JPH02188268A - Thermal printer - Google Patents

Abstract

PURPOSE:To enable a pressing force to be varied by a construction wherein a pressure cam having a sliding surface extending between the both sides of a straight line connecting the center of a rotating shaft and the center of a support shaft is fixed to the rotating shaft with a thermal printing head being mounted, and the sliding surface is pressed by a pressure pin. CONSTITUTION:When an operation lever 13 is rotated in a direction of an arrow C and a pressure pin 14 abuts against a claw part 162, the pressure pin 14 is disposed on a position 14a. The pressure pin 14 pressed up by a spring force through the operation lever 13 presses a sliding surface 161, whereby a force to rotate a rotating shaft 12 is shown by a product Fa of a base Ya of a perpendicular and a pressing force. Then, the operation lever 13 is rotated in a direction of an arrow D until the pressure pin 14 is nested into a notch groove 164. The rotating force of the rotating shaft 12 is shown by a product Fb of a base Yb of a perpendicular and a pressing force. The length dimensions of the bases of the perpendiculars meet a formula of Ya>Yb; therefore, a formula Fa>Fb is established because the pressing forces are approximately the same. The force to rotate the rotating shaft 12 when the pressure pin 14 is disposed on the position 14a is large in comparison with that when it is disposed on a position 14b.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a printing device that prints using a thermal print head, and more specifically, by operating one operating lever,
The present invention relates to a thermal printing device that changes the pressure applied to a thermal printing head and separates the thermal printing head from a printing paper.

<Prior art> Computers such as word processors require the use of a printer to print the results of their execution, but if the computer and printer are to be integrated, it is easy to downsize the computer. Generally, a thermal printing type printer is used.

In order to always perform the best printing using this printer, it is necessary to change the pressing force of the thermal print head (hereinafter simply referred to as head) depending on the thickness and type of printing paper. Therefore, an operating lever is provided to change the pressing force.

<Problems to be Solved by the Invention> As mentioned above, in thermal printing printers, an operating lever is provided to change the pressing force of the head against the printing paper. During the replacement period, it is necessary to keep the head away from the print paper, so it is also necessary to provide a dedicated lever for lifting the head.

Therefore, two levers are attached to the printer, and when operating the printer, one of the two levers must be selected and operated, which creates the possibility of erroneous operation and also causes the head to separate from the printing paper. When moving the head, the head must be lifted against the force that is trying to press it against the print paper, so if the setting is such that the pressing force is large, the lever for removing the head will have to move slowly, making it difficult to operate. The problem was that it was getting worse.

The present invention was devised to solve the above-mentioned problems, and its purpose is to provide a thermosensitive device that can change the pressing force and detach the head from the printing paper by light operation of a single lever. The purpose is to provide a printing device.

<Means for Solving the Problems> In order to solve the above problems, the thermal printing device of the present invention has a thermal printing head attached to a rotating shaft, and by rotating this rotating shaft, the pressure of the thermal printing head against the printing paper is reduced. Applied to a thermal printing device in which the temperature changes, the control lever rotates around a support shaft, is supported by the control lever, is pushed by a spring in a direction away from the support shaft, and when the control lever is rotated, the control lever rotates around a support shaft. A press pin that moves with rotation, is attached to a rotating shaft, and its sliding surface extends across both sides of a straight line connecting the center of the rotating shaft and the center of the support shaft, and extends around the support shaft. A configuration is adopted in which the sliding surface of the pressing cam is pressed by a pressing pin.

<Operation> Since the sliding surface of the pressing cam extends across both sides of the straight line connecting the rotating shaft and the support shaft, when the sliding surface of the pressing cam is pressed by the pressing pin, the pressure When the position changes from one side of the above straight line to the other side, the rotation of the rotating shaft caused by the pressing of the sliding surface of the pressing cam changes in direction from one side to the other side. Change.

In other words, the direction in which the thermal print head is pressed against the printing paper,
The thermal printing head is moved away from the printing paper.

When the rotating direction of the rotating shaft is in the direction of pressing the thermal print head against the printing paper, the leg of the perpendicular line drawn from the center of the rotating shaft is , changes its length in response to changes in the pressing position.

In addition, since the shape of the sliding surface of the pressing cam approximates an arc centered on the support shaft, the pressing force from the pressing pin remains almost constant even when the pressing position changes. Become.

On the other hand, the magnitude of the rotational force applied to the rotating shaft is expressed as the product of the length of the perpendicular leg (which becomes the rotational moment) and the pressing force. Therefore, when the pressing position of the pressing pin changes, the pressing force does not change, only the rotational moment relative to the rotating shaft changes, so the rotational force applied to the rotating shaft due to the pressing changes depending on the position. The size changes.

<Example> FIG. 1 is a partially fragmented external perspective view showing an example of the present invention, and FIG. 2 is a sectional view taken along line AA shown in FIG. 1.

In the figure, two rotating shafts 12 are arranged parallel to each other and facing each other.
The head mounting surface 1 is rotatably supported by a chassis 22.23, which is a metal plate, and is located approximately at the center of the rotating shaft 12 inside the chassis 22.23.
21 is formed. And this head mounting surface 121
One end of a head mounting bolt 211 is screwed into a screw hole 1211 formed in the center of the head mounting bolt 211 .

The other side of the head mounting bolt 211 is inserted into a shaft hole formed in the head mounting bracket 21, and the head mounting bracket 21 is centered around the head mounting bolt 211.
Head mounting bolt 2 so that it can rotate around it.
11. Further, a ring-shaped groove is formed at the tip of the head mounting bolt 211 that protrudes from the side surface of the head mounting bracket 21, and an E-ring 212 is inserted into this groove to prevent the head mounting bracket 21 from coming off.
is embedded.

The thermal printing head 11 includes a printing unit main body 1 consisting of a heating element, etc.
12, a heat sink 113 attached to the upper part of the printing part main body 112, and a cover part 111 attached to the lower part of the printing part main body 112 and provided for protecting electrical components.
It is composed of The heat sink 113 is fixed to the head mounting bracket 21.

At the bottom of the printing part of the thermal print head 11, a hard rubber plate is rotatably supported by the chassis 22, 23 by a rotating shaft 241 fixed at its center, and rotated by a drive device (not shown). A platen roller 24 is provided, and this platen roller 24
A printing paper 18, which is stored in a roll in the chassis 22, 23 and whose leading end is pulled out, is sandwiched between the printing paper 18 and the thermal printing head 11.

A pressing cam 16 formed by punching a metal plate with a thickness of several mm is attached to the end of the rotating shaft 12 that passes through a bearing hole 231 formed in the chassis 23 and protrudes to the outside of the chassis 22.23. It is being

As shown in FIG. 3, the pressing cam 16 includes a support portion 165 fixed to the end of the rotating shaft 12, and a substantially arch-shaped arm portion 166, and each end of the arm portion 166 has a Claw portions 162 and 163 serving as stoppers are formed. The inside of the arch-shaped arm portion 166 is a sliding surface 161, and this sliding surface 161 is formed on the rotating shaft 1.
2 and the center O of the support shaft 15, and a notched groove 164 is formed approximately in the middle thereof.

The lower part 136 of the operating lever 13 is constituted by a hollow prism with a substantially square cross section, and the lowermost portions of the two side walls 132 and 133 parallel to the chassis 23 are provided with identical lengths at the same position. A hole 135 is formed. Then, toward the top, the hollow portion is closed at approximately the center, and the side wall 134 that is perpendicular to the chassis 23 is replaced by the side wall 132 that is parallel to the chassis 23.
It has been removed leaving a thickness of 133 mm.

The side wall 133 on the side closer to the chassis 23 of the side walls 132 and 133 parallel to the chassis 23 has a length necessary to form the support portion 167 that supports the pressing pin 14 above the position where the hollow portion is closed. The other side wall 132 is elongated, and its tip 131 is finished in a rounded shape for better finger contact during operation.

The support portion 137 of the side wall 133 and the support portion 137
A support hole 138 is formed in the opposing side wall 132 for rotatably supporting the press pin 14, which is formed into a cylindrical shape with a thick center portion and thin ends.

The support shaft 15 has a flat dish-shaped head 151, a smooth cylindrical center portion 152 that is slightly thinner than the short diameter of the long hole 135 of the operating lever 13, and an end portion opposite to the head 151. A bolt in which a thread 153 is formed,
It passes through the elongated hole 135 of the operating lever 13 and is then screwed into a nut 153 which also serves as a sleeve and has a thread formed on its inner peripheral surface, and is fixed to the chassis 23 by the nut 153 and nut 154.

One end of the hollow part of the operating lever 13 has a support shaft 15.
, and the other end closes the hollow part 1
A spring 17 is provided that presses against 39.

The operation of one embodiment of the present invention having the above configuration will be described below.

Since the operating lever 13 is pushed up in the direction of arrow B by the spring 17, the pressing pin 14 rotatably supported by the operating lever 13 presses the sliding surface 161 of the pressing cam 16. In addition, the operation lever 13
When rotated around the support shaft 15, the sliding surface 1
The pressing position relative to 61 will change.

Now, when the operating lever 13 is rotated in the direction of arrow C until the pressing pin 14 hits the claw portion 162 and does not rotate any further, the pressing pin 14 moves to the position 14a in FIG.
It will come to the position shown. At this time, via the operating lever 13,
Press pin 1 pushed up by the force of spring 17
4 presses the sliding surface 161 to rotate the rotating shaft 12.
The force that tries to rotate is the foot Y of a perpendicular line drawn to the straight line Xa connecting the center of the pressing pin 14 and the center 0 of the support shaft 15.
It is expressed as the product of the length a and the pressing force by the spring 17. Let the value of this product be Fa.

Next, move the operating lever 13 in the direction of the arrow to release the pressure pin 1.
4 until it fits into the notch groove 164 (the third
In FIG. 14b), the rotational force of the rotating shaft 12 at this time is similarly expressed as the product of the length of the leg yb of the perpendicular line drawn to the straight line xb and the pressing force. Let the value of this product be Fb.

On the other hand, the lengths Za and Zb between the center of the pressing pin 14 and the center O of the support shaft 15 are determined when the shape of the sliding surface 161 is
Since the shape is approximated to a circular arc with the center at , the lengths Za and Zb are approximately equal to each other. Therefore, the force with which the pressing pin 14 presses the sliding surface 161 is also approximately equal.

When considering the above product values Fa and Fb, the length of the legs of each perpendicular line is Ya>Yb, and the pressing force is approximately equal in both cases, so the product value is Fa and Fb satisfy Fa>Fb. In other words, when the pressing pin 14 is located at 14a, the force that rotates the rotating shaft 12 is large (and when it is located at 14b, it is smaller.This rotational force of the rotating shaft 12 is
This is also the force that presses the pad 11 against the printing paper 18 for thermal printing, so by operating the operating lever 13, the pressing pin 4
When the position of is changed, the force of the pad 11 to press against the printing paper 18 for thermal printing changes corresponding to the change.

Furthermore, when the pressing pin 14 reaches the position shown at 14c in FIG. 3 due to further rotation of the operating lever 13 in the direction of the arrow, the force that attempts to rotate the operating lever 13 further is absorbed by the claw. 163 in the direction of arrow C, the rotating shaft 12 rotates in the direction of arrow E.

At this rotational position, the pressing position is at the rotating shaft 1.
2 and the center O of the support shaft 15, the pressing force by the spring 17 is on the opposite side of the straight line connecting the center of the rotation shaft 12
further rotates in the direction of arrow E.

Therefore, remove your finger from the operating lever 13 and
Even if the force applied to 3 is removed, the rotating shaft 12 remains rotated in the direction of the arrow E, and the thermal printing pad 11 is kept separated from the printing paper 18.

Next, after the printing paper 18 has been replaced, the operating lever 1
3 in the direction of arrow C, the thermal print head 11 is pressed against the printing paper 18 because a force is applied to rotate the rotating shaft 12 in the direction of the arrow C, as described above.

Note that the present invention is not limited to the above embodiment, and the pressing pin 14 is rotatably supported with respect to the operating lever 13, and the pressing force of the spring 17 is applied to the operating lever 1.
3, the pressure pin 14 is supported movably in the longitudinal direction of the operating lever 13, and the force of the spring 17 is directly applied to the pressure pin 14. (In this case, the hole provided at the bottom of the operating lever 13 for inserting the support shaft 15 may be a round hole instead of a long hole).

Furthermore, the shape of the sliding surface 161 has been described as an arcuate shape that approximates a circular arc centered on the support shaft 15, but other shapes such as a straight line are also possible. It is.

<Effects of the Invention> The thermal printing device according to the present invention is supported by an operating lever that rotates around a support shaft, and is provided with a pressing pin that is pressed by a spring in a direction away from the support shaft, and the sliding surface is rotated. A pressing cam, which extends across both sides of a straight line connecting the center of the shaft and the center of the support shaft, and has a shape similar to an arc centered on the support shaft, is fixed to the rotating shaft to which the thermal print head is attached. At the same time, since the sliding surface is pressed by a pressing pin, rotation of the operating lever causes a change in the magnitude of the force applied to the rotating shaft and a change in the direction of that force. By applying a light force to the lever, it is possible to vary the pressing force and to remove the thermal print head from the print paper.

[Brief explanation of the drawing]

FIG. 1 is a partially fragmented external perspective view showing one embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA shown in FIG. 1, and FIG. 3 shows the pressing position of the pressing pin and the rotation of the rotating shaft. FIG. 11... Thermal print head 12... Rotating shaft

Claims (1)

[Claims] (1) In a thermal printing device in which a thermal printing head is attached to a rotating shaft and the pressure of the thermal printing head against the printing paper changes by rotating this rotating shaft, an operating lever that rotates around a support shaft, and a pressing pin that is supported by the operating lever and is pressed by a spring in a direction away from the support shaft and moves with the rotation of the operating lever; and a pressing pin that is attached to the rotating shaft and that slides. a pressing cam whose surface extends across both sides of a straight line connecting the center of the rotation shaft and the center of the support shaft, and is formed in a shape approximating an arc centered on the support shaft; A thermal printing device characterized in that the pressing pin presses the sliding surface of the pressing cam.