US 7,547,087 B2Granted

Fault detection circuit for printers with multiple print heads

AssigneeInternational Business Machines Corporation

InventorsRobert T. Cato, Timothy W. Crocket, Charles R. Kirk

Life of this patent

Estimating the term…

Loading patent…

Abstract

A fault detector apparatus for a printer having a first print head and a second print head with a plurality of print head elements in each print head is disclosed. The apparatus includes a test circuit in signal communication with all the print heads to test the plurality of print head elements. The test circuit includes a test power supply for generating a test voltage, a first resistor, a second resistor, and an analog to digital converter in signal communication with the second resistor. The first resistor is in series connection between the test power supply and the plurality of elements in the first print head. The second resistor in series connection with the test power supply, the first resistor, and the plurality of elements in the second print head. The fault detector apparatus will also work for a printer with only one print head.

Claims13

Dependent claims

A fault detector apparatus for a printer having a first print head and a second print head with a plurality of print head elements in each print head, the apparatus comprising:

a test circuit in signal communication with all the print heads to test the plurality of print head elements, the test circuit comprising:
a test power supply for generating a test voltage;
a first resistor in series connection between the test power supply and the plurality of elements in the first print head;
a second resistor, the first resistor and the second resistor in series connection with the test power supply and the plurality of elements in the second print head;
and
an analog to digital converter in signal communication with the second resistor;
wherein in response to a flow of current from the test power supply through the first resistor and one of the plurality of elements in the first print head, the analog to digital converter detects a first voltage;
and
wherein in response to a flow of current from the test power supply through the first and second resistors and one of the plurality of elements in the second print head, the analog to digital converter detects a second voltage;
wherein in response to a flow of current through the one element in the first print head operating in accordance with an acceptable operational characteristic, the first voltage is described by:
res
⁢
⁢
116
res
⁢
⁢
116
+
element
⁢
⁢
1
⁢
(
v
⁢
⁢
66
)
;
and
wherein in response to a flow of current through the one element in the second print head operating in accordance with an acceptable operational characteristic, the second voltage is described by:
res
⁢
⁢
116
+
res
⁢
⁢
132
res
⁢
⁢
116
+
res
⁢
⁢
132
+
element
⁢
⁢
2
⁢
(
v
⁢
⁢
66
)
where:
v66 represents the test voltage;
res116 represents a resistance of the first resistor;
res132 represents a resistance of the second resistor;
element1 represents a resistance of the properly operating element in the first print head;
and
element2 represents a resistance of the properly operating element in the second print head.

67 more elements

A fault detector apparatus for a printer having an impact print head with a plurality of electromagnetic coils and a thermal print head with a plurality of heating elements, the apparatus comprising:

a test circuit in signal communication with the impact print head and the thermal print head to test the plurality of electromagnetic coils and the plurality of heating elements, the test circuit comprising:
a test power supply for generating a test voltage;
a first resistor in series connection between the test power supply and the plurality of electromagnetic coils, the first resistor having a resistance about equal to a resistance of one of the plurality of electromagnetic coils operating in accordance with an acceptable operational characteristic;
a second resistor, the first resistor and the second resistor in series connection with the test power supply and the plurality of heating elements, the first resistor and second resistor having a combined resistance about equal to a resistance of one of the plurality of heating elements operating in accordance with an acceptable operational characteristic;
an analog to digital converter in signal communication with the second resistor;
and
a processor in signal communication with the analog to digital converter;
wherein in response to a flow of current from the test power supply through the first resistor and one of the plurality of electromagnetic coils, the analog to digital converter detects a first voltage;
wherein in response to a flow of current from the test power supply through the first and second resistors and one of the plurality of heating elements, the analog to digital converter detects a second voltage;
wherein the processor is receptive of a signal representative of the first voltage detected by the analog to digital converter, and responsive to generate a notification signal if the detected first voltage deviates beyond a threshold from about half of the test voltage;
and
wherein the processor is receptive of a signal representative of the second voltage detected by the analog to digital converter, and responsive to generate a notification signal if the detected second voltage deviates beyond a threshold from about half of the test voltage.

9 more elements

A fault detector apparatus for a printer having an impact print head with a plurality of electromagnetic coils and a thermal print head with a plurality of heating elements, the apparatus comprising:

a test circuit in signal communication with the impact print head and the thermal print head to test the plurality of electromagnetic coils and the plurality of heating elements, the test circuit comprising:
a test power supply for generating a test voltage;
a first resistor in series connection between the test power supply and the plurality of electromagnetic coils;
a second resistor, the first resistor and the second resistor in series connection with the test power supply and the plurality of heating elements;
and
an analog to digital converter in signal communication with the second resistor;
wherein in response to a flow of current from the test power supply through the first resistor and one of the plurality of electromagnetic coils, the analog to digital converter detects a first voltage;
and
wherein in response to a flow of current from the test power supply through the first and second resistors and one of the plurality of heating elements, the analog to digital converter detects a second voltage;
wherein in response to a flow of current through the one electromagnetic coil operating in accordance with an acceptable operational characteristic, the first voltage is described by:
res
⁢
⁢
116
res
⁢
⁢
116
+
element
⁢
⁢
1
⁢
(
v
⁢
⁢
66
)
;
and
wherein in response to a flow of current through the one heating element operating in accordance with an acceptable operational characteristic, the second voltage is described by:
res
⁢
⁢
116
+
res
⁢
⁢
1322
res
⁢
⁢
116
+
res
⁢
⁢
132
+
element
⁢
⁢
2
⁢
(
v
⁢
⁢
66
)
where:
v66 represents the test voltage;
res116 represents a resistance of the first resistor;
res132 represents a resistance of the second resistor;
element1 represents a resistance of the properly operating electromagnetic coil;
and
element2 represents a resistance of the properly operating heating element.

67 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/678,288Filed 23 Feb 2007
Published: US 2008/0204035 A128 Aug 2008
Granted: 16 Jun 2009
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

B41J 2/0458
Control methods or devices therefor, e.g. driver circuits, control circuits: controlling heads based on heating elements forming bubbles
B41J 2/0451
Control methods or devices therefor, e.g. driver circuits, control circuits: for detecting failure, e.g. clogging, malfunctioning actuator
B41J 2/04541
Control methods or devices therefor, e.g. driver circuits, control circuits: specific driving circuit
B41J
Typewriters