JPH09136459A - Printer head gap adjusting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to manufacture a platen in the form of individual parts instead of composite members in a structure to detect a mechanical contact between a ribbon protector and a platen by electric conduction. SOLUTION: A printing head 37 is mounted on a carriage 35, then a ribbon protector 39 arranged between the printing head 37 and a printing medium is fixed to the carriage 35, and a platen 45 forming a sheet running path between the platen 45 and the ribbon protector 39 is provided at an opposite position to the printing head 37. In addition, a contact detection circuit 42 for detecting the contact between the ribbon protector 39 and the platen 45 by electric conduction is connected to the ribbon protector 39 and the platen 45. Further, a platen lifting mechanism 63 for bringing the platen 45 close to and separate it from the printing head 37 is mounted on a frame 65 consisting of an insulating material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gap adjusting structure for a dot print head in a serial printer.

[0002]

2. Description of the Related Art In order to enable printing on print media having different thicknesses, in order to secure an optimum impact force, a certain amount of gap corresponding to the print media of each thickness, that is, a head gap is set. Need to be adjusted. FIG. 6 is a schematic configuration diagram of a conventional printer head gap adjusting mechanism. A carriage 5 is slidably supported on the carriage shaft 1 and the guide shaft 3. A print head 7 is mounted on the carriage 5, and a ribbon protector 9 fixed to the carriage 5 is arranged below the print head 7. The ribbon protector 9 is connected to the contact detection circuit 11.

Below the print head 7, a paper path 13 is provided.
Platens 15 are arranged to face each other with the platen sandwiched therebetween. The platen 15 has a front end portion 15 a and a base end portion 15 b joined to each other with an insulating material 17 interposed therebetween. Therefore, the tip portion 15a of the platen 15 is in a state of being electrically insulated from the frames 19 and 21. The tip portion 15a is connected to the contact detection circuit 11.

In the conventional head gap adjusting mechanism thus constructed, the contact position between the ribbon protector 9 and the platen 15 is detected in order to perform the head gap adjusting operation. That is, when the platen 15 is raised during the initial operation in which the print medium 23 is not supplied to the paper path 13, the tip portion 15a of the platen 15 comes into contact with the ribbon protector 9, and this contact causes the electric power of the contact detection circuit 11. It was detected by electrical continuity. The contact position between the platen tip portion 15a and the ribbon protector 9 without the print medium 23 is stored in the control unit 25 as a reference position. The detection of the reference position has been an important factor when gaps are formed for print media 23 having various thicknesses.

[0005]

However, in the above-described conventional head gap adjusting structure, the tip end portion 15a and the base end portion 15b of the platen 15 are joined with the insulating material 17 sandwiched therebetween, and the tip end portion 15a and the frame 19 are connected. Since the contact detection circuit 11 detects the contact position between the two by electrically insulating the platen 15 from each other, the platen 15 originally manufactured as a single product must be manufactured as a composite member. However, there is a problem that the manufacturing cost increases. The present invention has been made in view of the above circumstances, and provides a printer head gap adjustment structure capable of detecting contact due to conduction between a ribbon protector and a platen without using the platen as a composite member, and it is possible to reduce the manufacturing cost. To aim.

[0006]

To achieve the above object, the structure of a printer head gap adjusting structure according to the present invention has a carriage slidably supported along a carriage shaft, and a printing mounted on the carriage. A head, a ribbon protector fixed to the carriage and arranged between the print head and the print medium, and a platen provided facing the print head to form a paper traveling path between the ribbon protector and the ribbon protector. A contact detection circuit that is conductively connected to the ribbon protector and the platen to detect contact between the ribbon protector and the platen by electrical conduction; a platen lifting mechanism that moves the platen toward and away from the print head; The entire platen lifting mechanism made of material is mounted to isolate the platen from the print head. It is characterized in that it has and a frame.

With the above arrangement, the contact between the ribbon protector and the platen is detected by the electrical continuity between the two.
Further, the entire platen lifting mechanism is mounted on a frame made of an insulating material to insulate the platen from the ribbon protector. This eliminates the need to intervene an insulating material between the tip and base ends of the platen to insulate the ribbon protector from the platen, which allows the platen that was manufactured as a composite member to be manufactured separately. Becomes

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the printer head gap adjusting structure according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a printer head gap adjusting structure according to the present invention. A carriage 35 is slidably supported by the carriage shaft 31 and the guide shaft 33. A print head 37 is mounted on the carriage 35, and a ribbon protector 39 fixed to the carriage 35 is arranged below the print head 37. The ribbon protector 39 is connected to the contact detection circuit 42 by a cord 41.

Below the print head 37, the paper path 4 is provided.
Platens 45 are disposed so as to face each other with 3 interposed therebetween. The platen 45 uses a cord 47 to detect the contact detection circuit 42.
Connected to. A rack 51 is fixed to the platen 45, and the rack 51 meshes with the pinion 53. Further, the pinion 53 meshes with a drive gear 57 fixed to one end of the drive shaft of the pulse motor 55. A slit disk 59 is fixed to the other end of the drive shaft of the pulse motor 55,
An optical sensor 61 is arranged at the edge of 9 so as to sandwich the edge.

The platen 45, the rack 51, the pinion 53, the pulse motor 55, the drive gear 57, the slit disc 59, and the optical sensor 61 described above constitute an integral platen lifting mechanism 63. The platen lifting mechanism 63 is mounted on a frame 65 made of an insulating material (for example, resin material). Therefore, the platen lifting mechanism 63 is in a state of being insulated from the ribbon protector 39.

A gap producing operation by the printer head gap adjusting structure thus constructed will be described with reference to FIGS. 2 is an explanatory view of the head gap, FIG.
FIG. 4 is an explanatory diagram at the time of initial operation, FIG. 4 is an explanatory diagram at the time of detecting the paper thickness, and FIG. 5 is an explanatory diagram at the end of gap formation. First,
Before describing the operation, the head gap G will be described. As shown in FIG. 2, the head gap G includes a gap g ₁ between the print head 37 and the ribbon protector 39 and the print medium 6.
The gap g ₀ between the surface of 7 and the ribbon protector 39. g ₁ is a gap secured by the processing accuracy of the print head 37 and the ribbon protector 39, and g ₀ is a gap secured by controlling the platen position by detecting the paper thickness.

In the past, this g ₀ was measured by a thickness gauge, and the operation was corrected and secured. This is because there is no means for detecting the difference C between the contact detection position and the paper thickness detection position from this point, which will be described later in the present application.

As shown in FIG. 3, during the initial operation, the ribbon protector 39 is stationary in a state where no external force is applied. When the operation is started, the platen 45 is raised by the platen lifting mechanism 63, reaches the position of δ ₁ , and comes into contact with the ribbon protector 39. At this moment, the ribbon protector 39 and the platen 45 are electrically connected and the cord 4
The contact detection circuit 42 detects the contact between the ribbon protector 39 and the platen 45 via 1, 47, and the position of the slit disk 59 at the time of contact is read by the optical sensor 61.
The “contact detection position” that is the reference position is stored in the control unit 69.

The ribbon protector 39 has a mechanism capable of rising from a normal printing position because it is necessary to print a print medium having a different thickness such as a seal stamp or a magnetic stripe. Further, the ribbon protector 39 also has a means for detecting when the amount of ascent rises from a normal printing position and becomes a constant amount. As this means, step-out (or stop) detection due to overload of the pulse motor 55, detection by a pressure sensor, detection by the amount of bending of the ribbon protector 39, and the like are used.

The position where this amount of rise is constant is called, for example, the "paper thickness detection position". Therefore, the platen 45
When the ribbon protector 39 contacts the ribbon protector 39 and then further rises, the ribbon protector 39 reaches the paper thickness detection position δ ₂ , as shown in FIG. This paper thickness detection position is also stored in the control unit 69 as the rotational position of the slit disk 59, as described above. The control unit 69 calculates and stores the difference C between the paper thickness detection position and the contact detection position.

As described above, after the contact detection at the initial time is completed, the normal printing, that is, the print medium 6 is performed.
In the state where 7 is present, the paper thickness detection position is detected again. That is, as shown in FIG. 4, the platen 45 is raised with the print medium 67 conveyed to the print position and stopped. Then, the print medium 67 comes into contact with the ribbon protector 39. At this time, since the platen 45 and the ribbon protector 39 have the print medium 67 which is an insulator interposed therebetween,
No contact detected. When the platen 45 is further raised, the ribbon protector 39 is pushed up by the platen 45 via the print medium 67 and reaches the paper thickness detection position δ ₂ again.

In this state, the platen 45 is stopped and the platen 45 is lowered. The platen 45 descends by a total amount (C + g ₀ ) of the above-described amount of C and g ₀ (fixed value) which is a gap between the print medium surface and the ribbon protector 39. That is, first, when the platen 45 is lowered by the amount C, the ribbon protector 39 is in contact with the surface of the print medium and is in a horizontal state in which no external force is applied. Further, when the platen 45 is lowered by the amount g ₀ , it has an arbitrary thickness. The proper gap G (see FIG. 2) of the print medium 67 is secured.

Originally, in a mechanism that does not cause any error, if the platen 45 is raised with the printing medium present to detect the paper thickness detection position and the platen 45 is lowered by a predetermined amount from that position, an appropriate gap is obtained. However, it is necessary to secure a proper head gap for the print medium 67 having an arbitrary thickness and a mechanism that may cause an error in reality. As can be understood from the above-described operation, in the gap finding operation using the adjustment structure of the present embodiment, the contact detection position that cannot be detected with the print medium 67 is obtained in advance during the initial operation. The C value is calculated by using the C value and the amount of lowering of the platen 45 during normal printing in which the print medium 67 is interposed is used to determine the optimum value by correcting the error for the print medium 67 having an arbitrary thickness. It will be possible to create a wide gap. That is, the detection of the contact detection position is an important factor for calculating the C value that determines the platen descending amount for the print medium 67 having an arbitrary thickness.

According to the above-described embodiment, the reference position, which is an important factor when performing the gap formation corresponding to the print media of various thicknesses, that is, the contact detection position is the ribbon protector 39 and the platen 45. It is detected by the conduction at the time of contact. In the structure for detecting the platen, the platen lifting mechanism 63 is mounted on the frame 65 made of an insulating material and insulated from the ribbon protector 39. Therefore, the platen 45 is manufactured as a single piece, not as a conventional composite member. It becomes possible. As a result, it is possible to reduce the number of parts, facilitate manufacturing, and reduce the manufacturing cost of the gap adjusting mechanism.

In the above embodiment, in order to achieve insulation between the platen 45 and the ribbon protector 39, the entire platen lifting mechanism 63 is mounted on the frame 65 made of an insulating material. The insulation can also be achieved by forming the frame 71 (see FIG. 1) on which the carriage 35 and the print head 37 are mounted from an insulating material.

[0021]

As described above in detail, according to the printer head gap adjusting structure of the present invention, in the structure in which the contact between the ribbon protector and the platen is detected by the conduction, the platen lifting mechanism is made of an insulating material. Since the ribbon protector and the platen are insulated by mounting on the board, the platen can be manufactured as a single item without using a composite member as in the past, the number of parts can be reduced, and the manufacturing is easy, and the gap adjusting mechanism can be easily manufactured. The manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a printer head gap adjusting structure according to the present invention.

FIG. 2 is an explanatory diagram of a head gap.

FIG. 3 is an explanatory diagram at the time of initial operation.

FIG. 4 is an explanatory diagram when a sheet thickness is detected.

FIG. 5 is an explanatory diagram at the end of gap formation.

FIG. 6 is a schematic configuration diagram of a conventional printer head gap adjusting mechanism.

[Explanation of symbols]

 31 Carriage Shaft 35 Carriage 37 Print Head 39 Ribbon Protector 42 Contact Detection Circuit 43 Paper Travel Path 45 Platen 51 Rack 53 Pinion 55 Pulse Motor 57 Drive Gear 59 Slit Disk 61 Optical Sensor 63 Platen Lifting Mechanism 65 Frame 67 Printing Medium

Claims (2)

[Claims] 1. A carriage slidably supported along a carriage shaft, a print head mounted on the carriage, and a ribbon protector fixed to the carriage and arranged between the print head and a print medium. A platen that faces the print head and forms a paper path between the ribbon protector and the ribbon protector; and the ribbon protector and the platen are electrically connected to electrically connect the ribbon protector and the platen. A contact detection circuit for detecting the platen, a platen elevating mechanism for moving the platen toward and away from the print head, and a frame made of an insulating material for insulating the platen from the print head by mounting the entire platen elevating mechanism. A printer head gap adjusting structure comprising: 2. The platen lifting mechanism is fixed to a rack fixed to the platen, a pinion that meshes with the rack, a pulse motor that meshes with the pinion via a drive gear, and a drive shaft of the pulse motor. 2. The printer head gap adjusting structure according to claim 1, further comprising: a slit disk; and an optical sensor disposed at an edge of the slit disk with the edge sandwiched therebetween.