JP4100017B2 - Release print head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a release type print head used for a dot printer or the like. More specifically, the present invention relates to a cantilever support plate having a print pin projecting from the surface side of a spring tip, and a cantilever by a magnetic attraction force by a permanent magnet. Pulls the spring part of the support plate against its elastic force, generates a magnetic circuit that attracts the back surface of the spring part of the cantilever support plate to the magnetic adsorption surface of the yoke, and generates a magnetic flux that cancels the magnetic flux generated by the permanent magnet flowing through the yoke The present invention relates to a release type print head provided with a coil for performing the above operation.
[0002]
[Prior art]
A schematic configuration of a conventional release print head is shown in FIGS. This is an example of a print head of a release dot printer having a 12-pin configuration. A yoke 10 serving as a base is provided with a horizontal portion 11 and a vertical portion 12, and a rectangular parallelepiped permanent magnet 20 magnetized in the vertical direction in the figure is fixed to the upper surface of the horizontal portion 11. On 20, a yoke 30 is fixed in the horizontal direction.
[0003]
As shown in FIG. 10, the yoke 30 is composed of a common yoke portion 31 fixed to the upper surface of the permanent magnet 20 and a comb-shaped split yoke portion 32 protruding leftward in FIG. The divided yoke portion 32 has 12 yoke teeth 32a corresponding to the number of pins. Further, a bobbin 35 is fitted to the divided yoke portion 32, and a total of 12 coils 40 are wound around the bobbin 35 so that magnetic flux can flow individually to each yoke tooth 32a ( A coil 40 is provided for each yoke tooth 32a). There are 12 pairs of terminals 35a provided on the bobbin 35, and the exciting current is independently supplied to the coil 40 wound around each yoke tooth 32a.
[0004]
The fins 45 are bonded to the coil 40 portion and radiate heat from the coil 40 portion. A support base 46 projects from the lower surface of the fin 45, and a printed board 50 as shown in FIG. 11 is fixed with a set screw 51. The printed board 50 has 12 pairs of holes 52 for inserting and soldering the terminals 35a, 12 pairs of holes 53 for inserting and soldering the terminals 55a of the connector 55, and 1 for inserting a set screw 51. Two holes 54 are formed.
[0005]
The cantilever support plate 60 has a lower end fixed to the vertical portion 12 of the yoke 10 with a bolt 80 so as to be sandwiched between the yoke 70 and the yoke 10 and is made of an elastic material having a high magnetic permeability. . As shown in FIG. 9, two holes 61 for inserting bolts 80 are formed in the lower portion of the cantilever support plate 60, and comb teeth facing the yoke teeth 32 a of the divided yoke portion 32 are formed in the upper portion. A spring portion 62 is formed.
[0006]
Further, printing pins 65 project from the front side of each tip of the spring part 62. The printing pin 65 strikes the paper 92 on the platen 91 via the ink ribbon 90 and performs printing. In order to ensure the movement of the printing pin 65, the printing pin 65 passes through the yoke 70. A recess 71 for avoiding interference between the hole 71 and the spring portion 62 of the cantilever support plate 60 is formed.
[0007]
The yokes 10 and 30 sandwiching the permanent magnet 20 constitute a magnetic circuit together with the yoke 70. A gap is provided between the yoke 30 and the yoke 70, and the spring of the cantilever support plate 60 is placed in the gap. The part 62 is located. For this reason, when the coil 40 is not energized, the magnetic attraction force by the permanent magnet 20 acts on the cantilever support plate 60, and the spring portion 62 of the cantilever support plate 60 is elastically deformed, as shown in FIG. As described above, the back surface of the spring portion 62 is drawn to a position where it contacts the magnetic attraction surface 32b of the yoke 30 (position attracted to the magnetic attraction surface 32b; reset position).
[0008]
In this state, when an exciting current is applied to the desired coil 40 via the connector 55 based on the print instruction, a magnetic flux that cancels the magnetic flux generated by the permanent magnet 20 is applied to the yoke teeth 32a around which the coil 40 is wound. appear. For this reason, the spring part 62 of the cantilever support plate 60 is released from the restraint by the magnetic attractive force, and tries to return to the natural state by the elastic restoring force. As a result, the printing pin 65 is also moved to the front side, hitting the paper 92 on the platen 91 via the ink ribbon 90, and dots are recorded. When the energization of the coil 40 is stopped after a certain period of time, the magnetic attractive force by the permanent magnet 20 acts again on the spring portion 62 of the cantilever support plate 60, and the spring portion 62 of the cantilever support plate 60 reaches the reset position. You will be drawn in and wait for the next print instruction.
[0009]
FIG. 12 shows the relationship between the position of the spring portion 62 of the cantilever support plate 60 (distance d from the reset position) and the magnetic attraction force F1 at that position and the elastic restoring force F2 of the spring portion 62 of the cantilever support plate 60. showed that. In this graph, point a represents the elastic restoring force F2 when the spring part 62 is drawn and held at the reset position, and point b represents the elastic restoring force F2 (= 0) when the spring part 62 is in the free state. Show.
[0010]
In FIG. 12, since the relationship of magnetic attraction force F1> elastic restoring force F2 is established at any position regardless of the distance d, when the energization to the coil 40 is stopped, the spring portion 62 of the cantilever support plate 60 is magnetic. It is possible to return to the reset position by the suction force F1. When the minimum value ΔF obtained by subtracting the elastic restoring force F2 from the magnetic attractive force F1 is defined as ΔFmin, the magnetic attractive force is adjusted between the yokes 10 and 30 so as to be an optimum value within a range satisfying ΔFmin> 0. The yokes 95 are connected.
[0011]
An example of the dimensions of the spring portion 62 of the cantilever support plate 60 in the conventional example is shown in FIG. Assuming that tool steel (SK5) is used as the material and Young's modulus E = 196000 N / mm ² , the spring constant K at the position of the printing pin 65 in this numerical example is the cantilever formula of material mechanics (see FIG. 13). ), K = 8.918 N / mm. Here, if ΔFmin is set to be large, it is not a good idea to increase the exciting current flowing through the coil 40 in order to cancel the magnetic attractive force F1 by the permanent magnet 20. Therefore, in this conventional example, the retracting stroke (displacement from the natural state) of the spring portion 62 is adjusted to 0.30 mm, and ΔFmin is adjusted to about 0.196 to 0.3920N. FIG. 14 shows this relationship.
[0012]
[Problems to be solved by the invention]
As a result of performing a life test in this conventional example, a sample that reached the end of life was generated without the printing pin 65 returning after about 600 million repeated operations. At this time, the contact portion between the back surface of the spring portion 62 of the cantilever support plate 60 and the magnetic adsorption surface 32b of the yoke 30 is crushed (consumed) by repeated contact, and the retracting stroke of the spring portion 62 of the cantilever support plate 60 is reduced. Increased by 0.04 mm. The increase in the elastic restoring force F2 of the spring portion 62 due to this is 8.918 × 0.04 = 0.35672N, and the elastic restoring force F2 is shifted to the position of the two-dot chain line as described with reference to FIG. It will be. In this state, ΔFmin is negative and cannot be returned to the reset position.
[0013]
As a method for extending the life, there is a method in which the cantilever support plate 60 and the yoke 30 are coated with a hard film such as titanium nitride or chromium nitride. However, in this case, the cost is considerably increased.
[0014]
The present invention was made to solve the above problems, and the problem to be solved by the present invention is to realize a long-life release print head that is low in cost and does not require a large excitation current in the coil. It is to be.
[0015]
[Means for solving problems]
The invention according to claim 1, which solves the above problem, is shown in FIG. 1 showing the first embodiment of the present invention, and a printing pin 65 projects from the surface side of the tip of the spring portion 62. The spring portion 62 of the cantilever support plate 60 is pulled in against the elastic force by the magnetic attraction force of the cantilever support plate 60 and the permanent magnet 20, and the back surface of the spring portion 62 of the cantilever support plate 60 is attached to the yoke 30. A release-type print head comprising a magnetic circuit to be attracted to the magnetic attracting surface 32 b and a coil 40 for generating a magnetic flux that cancels the magnetic flux generated by the permanent magnet 20 flowing in the yoke 30. formed follower spring portion 102 bent by being pushed by the proximal end portion of the spring portion 62 is Rutotomoni, served the a cantilevered leaf spring having a base end is supported so as to face the back surface of the cantilevered plate Plate 100 and said plate 100 and front And a film 110 for wear by repeating the drawing operation of the spring portion 62 of the sandwiched between a support plate 60 cantilevered該片lasting support plate 60, the spring portion rear surface and the yoke 30 of the cantilevered plate 60 As the contact portion with the magnetic attracting surface 32b is crushed by repeated contact and the retracting stroke of the spring portion 62 of the cantilever support plate 60 increases, the film 110 also wears and the driven spring portion 102 of the splicing plate 100 is worn. And the spring portion 62 of the cantilever support plate 60 are configured such that the average value of the combined spring constant in the pull-in stroke is reduced.
[0016]
In this invention, the contact portion between the back surface of the spring portion 62 of the cantilever support plate 60 and the magnetic attraction surface 32b of the yoke 30 is crushed by repeated contact, and the pull-in stroke of the spring portion 62 of the cantilever support plate 60 increases. Even so, the start timing of the driven spring portion 102 of the attached plate 100 relative to the start of bending of the spring portion 62 of the cantilever support plate 60 is delayed. For this reason, the average value of the combined spring constant of the driven spring portion 102 of the attachment plate 100 and the spring portion 62 of the cantilever support plate 60 decreases in the pull-in stroke, and therefore, the elastic restoring force F2 within the pull-in stroke. ΔFmin, which is the minimum value of ΔF obtained by subtracting the elastic restoring force F2 from the magnetic attractive force F1 by the permanent magnet 20, does not become negative. For this reason, the situation where the printing pin 65 does not return can be avoided, and the life is extended.
[0017]
Further, since it is possible to avoid the elastic restoring force F2 within the pulling stroke from increasing with time, it is not necessary to set the magnetic attractive force F1 large in order to avoid ΔFmin becoming negative. The exciting current that flows through the coil 40 to cancel F1 can also be reduced.
[0018]
Furthermore, it is not necessary to coat the cantilever support plate 60 and the yoke 30 with a hard film such as titanium nitride or chromium nitride, and the cost increase can be suppressed.
[0022]
Embodiment
(First embodiment)
FIG. 1 is a front view showing a schematic configuration of the first embodiment. 1, parts corresponding to those in FIGS. 7 to 11 are denoted by the same reference numerals, and description thereof is omitted.
[0023]
The present embodiment includes an attachment plate 100 in which a driven spring portion 102 that is pushed and bent by the proximal end portion of the spring portion 62 of the cantilever support plate 60 is formed. Further, the contact portion between the back surface of the spring portion 62 of the cantilever support plate 60 and the magnetic adsorption surface 32b of the yoke 30 is crushed by repeated contact, and the pulling stroke of the spring portion 62 of the cantilever support plate 60 increases. Accordingly, the average value of the combined spring constant of the driven spring portion 102 of the attachment plate 100 and the spring portion 62 of the cantilever support plate 60 is reduced in the above-described pull-in stroke.
[0024]
Specifically, the attachment plate 100 is a cantilever plate spring whose base end is supported so as to face the back surface of the cantilever support plate 60, and the attachment plate 100, the cantilever support plate 60, A film 110 is sandwiched between them. That is, the lower plate is fixed to the vertical portion 12 of the yoke 10 with the bolt 80 so that the accessory plate 100 and the cantilever support plate 60 stacked with the film 110 interposed therebetween are sandwiched between the yoke 70 and the yoke 10. Has been. Here, the attachment plate 100 may be an elastic material and does not necessarily have a high magnetic permeability. Since the most worn portion of the film 110 is a sliding contact portion with the vicinity of the upper end corner of the cover plate 100, the upper end position of the film 110 is set higher than the upper end position of the cover plate 100 as shown in FIG. It is preferable to do.
[0025]
As shown in FIG. 2, a hole 101 for inserting a bolt 80 is formed in the lower portion of the accessory plate 100, and the upper portion is comb-shaped so as to face the spring portion 62 of the cantilever support plate 60. The driven spring portion 102 is formed. The film 110 must be worn by repeated pulling operation of the spring portion 62 of the cantilever support plate 60. For example, a plastic film made of polyimide, fluorine resin, or the like is used.
[0026]
In this embodiment, when the number of repetitions of the pull-in operation of the spring portion 62 of the cantilever support plate 60 is small and the film 110 is not yet worn, the driven spring portion 102 of the attachment plate 100 is the spring of the cantilever support plate 60. From the beginning of the drawing of the part 62, it elastically deforms in synchronization with the spring part 62 of the cantilever support plate 60. Therefore, the combined spring constant K of the driven spring portion 102 of the attachment plate 100 and the spring portion 62 of the cantilever support plate 60 is the spring constant K1 of the spring portion 62 of the cantilever support plate 60 over the entire range of the pull-in stroke ( K1 + K2 obtained by adding the position of the printing pin 65) and the spring constant K2 of the driven spring portion 102 of the attached plate 100 (value converted to the position of the printing pin 65).
[0027]
On the other hand, the number of repetitions of the retraction operation of the spring portion 62 of the cantilever support plate 60 increases, and the contact portion between the back surface of the spring portion 62 of the cantilever support plate 60 and the magnetic adsorption surface 32b of the yoke 30 comes into contact. When the pulling stroke of the spring part 62 of the cantilever support plate 60 is increased due to repetition, the wear of the film 110 is progressively thinned, and the spring part 62 of the cantilever support plate 60 is initially attached. The driven spring portion 102 of the plate 100 does not start elastic deformation, and the driven portion starts after the spring portion 62 of the cantilever support plate 60 is elastically deformed by the wear amount (thickness reduction) of the film 110.
[0028]
Therefore, at the beginning of the pull-in, the combined spring constant K of the driven spring portion 102 of the attachment plate 100 and the spring portion 62 of the cantilever support plate 60 is the spring constant K1 of only the spring portion 62 of the cantilever support plate 60. (K = K1).
[0029]
Thereafter, when the driven spring portion 102 of the attachment plate 100 starts to follow, the spring constant K2 of the driven spring portion 102 of the attachment plate 100 is added, and the combined spring constant K becomes K = K1 + K2. Therefore, the average value of the combined spring constant K in the above-described pull-in stroke is reduced. When described with reference to FIG. 12, even if the point b in FIG. 12 moves to the right, the point a does not move upward. That is, the elastic restoring force F2 within the pulling stroke does not increase, and ΔFmin, which is the minimum value ΔF obtained by subtracting the elastic restoring force F2 from the magnetic attractive force F1 by the permanent magnet 20, does not become negative. For this reason, the situation where the printing pin 65 does not return can be avoided, and the life is extended.
[0030]
Further, since it is possible to avoid the elastic restoring force F2 within the pulling stroke from increasing with time, it is necessary to set the magnetic attraction force F1 large in order to prevent ΔFmin from becoming negative (in FIG. 12, F1 Therefore, the exciting current flowing through the coil 40 to cancel the magnetic attractive force F1 can be reduced.
[0031]
Furthermore, it is not necessary to coat the cantilever support plate 60 and the yoke 30 with a hard film such as titanium nitride or chromium nitride, and the cost increase can be suppressed. Further, only the film 110 and the attachment plate 100 need be added, and the cost increase can be suppressed.
[0032]
An example of the dimension of the spring part 62 of the cantilever support plate 60 in this embodiment is shown in FIG. 3, and an example of the dimension of the driven spring part 102 of the accessory plate 100 is shown in FIG. Both use tool steel (SK5) as the material and Young's modulus E = 196000 N / mm ² . In this numerical example, the spring constants K1 and K2 at the position of the printing pin 65 are K1 = 7.546 N / mm and K2 = 1.274 N / mm. The combined spring constant K in the case of close contact through the film 110 is
K = K1 + K2 = 8.82 N / mm.
[0033]
Next, the spring of the cantilever support plate 60 when the pull-in stroke of the spring portion 62 of the cantilever support plate 60 is increased by 0.04 mm from 0.3 mm to 0.34 mm (= 0.3 + 0.04). FIG. 6 shows a deflection curve of the unit 62 alone. If the film 110 having the same thickness as the deflection of 0.026 mm at the tip position of the attachment plate 100 is used, the attachment plate 100 does not act as a spring when the film 110 is worn and a hole is formed. Therefore, the composite spring constant K decreases from 8.82 N / mm to 7.546 N / mm at which the splicing plate 100 does not function. As a result, the elastic restoring force F2 = 2.205N (= 8.82 × 0.25) at the initial ΔFmin and the elastic restoring force F2 = 2.188 at ΔFmin when the pull-in stroke is increased by 0.04 mm ( = 7.546 × (0.25 + 0.04)) is substantially the same, ΔFmin> 0 can be maintained, and even if the retracting stroke of the spring portion 62 of the cantilever support plate 60 is increased by 0.04 mm, the service life is reached. I never did.
(Second Embodiment)
Only the features of the second embodiment are shown in FIG. Since the configuration other than that shown in FIG. 6 is the same as that of the first embodiment, the reference numerals in FIG. 1 are quoted as they are in the following description. In this embodiment, the support plate 100 is directly adhered to the back surface of the base end portion side of the cantilever support plate 60 (sliding contact state) without using the film 110 and is cantilever supported together with the cantilever support plate 60. Thus, the support plate 100 is made of a softer material than the cantilever support plate 60. For example, the material of the cantilever support plate 60 is tool steel (SK5, Vickers Hv500), and the material of the splicing plate 100 is spring phosphor bronze (Hv250).
[0034]
In this embodiment, the sliding contact portion of the soft support plate 100 with the cantilever support plate 60 is mainly consumed by repeating the pull-in operation of the spring portion 62 of the cantilever support plate 60. For this reason, the contact portion between the back surface of the spring portion 62 of the cantilever support plate 60 and the magnetic adsorption surface 32b of the yoke 30 is crushed by repeated contact, and the pull-in stroke of the spring portion 62 of the cantilever support plate 60 increases. However, in response to this, a depression is generated in the soft baffle plate 100, and the start timing of the driven spring portion 102 of the baffle plate 100 with respect to the start of bending of the spring portion 62 of the cantilever support plate 60 is delayed. Therefore, the elastic restoring force F2 within the pull-in stroke does not increase, and ΔFmin, which is the minimum value of ΔF, does not become negative. For this reason, the situation where the printing pin 65 does not return can be avoided, and the life is extended. Further, the same effect as that of the first embodiment can be obtained, for example, only the attachment plate 100 is added and the cost can be suppressed. In addition, since the base end part of the spring part 62 of the cantilever support plate 60 that receives the printing reaction force is not worn, breakage or the like does not occur.
(Other embodiments)
The present invention is not limited to the configuration of the above embodiment. For example, the present invention includes the following embodiments.
(1) The yoke 70 constituting a part of the magnetic circuit is provided to increase the magnetic flux density in the gap, and is not necessarily required.
(2) A plurality of attachment plates 100 may be provided.
[0035]
【The invention's effect】
As described above, according to the first to third aspects of the invention, the cantilever support plate includes the follower plate formed with the driven spring portion that is pushed and bent by the base end portion of the spring portion of the cantilever support plate. As the contact portion between the back surface of the spring portion of the plate and the magnetic adsorption surface of the yoke is crushed by repeated contact, and the retracting stroke of the spring portion of the cantilever support plate increases, the follower spring portion and cantilever support of the support plate Since the average value in the pulling stroke of the combined spring constant with the spring part of the plate is reduced, it is low-cost and does not require a large excitation current in the coil, so it has a long life and is free to print A head can be realized.
[0036]
Further, according to the invention according to claim 2, since only the film and the attachment plate are added to the conventional configuration, and according to the invention according to claim 3, only the attachment plate is required, so that Low cost can be realized.
[Brief description of the drawings]
FIG. 1 is a front view showing a schematic configuration of a first embodiment of the present invention.
FIG. 2 is an external view of the accessory plate viewed from the front surface side (left side of FIG. 1).
FIG. 3 is a diagram illustrating an example of dimensions of a spring portion of a cantilever support plate.
FIG. 4 is a diagram illustrating an example of a dimension of a driven spring portion of a splicing plate.
FIG. 5 is a diagram showing a deflection curve of a single spring portion of a cantilever support plate.
FIG. 6 is a front view showing the characteristic part of the second embodiment.
FIG. 7 is a front view showing a schematic configuration of a conventional release print head.
8 is a right side view showing a connector portion of the print head of FIG. 7. FIG.
9 is an external view of a cantilever support plate as viewed from the front surface side (left side of FIG. 7).
FIG. 10 is a view showing an appearance of a yoke.
FIG. 11 is a diagram illustrating an appearance of a printed board.
FIG. 12 is an explanatory diagram of magnetic attractive force and elastic restoring force.
FIG. 13 is a diagram illustrating an example of dimensions of a spring portion of a cantilever support plate.
14 is a diagram showing a magnetic attractive force and an elastic restoring force in the numerical example of FIG.
[Explanation of symbols]
10, 30, 70 Yoke 20 Permanent magnet 32 Divided yoke portion 32a Yoke teeth 32b Magnetic attracting surface 35 Bobbin 40 Coil 45 Fin 50 Print board 55 Connector 60 Cantilever support plate 62 Spring portion 65 Printing pin 80 Bolt 90 Ink ribbon 91 Platen 92 Paper 100 Attached plate 110 Film

Claims (1)

A cantilever support plate having a printing pin projecting from the front surface of the spring portion;
A magnetic circuit that pulls the spring portion of the cantilever support plate against its elastic force by a magnetic attraction force by a permanent magnet, and attracts the back surface of the spring portion of the cantilever support plate to the magnetic adsorption surface of the yoke; A release-type print head comprising a coil for generating a magnetic flux that cancels out the magnetic flux generated by the flowing permanent magnet,
A cantilevered leaf spring in which a driven spring portion that is pushed and bent by the proximal end portion of the spring portion of the cantilever support plate is formed and the proximal end is supported so as to face the back surface of the cantilever support plate. An attachment plate, and a film that is sandwiched between the attachment plate and the cantilever support plate and is worn by repeated pull-in operations of the spring portion of the cantilever support plate,
As the contact portion between the back surface of the spring portion of the cantilever support plate and the magnetic adsorption surface of the yoke is crushed by repeated contact, the film wears as the pulling stroke of the spring portion of the cantilever support plate increases. A release-type print head configured to reduce an average value of the combined spring constant of the driven spring portion of the attachment plate and the spring portion of the cantilever support plate in the pull-in stroke.

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