state or the horizontally set state, wherein, when printing sheets are transported from a sheet-holding block to a sheet-discharging block, the pressure exerted upon the printing sheets by each component part pushed against the printing sheets is made substantially constant in accordance with the results of the recognizing operation of the state recognizing means.

Therefore, in the printer of the present invention, the printing sheets are transported with a substantially constant pressure being exerted upon the printing sheets in both the vertically set state and the horizontally set state.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereunder, a description of an embodiment of the present invention will be given with reference to the attached drawings.

A printer of the embodiment of the present invention described below is used at, for example, a hospital and is a thermal head printer for printing image data obtained by computed tomography (CT) onto a printing film (printing sheet) by heat transfer using a thermal head.

A printer1is a horizontally-setting-and-vertically-setting type which can be set horizontally so that a printing sheet is transported with its surface being faced vertically and which can be set vertically so that a printing sheet is transported with its surface being faced horizontally. In the description below, the printer1is set vertically.

Since the printer1can be set both horizontally and vertically as mentioned above, it can be set in accordance with the space of an installation place, so that it can be set more freely at the installation place.

Since a large installation space is not required when the printer1is set vertically, the printer1can be set, for example, below a personal computer2000set on a personal computer table1000. (SeeFIG. 1.)

The printer1has a structure in which required blocks, a sheet-holding block100, a picking-up block200, a transporting block300, a positioning block400, a printing block500, an intermediate transporting block600, a density measuring block700, a sheet-discharging block800, and a sheet taking-out block900, are disposed inside a housing2. (SeeFIG. 2.)

In the printer1, printing sheets3000are picked up from the sheet-holding block100by the picking-up block200, and are transported to the sheet taking-out block900through the transporting block300, the positioning block400, the printing block500, the intermediate transporting block600, the density measuring block700, and the sheet-discharging block800. (SeeFIG. 2.)

An opening2afor inserting and taking out the sheet-holding block100is provided in the front surface of the housing2. (SeeFIGS. 1to3.)

The sheet-holding block100is disposed at the right end portion inside the housing2(see FIG.2), and has a flat, box-shaped sheet cassette3which is long in the forward-and-backward direction. (SeeFIGS. 3to6.)

The sheet cassette3is removable from the housing2, and has a case member4having an open left side and a cover member5which covers the opening of the case member4. (SeeFIGS. 3to5.) A sheet picking-up opening3ais provided in the back end portion of the sheet cassette3.

The cover member5has the shape of a flat plate, and is provided as a sheet-receiving plate for receiving one of the surfaces of each printing sheet3000inside the sheet cassette3. Rollers6and6, which are spaced apart in the forward-and-backward direction and which are long in the vertical direction, are rotatably supported at the inside surface of the cover member5. (SeeFIGS. 3 and 5.)

A holding plate7, serving as holding means for holding the other surface of each printing sheet3000, is supported inside the sheet cassette3so as to be movable towards the left and right. (SeeFIGS. 3,5, and6.) The holding plate7is formed into the shape of a flat plate, is disposed opposing the cover member5, and is formed with approximately the same size as or one size larger than the printing sheets3000.

An adjusting mechanism8is disposed between a right surface4aof the case member4and the holding plate7. (SeeFIG. 6.) The adjusting mechanism8comprises a drive motor9, a worm gear10, a main gear11, driven gears12and12, rack members13and13, and pairs of adjusting gears14, and is a mechanism for moving the holding plate7away from the cover member5depending upon the thickness of the printing sheets3000held in a stack inside the sheet cassette3.

The drive motor9is mounted to the front end portion of the case member4, with the worm gear10being secured to the shaft of the drive motor9.

The main gear11is a two-speed gear comprising a small-diameter portion11aand a large-diameter portion11b, with the large-diameter portion11bengaging the worm gear10.

The rack members13and13are supported on a top surface4band a bottom surface4cof the case member4, respectively, so as to be movable in the forward-and-backward directions. Main rack portions13aand13a, which are long in the forward-and-backward directions, and protruding plate portions13band13b, which protrude towards each other from the forward-and-backward-direction central portions of the rack members13, are integrally formed. Racks13cand13care formed at the front edges of the respective protruding plate portions13band13b, with the small-diameter portions12band12bof the driven gears12and12engaging the respective racks13cand13c.

In each adjusting gear14, a disc portion14a, a geared portion14b, provided on one surface of the disc portion14a, and a cam protruding portion14c, protruding from the other surface of the disc portion14a, are integrally formed, with the cam protruding portions14cbeing formed on the outer peripheral portions of the respective disc portions14a. With the pairs of adjusting gears14being supported, one pair on the top surface4band the other pair on the bottom surface4cof the case member4, and with the adjusting gears14of each pair being separated from each other in the front and back, the pairs of geared portions14bengage the main rack portions13aof their respective rack members13.

The cam protruding portions14cof each pair of adjusting gears14slidably engage the top and bottom edges of the holding plate7, disposed inside the case member4, from the right side, respectively.

In the adjusting mechanism8, when the drive motor9rotates, the driving force thereof is transmitted to the worm gear10, the main gear11, the driven gears12and12, the rack members13, and the adjusting gears14in that order, causing the adjusting gears14rotate, so that the cam protruding portions14cchange their positions. Therefore, the rotation of the adjusting gears14causes the holding plate7engaging the cam protruding portions14cto move horizontally, that is, in the direction in which the holding plate7moves away from the cover member4.

The picking-up block200is disposed behind the sheet-holding block100(see FIG.2), and has a picking-up mechanism15for picking up the printing sheets3000inside the sheet cassette3one at a time (seeFIGS. 3to5).

The picking-up mechanism15has a pick-up roller16. The pick-up roller16is linked to one of a pair of separation rollers17and17, supported behind the pick-up roller16, by a timing belt18.

A detection member19is provided so as to link the rotary shaft of the pick-up roller16and the rotary shaft of the separation roller17, which are linked to each other by the timing belt18. A detection portion19aof the detection member19protrudes forwardly of the pick-up roller16. (SeeFIG. 5.) The detection member19is biased towards the right surface4aof the case member4by a biasing spring20, and the pick-up roller16is pushed against the printing sheets3000held inside the sheet cassette3.

The detection portion19aof the detection member19is detected by a roller position sensor21in order to detect the position of the pick-up roller16based on the detection result.

A pick-up motor22is disposed behind the separation rollers17, and a gear group23is supported between the separation rollers17and the pick-up motor22. (SeeFIG. 3.)

In the picking-up mechanism15, when the pick-up motor22is rotated, the driving force is transmitted to the gear group23, the separation rollers17, and the pick-up roller16in that order, so that the pick-up roller16rotates, causing the printing sheets3000to be picked up from the sheet cassette3. Then, the picked up sheets pass between the separation rollers17, and are sent towards the transporting block300.

The transporting block300is disposed at the back end of the inside of the housing2(see FIG.2), and has a rotationally driving portion24, a first rotary member25, and a second rotary member26. (SeeFIGS. 3 and 4.)

The rotational drive portion24has a transportation motor24aand a gear group24bwhich is rotated by the transportation motor24a. (SeeFIG. 4.)

The first rotary member25comprises a vertically extending shaft25a, transportation rollers25b, spaced apart in the axial direction of the shaft25a, and a drive gear25c, provided at one end of the shaft25a. The drive gear25cengages one of the gears of the gear group24b. When the gear group24bis rotated by the rotation of the transportation motor24a, the drive gear25cis rotated. The rotation of the drive gear25ccauses the shaft25aand the transportation rollers25bto rotate integrally.

Presser members27are disposed at the outer peripheral surfaces of the respective transportation rollers25bso as to oppose them, and are pushed against the respective transportation rollers25bby springs.

The second rotary member26comprises a vertically extending shaft26a, transportation rollers26b, spaced apart in the axial direction of the shaft26a, and a drive gear26c, provided at one end of the shaft26a. The drive gear26cengages one of the gears of the gear group24b. When the gear group24bis rotated by the rotation of the transportation motor24a, the drive gear26cis rotated. The rotation of the drive gear26ccauses the shaft26aand the transportation rollers26bto rotate integrally. Therefore, the first rotary member25and the second rotary member26rotate in synchronism.

Presser members28and presser members29are spaced apart and disposed at the outer peripheral surfaces of the respective rollers26bin the peripheral direction of the transportation rollers26bso as to oppose them. The presser members28and the presser members29are pushed against the transportation rollers26bby springs.

The positioning block400is disposed at the left side of the inside of the housing2and in front of the transporting block300(see FIG.2), and has a stationary base plate30and a movable base plate31(see FIGS.7and8).

In the stationary base plate30, a planar portion32having its principle surface faced horizontally, a bottom edge portion33protruding towards the right from the bottom edge of the planar portion32, a top edge portion34protruding towards the left from the top edge of the planar portion32, and a mechanism mounting portion35protruding upwards from the left edge of the top edge portion34are integrally formed.

A roller disposition hole32ais formed in a location of the planar portion32towards the forward end, and roller mounting portions32band32bprotrude leftwards from the upper edge and the lower edge defining the roller disposition hole32a. A presser roller36is supported by the roller mounting portions32band32b, with a portion of the presser roller36protruding rightwards from the roller disposition hole32a. (SeeFIG. 8.) A spring catch portion32cis provided behind the roller disposition hole32a, on the planar portion32. A sheet detecting sensor37is mounted to a location of the planar portion32towards the back end.

A spring insertion hole34ais formed in substantially the forward-and-backward-direction central portion of the top edge portion34.

A moving mechanism38is provided on the mechanism mounting portion35, and comprises a positioning motor39, a worm gear40, and a cam gear41. The positioning motor39is mounted to substantially the forward-and-backward direction central portion of the mechanism mounting portion35, with the worm gear40being secured to the shaft of the motor39. The cam gear41is supported by the mechanism mounting portion35behind the positioning motor39, and comprises a geared portion41aand a cam pin41bprovided at the outer periphery of the geared portion41aso as to protrude rightwards (see FIG.9). The geared portion41aof the cam gear41engages the worm gear40.

A position sensor42is mounted near the cam gear41of the mechanism mounting portion35. The position sensor42detects the position of the cam pin41awhen the cam gear41has been rotated.

Linking members43and43are rotatably supported at the front and back ends of the mechanism mounting portion35, respectively, with one end of each linking member43serving as a fulcrum.

The stationary base plate30is secured to vertically long shaft members44provided inside the housing2.

The movable base plate31has a planar portion45having its principle surface faced horizontally, a positioning edge portion46protruding leftwards from the bottom edge of the planar portion45, and a mounting edge portion47protruding leftwards from the top edge of the planar portion45. The positioning edge portion46acts as a positioning portion for positioning the printing sheets at a predetermined position.

A roller insertion hole45ais formed in a location of the planar portion45towards the front end.

An action portion48is provided at a location of the presser edge portion47towards the back end. (SeeFIGS. 7 and 9.) The action portion48has a base end portion48aprotruding upward from the presser edge portion47and an engaging portion48bprotruding leftwards from the top edge of the base end portion48a.

Upwardly protruding supporting portions49and49are provided on the front and back edges of the presser edge portion47, respectively. The linking members43and43are rotatably supported at the respective supporting portions49and49with the other end of each linking member43serving as a fulcrum.

The movable base plate31is supported by the shaft member44so as to be movable axially, that is, vertically.

As described above, the linking members43and43are rotatably supported at the mechanism mounting portion35of the stationary base plate30and the supporting portions49of the movable base plate31. The planar portion32of the stationary base plate30and the planar portion45of the movable base plate31are positioned so as to oppose each with a slight gap therebetween (see FIG.8). The space between the planar portion32and the planar portion45corresponds to an insertion space50for inserting the printing sheets3000that have been transported by the transporting block300.

The bottom edge portion33of the stationary base plate30is positioned above the positioning edge portion46of the movable base plate31, and the top edge portion34of the stationary base plate30is positioned below the presser edge portion47of the movable base plate31(see FIG.8). The cam pin41bof the cam gear41slidably engages the bottom surface of the engaging portion48bof the action portion48of the movable base plate31(see FIG.9).

One end of an extension spring51is supported at the presser edge portion47of the movable base plate31. The extension spring51is inserted in the spring insertion hole34ain the top edge portion34of the stationary base plate30. The other end of the extension spring51is supported at the spring catch portion32cof the stationary base plate30. Therefore, the movable base plate31is urged downward with respect to the stationary base plate30.

In the moving mechanism38, when the positioning motor39is rotated, the driving force thereof is transmitted to the worm gear40and the cam gear41in that order, causing the cam gear41to rotate, so that the position of the cam pin41bchanges. When the position of the cam pin41bchanges, the movable base plate31including the action portion48engaging the cam pin41bis guided by the shaft member44and moves vertically with respect to the stationary base plate30.

A rotational drive portion52is disposed at the right side of the planar portion32of the stationary base plate30, and comprises a roller rotation motor52aand a gear group52bwhich is rotated by the roller rotation motor52a(see FIG.4). One end of a rotary lever53is supported at the last gear of the gear group52b, and a vertically long roller shaft54is supported at the other end of the rotary lever53. An intermediate pick-up roller55is provided at the axial-direction central portion of the roller shaft54. (SeeFIGS. 3,4, and8.) The intermediate pick-up roller55is provided as intermediate pick-up means for picking up a printing sheet3000that has been inserted into the insertion space50and sending it towards the printing block500, and moves substantially horizontally when the rotary lever53is rotated by the rotational drive portion52.

When the intermediate pick-up roller55is rotated leftwards, it is inserted into the roller insertion hole45aof the movable base plate31, and is pushed against the presser roller36with the printing sheet3000that has been inserted into the insertion space50being disposed therebetween in order to send the printing sheet3000towards the printing block500.

The printing block500is disposed in front of the positioning block400(see FIG.2), and comprises a head mechanism56and a head drive mechanism57(see FIGS.3and4).

The head mechanism56has a printing head59provided at a head supporting member58. A thermal head for performing printing on the printing sheets3000by heat transfer is used as the printing head59.

The head drive mechanism57is positioned at the left side of the head mechanism56, and comprises a head pressure adjusting member60, an action member61, and a head pressure adjusting cam62. (SeeFIGS. 10to12.)

The head pressure adjusting member60is long in substantially the forward-and-backward directions, and is rotatably supported with a rotary shaft63positioned at the back end of the head pressure adjusting member60serving as a fulcrum. A rightwardly protruding pressure roller60ais supported at the front end of the head pressure adjusting member60.

The action member61is long in substantially the forward-and-backward direction, and is rotatably supported with the rotary shaft63at the back end of the action member61serving as a fulcrum. The action member61is longer than the head pressure adjusting member60, with its front end being positioned forwardly of the head pressure adjusting member60. A leftwardly protruding action roller61ais supported at the front end of the action member61.

A helical compression spring64is provided in a compressed state between the head pressure adjusting member60and the action member61. Therefore, the head pressure adjusting member60and the action member61are biased in directions in which they move away from each other by the helical compression spring64, that is, the head pressure adjusting member60is urged towards the head mechanism56, and the action member61is urged away from the head mechanism56.

The head pressure adjusting cam62is secured to a vertically long rotary shaft65rotatably supported inside the housing2. (SeeFIG. 4.) The outer peripheral surface of the head pressure adjusting cam62is formed into a cam surface66. With increasing distance from the rotational center of the rotary shaft65, a standby cam portion66a, a cam portion66bfor horizontal setting, and a cam portion65cfor vertical setting are formed on the cam surface66(seeFIGS. 10to12). The cam surface66of the head pressure adjusting cam62is in contact with the action roller61asupported at the action member61.

A cam position detecting plate67is secured at the left side of the head pressure adjusting cam62. The cam position detecting plate67has a substantially disc shape, and has three detecting slits67a,67b, and67cspaced at equal intervals in the peripheral direction.

A platen roller68is supported and opposes the printing head59of the head mechanism56. The head mechanism56can move away from the platen roller68.

When the head pressure adjusting cam62is rotated as the rotary shaft65rotates by a rotary mechanism (not shown), the position of the cam surface66with respect to the action roller61achanges, so that the action member61rotates with the rotary shaft63as the fulcrum. Therefore, when the action member61rotates, the rotational force thereof is exerted upon the head pressure adjusting member60through the helical compression spring64, causing the head pressure adjusting member60to rotate in the direction in which the pressure roller60amoves away from the head supporting member58with the rotary shaft63as the fulcrum. In accordance with the pushing force exerted upon the head supporting member58by the pressure roller60a, the pressure upon the platen roller68by the printing head59changes.

The rotary mechanism is operated based on the results provided by state recognizing means (not shown). When the state recognizing means recognizes that the printing block500is in a standby mode in which a printing operation on the printing sheets3000is not performed, the head pressure adjusting cam62is rotated so that the standby cam portion66acomes into contact with the action roller61a(see FIG.10). When the state recognizing means recognizes that the printer1is in a horizontally set mode when a printing operation is to be performed on the printing sheets3000, the head pressure adjusting cam62is rotated so that the horizontal setting cam portion66bcomes into contact with the action roller61a(see FIG.11). When the state recognizing means recognizes that the printer1is in a vertically set mode when a printing operation is to be performed on the printing sheets3000, the head pressure adjusting cam62is rotated so that the vertical setting cam portion66ccomes into contact with the action roller61a(see FIG.12).

The recognizing operation by the state recognizing means may be automatically performed using a gravity sensor, may be manually performed by a user by inputting a state, etc.

As described above, when the standby cam portion66ais in contact with the action roller61adue to the rotation of the head pressure adjusting cam62, the detecting slit67ais covered by the head pressure adjusting cam62, so that a detection is made that the standby cam portion66ais in contact with the action roller61a(see FIG.10). When the standby cam portion66ais in contact with the action roller61a, the pressure roller60aat the head pressure adjusting member60moves away from the head supporting member58, so that the printing head59moves away from the platen roller68.

When the horizontal setting cam portion66bis in contact with the action roller61adue to the rotation of the head pressure adjusting cam62, the detecting slit67bis covered by the head pressure adjusting cam62, so that a detection is made that the horizontal setting cam portion66bis in contact with the action roller61a(see FIG.11). When the horizontal setting cam portion66bis in contact with the action roller61a, the head supporting member58is pushed by the pressure roller60aat the head pressure adjusting member60, so that the printing head59press-contacts the platen roller68.

When the vertically setting cam portion66cis in contact with the action roller61adue to the rotation of the head pressure adjusting cam62, the detecting slit67cis covered by the head pressure adjusting cam62, so that a detection is made that the vertical setting cam portion66cis in contact with the action roller61a(see FIG.12). When the vertical setting cam portion66cis in contact with the action roller61a, the head supporting member58is pushed by the pressure roller60aat the head pressure adjusting member60, so that the printing head59press contacts the platen roller68. At this time, the printing head59is pushed more strongly against the platen roller68than when the horizontal setting cam portion66bis in contact with the action roller61a. It is pushed with, for example, 1.5 times the pressure.

Accordingly, comparing the vertical set mode with the horizontal set mode, the pressure exerted upon the platen roller68from the printing head59by the head drive mechanism57is larger. Considering the pressure produced by weight exerted upon the platen roller68by the head mechanism56when the printer1is in the horizontally set mode, a substantially constant pressure is exerted upon the platen roller68from the head mechanism56in both modes.

Therefore, regardless of whether the printer1is in a horizontally or vertically set mode, the printer1performs a proper printing operation on the printing sheets3000by a constant head pressure.

In the standby mode in which printing is not performed on the printing sheets3000by the printing head59, since a predetermined gap is provided between the printing head59and the platen roller68, undesired contact between the printing head59and the platen roller68can be prevented, so that it is possible to prevent, for example, wearing thereof, and to properly transport the printing sheets3000to the printing block500.

When a recognizing operation is performed by the state recognizing means, as mentioned above, the pressure exerted upon the platen roller68from the printing head59is adjusted. At this time, when the printing sheets3000are transported to the sheet taking-out block900from the sheet-holding block100, the pressure exerted upon the printing sheets3000by each portion pushed against the printing sheets3000, that is, the pick-up roller16, the separation rollers17and17, the transportation rollers25band26b, the intermediate pick-up roller55, pinch rollers69and69, a first turn-around roller71, a second turn-around roller75, a discharging roller77, etc., is adjusted based on the results of the recognizing operation of the state recognizing means, so that a substantially constant pressure is exerted upon the printing sheets3000in both the horizontally set mode and the vertically set mode.

Therefore, a constant pressure is exerted upon the printing sheets3000when they are transported regardless of whether the printer1is in a horizontally or vertically set mode, so that it is possible to properly transport the printing sheets3000.

The pinch rollers69and69and capstans70and70, which the pinch rollers69and69press contact, are supported at the front and back of the platen roller68in the printing block500(see FIG.3).

The first turn-around roller71is supported in front of the pinch rollers69and69, and an endless transportation belt72press-contacts the first turn-around roller71. (SeeFIG. 3.) Rotation of tension rollers73, which brings the transportation belt72under a constant tension, causes the transportation belt72to move as the first turn-around roller72rotates.

The intermediate transporting block600is disposed behind the printing block500(see FIG.2), and has a presser roller74(see FIG.3). The presser roller74is supported at a location opposite to the presser roller36in the positioning block400with the intermediate pick-up roller55being disposed between them. When the intermediate pick-up roller55is rotated towards the right, the intermediate pick-up roller55is pushed against the presser roller74, so that the printing sheets3000can be transported towards the density measuring block700.

The density measuring block700is disposed behind the intermediate transporting block600(see FIG.2), and has a density measuring device (not shown) for measuring the printing density on the printing sheets3000transported to the density measuring block700.

The second turn-around roller75is supported in the density measuring block700. Press-contact rollers76and76, which press-contact the second turn-around roller75, are supported at opposing locations on both sides of the rotational center of the second turn-around roller75(see FIG.3). The second turn-around roller75is rotated by transmission of the driving force of the roller rotation motor52aof the rotational drive portion52.

The sheet-discharging block800is disposed in front of the density measuring block700(see FIG.2), and includes the discharging roller77for discharging the printing sheets3000and a transportation roller78which press-contacts the discharging roller77(see FIG.3).

The sheet taking-out block900is disposed at the left side of the sheet-holding block100(see FIG.2), and includes a sheet taking-out space79for taking out the printing sheets3000that have been discharged by the discharging roller77(see FIG.3).

Fans80are spaced apart vertically and disposed towards the left at the front end of the inside of the housing2.

Hereunder, the transportation of the printing sheets3000and the operation of each block in the printer1will be described. Hereunder, unless otherwise specified, the operation of the printer1in the vertically set mode will be described.

The printing sheets3000being stacked with their surfaces faced horizontally are held inside the sheet cassette3of the sheet-holding block100. When the sheet cassette3is inserted into the opening2aand mounted to the inside of the housing2, the printing sheets3000can be picked up by the picking-up mechanism15.

The sheet-holding block100has detecting means for detecting the total thickness or the total number of printing sheets3000held in the sheet-holding block100. The adjusting mechanism8operates based on the results of detection of the detecting means. When the drive motor9of the adjusting mechanism8is rotated, as mentioned above, the holding plate7moves in a direction opposite to the printing sheets3000held in the sheet cassette3.

When the printing sheets3000are not picked up from the sheet cassette3, the holding plate7moves to the side of the printing sheets3000held in the sheet cassette3. By the holding plate7, the printing sheets3000held in the sheet cassette3are pushed towards the cover member5of the sheet cassette3, and are brought into contact with the rollers6and6(see FIG.13). Therefore, the printing sheets3000held inside the sheet cassette3are not warped, thereby making it possible to, for example, prevent the printing sheets3000from being improperly picked up by the picking-up mechanism15of the picking-up block200and prevent damage to the printing sheets3000when they are picked up.

The printing sheets3000are held by the holding plate7when the printer1is in the horizontally set mode or the vertically set mode. In the vertically set mode, the printing sheets3000tend to be warped, so that the holding plate7functions particularly effectively in the vertically set mode.

On the other hand, when the printing sheets3000are picked up from the sheet cassette3, the adjusting gears14are rotated in order to temporarily move the holding plate7in the direction opposite to the printing sheets3000, so that the printing sheets3000held in the sheet cassette3are no longer pushed towards the cover member5of the sheet cassette3(see FIG.14). Therefore, the printing sheets3000held inside the sheet cassette3are reliably picked up one at a time by the picking-up mechanism15.

Although, in the printer1, the holding plate7for holding the entire surfaces of the printing sheets3000is provided as the holding means, other holding means may be used. For example, two vertically long holding shafts spaced apart in the forward-and-backward direction, that is, in the direction in which the printing sheets3000are transported, may be disposed inside the sheet cassette3in order to hold portions of the surfaces of the printing sheets3000. It is desirable that the lengths of the holding shafts be substantially the same as or greater than the vertical widths of the surfaces of the printing sheets3000.

Accordingly, it is possible to effectively prevent warping of the printing sheets3000even by holding them with at least two holding means in the direction in which they are transported.

The printing sheets3000are picked up one at a time from the sheet cassette3by the pick-up roller16of the picking-up block200, and are transported towards the transporting block300by the separation rollers17and17. The printing sheets3000which are picked up by the picking-up mechanism15each come into contact with the rollers6supported at the cover member5of the sheet cassette3. Therefore, since the rollers6and6are rotated when the printing sheets3000are picked up by the picking-up mechanism15, the printing sheets3000can be reliably and easily picked up.

The detection portion19aof the detection member19is detected by the roller position sensor21when the printing sheets3000are picked up, so that the position of the pick-up roller16is detected based on the detection results.

The printing sheets3000which have been picked up by the picking-up block200and transported to the transporting block300are transported towards the positioning block400. In the transporting block300, the printing sheets3000are transported by the transportation rollers25band the transportation rollers26bin that order.

The printing sheets3000transported to the positioning block400are inserted one at a time into the insertion space50between the stationary base plate30and the movable base plate31. When the printing sheets3000are inserted into the insertion space50, the insertion of each printing sheet3000is detected by the sheet detecting sensor37.

The position of each printing sheet3000held in the sheet cassette3is shifted upward by a distance H from a predetermined location where each printing sheet3000is positioned in the positioning block400one at a time (see FIG.15). The printing sheets3000that have been picked up from the sheet cassette3are transported to the positioning block400through the picking-up block200and the transporting block300. The printing sheets3000may be transported to the positioning block400while being shifted downward by, for example, H′ due to gravity during the transportation of the printing sheets3000. However, H is larger than the expected shift amount H′. Therefore, when the printing sheets3000move downward due to their own weights when they are inserted into the insertion space50one at a time, the bottom ends of the printing sheets3000inserted in the insertion space50one at a time are brought into contact with the positioning edge portion46of the movable base plate31, and are positioned one at a time at the predetermined location (see FIG.15).

In the printer1, since the transported printing sheets3000are positioned one at a time at the predetermined location in the positioning block400, the positioning sheets3000are each transported to a proper printing location of the printing block500from the positioning block400, so that proper printing can be carried out on the printing sheets3000in the printing block500.

Since the printing sheets3000can be positioned in the positioning block400by only shifting them upward from the predetermined location in the positioning block400, the printing sheets3000can be easily and reliably positioned.

As mentioned above, the position of each printing sheet3000held in the sheet cassette3is shifted upward by the distance H from the predetermined positioning location in the positioning block400(see FIG.15). Therefore, in the case where the printer1is in the horizontally set mode, when a printing sheet3000has been inserted into the insertion space50, the moving mechanism38operates to position the printing sheet3000at the predetermined location.

In the case where the printer1is in the horizontally set mode, when a printing sheet3000is inserted into the insertion space50, the cam gear41is rotated by the rotation of the positioning motor39, causing the movable base plate31to move with respect to the stationary base plate30, so that the printing sheet3000is positioned at the predetermined location. When the cam gear41is rotated, its position is detected by the position sensor42.

Accordingly, even if the printer1is in the horizontally set mode, the printing sheets3000can be simply and reliably positioned by the moving mechanism38.

When the positioning of the printing sheet3000at the predetermined location in the positioning block400is completed, the rotary lever53is rotated by the roller rotation motor52a, causing the intermediate pick-up roller55to press-contact the presser roller36through the printing sheet3000, so that the printing sheet3000is transported towards the printing block500by the rotation of the intermediate pick-up roller55.

When the printing sheet3000is transported to the printing block500, driving the head drive mechanism57causes the printing head59separated from the plate roller68in the standby mode to press-contact the platen roller68through the printing sheet3000and a recording ribbon (not shown). The printing head59scans the printing sheet3000transported by the pinch rollers69and69, so that thermal transfer printing is performed on the printing sheet3000. At this time, as mentioned above, the head pressure adjusting cam62rotates, so that the position of the cam surface66with respect to the action roller61achanges, thereby changing the pressure exerted upon the platen roller68by the printing head59in accordance with whether the printer1is in the vertically set mode or the horizontally set mode.

After the printing operation on the printing sheet3000has been completed, the printing sheet3000has its direction of transportation changed by the first turn-around roller71and the transportation belt72, and is transported towards the intermediate transporting block600.

When the printing sheet3000is transported to the intermediate transporting block600, the roller rotation motor52ais rotated in a direction opposite to the earlier direction. Rotation of the rotary lever53causes the intermediate pick-up roller55to press-contact the presser roller74through the printing sheet3000, so that the printing sheet3000is transported towards the density measuring block700.

When the printing sheet3000is transported to the density measuring block700, the printing density on the printing sheet3000is measured by the density measuring device. When the measurement results show that there are, for example, variations in the printing density, information of such a problem is displayed on a display section (not shown) on the housing2.

The printing sheet3000has its direction of transportation changed by the second turn-around roller75and the press-contact rollers76and76, and is transported towards the sheet discharging block800.

The printing sheet3000that has been transported to the sheet-discharging block800is transported to the sheet taking-out space79of the sheet taking-out block900by the discharging roller77and the transportation roller78, whereby the transportation of the printing sheet3000is completed.

The specific forms and structures of each portion in the above-described embodiment are only practical examples in carrying out the present invention, so that these are not to be construed as limiting the technical scope of the present invention.

As is clear from the foregoing description, a printer of the present invention comprises a sheet-holding block which can hold a plurality of printing sheets in a stack; a picking-up block for picking up the printing sheets held in the sheet-holding block one at a time; a transporting block for transporting the printing sheets picked up by the picking-up block; a printing block for performing printing on the printing sheets transported by the transporting block; and a sheet-discharging block for discharging the printing sheets that have been subjected to printing at the printing block. In the printer, the blocks are disposed inside a housing. A positioning block is disposed between the transporting block and the printing block and positions the printing sheets transported by the transporting block at a predetermined location of the positioning block one at a time, so that they are positioned one at a time at a printing location of the printing block where each printing sheet is subjected to printing. Intermediate picking-up means for picking up the printing sheets positioned at the predetermined location of the positioning block one at a time in order to transport the printing sheets to the printing block is provided.

Therefore, each of the printing sheets is transported to the proper printing location of the printing block from the positioning block, so that it is possible to perform proper printing on the printing sheets at the printing block.

In one form, the positioning block comprises a stationary base plate secured with respect to the housing, a movable base plate positioned opposing the stationary base plate, being orthogonal to the stationary base plate in the direction in which the printing sheets are transported, and being capable of moving in the direction of the surfaces of each printing sheet, and a moving mechanism for moving the movable base plate with respect to the stationary base plate. Here, an insertion space is provided between the stationary base plate and the movable base plate for inserting each printing sheet that has been transported by the transporting block. When one printing sheet has been inserted into the insertion space, the movable base plate is moved with respect to the stationary base plate by the moving mechanism in order to position the printing sheet at the predetermined location. Therefore, it is possible to simply and reliably position the printing sheets by the moving mechanism.

In another form, the printing sheets are transported from the sheet-holding block to the sheet-discharging block with their surfaces faced horizontally, the position of each printing sheet held in the sheet-holding block is set above the predetermined location of each printing sheet of the positioning block; and a positioning portion for positioning the printing sheets at the predetermined location one at a time by receiving the printing sheets that have been transported to the positioning block and that have moved downward due to their weights is provided. Therefore, it is possible to easily and reliably position the printing sheets.

A printer comprises a sheet-holding block which can hold a plurality of printing sheets in a stack; a picking-up block for picking up the printing sheets held in the sheet-holding block one at a time; a transporting block for transporting the printing sheets picked up by the picking-up block; a printing block for performing printing on the printing sheets transported by the transporting block; and a sheet-discharging block for discharging the printing sheets that have been subjected to printing at the printing block. The sheet-holding block comprises a sheet-receiving plate for receiving one of the surfaces of each printing sheet held in the sheet-holding block, and holding means, disposed opposing the sheet-receiving plate and moving away from the sheet-receiving plate depending upon the thickness of the printing sheets held in the sheet-holding block, for holding the other surface of each printing sheet held in the sheet-holding block, the other surface being opposite to the one surface.

Therefore, the printing sheets held inside the sheet-holding block are not warped, so that it is possible to, for example, prevent damage to the printing sheets when they are picked up and prevent the printing sheets from being improperly picked up by the picking-up block.

In one form, when the printing sheets held in the sheet-holding block are picked up by the picking-up block, the holding means is moved in a direction opposite to the other surfaces of the printing sheets, and, when the printing sheets held in the sheet-holding block are not picked up by the picking-up block, the holding means is moved to the side of the other surfaces of the printing sheets and holds the printing sheets. Therefore, it is possible to reliably pick up the printing sheets held in the sheet-holding block one at a time by the picking-up block.

In another form, the sheet-receiving plate has a roller provided thereat that contacts the printing sheets held by the holding means. Therefore, the roller is rotated when the printing sheets are picked up by the picking-up block, so that it is possible to reliably and easily pick up the printing sheets.

The printing sheets may be transported from the sheet-holding block to the sheet-discharging block with their surfaces faced horizontally. Therefore, it is possible to effectively prevent warping of the printing sheets in a state in which they tend to warp.

The holding means may hold at least two locations of the printing sheets that are separated in the direction in which the printing sheets are transported, and the size of the holding means in the vertical direction may be substantially equal to or the widths of the printing sheets in the vertical direction. Therefore, it is possible to effectively prevent warping of the printing sheets.

A printer comprises a sheet-holding block which can hold a plurality of printing sheets in a stack; a picking-up block for picking up the printing sheets held in the sheet-holding block one at a time; a transporting block for transporting the printing sheets picked up by the picking-up block; a printing block for performing a printing operation on the printing sheets by scanning the printing sheets by a printing head pushed against a platen roller with the printing sheets transported by the transporting block being interposed between the printing head and the platen roller one at a time; and a sheet-discharging block for discharging the printing sheets subjected to printing at the printing block. The printer can be set vertically so that the printing sheets are transported with their surfaces faced horizontally, and can be set horizontally so that the printing sheets are transported with their surfaces faced vertically. The printer further comprises state recognizing means for recognizing the vertically set state or the horizontally set state. When the printing sheets are transported from the sheet-holding block to the sheet-discharging block, the pressure exerted upon the printing sheets by each component part pushed against the printing sheets is made substantially constant in accordance with the results of the recognizing operation of the state recognizing means.

Therefore, a constant pressure is exerted upon the printing sheets being transported regardless of whether the printer is set vertically or horizontally, so that the printing sheets can be properly transported.

In one form, the printer further comprises head pressure adjusting means for causing the pressure exerted upon the printing sheets by the printing head when the printing sheets are subjected to printing to be substantially constant in accordance with the results of the recognizing operation of the state recognizing means. Therefore, it is possible to perform a proper printing operation on the printing sheets under a constant head pressure regardless of whether the printer is set horizontally or vertically.

In another form, a predetermined gap is provided between the printing head and the platen roller when printing is not performed on the printing sheets by the printing head. Therefore, undesired contact between the printing head and the platen roller can be prevented, so that it is possible to prevent, for example, wearing thereof, and to properly transport the printing sheets to the printing block.