Abstract A conventional thermal printer has had a structure in which a platen roller cannot be removed from a frame. Therefore, it has been necessary to insert a printing paper between a thermal head and the platen roller. Thus, it has been hard to load the printing paper. In order to solve the problem, there has been devised means for engaging the platen roller with the frame by the biasing force of the thermal head pressing the platen roller to forcibly lift up the platen roller, thereby removing the platen roller. However, there have been problems in that great operating force is required for the removal and the precision in a platen roller support position is low. A frame is provided with a slit ( 1 c ) having such a shape as to guide a bearing of a platen roller ( 2 ), and the bearing of a platen roller ( 2 ) is pushed against the slit by a lock arm using the biasing force of a pressure spring ( 8 ) for causing a thermal head ( 5 ) to come in press-contact with the platen roller ( 2 ). Consequently, the platen roller ( 2 ) is supported.
A thermal printer comprising: a body frame; a line dot type thermal head and a head support member provided integrally with a back face thereof; a platen roller provided in parallel with the thermal head; and a lock arm for supporting a bearing of the platen roller, the bearing allowing the platen roller to freely rotate; wherein the bearing of the platen roller is carried by the lock arm and a slit which has such a shape as to guide, into predetermined positions, the bearing of the platen roller is provided on a side wall of the body frame, and wherein the lock arm pushes the bearing of the platen roller against the frame by utilizing biasing force of a pressure spring for pressing the thermal head.
Claim 2
Dependent Claim
127 words
A thermal printer comprising: a body frame; a line dot type thermal head and a head support member provided integrally with a back face thereof; a platen roller provided in parallel with the thermal head; and a lock arm for supporting a bearing of the platen roller, the bearing allowing the platen roller to freely rotate; wherein the bearing of the platen roller is carried by the lock arm and a slit which has such a shape as to guide, into predetermined positions, the bearing of the platen roller is provided on a side wall of the body frame, and wherein the lock arm pushes the bearing of the platen roller against the frame by utilizing biasing force of a pressure spring for pressing the thermal head.
Claim 3
Dependent Claim
61 words
A thermal printer according to claim 1 , wherein the slit of the body frame is provided with a slope shape in a direction in which the thermal head presses the platen roller, and wherein the thermal head pushes up the platen roller by using the slope provided on the slit of the frame as the lock arm is moved away.
Claim 4
Dependent Claim
64 words
A thermal printer according to claim 1 , wherein when the lock arm is returned by the biasing force of the pressure spring after the thermal head pushes up the platen roller, the bearing of the platen roller is further pushed upward to completely remove the platen roller from the body frame by a cam face formed on an edge of the lock arm.
Claim 5
Dependent Claim
30 words
A thermal printer according to claim 1 , wherein the lock arm is operated by the cam integrated with a lever provided outside the side wall of the body frame.
Claim 6
Dependent Claim
53 words
A thermal printer according to claim 1 , 2 , or 3 , wherein the lock arm is provided with a stopper for interfering with the head support member before the pressure spring is excessively deformed even if the lever is operated with the platen roller depressed so as not to be removed.