JPH0361065A - Automatic printing gap adjusting mechanism in dot impact printer - Google Patents

Abstract

PURPOSE:To reduce the number of component parts, to improve assembling properties, and to lower a cost by a method wherein a frictional drive belt is used as a part of a drive means for moving a carrier frame, and the power of the drive means is cut by a slip between the frictional drive belt and a drive pulley. CONSTITUTION:By moving a carrier frame 8 toward a platen 2, an automatic gap adjusting arm 1 firstly comes into contact with the platen 2. When the automatic gap adjusting arm 1 is pressed against the platen 2, a slip is generated between a drive pulley 9 and a frictional drive belt 6, thus preventing the transmission of power to a driven pulley gear 5 and succeeding members. A stepping motor 7 is reversely rotated by a specified amount from this position and, thereby, the carrier frame 8 is returned by a specified amount. Thus, a proper printing gap can be automatically obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic printing gap adjustment mechanism for a dot impact printer, which is characterized by a method of canceling power transmission of a drive means for moving a print head.

[Prior Art] Conventionally, this type of automatic printing gap adjustment mechanism has a pair of friction plates in a part of the first drive stage of the print head and a spring for pressing the friction plates against each other with an appropriate pressure. However, power was transmitted by the frictional force between the friction plates generated by the pressure of the spring.

Therefore, when positioning the print head, P? ! Power transmission was released by adding a force that exceeded the frictional force between the friction plates and causing the friction plates to slip.

[Problems to be solved by the invention] - The conventional automatic printing gap adjustment mechanism described above increases the elastic force of the spring that pushes up the friction plate in order to provide sufficient frictional force to move the print head. It had the disadvantage of being difficult to assemble.

Furthermore, since a power transmission canceling means is provided in the driving means, regardless of the speed ratio setting means, the number of parts increases, the structure becomes complicated, and the cost increases.

[Pth stage to solve the problem] The automatic print gap adjustment mechanism of Kinei II that solves the above-mentioned conventional problems includes a drive means that reciprocates the print head toward the platen side, and a drive means that adjusts the thickness of the paper. In the automatic printing gap adjustment mechanism of a dot impact printer, the paper thickness detection means is located closer to the platen than the print head, and the paper thickness detection means is located closer to the platen than the print head. The driving means includes an automatic gap adjustment arm that moves together with the print head, and the driving means transmits the power of the stepping motor, and when the automatic gap adjustment arm contacts the platen, the automatic gap adjustment arm slips and transmits the power. It is characterized by having a friction drive belt that releases the.

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

FIG. 1 shows an outline of an automatic printing gap adjustment mechanism according to an embodiment of the present invention.

The printing gap adjustment mechanism of this embodiment includes a drive unit that reciprocates a carrier frame 8 equipped with a print head (not shown) in the direction of arrow A, and a drive unit that detects the thickness of the paper and adjusts the printing gap to an appropriate value. and paper thickness detection means to be used as a reference for obtaining the paper thickness.

The driving means includes a stepping motor 7 as a power source, a friction drive belt 6, a driven pulley gear 5, and a shaft drive gear 4 as power transmission means.

The stepping motor 7 rotates the main shaft 3 via the friction drive belt 6, driven pulley gear 5, and shaft drive gear 4, and moves the carrier frame 8 in the direction of arrow A.

The paper thickness detection means includes an automatic gap adjustment arm 1 provided on the carrier frame 8 and a sensor (not shown).

The automatic gap adjustment l is located closer to the platen 2 than the print head and is integrally molded with the carrier frame 8. As a result, when the carrier frame 8 moves toward the platen 2, the automatic gap adjustment arm 1 first contacts the platen 2 and becomes a stopper. Sensors etc. are automatic gap adjustment arm 1
The printing gap is adjusted using the position of the carrier frame 8 at this time as a reference for paper thickness detection.

In this embodiment, the automatic gap adjustment arm l is molded integrally with the carrier frame 8, but it may be molded separately and provided by screws or the like.

Next, the operation of this embodiment will be explained.

When this embodiment is operated, the carrier frame 8 is moved to the platen 2.
When moved to the side, the automatic gap adjustment arm 1 first contacts the platen 2. Automatic gap adjustment arm 1 is platen 2
When the drive pulley 9 and the friction drive belt 6 are pressed against each other, slip occurs between the driven pulley gear 5,
Power will not be transmitted to subsequent parts. By reversing the stepping motor 7 by a specified amount from this position, the carrier frame 8 is returned by a certain amount, and an appropriate printing gap can be automatically obtained.

[Effect of the Invention J As explained above, the present invention uses a friction drive belt as a part of the drive means for moving the carrier frame, and releases the power of the drive means by sliding between the friction drive belt and the drive pulley. By doing so, the number of parts can be reduced, ease of assembly can be improved, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an automatic printing gap adjustment mechanism of a dot impact printer according to an embodiment of the present invention. 1: Automatic gap adjustment arm 2 Nibraten 3: Main shaft 4: Shaft drive gear 5: Driven pulley 6: Friction drive belt 7: Stepping motor 8: Carrier frame 9 Nidrive pulley

Claims (1)

[Scope of Claims] A printing gap of a dot impact printer comprising a driving means for reciprocally moving the print head toward the platen side, and a paper thickness detection means for detecting the thickness of the paper and using it as a reference for the printing gap. In the automatic adjustment mechanism, the paper thickness detection means has an automatic gap adjustment arm that is located closer to the platen than the print head and moves together with the print head, and the drive means includes a stepping motor and a stepper motor. An automatic printing gap adjustment mechanism for a dot impact printer, comprising a friction drive belt that transmits power and slips to release power transmission when the automatic gap adjustment arm contacts the platen. .