US 4,568,208 AGranted

Printer

AssigneeBrother Kogyo Kabushiki Kaisha

InventorsTakayuki Iwase, Junji Shiota, Kazuo Nakamura

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Abstract

In a printer, a printing clutch and a hammer impact changeover mechanism are controlled through a control member by one electromagnet, in such a manner that in response to a printing signal the clutch is engaged through the control member by the electromagnet to start one printing cycle and, in the second half of the printing cycle, the electromagnet is operated to enable a hammer impact change-over mechanism with the aid of the control member. The energizing forces of two weak spring members are applied to a cam follower member operatively coupled to the printing hammer so that when a printing type element having a large printing surface is selected, the energizing forces of the two spring members are utilized to allow the printing hammer to strike the type element strongly, and when a type element having a small printing surface is selected, the energizing force of only one of the two spring member is utilized to allow the printing hammer to strike the type element less strongly.

Claims12

Dependent claims

An impact printer for forming images of selected print elements on a web comprising:

a first print element having a first type surface of a first area;
a second print element having a second type surface of a second area that is smaller than said first area;
a print hammer for selectively striking said first and second print elements;
a primary print hammer driving mechanism for applying a first force to said print hammer in response to the selection of the second print element to cause said print hammer to strike said selected print element and to impart said web with said first force, said primary print hammer driving mechanism including a rotatable cam member having a cam surface with a print enable position, a rotatable cam follower member having one end for contacting said cam surface and another end coupled to said print hammer, and a first spring for exerting said first force on said cam follower member to bias said end of said cam follower member into contact with said cam surface, complete rotation of said cam member causing said end of said cam follower member to be positioned in said print enable position wherein said first force of said first spring is applied to said print hammer through said cam follower member;
and
a secondary spring hammer driving mechanism including a turning member having a first position in contact with a portion of said cam follower member and a second position not in contact with said portion of said cam follower member, a second spring for exerting a second force on said turning member to move said turning member into said first position to transmit said second force to said print hammer in addition to said first force when said end of said cam follower member is positioned in said print enable position, and a force limiting mechanism responsive to the selection of said second print element for positioning said turning member in said second position to prevent said second force from being applied to said print hammer whereby a greater force is applied to said print hammer responsive to the selection of said first print element than to the selection of said second print element.

3 more elements

An impact printer in which a ribbon lifting mechanism and a print hammer driving mechanism having a print hammer impact changing mechanism are driven through one clutch by an electric motor, said print hammer impact changing mechanism being operated in response to selection of one of large and small print elements of a print head, so that a selected printing character is typed on a printing web, thus accomplishing one printing cycle, the printer comprising:

an electromagnet;
a printing hammer;
a control member operated by said electromagnet to control engagement and disengagement of said clutch, said control member having an operating part which acts on said print hammer impact changing mechanism in association with the operation of said control member;
and
said print hammer driving mechanism having a cam member for operating said printing hammer in the second half of said printing cycle, and means to enable said electromagnet to be selectively operated in the second half of said printing cycle either by continuously operating said control member or to operate said control member a second time so that said print hammer impact changing mechanims is acted on by said operating part.

2 more elements

An impact printer for forming printed images on a web by selectively impacting a ribbon against the web with either a first printing element having a first type surface of a first area or a second printing element having a second type surface of a second area that is smaller than the first area, the impact force of the first printing element being greater than the impact force of the second printing element, the printer comprising:

a print hammer for selectively striking the first print element or the second print element;
a print hammer driving mechanism including a rotatable cam member having a cam surface with a print enable position, a rotatable cam follower member having a first end for contacting said cam surface and a second end coupled to said print hammer, and a first biasing spring for applying a first force on said cam follower member to bias said first end of said cam follower member into contact with said cam surface, said first force being applied to said print hammer during each rotation of said cam member when said first end of said cam follower member is in contact with said print enable position of said cam surface, and
a print hammer impact force changing mechanism for applying a second force to said print hammer through said cam follower member responsive to the selection of the first print element, the print hammer impact force changing mechanism comprising a rotatable turning member having a first position in contact with said cam follower member proximate said second end thereof and a second position not in contact with said cam follower member, a second spring for applying said second force to said turning member to rotate said turning member into said first position to transmit said second force to said print hammer, an operating pawl, and an electromagnet connected to said operating pawl and adapted to be energized in response to the selection of the second print element to engage said operating pawl and said turning member and to position said turning member in said second position.

Dependencies are inferred from the claim text.