A printer including platen-yoke apparatus

Abstract: A printer including a platen-yoke apparatus. The platen (16) for e.g. wire matrix printer is mounted in a U-shaped channel (58). When the printer head (38) is moved to one side of a document feeding surface (12-1), a ramp (48) on one end of the platen (16) cooperates with a roller (46) secured to the print head (38) to depress that end of the platen to cause it to be moved below the feeding surface (12-1). A yoke member (22) rotatably secured to the underside (12-2) of the feeding surface (12-1) and coupled to the ends of the platen (16) causes the platen (16) to be moved parallel to the feeding surface (12-1) to lower the platen (16) below the feeding surface (12-1) to facilitate the insertion of a document (24) to a printing station (14) associated with the printer.

Description: The present invention relates to a printer. In some printers it is necessary for the printer to be able to print on record media having a varying thickness. One example of such a printer is shown in US Patent 4,676,675 which discloses a media thickness compensating device which senses the thickness of the record medium and causes the print head to be moved towards or away from a fixed platen to maintain a current printing gap. This type of printer tends to be complex because it requires sensing devices and additional motor drive means to move the print head to the appropriate position. Accordingly, an object of the present invention is to provide a printer which has the capability of printing on record media of varying thickness and which is of simple construction. It is a further object of the present invention to provide a printer which has a resiliently mounted movable platen for the purpose of enabling the printer to print on record media of varying thickness, and which is provided with means for ensuring that the platen does not interfere with the record medium when the record medium is moved to a print station. According to the present invention there is provided a printer including support means having a support surface for supporting a record medium, and a print station including print means adapted to cooperate with a cooperating surface of an elongated platen for the purpose of printing data on said record medium, characterized in that said platen is movable relative to said support means and is associated with resilient means arranged to hold said platen in an operative position during a printing operation, and in that there is provided engagement means arranged to engage a first position of said platen for the purpose of moving said platen below said support surface against the action of said resilient means to enable said record medium to be moved to said print station without interference from said platen, said platen being connected to a yoke member having first and second end portions and an intermediate portion therebetween, said first and second end portions being respectively pivotally connected to opposite end portions of said platen, and said intermediate portion being rotatably connected to said support means so as to maintain said cooperating surface of said platen substantially parallel with respect to said support surface during movement of said platen relative to said support means. It should be understood that, in a printer in accordance with the present invention, the fact that the platen is resiliently held in its operative position ensures that the printer can print on record media of varying thickness. An embodiment of the invention will now be described with reference to the accompanying drawings in which:- Fig. 1 is a general isometric view, shown partly in diagrammatic form, of a printer in which a preferred embodiment of the apparatus of this invention may be used. Fig. 2 is an isometric view of the platen (shown in Fig. 1) and a yoke member which are part of the apparatus of this invention. Fig. 3 is an isometric view of the underside of the support means shown in Fig. 1, and it also shows the platen and yoke member shown in Fig. 2. Fig. 4 (shown on the sheet containing Fig. 2) is an isometric view of the platen and yoke member shown in Fig. 2, and is taken from the direction of arrow A shown in Fig. 2. Fig. 1 is a general isometric view, shown partially in diagrammatic form, of a printer in which a preferred embodiment or apparatus 10 of this invention may be used. In broad terms, the apparatus 10 includes a support means 12 for guiding media to be printed upon to a print station 14 and a platen 16. The apparatus 10 also includes certain elements not shown in Fig. 1. These elements (shown best in Fig. 2) include a first resilient member 18 positioned between a first end 16-1 of the platen 16 and the support means 12 and a second resilient member 20 correspondingly positioned between a second end 16-2 of the platen 16 and the support means 12. The apparatus 10 also includes a yoke member 22. The support means 12 has a media feeding surface 12-1, a bottom surface 12-2 (Fig. 3) and an elongated slot 12-3 in which the platen 16 is mounted. The slot 12-3 is located at the print station 14 and it passes through the support means 12. The width of the slot 12-3 is shown by the arrows 12-3-1 and 12-3-2. The support means 12 also includes media guides 12-4 and 12-5 which are used for moving a record medium, like 24, in the direction of arrow 26 to the print station 14. The slot 12-3 is perpendicular to the media guides 12-4 and 12-5. The support means 12 also includes the usual supports, like support 28, for supporting one end of a traversing screw 30, with the other end of the traversing screw 30 being similarly supported; however, it is not shown. The apparatus 10 also includes a carriage 32 (shown only diagrammatically in Fig. 1) which is mounted on the traversing screw 30, and is moved along the print station 14 by a motor 34. The motor 34 is bi-directional and is operatively coupled to the traversing screw 30 to rotate it in either direction under the control of a control means 36. A print head 38 (shown only diagrammatically in Fig. 1) is secured to the carriage 32 so as to: maintain a fixed relationship therebetween; maintain the print head 38 a fixed distance above the media feeding surface 12-1 of the support means 12; and maintain the print head 38 in operative relationship with the platen 16 as the print head 38 is moved along the length of the platen 16 by the carriage 32. In the embodiment described, the print head 38 is a wire matrix printer having a single line of nine wire actuators (not shown) which are aligned parallel to the media guide 12-4, for example. The characters to be printed are developed as the print head 38 is traversed along the length of the platen 16. The particular wire actuators which are energized to complete a character are under the control of the control means 40 which receives its input from a data source 42. While the print head 38 is a wire matrix printer in the embodiment described, the principles of this invention may be extended to other printers, like thermal printers, for example. Because the print head 38, carriage 32, traversing screw 30, and the control means 36 are conventional, no additional discussion about these elements is deemed necessary. The print head 38 (Fig. 1) also has shaft 44 extending therefrom, with the shaft 44 rotatably supporting a roller 46. The function of the roller 46 is to coact with a ramp 48 which is located on the first end 16-1 of the platen 16. When the print head 38 is moved to the extreme left, as viewed in Fig. 1, the roller 46 engages the ramp 48 to cam the first end 16-1 of the platen 16 in a downward direction as viewed in Fig. 1. This action, in conjunction with the action of the yoke member 22 (to be later described herein), moves the entire length of the platen 16 in the downward direction mentioned so that it is parallel to the media feeding surface 12-1 and slightly below it. With the platen 16 below the media feeding surface 12-1, a record medium 24, like a passbook, for example, may be inserted at the print station 14 without interference by the platen 16. If a passbook (for keeping a record of bank deposits and withdrawals) were to be the thickest record medium 24 anticipated by the apparatus 10, then the fixed distance which the print head 38 is above the media feeding surface 12-1 would be slightly greater than the thickness of the passbook itself. The platen 16 is elongated and has a first end portion 16-1 and a second end portion 16-2. The end portions are located at opposed ends of the platen 16 as shown best in Fig. 2. The first resilient member 18 is positioned between between the first end portion 16-1 and the support means 12, and correspondingly, the second resilient member 20 is positioned between the second end portion 16-2 and the support means 12 to resiliently bias the platen 16 towards the print head 38. When the print head 38 is in the position shown in Fig. 1, the platen is kept slightly below the media feeding surface 12-1 as previously described. After a record medium 26 is inserted at the print station 14, the control means 36 energizes the motor 34 in the appropriate direction to move the carriage 32 and print head 38 to the right of the position shown in Fig. 1. When this occurs, the roller 46 moves off the ramp 48, permitting the first and second resilient members 18 and 20 to resiliently bias the platen 16 towards the print head 38, and a proper distance between the print head 38 and the record medium 24 is maintained so as to effect proper printing. As previously alluded to, the first and second resilient members 18 and 20 are positioned between the platen 16 and the support means 12. In this regard, the support means 12 has wells 54 and 56 (Fig. 3) to receive the first and second resilient members 18 and 20, respectively. The first and second resilient members 18 and 20 may be made out of foam rubber, for example, or they may be made of compression type coil springs which may be positioned in mating recesses (not shown) in the first and second end portions 16-1 and 16-2 of the platen 16. The wells 54 and 56 mentioned are part of a U-shaped channel 58 which is dimensioned to receive the platen 16 to enable it to move towards and away from the print head 38. In the embodiment described, the platen 16 is quadrilaterally shaped, has a rectangular steel bar for a centre (to provide rigidity along the length of the platen 16) and is coated with conventional plastic material to provide a resilient impact surface for the associated print head 38. The U-shaped channel 58 extends along the length of the platen 16; however, it is broken away in Fig. 3 to show additional details of the platen 16. The yoke member 22 (Fig. 2), alluded to previously herein, has a central portion 22-1 and end portions 22-2 and 22-3 which extend at substantially right angles to the central portion 22-1 to form a generally U-shaped member. The platen 16 has first and second projections 60 and 62, respectively, extending from the first end portion 16-1 of the platen 16, and correspondingly, the second end portion 16-2 of the platen 16 has third and fourth projections 64 and 66 (Fig. 4), respectively, extending therefrom. When the yoke member 22 is pivotally coupled to the platen 16, the first end portion 22-2 of the yoke member 22 is positioned between the first and second projections 60 and 62, and the second end portion 22-3 is positioned between the third and fourth projections 64 and 66 of the platen 16. The U-shaped channel 58 has a first slot 68 (Fig. 3) therein to receive the first end portion 22-2 of the yoke member 22, and correspondingly, the U-shaped channel 22 has a second slot 70 therein to receive the second end portion 22-3 of the yoke member 22. The yoke member 22 (which is made of steel) is supported on the bottom surface 12-2 of the support means 12 by first and second support members 12-6 and 12-8 shown best in Fig. 3. The support means 12 is made of a tough resilient plastic material, and the support members 12-6 and 12-8 depend from the bottom surface 12-2 as mentioned. Each of the support members 12-6 and 12-8 is slotted to produce the ends 12-61 and 12-62 (shown for support member 12-6) which can be resiliently biased away from each other to permit the central portion 22-1 of the yoke member 22 to pass therethrough, and each of these support members has an opening (not numbered) therein which is shaped to receive and retain the diameter of the central portion 22-1 therein. To assemble the apparatus 10, the first and second resilient members 18 and 20 are placed in the wells 54 and 56 (Fig. 3), respectively, and then the platen 16 is placed in the U-shaped channel 58. From the underside of the support means 12, the first end portion 22-2 of the yoke member 22 is inserted through the slot 68 and is positioned between the first and second projections 60 and 62 on the first end portion 16-1 of the platen 16. Correspondingly, the second end portion 22-3 of the yoke member 22 is inserted through the slot 70 and is positioned between the third and fourth projections 64 and 66 on the second end portion 16-2 of the platen 16. Thereafter, the centre portion 22-1 of the yoke member 22 is pushed into the support members 12-6 and 12-8. When the apparatus 10 is assembled as described, the upper end of the slot 68 and the upper end of the slot 70 (as viewed in Fig. 3) limit the extent of travel of the platen 16 in moving towards and beyond the print head 38; however, there is sufficient movement of the platen 16 to handle the range of documents anticipated by the apparatus 10. With the apparatus 10 assembled as described, and with the print head 38 moved to the left, as viewed in Fig. 1, the roller 46 engages the ramp 48 to depress the left side or the first end portion 16-1 of the platen 16. As this is done, the first end portion 16-1 of the platen 16 pivots the first end portion 22-2 of the yoke member 22 in a counter-clockwise direction as viewed in Fig. 3. The first end portion 22-2 functions as a "crank" at this time. When the yoke member 22 is so rotated, the second end portion 16-2 of the platen 16 is also depressed or moved away from the print head 38 so as to keep the platen 16 parallel to the media feeding surface 12-1 and to keep the platen 16 below this surface. With the platen 16 so positioned, a record medium 26 may be freely inserted at the print station 14. In some situations, it may be desirable to employ more than the two support members 12-6 and 12-8 shown in Fig. 3. For example support members 72 and 74 may be added. When this is done, support member 12-6 may be used to restrain movement of the yoke member 22 away from the print head 38 and support member 72 may be used to restrain movement of the yoke member 22 towards the print head 38. The support members 12-8 and 74 would function in the same manner as the support members 12-6 and 72, respectively. Another advantage of the apparatus 10 is that the resilient members 18 and 20 (Fig. 2) deflect at the same time. This produces a constant force between the roller 46 and carriage 32 combination and the platen 16 along the length of the platen 16. The constant force mentioned improves print quality and reduces the chance of fatigue failure in the apparatus 10. In prior art printers without the yoke member 22, the associated springs supporting the platen deflect individually with the result that force between the platen and associated print head is not constant.

Claims: A printer including support means (12) having a support surface (12-1) for supporting a record medium (24), and a print station (14) including print means (38) adapted to cooperate with a cooperating surface of an elongated platen (16) for the purpose of printing data on said record medium, characterized in that said platen (16) is movable relative to said support means (12) and is associated with resilient means (18,20) arranged to hold said platen (16) in an operative position during a printing operation, and in that there is provided engagement means (46) arranged to engage a first portion (48) of said platen (16) for the purpose of moving said platen below said support surface (12-1) against the action of said resilient means (18,20) to enable said record medium (24) to be moved to said print station (14) without interference from said platen (16), said platen (16) being connected to a yoke member (22) having first and second end portions (22-2,22-3) and an intermediate portion (22-1) therebetween, said first and second end portions (22-2,22-3) being respectively pivotally connected to opposite end portions of said platen (16), and said intermediate portion (22-1) being rotatably connected to said support means (12) so as to maintain said cooperating surface of said platen (16) substantially parallel with respect to said support surface (12-1) during movement of said platen (16) relative to said support means (12). A printer according to claim 1, characterized in that said print means is formed by a movable print head (38) arranged to move parallel to said platen (16) during a print operation, and said first end portion of said platen is provided with a ramp (48), said print head (38) being provided with said engagement means (46) arranged to engage said ramp for the purpose of moving said platen (16) below said support surface (12-1). A printer according to either claim 1 or 2, characterized in that said platen (16) is accommodated within a U-shaped channel means (58) providing an elongate slot (12-3) in said support surface (12-1) at said print station (14). A printer according to claim 3, characterized in that said channel means (58) is provided with locating means (54,56) in a bottom surface thereof, for accommodating said resilient means (18,20) for supporting said platen (16). A printer according to either claim 3 or 4, characterized in that said channel means (58) is provided with first and second openings (68,70) respectively permitting said first and second end portions (16-1,16-2) of said yoke member (22) to pass therethrough for attachment to said platen (16). A printer according to any preceding claims, characterized in that said support means (12) is provided with support members (12-6,12-8, 72,74) on an underside (12-2) thereof, for rotatably mounting said intermediate portion (22-1) of said yoke member (22). A printer according to any preceding claim, characterized in that at each end of said platen (16) there are provided two projections (60,62;64,66) which are spaced apart and which are arranged to receive the respective end portion (22-2,22-3) of said yoke member (22) therebetween so as to provide the relevant pivotal connection.

Inventors: DELANEY ROBERT, MERRIMAN RICHARD ALLEN JR, DELANEY, ROBERT, MERRIMAN, RICHARD ALLEN, JR.
Applicants: NCR INT INC, NCR INTERNATIONAL INC.
Application year: 1990
Main classification: B41J11
IPC codes: B41J11