US 4,917,512 AGranted

Apparatus for automatically adjusting a gap between a platen and a print head

AssigneeSeiko Epson Corporation

InventorsTakao Mimura, Atsushi Nishizawa, Masayuki Kumazaki

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Abstract

A mechanism for automatically adjusting the gap between the platen and print head of a printer includes a paper thickness lever detecting lever pivotably mounted on the printer base so that one end selectively contacts the surface of the platen. The opposite end of the lever contacts a pressure sensitive conductive member or adjusts the amount of light striking a photosensitive member of a paper thickness detector to generate an initial signal. After paper is fed onto the platen the lever contacts the surface of the paper and the paper thickness detector generates a second paper thickness signal corresponding to the different position of the lever. A carriage control circuit receives this signal and controls a print head carriage guide to adjust the relative position between the carriage and the platen to provide a suitable distance for printing.

Claims17

Dependent claims

A mechanism for automatically adjusting a gap between a platen and a print head in a printer for printing on a print medium comprising:

a frame having side walls and a base;
a carriage guide means for carrying a print head mounted between said frame walls and for adjusting the relative position between the carriage and the platen;
a carriage mounted for reciprocal displacement on said carriage guide means, the print head being mounted on the carriage;
a print medium thickness detecting lever pivotably mounted on said base adjacent to the platen with one end of the lever selectively contacting one of said platen and said print medium;
a print medium detecting lever;
print medium presence detecting means for detecting whether the print medium is within said printer in response to the position of the print medium detecting lever and providing a print medium presence detecting signal corresponding to the presence of the print medium;
print medium thickness detecting means for detecting the distance between said platen and said print medium thickness detecting lever in response to the position of said lever and providing a print medium thickness detecting signal corresponding thereto in response to said paper presence signal;
and
carriage control means for controlling said carriage guide means in response to said print medium detecting signal whereby said carriage guide adjusts the relative position between the carriage and platen to a suitable distance for printing base on the thickness of the print medium.

6 more elements

A device for detecting the thickness of a print medium in a printer, comprising:

a frame including side wall and a base;
a platen mounted in said frame;
a print medium detecting lever;
print medium presence detection means for detecting whether the print medium is within said printer in response to the position of said print medium detecting lever and producing a print medium detection signal in response thereto;
a print medium thickness detecting lever pivotally mounted on said base adjacent the platen with the lever selectively contacting said platen;
gap detecting means for detecting the thickness of the gap between said lever and said platen print medium thickness detecting lever in response to said print medium detection signal by generating a first reference signal when the lever contacts the platen and a second thickness signal when the lever contacts the print medium corresponding to the gap between the lever and the platen.

3 more elements

Dependencies are inferred from the claim text.