A drive circuit for a printer

Claim 2

A drive circuit for driving plural printing elements of a print head for a printer, comprising a store (14) for receiving signals representing printing data for at least a portion of a line of print, output circuit means (18) responsive to such signals for generating plural outputs for driving the printing elements respectively for printing the at least a portion of the line of print, and output control means (17) responsive to predetermined correction codes for selectively adjusting the outputs whereby to compensate for variation in the characteristics of the respective printing elements and/or of circuit elements of the output circuit means for supplying the respective outputs, characterised in that the output control means and the output circuit means are arranged to co-operate such that the amplitudes of the outputs are adjusted according to the correction codes.

Claim 3

A drive circuit according to claim 1 characterised by a second store (16) for receiving signals representing the correction codes, the output control means being arranged to receive the signals representing the correction codes and, in response to such signals, to generate corrected printing data signals.

Claim 4

A drive circuit according to claim 1 or 2 charac­terised in that the output control means comprise plural circuit portions (17-1 to 17-m) each comprising a control circuit (21) for determining the printing mode of a corresponding one of the printing elements and a level shifting circuit (22) for generating control voltages for application to the output circuit means.

Claim 5

A drive circuit according to any preceding claim characterised in that the output circuit means comprises means for generating plural current outputs of selectively adjustable current amplitude.

Claim 6

A drive circuit according to any preceding claim characterised in that the output circuit means comprises plural circuit portions (18-1 to 18-m), each including a plurality of switching elements (F T1 to F T15 ) for controlling the supply of current from a current source.

Claim 7

A drive circuit according to claim 5 characterised in that the switching elements of each output circuit portion are connected in parallel so as to form a current synthesising circuit.

Claim 8

A drive circuit according to claim 6 characterised in that each output circuit portion has a number N of the switching elements divided into n groups with the number of switching elements belonging to the i-th group being 2 i-1 (wherein n<N, 1≦ i ≦ n), each group of the switching elements being controlled by a corresponding bit of an n-bit digital control signal supplied by the output control means.

Claim 9

A drive circuit according to claim 7 characterised in that the switching elements of each group are arranged symmetrically of the centre of the array of the switching elements and at equi-spaced intervals.

Claim 10

A drive circuit according to any of claims 5 to 8 characterised in that each of the switching elements comprises at least one field effect transistor.

Claim 11

A drive circuit according to any of claims 5 to 9 characterised in that each of the output circuit portions further comprises at least one off-setting field effect transistor (F OS1 ).

Claim 12

A printer having a print head (19) including plural printing elements (19-1 to 19-m), means (1, 11 and 12) for generating printing data and correction codes and for supplying signals representing such printing data and correction codes as outputs, and characterised by a drive circuit according to any preceding claim.

Claim 13

A drive signal supply circuit for generating plural drive signals for driving, respectively, plural elements to be driven having a respective circuit block (19-1 to 19-m) for generating each drive signal, and characterised in that each circuit block comprises an array of switching elements (F T1 to F T15 ) connected to one another in parallel so as to form a current synthesising circuit.

Claim 14

A drive signal supply circuit for generating plural drive signals for driving, respectively, plural elements to be driven having a respective circuit block (19-1 to 19-m) for generating each drive signal, and characterised in that each circuit block comprises an array of switching elements (F T1 to F T15 ) connected to one another in parallel so as to form a current synthesising circuit.

Claim 15

A current supplying integrated circuit having plural outputs (01 to 0m) for controlling current supply from a current source to a plurality of elements to be driven, characterised by a plurality of switching means (18-1 to 18-m) for controllably supplying current from the current source to the corresponding element to be driven, each of the switching means having a plurality of switching elements (F T1 to F T15 ) connected in parallel so as to form a current synthesising circuit, each of the switching elements having substantially the same current capacity.

Claim 16

A current supplying integrated circuit having plural outputs (01 to 0m) for controlling current supply from a current source to a plurality of elements to be driven, characterised by a plurality of switching means (18-1 to 18-m) for controllably supplying current from the current source to the corresponding element to be driven, each of the switching means having a plurality of switching elements (F T1 to F T15 ) connected in parallel so as to form a current synthesising circuit, each of the switching elements having substantially the same current capacity.

Claim 17

An electronic device for controlling a plurality of elements which are controlled in their driving state by the level of electric current applied thereto, characterised by means (17) for receiving output data signals and correction data signals, and current supplying means (18) arranged to be controlled in response to said output data signals and said correction data signals, said output data signals determining whether said current supplying means is to drive a corresponding element and said correction data signals determining the level of the electric current supplied by said current supplying means for driving said corresponding element, whereby said current supplying means produces currents of selected levels for driving said elements to be driven.

Claim 18

An electronic device for controlling a plurality of elements which are controlled in their driving state by the level of electric current applied thereto, characterised by means (17) for receiving output data signals and correction data signals, and current supplying means (18) arranged to be controlled in response to said output data signals and said correction data signals, said output data signals determining whether said current supplying means is to drive a corresponding element and said correction data signals determining the level of the electric current supplied by said current supplying means for driving said corresponding element, whereby said current supplying means produces currents of selected levels for driving said elements to be driven.

Claim 19

An electronic device for controlling a plurality of elements which are controlled in their driving state by the level of electric current applied thereto, comprising data signal generating means (1) for generating data signals based on which said elements are to be driven, correction data generating means (12) for generating correction data signals, data storage means (14, 15) for receiving said data signals from said data signal generating means and storing them, and characterised by means (17) for receiving said data signals stored in said data storage means and said correction data signals from said correction data generating means and, in accordance with said received data, controlling current supplying means (18) for driving said elements, said current supplying means being arranged to be controlled by said data signals for determining whether to drive a corresponding element and by said correction data signals for determining the level of the electric current supplied for driving said corresponding element whereby to produce currents of selected levels for said elements to be driven.

Claim 20

An electronic device for controlling a plurality of elements which are controlled in their driving state by the level of electric current applied thereto, comprising data signal generating means (1) for generating data signals based on which said elements are to be driven, correction data generating means (12) for generating correction data signals, data storage means (14, 15) for receiving said data signals from said data signal generating means and storing them, and characterised by means (17) for receiving said data signals stored in said data storage means and said correction data signals from said correction data generating means and, in accordance with said received data, controlling current supplying means (18) for driving said elements, said current supplying means being arranged to be controlled by said data signals for determining whether to drive a corresponding element and by said correction data signals for determining the level of the electric current supplied for driving said corresponding element whereby to produce currents of selected levels for said elements to be driven.