US 5,631,689 AGranted

Controlling method for heat of thermal head

AssigneeAlps Electric Co., Ltd.

InventorHiroshi Izumi

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Abstract

A method for controlling heat generated by the heat-generating elements of a thermal head, the elements being successively actuated to heat the thermal head in response to an electrical current which is applied to each of the plurality elements from a control circuit for a power-on time which is n times a minimum time period. The method includes determining a calculated power-on time for a selected element and assigning the power-on time for the selected element one of: a value equal to the calculated power-on time if the calculated power-on time is equal to n times the minimum time period; a value equal to the calculated power-on time, rounded up to a nearest multiple of the minimum time period, if the calculated power-on time is not equal to n times the minimum time period, and if the selected element is an even-numbered one of said plurality of elements; and an actual power-on time equal to the calculated power-on time, rounded down to a nearest multiple of the minimum time period, if the calculated power-on time is not equal to n times the minimum time period, and if the selected element is an odd-numbered one of said plurality of elements.

Claims7

Dependent claims

A method for controlling an amount of heat generated by a thermal head device, the thermal head device including:

a thermal head having a plurality of heat-generating elements arranged in a row, successive elements of the plurality of heat-generating elements being alternately designated as an odd-number element and an even-number element;
a calculation circuit for generating a power-on time for each heat-generating element of said thermal head;
a plurality of latches, each of the plurality of latches being connected to an associated group of the plurality of heat-generating elements;
and
a control circuit for controlling said plurality of latches such that each of the plurality of latches applies power to selected elements of the associated group of heat-generating elements for a duration equal the power-on time output from the calculation circuit
wherein said method comprises the steps of:
(a) calculating a power-on time for a selected element of the plurality of heat-generating elements in units of time shorter than a minimum power-on time, the selected element being connected to a first latch of the plurality of latches;
(b) determining whether the calculated power-on time is equal to an integral multiple of the minimum power-on time or not;
(c) if the calculated power-on time is equal to such an integral multiple:
(i) writing the calculated power-on time directly to said first, latch as the power-on time for said selected element, and
(ii) applying electrical current to the selected element via said first latch for a period equal to said power-on time;
and
(d) if the calculated power-on time is not equal to such an integral multiple:
(i) determining whether the selected element is an odd-number element or an even-number element;
(ii) changing the calculated power-on time for the selected element to an integral value obtained by rounding up fractions below a decimal point of the calculated power-on time if the selected element is a first one of an odd-numbered element and an even-number element, and to an integral value obtained by rounding down fractions below a decimal point of the calculated power-on time if the selected element is a second one of an odd-number element and an even-number element;
(iii) writing the changed calculated power-on time directly to said first latch as the power-on time for said selected element;
and
(iv) applying electrical current to the selected element via said first latch for a period equal to said power-on time.

15 more elements

A method for controlling an amount of heat generated by a thermal head device the thermal head device including:

a thermal head having a plurality of heat-generating elements arranged in a row, successive elements of the plurality of heat-generating elements being alternately designated as an odd-number element and an even-number element;
a calculation circuit for generating a power-on time for each heat-generating element of said thermal head;
a plurality of latches, each of the plurality of latches being connected to an associated group of the plurality of heat-generating elements;
and
a control circuit for controlling said plurality of latches such that each of the plurality of latches applies power to selected elements of the associated group of heat-generating elements for a duration equal the power-on time output from the calculation circuit,
wherein said method comprises the steps of:
(a) calculating a power-on time for a selected element of the plurality of heat-generating elements in units of time shorter than a minimum power-on time, the selected element being connected to a first latch of the plurality of latches;
(b) determining whether the calculated power-on time is equal to an integral multiple of the minimum power-on time or not;
(c) if the calculated power-on time is equal to such an integral multiple:
(i) writing the calculated power-on time directly to said first latch as the power-on time for said selected element, and
(ii) applying electrical current to the selected element via said first latch for a period equal to said power-on time;
and
(d) if the calculated power-on time is not equal to such an integral multiple:
(i) determining whether the selected element is an odd-number element or an even-number element;
(ii) changing the calculated power-on time for the selected element to an integral value obtained by rounding up fractions below a decimal point of the calculated power-on time if the selected element is an odd-number element, and to an integral value obtained by rounding down fractions below a decimal point of the calculated power-on time if the selected element is an even-number element;
(iii) writing the changed calculated power-on time directly to said first latch as the power-on time for said selected element;
and
(iv) applying electrical current to the selected element via said first latch for a period equal to said power-on time.

15 more elements

A method for controlling an amount of heat generated by a thermal head device, the thermal head device including:

a thermal head having a plurality of heat-generating elements arranged in a row, successive elements of the plurality of heat-generating elements being alternately designated as an odd-number element and an even-number element;
a calculation circuit for generating a power-on time for each heat-generating element of said thermal head;
a plurality of latches, each of the plurality of latches being connected to an associated group of the plurality of heat-generating elements;
and
a control circuit for controlling said plurality of latches such that each of the plurality of latches applies power to selected elements of the associated group of heat-generating elements for a duration equal the power-on time output from the calculation circuit,
wherein said method comprises the steps of:
(a) calculating a power-on time for a selected element of the plurality of heat-generating elements in units of time shorter than a minimum power-on time, the selected element being connected to a first latch of the plurality of latches;
(b) determining whether the calculated power-on time is equal to an integral multiple of the minimum power-on time or not;
(c) if the calculated power-on time is equal to such an integral multiple:
(i) writing the calculated power-on time directly to said first latch as the power-on time for said selected element, and
(ii) applying electrical current to the selected element via said first latch for a period equal to said power-on time;
and
(d) if the calculated power-on time is not equal to such an integral multiple:
(i) determining whether the selected element is an odd-number element or an even-number element;
(ii) changing the calculated power-on time for the selected element to an integral value obtained by rounding up fractions below a decimal point of the calculated power-on time if the selected element is an even-number element, and to an integral value obtained by rounding down fractions below a decimal point of the calculated power-on time if the selected element is an odd-number element;
(iii) writing the changed calculated power-on time directly to said first latch as the power-on time for said selected element;
and
(iv) applying electrical current to the selected element via said first latch for a period equal to said power-on time.

15 more elements

A printing method for a thermal head device, the thermal head device including:

a thermal head having a plurality of heat-generating elements arranged in a row, successive elements of the plurality of heat-generating elements being alternately designated as an odd-number element and an even-number element;
a calculation circuit for generating a power-on time for each heat-generating element of said thermal head;
a plurality of latches, each of the plurality of latches being connected to an associated group of the plurality of heat-generating elements;
and
a control circuit for controlling said plurality of latches such that each of the plurality of latches applies power to selected elements of the associated group of heat-generating elements for a duration equal the power-on time output from the calculation circuit,
wherein said method comprises the steps of:
(a) calculating a power-on time for a selected element of the plurality of heat-generating elements in units of time shorter than a minimum power-on time, the selected element being connected to a first latch of the plurality of latches;
(b) determining whether the calculated power-on time is equal to an integral multiple of the minimum power-on time;
(c) if the calculated power-on time is equal to such an integral multiple:
(i) writing the calculated power-on time directly to said first latch as the power-on time for said selected element, and
(ii) applying electrical current to the selected element via said first latch for a period equal to said power-on time;
and
(d) if the calculated power-on time is not equal to such an integral multiple:
(i) determining whether the selected element is an odd-number element or an even-number element,
(ii) changing the calculated power-on time for the selected element to an integral value obtained by rounding up fractions below a decimal point of the calculated power-on time if the selected element is a first one of an odd-numbered element and an even-number element, and to an integral value obtained by rounding down fractions below a decimal point of the calculated power-on time if the selected element is a second one of an odd-number element and an even-number element,
(iii) writing the changed calculated power-on time directly to said first latch as the power-on time for said selected element,
(iv) applying electrical current to the selected element via said first latch for a period equal to said power-on time, and
(v) applying said thermal head to a recording medium.

15 more elements

Dependencies are inferred from the claim text.