JPH05262006A - Equalizer for printer - Google Patents

Abstract

PURPOSE:To miniaturize the whole device by installing an equalizer cam, which is driven and rotated by a driving section rotatably mounted to a head holder and in which a cam edge is abutted selectively against an elastic body and an abutting body. CONSTITUTION:When an equalizer cam is 18 rotated and the cam edges 31a of the equalizer cam are abutted against a leaf spring 32, the equalizer 31 is pushed down by the elasticity of the leaf spring 32, and a head holder 7 is turned downward centering around a support shaft 10. Consequently, a pinch roller 12 is abutted against a feed roller 11, and a printing head 3 is faced oppositely to a platen 1. As a result, the equalizer 31 is revolved, and the cam corners 31a are only abutted selectively against the leaf spring 32 and an abutting body 34, thus easily setting a form 23 without largely burdening the leaf spring 32. Accordingly, a structure, in which the head holder 7 is rotated, and a structure, in which the pinch roller 12 is abutted against the feed roller 11, are simplified extremely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an equalizer device for a printer, which keeps a space between a sheet and a print head constant regardless of the number and thickness of sheets to be printed.

[0002]

2. Description of the Related Art An example of a conventional device of this type is shown in FIGS. First, a plate-shaped platen 1 is provided, and a print head 3 which is a dot printer head is arranged to face the platen 1 via a paper guide path 2. The print head 3 is fixed to a head carrier 5 slidably held by two carrier shafts 4 arranged in parallel with each other. Here, the carrier shaft 4a located near the print head 3 is fixedly provided to the printer body (not shown) as a whole.
The connecting portion of the head carrier 5 to the carrier shaft 4a is an oval hole 6. With respect to the platen 1, the longitudinal direction of the oval hole 6 is different from that of the print head 3.
This is the direction in which the tip end portion 3a of the above moves toward and away from each other. On the other hand, the carrier shaft 4 b located at a position away from the print head 3 forms a part of the head holder 7. The head holder 7 is formed by connecting a pair of flat plates 8 with the carrier shaft 4 and the equalizer shaft 9 which are arranged in parallel to each other. It is supported freely.

Therefore, a feed roller 11 driven by a drive unit (not shown) is rotatably provided so as to be adjacent to the platen 1 and positioned at a position contacting the sheet guide path 2 in the same direction as the platen 1. ing. The head holder 7 has a feed roller 11
A pinch roller 12 is rotatably attached at a position where the pinch roller 12 can be freely contacted and separated via the paper guide path 2. here,
When the pinch roller 12 comes into contact with the feed roller 11, the respective parts are positioned so that the tip 3a of the print head 3 faces the platen 1 with a slight gap.

Next, a structure for rotating the head holder 7 will be described. First, an equalizer lever 13 is provided near the equalizer shaft 9 so as to be rotatable around a lever support shaft 14. The lever support shaft 14 is attached to the printer main body (not shown) so that the lever support shaft 14 is axially aligned with the equalizer shaft 9. Further, a curved pressing surface 15 is formed on a part of the equalizer lever 13, and the respective parts are positioned so that the pressing surface 15 comes into contact with the equalizer lever 13 as the equalizer lever 13 rotates. ing. On the other hand, a flat contact surface 16 is formed at a portion of the equalizer lever 13 that faces the pressing surface 15 across the lever support shaft 14. A cam shaft 17 is rotatably attached to the main body of the printer so as to be axially aligned with the equalizer shaft 9, and an equalizer cam 18, which is a peripheral cam, is fixed to the center of the cam shaft 17. Cam mountain 18 of cam 18
It is configured that a comes into contact with the contact surface 16.

Next, a structure for ensuring the pinch pressure of the pinch roller 12 with respect to the feed roller 11 will be described. First, pressure cams 19 which are peripheral cams smaller than the equalizer cam 18 are fixed to both ends of the cam shaft 17 in the same direction as the equalizer cam 18. In addition, the plate 8
A pair of spring supports 20 that are bent outward are formed on the top of the tip of the pair of spring supports 20. The pair of spring supports 20 are located slightly below the straight line connecting these spring supports 20 and the upper surface of the peripheral edge of the pressure cam 19. The pressure pin 21 is provided on the printer body. And these pressure pins 21
The pair of leaf springs 2 are provided between the upper surface of the peripheral edge of the pressure cam 19 and the spring support body 20 so that the leaf springs 2 are bent.
2 is held.

In such a structure, the print head 3 is moved in the line direction and the paper 2 is formed by the feed roller 11.
Predetermined printing is performed on the paper 23 in combination with the conveyance of No. 3.

On the other hand, to set the paper 23, the head holder 7 is rotated to separate the pinch roller 12 from the feed roller 11, and the tip 3a of the print head 3 is retracted from the platen 1. In order to rotate the head holder 7, the drive shaft (not shown) is driven to rotate the cam shaft 17, and the cam crest 18a of the equalizer cam 18 is brought into contact with the contact surface 16 of the equalizer lever 13. Then, the equalizer lever 13 rotates around the lever support shaft 14 and the equalizer shaft 9 is pressed against the pressing surface 15, and the head holding body 7 rotates upward about the support shaft 10. As a result, the pinch roller 12 is separated from the feed roller 11, the tip 3a of the print head 3 is retracted from the platen 1, and the paper 23 can be set. The state at this time is shown in FIG.

On the other hand, in order to return the print head 3 to the print position, the cam shaft 17 is rotated again, and the cam crest 18a of the equalizer cam 18 is retracted from the contact surface 16 of the equalizer lever 13. Then, due to the weight of the print head 3 or the like and the restoring force of the leaf spring 22, the equalizer shaft 9
While pushing down the pressing surface 15 of the equalizer lever 13, the head holder 7 rotates downward about the support shaft 10. As a result, the feed roller 11 and the pinch roller 1
2 and the tip portion 3a of the print head 3 faces the platen 1 with a slight gap. The state at this time is shown in FIG.
Shown in.

However, when the paper 23 is positioned between the feed roller 11 and the pinch roller 12, the feed roller 11 and the pinch roller 12 are changed depending on the number and thickness of the paper 23.
And the distance between the tip 3a of the print head 3 and the platen 1 changes accordingly, and the distance between the tip 3a of the print head 3 and the paper 23 becomes constant. As a result, the paper 2 of the print head 3 at the time of printing
The impact pressure on No. 3 becomes constant and the printing quality is improved.

On the other hand, in the state shown in FIG.
Since the cam crest of the pressure cam 19 abuts on the other end of the plate spring 2 to ensure a certain amount of bending of the leaf spring 22, the restoring force of the leaf spring 22 secures the pinch pressure of the pinch roller 12 with respect to the feed roller 11. .. In contrast, Fig. 3 (b)
In the state shown in (1), the cam crest of the pressure cam 19 is retracted from the other end of the leaf spring 22, so that the amount of bending of the leaf spring 22 is reduced and the load on the leaf spring 22 is reduced. In this way, the leaf spring 22 is synchronized with the rotational movement of the head holder 7.
The amount of deflection of is adjusted.

[0011]

The equalizer cam 18 and the pressure cam 19 are fixed to the same cam shaft 17 as a structure for adjusting the amount of bending of the leaf spring 22 in synchronization with the rotational movement of the head holder 7. , A structure for rotating the head holder 7 and a pinch roller 12 for the feed roller 11
Is related to the structure for abutting. However, since these two structures are both complicated, there is a drawback that the structure becomes complicated.
For this reason, there is an inconvenience that the number of parts increases and the entire apparatus becomes large.

[0012]

According to the present invention, there is provided a head holder for holding a print head at a position facing a platen via a paper guide path, and displacing the print head in a direction of moving the print head closer to and away from the platen. The feed roller is disposed in a position in contact with the paper guide path in the same direction as the platen, and the feed roller is rotatably mounted on the head holder and positioned so as to be in contact with and separated from the feed roller. A pinch roller that keeps the print head and the platen at a predetermined distance by contacting each other, an elastic body that has an elastic direction oriented substantially in the same direction as the displacement direction of the head holder, and a print head on this elastic body. The abutting body, which is arranged in a position facing the platen in the direction close to the platen, is rotatably attached to the head holding body and is driven by the driving unit to rotate. Cam lobes are provided and selectively abuts the equalizer cam and the elastic member and the abutting member in.

[0013]

Therefore, when the equalizer cam is driven and rotated by the drive unit and its cam crest is brought into contact with the contact body, the equalizer cam is displaced in the direction away from the contact body. Along with this, the head holder is also displaced in the same direction, the pinch roller is separated from the feed roller, and the print head is retracted from the platen. As a result, the paper guide path is opened and the paper can be set. And at this time,
Since the cam peaks of the equalizer cam do not come into contact with the leaf spring, the leaf spring does not largely bend and the load on the leaf spring is reduced.
On the other hand, when the equalizer cam is rotated and its cam crest is brought into contact with the elastic body, the elastic body exerts a biasing force on the equalizer cam in a direction away from the elastic body, and the feed roller is brought into contact with the pinch roller. The pinch pressure of the pinch roller is secured. At this time, the distance between the feed roller and the pinch roller changes according to the number of sheets and the thickness of the paper. Therefore, the distance between the platen and the print head also changes, and the distance between the paper and the print head changes. Becomes constant.
In this way, the turning operation of the head holding member and the pinch pressure of the pinch roller can be secured only by selectively bringing the cam peak of the equalizer cam into contact with the leaf spring and the contact member. Therefore, the structure can be simplified.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The same parts as those described with reference to FIGS. 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted. In this example,
As a structure for rotating the head holding body 7, the equalizer shaft 9, the equalizer lever 13, the cam shaft 17, and the equalizer cam 18 are not provided. Further, as the structure for bringing the pinch roller 12 into contact with the feed roller 11, the cam shaft 17, the pressure cam 19, the spring support body 20, the pressure pin 21, and the leaf spring 22 are not provided.

That is, the carrier shaft 4b is provided on the head holder 7 at a position adjacent to the carrier shaft 4b.
The cam shaft 30 is rotatably attached so that the axial center directions thereof coincide with each other. At both ends of the cam shaft 30, the plate 8
A pair of equalizer cams 31, which are peripheral edge cams, are fixed to the outside of the. Above the equalizer cams 31, a pair of leaf springs 3 as elastic bodies are provided.
2 is sandwiched between a pair of support pins 33 fixedly provided on the printer body, and below the equalizer cam 31, a flat plate-shaped contact body 34 fixedly provided on the printer body is provided. Are arranged. Then, as the equalizer cam 31 rotates, the cam mountain 31a
The respective parts are positioned so that they selectively contact the leaf spring 32 and the contact body 34.

Next, a pulley 35 is attached to one end of the cam shaft 30 and one end of the support shaft 10 of the head holder 7.
Are fixed, and a belt 36 is stretched between these pulleys 35. A motor 37 as a drive unit is provided, and a rotary shaft 37a of the motor 37 and the support shaft 10 are connected via a power transmission mechanism 38.

In such a structure, when the equalizer cam 31 is rotated and its cam crest 31a is brought into contact with the plate spring 32, the pinch roller 12 comes into contact with the feed roller 11 as shown in FIG. When the ridge 31a is brought into contact with the contact body 34, the pinch roller 12 separates from the feed roller 11 and the state shown in FIG. Therefore, FIG. 1A shows a state after the paper 23 is set, and FIG. 1B shows a state when the paper 23 is set.

In order to rotate the equalizer cam 31, the motor 37 is driven. Then, the driving force is transmitted to the cam shaft 30 via the power transmission mechanism 38 and the belt 36, and the equalizer cam 31 rotates. When the equalizer cam 31 rotates and its cam crest 31a comes into contact with the contact body 34, the equalizer cam 31 is pushed up, and the head holding body 7 rotates upward about the support shaft 10. As a result, the pinch roller 12 is separated from the feed roller 11, and the print head 3 is retracted from the platen 1.
The state becomes as shown in (b). At this time, since the cam crests 31a of the equalizer cam 31 do not contact the leaf spring 32, the leaf spring 3
2 does not largely bend, and the load on the leaf spring 32 is reduced. On the other hand, when the equalizer cam 31 rotates and the cam crest 31a contacts the leaf spring 32, the leaf spring 3
The equalizer cam 31 is pushed down by the elasticity of 2,
The head holder 7 rotates downward about the support shaft 10. As a result, the feed roller 11 and the pinch roller 1
1 and the print head 3 faces the platen 1.
The state becomes as shown in (b).

As described above, in this embodiment, the equalizer cam 31 is rotated and the cam crest 31a is selectively brought into contact with the leaf spring 32 and the abutment body 34, whereby a large load is exerted on the leaf spring 32. The paper 23 can be easily set without hanging. Therefore, the structure for rotating the head holder 7 and the structure for bringing the pinch roller 12 into contact with the feed roller 11 are extremely simplified,
The structure is simplified. As a result, it is possible to reduce the number of parts and downsize the entire apparatus.

In practice, the head holder 7
The structure may not be displaced by rotating about the support shaft 10 but displaced by sliding, and the equalizer cam 31, the leaf spring 32, the contact body 34, and the like are provided in pairs. Alternatively, only one structure may be provided for each.

[0021]

According to the present invention, a head holder for holding a print head facing a platen and a pinch roller abutting against a feed roller is provided, and has elasticity in a direction substantially the same as the displacement direction of the head holder. An elastic body and an abutting body are faced to each other, and a cam mountain of an equalizer cam rotatably provided on the head holding body is brought into abutment with the abutting body to separate the pinch roller from the feed roller and thereby the print head from the platen. The equalizer cam is selected between the contact body and the elastic body because the pinch roller is brought into contact with the feed roller so that the print head faces the platen by retracting the cam and the cam lobe against the elastic body. The head holder can be rotated and the pinch roller can be brought into contact with the feed roller by merely bringing the head holder into contact with the head holder. Can be simplified, an effect such as can be achieved and the overall size of the reduction and apparatus parts.

[Brief description of drawings]

1A and 1B show an embodiment of the present invention, in which FIG. 1A is an overall side view showing a state where sheets are set, and FIG. 1B is an overall side view showing a state when sheets are set.

FIG. 2 is an overall perspective view.

3A and 3B show an example of a conventional example, FIG. 3A is an overall side view showing a state in which a sheet is set, and FIG. 3B is a side view showing a state in which a sheet is set.

FIG. 4 is an overall perspective view.

[Explanation of symbols]

 1 Platen 2 Paper Guide Path 3 Print Head 7 Head Holding Body 11 Feed Roller 12 Pinch Roller 31 Equalizer Cam 31a Cam Mountain 32 Elastic Body 34 Contact Body

Claims (1)

[Claims] 1. A head holder for holding a print head at a position facing the platen via a paper guide path and displacing the print head in a direction of moving the print head toward and away from the platen; and a head holder from the same direction as the platen. A feed roller disposed at a position in contact with the paper guide path, and a feed roller disposed at a position where the paper guide path is in contact with and separated from the feed roller and rotatably attached to the head holder to contact the feed roller. And a pinch roller for keeping the print head and the platen at a predetermined distance, an elastic body arranged so that the elastic direction is substantially the same as the displacement direction of the head holder, and the printing is performed on the elastic body. An abutment body disposed at a position where the head faces the direction approaching the platen, and a drive unit rotatably attached to the head holding body. An equalizer device for a printer, comprising: an equalizer cam, which is driven by and rotates to selectively contact the elastic body and the contact body with a cam lobe.