US 4,398,837 AGranted

Printing apparatus and method for preventing printing errors in same

AssigneeBrother Kogyo Kabushiki Kaisha

InventorsHiroshi Torii, Masaharu Mori

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Abstract

A printing apparatus comprising a print wheel having a multiplicity type elements, and a detecting unit for detecting angular positions of the print wheel including its fixed home position. The apparatus further comprises a control unit which includes a first counter which stores data representative of an angular distance of a type element currently located at the printing position as measured from the home position, and a second counter which stores data representative of an angular position of a type element designated by a print signal. Both counters are operated as they receive position signals from the detecting unit. The control unit is so arranged that in the event of an unexpected rotation of a wheel driving rotary shaft which is not a result of the actuation of a wheel driving motor in response to the print signal, the print wheel is first reset to the home position before it is rotated to bring a designated type element to the printing position, whereby chances for printing errors due to such unexpected rotation are eliminated. A method for controlling to prevent the printing errors is also disclosed.

Claims14

Dependent claims

A printing apparatus comprising:

a printing mechanism having
a platen for supporting and feeding a sheet of print paper,
carriage means,
carriage driving means coupled to said carriage means for moving same along a print line defined on the print paper, and
a print head assembly mounted on the carriage means and including a print wheel, a motor driving said print wheel and a print hammer, said print wheel having a plurality of type elements and being connected a rotary shaft of said print wheel driving motor:
a detecting unit generating angular position signals and a home position signal representative of angular positions and a home position of said print wheel, respectively;
and
a control unit including
wheel rotation controlling means, responsive to printing signals representative of said type elements, for controlling said print wheel driving motor to operate to rotate said print wheel so that one of said type elements designated by any of said printing signals is brought to a fixed printing position of said print wheel,
detecting means for detecting an unexpected rotation of said print wheel which is not a result of actuation of said print wheel driving motor, said detecting means generating a warning signal when said unexpected rotation is detected, and
wheel resetting means for resetting, in response to said warning signal, said print wheel to said home position when a first one of said printing signals is received after generation of said warning signal, and before said print wheel is controlled, by said wheel rotation controlling means, to rotate for a normal printing action in response to said first printing signal.

8 more elements

A process for preventing printing errors in a printing apparatus having a printing mechanism including a print head assembly comprising a print wheel driving motor, and a print wheel having a plurality of type elements and connected to a rotary shaft of said print wheel driving motor, said printing apparatus further having a control unit, and a detecting unit generating angular position signals and a home position signal representative of angular positions and a home position of said print wheel, respectively;

said process comprising the steps of:
checking to see if said rotary shaft is in rotation not through an actuation of said print wheel driving motor;
generating a warning signal if said rotary shaft is in rotation not through said actuation;
and
in the event said warning signal has been detected to be present, resetting said print wheel to said home position before said print wheel is controlled to rotate for a normal printing action in response to one of printing signals representative of said type elements.

2 more elements

Dependencies are inferred from the claim text.