JPH0736759Y2 - Shaft support structure for sliding carriage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a dot impact printer that prints characters, numbers, etc. on a paper in a dot configuration, and in particular, a carriage that slidably supports a carriage to which a print head is attached. The present invention relates to a supporting structure for a sliding shaft.

[Prior Art] As a conventional shaft support structure for sliding a carriage, there are those described in, for example, JP-A-61-237670 and JP-A-61-170558.

In these documents, an example in which both ends of a carriage sliding shaft are supported at both ends by a frame is described, and the carriage is slidably supported by the shaft.

[Problems to be Solved by the Invention] However, in such a conventional carriage sliding shaft supporting structure, since the carriage sliding shaft is supported only at both ends thereof, the print head during printing. There is a problem that the rear shaft is bent due to the impact reaction force applied to the rear shaft, which changes the carriage posture and deteriorates the printing quality.

That is, for example, when printing is performed by a printer having a shaft support structure as shown in FIGS. 4 and 5, the pressure generated from the wire of the print head 1 is P ₀ , and the distance from the print center to the center of the front shaft 2 is l. ₁ , and assuming that the distance from the center of the front shaft 2 to the center of the rear shaft 3 is l ₂ , the pressure P ₁ acting on the rear shaft 3 by static calculation
Is Becomes

Further, the deflection amount of the rear shaft 3 becomes maximum when the carriage 4 is located at the central portion in the axial direction thereof, and when the deflection amount is δ _max , Here, L is the distance between supporting points of the shaft, E is Young's modulus of the shaft material, and I is the second moment of area of the shaft. Therefore, the flexure amount δ of the shaft appears in proportion to the cube of the distance between the supporting points. In order to reduce the amount of deflection of the rear shaft 3, it is necessary to increase the rigidity of the shaft, which can suppress shaft vibration and improve printing quality.

By the way, the rigidity of the shaft can be increased by increasing its diameter, but if this is done, it is necessary to increase the size of other parts as the diameter of the shaft increases, so not only does the overall size of the device increase. It also leads to higher costs.

The present invention has been made in view of the above problems, and an object thereof is to solve the above problems by shortening the distance between the support points of the rear shaft.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a carriage having a dot impact type print head, which is arranged in parallel to each other, and which has a frame on which both ends are supported. A rear shaft whose both ends are supported by a frame in a carriage-sliding shaft support structure in which a front shaft penetrates and a rear shaft is fitted on the side opposite to the print head side, and the carriage is slidably supported by both shafts. An engaging hole is provided in the lateral direction of the middle part of the rear shaft, and a supporting member fixed to the frame is engaged in the engaging hole to support the middle part of the rear shaft in the axial direction. .

[Operation] In the present invention, the support member supports the middle portion of the rear shaft in the axial direction on the frame, and the rear shaft is supported at three or more points. It is possible to reduce the amount of flexure as much as possible and prevent deterioration of printing quality due to a change in the posture of the carriage due to the flexure of the rear shaft.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention.
The figure is an enlarged cross-sectional view of the supporting portion of the rear shaft.

First, the structure will be described. As shown in FIG. 1, 5 is a front shaft, 6 is a rear shaft arranged parallel to the front shaft 5, both shafts 5 and 6 are round shafts, and both ends thereof are Are supported by bearings (not shown) and the frames 7 are fixed.

Reference numeral 8 denotes a carriage through which the front shaft 5 and the rear shaft 6 penetrate. The carriage 8 has a through hole 9 and a groove provided in parallel with the through hole 9 and opening in the lateral direction.
The front shaft 5 passes through the through hole 9 and the rear shaft 6 is fitted in the groove 10.

11 is a carriage motor fixed to the frame 7, 12
Is an endless timing belt arranged in parallel with the front shaft 5 and the rear shaft 6, and is a belt wheel rotatably supported by a belt wheel 13 fixed to the rotation shaft of the carriage motor 11 and a shaft fixed to the frame 7. I am passing over between 14. A part of the timing belt 12 is fixed to the carriage 8, and the timing belt 12 reciprocates in the axial direction of the shafts 5 and 6 by driving the carriage motor 11.

In addition, the groove is formed in the middle portion of the rear shaft 6 in the axial direction.
Similar to 10, an engaging hole 15 that opens in the lateral direction is provided. Corresponding to the engagement hole 15, the frame 7 is provided with a long hole 16 extending in the axial direction of the rear shaft 6. 17 is
A fixing screw showing a specific example of a supporting member, a screw shaft portion 17a continuous to the head, and an eccentric shaft portion 17b continuous to the screw shaft portion 17a and having its axis eccentric by a predetermined amount α. It consists of Then, the screw shaft portion 17 that is the base of the fixing screw 17
Insert a through the long hole 16 of the frame 7, and insert the eccentric shaft 1
7b is engaged with the engagement hole 15 of the rear shaft 6. 18 is
A nut for fixing the screw shaft portion 17a of the fixing screw 17 to the frame 7, and 19 is a washer thereof.

A dot impact type print head (not shown) is attached to the carriage 8 and
Printing is performed on a sheet supplied to a platen (not shown) disposed on the side.

Next, the operation of this embodiment will be described.

The rear shaft 6 according to the present embodiment has an intermediate portion fixed to the frame 7 with fixing screws 17, and the entire shaft is supported by the frame 7 at three positions, both ends and an intermediate portion. This state is shown in FIG.

Therefore, as shown in FIG. 3, when the distance from the support center of both ends to the support center of the fixing screw 17 is L / 2, the maximum deflection amount δ ′ _max of the rear shaft 6 is Is.

Therefore, comparing this equation with the above equation (1), δ ′ _max
= 1/8 × δ _max , and comparing the shafts with the same thickness, by supporting the central portion of the shaft as in the present embodiment, the amount of deflection can be reduced to 1/8 of the conventional value. The rear shaft 6 supports the opposite side of the carriage 8 to the print head, and when the supporting position changes, the posture of the carriage 8 changes according to the change amount.
The change in the posture of the print head can be suppressed by the amount of decrease in the amount of bending of the rear shaft 6.

Thus, since the posture change of the carriage 8 is suppressed in proportion to the reduction rate of the flexure amount δ of the rear shaft 6, the posture change of the print head is reduced accordingly, and the characters and numbers with clear contours are beautiful. Etc. can be printed.
Especially, set the gap between the print head wire tip and the platen surface. For printers that require adjustment within the range
Since the size of the flexure amount δ of the rear shaft 6 has a great influence on the print quality, the structure of this embodiment can greatly contribute to the improvement of the print quality.

The attitude of the print head can be easily adjusted by rotating the fixing screw 17 to change the attitude of the carriage 8. In that case, first loosen the nut 18, then loosen the support portions at both ends of the rear shaft 6, and then rotate the fixing screw 17 in an arbitrary direction by a predetermined amount. Then, since the eccentric shaft portion 17b is set by giving the screw shaft portion 17a of the fixing screw 17 an eccentric amount α, the carriage 8 moves the front shaft 5 at an angle corresponding to twice the eccentric amount α. Rotate to the center. In this way, by rotating the fixing screw 17 and changing the posture of the print head within the range in which the carriage 8 can be rotationally displaced, the collision angle of the wire with respect to the platen and the gap between the head and the platen can be arbitrarily adjusted. Can be adjusted.

In the above embodiment, the front shaft 5 is passed through the through hole 9 provided in the carriage 4, but the present invention is not limited to this, and the carriage may be laterally arranged on the print head side. A structure may be adopted in which a groove that opens is provided and the front shaft penetrates through the groove, and the cross-sectional shape of the shaft may be square. Further, it is needless to say that the rear shaft 6 may be provided with two or more engaging holes 15 and the rear shaft 6 may be supported at four or more points by a corresponding number of fixing screws.

Further, in the above-described embodiment, an example in which the groove 10 of the carriage 8 and the engagement hole 15 of the rear shaft 6 are opened directly laterally has been described, but the groove 10 and the engagement hole 15 are obliquely laterally provided with a certain angle. The structure may be opened in any direction. Furthermore, by providing a support member such as a fixing screw 17 on the rear shaft 6 and fixing the tip of the screw shaft to the frame 7 with a nut 18 or the like, the same effect as the above embodiment can be obtained. be able to.

[Advantage of Device] As described above, according to the present invention, the structure is such that the rear shaft penetrates the groove provided in the carriage and the middle part of the rear shaft is supported by the frame by the support member. The rigidity of the rear shaft can be increased without increasing the thickness of the rear shaft, and thus the amount of deflection of the rear shaft caused by the pressure during printing can be significantly reduced. Therefore, since the change in the posture of the print head attached to the carriage can be suppressed by the amount of reduction in the deflection amount of the rear shaft, it is possible to always print in a state close to the posture at the time of setting, and the contour and the like are clear and neat. There is an effect that printing can be realized and the printing quality can be greatly improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG.
FIG. 3 is a cross-sectional view showing an essential part of the drawing, FIG. 3 is a view for explaining the operation of the present invention, and FIGS. 4 and 5 are views for explaining the operation of a conventional carriage sliding shaft support structure. is there. 5: Front shaft, 6: Rear shaft 7: Frame, 8: Carriage 9: Through hole, 10: Groove 15: Engagement hole, 16: Long hole 17: Fixing screw (supporting member) 17a: Screw shaft part, 17b: Eccentric shaft

Claims (3)

[Scope of utility model registration request] 1. A carriage having a dot impact type print head has a front shaft on the side of the print head, which is arranged in parallel with each other and whose both ends are supported by a frame, penetrated through the carriage, and a rear side on the side opposite to the print head side. In the shaft support structure for carriage sliding in which the shaft is fitted and the carriage is slidably supported by both shafts,
An engaging hole is provided in the lateral direction of the middle portion of the rear shaft whose both ends are supported by the frame, and a supporting member fixed to the frame is engaged in the engaging hole, so that the middle portion of the rear shaft in the axial direction is engaged. A shaft supporting structure for sliding a carriage, characterized in that a part is supported. 2. The utility model registration claim according to claim 1, wherein the support member is capable of relative displacement with respect to the frame, and the mounting position of the rear shaft can be adjusted by the relative displacement. The shaft supporting structure for sliding the carriage according to the item. 3. The support member includes a screw shaft portion fixed to the frame, and an eccentric shaft portion eccentrically provided with respect to an axial center line of the screw shaft portion and engaging with a hole provided in the rear shaft. The shaft supporting structure for carriage sliding according to claim 1 or 2, wherein the mounting position of the rear shaft is adjustable by rotational displacement of the screw shaft portion.