Print gap setting in an impact printer

An impact printer having a print head movable with respect to a home position, said print head having an armature, a printing wire fixed to said armature for reciprocal movement therewith toward and away from a platen, said platen disposed in opposition to said print head, and a sensor for detecting movement of said armature, said impact printer comprising:

• (a) monitoring means for monitoring a position of said printing wire, based on an output of said sensor while said printing wire is moved relative to said platen, said monitoring means including speed waveform determining means for determining a speed waveform indicative of a speed of said printing wire while said printing wire is moved relative to said platen under predetermined conditions;
• (b) detecting means for detecting an operation time of said printing wire during which said printing wire is moved with respect to said platen, based on the determined speed waveform;
• (c) a memory storing in advance a standard information value, the standard information value representing a standard operation time of said printing wire;
• (d) means for
• renewing the standard information value based on the operation time detected by said detecting means, and
• replacing the standard information value stored in advance in said memory by the renewed standard information value;
• and
• (e) means for adjusting a gap between said printing wire and said platen based on the stored renewed standard information value and an operation time detected by said detecting means.

A method for driving an impact printer having a print head, the print head having an armature, a printing wire fixed to said armature for movement therewith toward a platen, the platen disposed in opposition to the print head, and a sensor for detecting movement of the armature, the print head being movable lengthwise of the platen with respect to a home position at one end of the platen, said method comprising steps of:

• (a) detecting with a home sensor whether the print head is at the home position;
• (b) detecting with a paper sensor the existence of a printing medium in the printer between the platen and the print head;
• and
• (c) adjusting a gap between the printing wire and the platen, in response to detection signals respectively output by said home sensor and said paper end sensor when the detection signal output by the home sensor means indicates that the print head is not at the home position and the detection signal output by the paper detector indicates an absence of paper between the print head and the platen, including
• controlling the print head to swing the armature so as to cause a tip of the printing wire to strike the platen;
• determining a time of impact of the tip with the platen, based on a position of the armature,
• performing a comparison of the time of impact with a predetermined impact time, and
• outputting a drive signal for adjusting the gap according to a result of the comparison.

A method for driving an impact printer having a print head movable with respect to a home position, the print head having an armature, a printing wire fixed to the armature for reciprocal movement therewith toward and away from a platen, the platen disposed in opposition to the print head, and a sensor for detecting movement of the armature, the method comprising steps of:

• (a) monitoring a position of the printing wire based on an output of the sensor while the printing wire is moved relative to the platen;
• (b) determining a speed waveform indicative of a speed of the printing wire while the printing wire is moved under predetermined conditions;
• (c) detecting an operation time of the printing wire during which the printing wire is moved with respect the platen based on the determined speed waveform;
• (d) storing a standard information value prior to said step a, the standard information value representing a standard operation time of the printing wire;
• (e) adjusting a gap between the printing wire and the platen disposed in opposition to the print head, based on the operation time detected by said detecting means and the stored standard information value stored in said step d;
• (f) renewing the standard information value, based on the operation time detected in said step c;
• (g) storing the renewed standard information value obtained in said step f in place of the standard information value stored in said step d;
• and
• (h) adjusting the gap between the printing wire and the platen disposed in opposition to the print head, according to the renewed standard information value stored in said step g.

An impact printer having a print head, said print head having an armature, a printing wire fixed to said armature for movement therewith toward a platen, said platen disposed in opposition to said print head, and a sensor for detecting movement of said armature, said print head being movable lengthwise of said platen with respect to a home position at one end of said platen, said impact printer comprising:

• (a) monitoring means for monitoring a position of said armature, based on an output of said sensor while said armature is moving;
• (b) home sensor means for detecting whether or not said print head is at said home position;
• (c) a paper detector for detecting existence of a printing medium in said printer between said platen and said print head;
• (d) gap motor means, responsive to a drive signal, for adjusting a gap between said printing wire and said platen;
• and
• (e) gap control means, responsive to a detection signal output by said home sensor and a detection signal output by said paper detector, for
• controlling said print head to swing said armature so as to cause a tip of said printing wire to strike said platen,
• determining a time of impact of said tip with said platen based on a position of said armature as monitored by said monitoring means,
• performing a comparison of the time of impact with a predetermined impact time, and
• generating the drive signal according to a result of the comparison and applying the drive signal to said gap motor means to adjust the gap according to the result;
• wherein the detection signal output by said home sensor means indicates that said print head is not at the home position and the detection signal output by said paper detector indicates an absence of paper between said print head and the platen.