Led printhead and driver chip for use therewith having boundary scan test architecture

A printhead comprising:

• a recording element;
• an integrated circuit driver for generating current for driving the recording element for recording, the driver including means for storing first image data for recording a current pixel and means for storing second image data for recording a subsequent pixel by the recording element;
• the driver including a test circuit that includes register means having a boundary scan architecture for testing connectivity on the driver, the test circuit including a data input terminal and a data output terminal;
• the register means including means for storing control data other than image data for determining a control feature for operation of the driver in a non-test mode;
• means for storing in said register means new control data during loading of second image data and printing of first image data without affecting said control feature of the driver during printing of the first image data;
• and
• a circuit device for providing a signal that updates said control feature in accordance with the new control data after recording of said first image data to affect control of said feature for recording said second image data.

A method of non-impact printing using a plurality of recording elements, the method comprising the steps of:

• selectively energizing a plurality of current-carrying channels that are operative for carrying current to respective recording elements for recording a current line of pixels;
• and
• controlling operation of current in the channels;
• the step of controlling including:
• (a) providing a test circuit interface that includes a test access port for receiving inputs of update command signals and clock inputs to said test circuit;
• and
• (b) inputting new control data, for controlling current in the channels for recording a subsequent line of pixels, into a plurality of register cells connected to the test data input terminal during operation of the recording elements for recording the current line of pixels without affecting current in the channels for recording the subsequent line of pixels.

A printhead comprising:

• a plurality of recording elements;
• and
• a plurality of integrated circuit driver chips having circuits for generating current for driving respective ones of the recording elements for recording,
• each integrated circuit driver chip including:
• (a) a first data storage device for storing first image data for recording a current pixel and a second data storage device for storing second image data for recording a subsequent pixel by each of the respective recording elements;
• (b) a test circuit that includes a plurality of registers including at least one register for testing connectivity on the driver chip, the test circuit including a test data input terminal and a test data output terminal, the plurality of registers including a register that stores new control data other than image data for determining a control feature for operation of the driver chip in a non-test mode, the new control data being stored in the register during loading of second image data in the second data storage device, the test circuit including an instruction register for storing instructions for selecting said register for outputting the new control data for controlling said driver after recording of the current pixel to affect a new control for recording the subsequent pixel, the presence of said new control data in said register not affecting control of the recording of the current pixel.

A driver IC chip for use in driving at least one recording element comprising:

• a driver circuit for generating current for driving the recording element for recording, the driver circuit including a data store for storing first image data for recording a current pixel and a data store for storing second image data for recording a subsequent pixel by the recording element;
• a test circuit controller that includes a plurality of registers having a boundary scan architecture for testing connectivity on the driver IC chip or with a component connected to the driver IC chip, the test circuit controller including a test data input terminal and a test data output terminal;
• the registers including a register for storing control data other than image data for determining a control feature for operation of the driver IC chip in a non-test mode;
• the controller providing control to said plurality of registers to store new control data during loading of second image data and printing of first image data without affecting said control feature of the driver IC chip during printing of the first image data;
• and wherein
• the controller provides a signal that updates said control feature in accordance with the new control data after recording of said first image data to affect control of said feature for recording said second image data.

A method of operating a printhead that includes a recording element and an integrated circuit driver chip for generating current for driving the recording element for recording, the method comprising:

• storing on the driver chip first image data for recording a current pixel and second image data for recording a subsequent pixel by the recording element;
• operating a test circuit that includes registers having a boundary scan architecture and testing connectivity on the driver, the test circuit including a data input terminal and a data output terminal;
• storing in the registers control data other than image data for determining a control feature for operation of the driver in a non-test mode, the registers storing the new control data during loading of second image data and printing of first image data without affecting said control feature of the driver during printing of the first image data;
• and
• providing a signal that updates said control feature in accordance with the new control data after recording of said first image data to affect control of said feature for recording said second image data.