JP2963623B2 - Carrier drive for serial printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer such as a dot printer used in an ECR or POS system in which a carrier on which a print head is mounted is linearly reciprocated by using a combination of a drive cam and a cam follower. The present invention relates to an apparatus for driving a carrier.

[0002]

2. Description of the Related Art Generally, in a serial printer,
A carrier on which a print head is mounted is provided so as to be linearly reciprocable by a guide shaft. In order to linearly reciprocate such a carrier, for example, a carrier driving method is employed in which a part of a driving wire laid in a main scanning direction via a motor pulley or the like is locked to the carrier. However, such a carrier driving method has drawbacks such as the necessity of a motor capable of rotating forward and backward as a driving source, and the necessity of taking into account expansion and contraction of a driving wire.

In view of the above, a drive system has been proposed and implemented in which a carrier can be driven linearly reciprocally by a drive source such as a DC motor that rotates only in one direction by using a combination of a drive cam and a cam follower. Have been. FIG. 8 is an exploded perspective view showing a schematic configuration of a serial printer employing such a driving method. For example, one guide shaft 2 is attached along the main scanning direction to the main body frame 1 having a divided frame assembly structure, and a carrier 4 on which a print head 3 is mounted is slidably attached to the guide shaft 2. Have been. Further, a round bar-shaped drive cam 5 parallel to the guide shaft 2 is provided below the carrier 4. This drive cam 5 has both ends at the body frame 1.
, And is rotatably driven in only one direction by a DC motor (not shown) at one end outside the main body frame 1. On the peripheral surface of such a drive cam 5, spiral grooves 6a and 6b having different inclination directions intersect each other in the middle, but are continuous at the end of the movement area (both ends of the drive cam 5). It is formed endless so as to form one groove 6.

[0004] A through hole 7 having a circular cross section is formed in the center bottom surface of the carrier 4, and a cam follower 8 is rotatably attached to the through hole 7 so as to prevent the cam follower 8 from coming off. That is, the cam follower 8 has a columnar shape having a diameter substantially equal to that of the through hole 7, and has a large diameter at the top to prevent falling from the through hole 7.
A stopper such as an E-ring 9 is engaged with the part that has escaped from the part as shown in FIG.
An upward drop is prevented. Further, the lower end surface of the cam follower 8 has a boat-shaped convex portion 1 fitted into the spiral groove 6.
0 is formed. That is, the boat-shaped projection 10 is always fitted in the spiral groove 6 at the top of the outer peripheral surface of the drive cam 5, and follows the spiral groove 6 according to the rotation of the drive cam 5. 4 will move linearly in the axial direction. Here, the boat-shaped convex portion 10 is formed in a boat-shaped shape in order to smoothly follow at the intersection between the spiral grooves 6a and 6b, and for example, follows the spiral groove 6a. If it moves rightward sometimes, it is set to move leftward when following the spiral groove 6b.

The main body frame 1 has a guide rail 1
1 is formed in parallel with the guide shaft 2, and a concave groove 12 slidably engaged with the guide rail 11 is formed on the side of the carrier 4, so that floating is prevented when the carrier 4 moves.

[0006]

However, according to such a conventional structure, a special stopper such as an E-ring 9 is required to prevent the cam follower 8 from coming off, resulting in an increase in cost and loss. There are also concerns such as.

[0007]

In the carrier driving device for a serial printer according to the present invention, a carrier is mounted on which a print head is mounted and linearly reciprocates along a guide shaft, and spiral grooves having different inclination directions are formed on the outer peripheral surface. A drive cam continuously formed at both ends in an endless shape is provided in parallel with the guide shaft, and is rotatably attached to a through hole of the carrier and is provided in the spiral groove of the drive cam which rotates in one direction. In a carrier driving device for a serial printer, wherein the carrier is linearly reciprocated through a cam follower having a boat-shaped projection to be fitted therein, a detachable concave groove is provided around the through hole of the carrier along the penetrating direction. Forming a retaining projection that penetrates the detachable concave groove and engages with the carrier bottom surface at a position other than the detachable concave groove. The retainer protrusion and the boat-shaped convex portion fitted into the helical groove are formed so that the cam follower rotates within a range in which the retainer protrusion engages with the carrier bottom surface. I decided.

[0008]

The cam follower is inserted into the through-hole by aligning the retaining projection with the position of the detachable concave groove so that the retaining projection is engaged with the bottom of the carrier when the retaining projection comes out of the through-hole. The cam follower is rotated at the through hole. Then, by fitting the boat-shaped projection into the spiral groove of the drive cam, the carrier can be driven in a linear reciprocating manner using a combination of the drive cam and the cam follower. In this state, the boat-shaped protrusion fits into the helical groove. However, in this case, in the positional relationship between the stopper-shaped protrusion and the boat-shaped protrusion that regulate the rotation of the cam follower, the stopper-shaped protrusion is located on the bottom surface of the carrier. Since it is always engaged, it does not come out through the concave / detachable concave groove. Therefore, the cam follower can be reliably prevented from coming off without using a component such as an E-ring.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. 8 and 9 are denoted by the same reference numerals, and description thereof is omitted. In particular, since the overall configuration may be the same as the conventional configuration, for example, only the main components are illustrated in the exploded perspective view of FIG. First, in the carrier 4 of the present embodiment, a through hole 21 having a circular cross section is formed in the center bottom surface portion. Around the through hole 21, two large-diameter detachable grooves 21 a and 21 b having the same shape and facing each other via the through hole 21 are formed along the through direction. These detachable concave grooves 21a,
Reference numeral 21b is provided at a position orthogonal to the moving direction of the carrier 4. Cam follower 2 inserted through through hole 21
A boat-shaped convex portion 10 is formed at the lower end of 2. Also,
The cam follower 22 has two retaining projections 22a and 22b located on the peripheral surface portion that has exited the through hole 21.
Are integrally formed. These retaining projections 22
a, 22b are penetrated from above into the attaching / detaching concave grooves 21a, 21b from above.
A protrusion is formed at a shape and position corresponding to 21b.
After the retaining protrusions 22a and 22b are inserted into the attaching / detaching concave grooves 21a and 21b, the cam follower 22 is rotated, whereby the retaining protrusions 22a and 22b are attached to the carrier bottom surface 4 of the carrier 4.
a. A concave portion 23 for accommodating the large top portion 22c of the cam follower 22 is formed in the upper edge portion of the through hole 21 at the center bottom surface of the carrier 4.

Here, the boat-shaped convex portion 10 and the detachable concave groove 21 are provided.
The positional relationship between the retaining projections 22a and 22b and the retaining projections 22a and 22b will be described. First, when the crossing angle formed by the spiral grooves 6a and 6b formed in the drive cam 5 is a as shown in FIG. 2, a boat-shaped convex portion 10 that fits and follows the spiral grooves 6a and 6b. Also, as shown in FIG. 1 (b), this angle a is rotated and displaced with the angle a as a rotation range. And drive cam 5
At the both ends side switching passage point 6c, the direction is orthogonal to the axis of the drive cam 5. Now, assuming that the detachable concave grooves 21a and 21b are formed at positions corresponding to both ends of the boat-shaped convex portion 10 as shown in FIG. 1B with the switching passage point 6c as a reference position, the retaining projection 22a , 22b are formed at positions outside the range of the angle a for restricting the rotation range. As an example, the retaining projections 22a and 22b are formed at positions different from the boat-shaped projection 10 by 90 °. This means that, from a different viewpoint, the retaining projections 22a, 22
This means that the positional relationship between the retaining projections 22a and 22b and the boat-shaped convex portion 10 is set so that the cam follower 22 rotates within a range in which the cam follower 2b engages with the carrier bottom surface 4a.

In such a configuration, the mounting of the cam follower 22 will be described first. This attachment is performed by inserting the cam follower 22 into the through hole 21 from above by adjusting the positions of the retaining projections 22a and 22b to the positions of the detachable concave grooves 21a and 21b as shown in FIG. At this time, the top portion 22c fits into the concave portion 23, and the cam follower 22 does not fall. Further, since the retaining projections 22a and 22b come off from the carrier bottom surface 4a, the cam follower 22 is rotatable with respect to the through hole 21. In this state, for example, the boat-shaped convex portion 10 is gripped, and as shown in FIG. 4, the cam follower 22 is rotated by 90 °, and the retaining projections 22a, 22b come off the positions of the concave / detachable concave grooves 21a, 21b. To engage the carrier bottom surface 4a. This becomes the reference position, which means that the cam follower 22 has been attached in a state where it cannot be removed. FIG. 5 shows a cross-sectional structure in this state.

In such a state, the boat-shaped projection 10 is fitted into the spiral groove 6a or 6b of the drive cam 5, as shown in FIG. Thereby, even when the boat-shaped convex part 10 operates following the spiral groove 6a as shown in FIG. 1A, the boat-shaped convex part 10 is spirally formed as shown in FIG. Even when operating following the groove 6b, FIG.
As shown in FIG. 7, even when the boat-shaped convex portion 10 follows the switching passage point 6c between the spiral grooves 6a and 6b, the retaining projection 2 can be prevented.
2a and 22b do not pass or coincide with the positions of the concave / detachable concave grooves 21a and 21b. Therefore, the cam follower 22 can be used in the actual use range in which the boat-shaped projection 10 rotates in the range of the angle a.
Does not fall out of the through hole 21. From another viewpoint, in order to attach and detach the cam follower 22,
Only when the boat-shaped convex portion 10 (therefore, the cam follower 22) can freely rotate without being restricted by the rotation range of the angle a (a state in which the engagement with the spiral grooves 6a and 6b is released). By making the positions of the retaining projections 22a, 22b coincide with the positions of the concave / detachable concave grooves 21a, 21b, it becomes possible to carry out the detachment.

As described above, according to the present embodiment, the cam follower 22 can be prevented from coming off at low cost only by devising the shapes of the cam follower 22 and the through hole 21 without using components such as the E-ring. And no trouble due to missing parts.

In the present embodiment, as shown in FIG. 1 and the like, the concave / detachable concave grooves 21a and 21b are formed at positions orthogonal to the moving direction of the carrier 4, so that the cam followers 22 are provided.
In FIG. 2, two retaining projections 22a and 22b are formed at positions orthogonal to the boat-shaped convex portion 10, but the detachable concave grooves 21 are formed.
a, 21b, depending on the position of the protrusions 22a, 22b.
The position of “b” is also appropriate. For example, the retaining protrusions 22 a and 22 b may be formed at positions corresponding to both ends of the boat-shaped convex portion 10. In short, if the positional relationship between the retaining projections 22a, 22b and the boat-shaped convex portion 10 is determined so that the cam follower 4 rotates within a range where the retaining projections 22a, 22b engage with the carrier bottom surface 4a. Good.

To explain with a modification shown in FIG. 7, retaining projections 22c and 22d corresponding to both ends of the boat-shaped convex portion 10 are shown.
Is within the angle a indicating the range of rotation of the boat-shaped convex portion 10,
Even when the boat-shaped protrusion 10 is operating following the spiral groove 6a as shown in FIG. 7 (a), the boat-shaped protrusion 10 is inserted into the spiral groove 6b as shown in FIG. 7 (c). 7 (b), the boat-shaped protrusion 10 follows the switching passage point 6c between the spiral grooves 6a, 6b, as shown in FIG. 7 (b). The detachable concave grooves 21c and 21d may be formed at positions where does not pass through. In this modification, the detachable concave grooves 21c and 21d are formed so as to face each other in the same direction as the moving direction of the carrier 4.

In this embodiment, the retaining projections 22 are provided.
Although the recesses a and 22b (therefore, the attaching / detaching concave grooves 21a and 21b) are formed as short arcs, they may be formed into a shape having a considerably long arc length extending over substantially a half circumference. Further, the retaining projections 22a and 22b (accordingly, the detachable concave grooves 21a and 21b) are formed at symmetrical positions different from each other by 180 °. For example, the retaining projections 22a and the detachable concave grooves 21b can be attached and detached. Although two detachable positions are provided, it is not always necessary to form them at symmetrical positions (the detachable portion of the cam follower 22 may be one). Similarly, the retaining projections 22a, 22
The b may be formed so as to have different shapes, sizes, and the like (the detachable concave grooves 21a and 21b also correspond). These points are the same in the case of the above-described modification. Further, the number of retaining projections (removable concave grooves) is not limited to two, and may be set as appropriate.
Each of them may be formed at a different position. Alternatively, it is also possible to use one.

[0017]

According to the present invention, as described above, a carrier that carries a print head and reciprocates linearly along a guide shaft is provided, and spiral grooves having different inclination directions are continuously formed at both ends on the outer peripheral surface. A drive cam formed in an endless shape is provided in parallel with the guide shaft, and is fitted to the spiral groove of the drive cam which is rotatably attached to a through hole of the carrier and rotates in one direction. In a carrier drive device for a serial printer that linearly reciprocates the carrier through a cam follower having a mold convex portion, a detachable concave groove is formed around the through hole of the carrier along the penetrating direction, The cam follower is formed with a retaining projection which penetrates the concave / detachable concave groove and engages with the bottom surface of the carrier at a position other than the concave / detachable concave groove. Since the positions of the retaining protrusion and the boat-shaped projection fitted into the spiral groove are determined so that the cam follower rotates within a range where the projection engages with the carrier bottom surface, the boat-shaped projection is formed. The cam follower can be prevented from coming off by the positional relationship between the portion, the retaining protrusion, and the concave / detachable concave groove. Therefore, the cam follower can be securely and reliably prevented from coming off without using a component such as an E-ring.

[Brief description of the drawings]

FIG. 1 is a bottom view illustrating a vicinity of a through hole and a cam follower according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing main components.

FIG. 3 is an exploded perspective view showing when a cam follower is attached.

FIG. 4 is a perspective view of the vicinity of a through hole and a cam follower showing an operation after mounting.

FIG. 5 is a sectional view showing the vicinity of a through hole and a cam follower in a retaining state.

FIG. 6 is a perspective view for explaining a fitting state with a spiral groove.

FIG. 7 is a bottom view illustrating a vicinity of a through hole and a cam follower according to a modified example.

FIG. 8 is an exploded perspective view showing a conventional example.

FIG. 9 is a partial perspective view showing a retaining state by an E-ring.

[Explanation of symbols]

 2 Guide Shaft 3 Print Head 4 Carrier 4a Carrier Bottom 5 Drive Cam 6a, 6b Helical Groove 10 Boat Shape 21 Through Hole 21a-21d Detachable Recessed Groove 22 Cam Follower 22a-22d Retaining Protrusion

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 19/20 B41J 29/02

Claims (1)

(57) [Claims] 1. A drive cam having a print head mounted thereon and linearly reciprocating along a guide shaft, and a drive cam in which spiral grooves having different inclination directions are continuously formed at both ends in an endless shape on an outer peripheral surface. Provided parallel to the guide shaft,
The carrier is linearly reciprocated via a cam follower having a boat-shaped projection fitted into the spiral groove of the drive cam which is rotatably mounted in a through hole of the carrier and rotates in one direction. In the carrier driving device for a serial printer, a detachable concave groove is formed around the through hole of the carrier along the penetrating direction, and the detachable concave groove is penetrated, and the detachable concave groove is formed at a position other than the detachable concave groove. The cam follower is formed with a retaining projection that engages with the bottom surface of the carrier, and is fitted into the retaining projection and the spiral groove so that the cam follower rotates within a range where the retaining projection engages with the bottom surface of the carrier. A carrier driving device for a serial printer, wherein a position of the boat-shaped convex portion is determined.