Abstract: A thermal head control device includes: a printing rate calculation range determination unit configured to determine, as a printing rate calculation range, a range from a left-end energization dot to a right-end energization dot among energization dots present in printing data corresponding to heating elements to be controlled among a plurality of heating elements included in a thermal head; a printing rate calculation unit configured to calculate a printing rate of the printing rate calculation range determined by the printing rate calculation range determination unit; an energizing time calculation unit configured to calculate an energizing time for which a current is caused to flow through the heating elements based on the printing rate calculated by the printing rate calculation unit; and an output unit configured to output a control signal for driving the heating elements to be controlled of the thermal head, based on the calculated energizing time.

Abstract: A printer includes a processor and a thermal head having a plurality of heating elements to print an image having a plurality of print lines on a printing medium on the basis of printing data, wherein in an initial control period, for any printing data, the processor causes the thermal head to perform a division printing for each of the print lines that are to be printed in the control period, the division printing being such that for each print line to be printed, the plurality of heating elements are divided into a plurality of subgroups and the respective subgroups of the heating elements are activated in a time-divided manner, and wherein in a normal period after the control period, the processor causes the thermal head performs a non-division printing for at least some of the print lines that are to be printed in the normal period.

Abstract: N is defined to be an integer of 2 or more, and K is a positive integer that satisfies K<N. An arithmetic operation unit performs 2K ways of processing, which are a sum of 2K?1 ways of processing for obtaining converted gradation data based on addition of high-order gradation data composed of high-order (N?K) bits of N-bit original gradation data and low-order K-bit data of the original gradation data, and processing directly using the high-order gradation data as the converted gradation data. A selector selects, in response to each of a plurality of heating resistors, any of the converted gradation data as gradation data for performing gradation recording by using a line thermal head including the plurality of heating resistors, the converted gradation data being obtained by the 2K ways of processing.

Abstract: The temperature of heat elements of a thermal head can be controlled with high precision by a process with a low processor load. A printer 100 that prints on thermal roll paper 102 based on print data has a thermal head 134 with multiple heat elements 136 arrayed in a sub-scanning direction CR perpendicular to the conveyance direction F of the thermal roll paper 102. The printer 100 has a current control unit 112 that segments the heat elements of the thermal head 134 into plural blocks, and controls the energize timing of the heat elements in each block based on the number of heat elements 136 that are energized in the thermal head 134.

Abstract: An electric power control section includes: a temperature detecting section for detecting temperatures of a battery; and an accumulation counter for accumulating numerical values assigned to the respective temperatures of the battery which have been detected by the temperature detecting section. The electric power control section reduces electric power supply to an LCD display section when an accumulated value obtained by the accumulation counter exceeds a preset value.

Abstract: This is disclosed a printer comprising a feeder, a printing head, a take-up body, and a print control portion. The feeder feeds a recording medium. The printing head forms desired print in a predetermined print area of the recording medium fed by the feeder. The take-up body sequentially takes up the recording medium on an outer circumference part with a tip end region of the recording medium positioned on downstream side in a transport direction than the print area connected to the outer circumference part and produces a roll-shaped printed matter. The print control portion controls the printing head so as to form a print part for preheating the printing head in a position that serves as a border between the tip end region and the print area of the recording medium.

Abstract: Every print line lined up to the number of “preset line number 1”, the dot number that the main pulse MP is added is counted, and when the variable number M which is the most count number is larger than the variable number A, the value of variable number M/variable number A is set to the variable number of “divisional number” and “9” is set to the variable number of “target speed”. When the variable number M corresponding to the most count number is not larger than the variable number A, the dot number that the supplemental pulse HP is added is counted every print line lined up to the number of “preset line number 1” and when the variable number S corresponding to the most count number is larger than the variable number A, “0” is set to the variable number of “divisional number” and “24” is set to the variable number of “target speed”.

Abstract: When printing a first line, a control device controls energizing heat elements corresponding to pixels where a dot is formed on a second line that is printed continuously. A control device of a thermal head having a plurality of heat elements arranged in a line includes: an acquisition unit that acquires information of pixels forming dots when printing the second line during line printing of a first line and a second line by continuous line printing by the plural heat elements; and an energization control unit that controls energizing the heat elements during the first energizing period based on image data related to printing the first line when printing the first line, and controls energizing the heat elements in the second energizing period when printing the first line based on the image data related to printing the first line and the pixel information acquired by the acquisition unit.

Abstract: A method and apparatus for transferring an image of predetermined length onto a substrate by selective energization of a row of printing elements in a printhead of a printing apparatus. Operational characteristics of the printing apparatus are determined, and the image is rendered such that the number of rows of the pixels in the rendered image is no greater than the maximum number of rows of pixels which can be printed in the length of the image given the operational characteristics of the printing apparatus. Additional rows of pixels may be printed between pairs of rows of printed which correspond to consecutive rows in the rendered image. The pixel content of each additional row is a function of the pixel content of the adjacent pairs of rows.

Abstract: A method for controlling a printing speed of a thermal head having a plurality of heater elements arranged in a line includes: dividing a set of printing data into blocks each comprising one or more printing lines aligned in a main scanning direction, in which the dividing is in a sub scanning direction, and in which a block including a first predetermined number of printing lines is regarded as a unit block; calculating the number of the heater elements to be driven for each of printing lines included in a block as the number of on-dots, and comparing the numbers of on-dots for the block to obtain a maximum number of on-dots for the block; and setting a printing speed for one block to be slower than a printing speed for another block with smaller maximum number of on-dots than maximum number of on-dots for the one block.

Abstract: A thermal printer includes a first thermal head which is so provided as to be brought into contact with one side of a paper, a second thermal head which is so provided as to be brought into contact with the other side of the paper, and a controller. The first thermal head energizes a plurality of heater elements to print dot image data on one side of the paper. The second thermal head energizes a plurality of heater elements to print dot image data on the other side of the paper. The controller is configured to shift the energization times between the first thermal head and second thermal head.

Abstract: An entire block of print data for a message is subdivided into sub-blocks of print data. During printing of sub-blocks, an earlier received sub-block of data is used to print one portion of a substrate moving in the downstream direction. The substrate is moved upstream for a back distance and then moved downstream with the next sub-block of data being printed on the substrate as it is moved downstream. As a back distance section of the substrate again travels in the downstream direction, data from the subsequent sub-block of data that corresponds to data printed on the back distance section of the substrate during printing of the immediately preceding sub-block of data, is printed on the back distance section of the substrate. The sub-blocks of data are in effect stitched together by the dual printed back distance to minimize transition artifacts.

Abstract: A thermal printer includes a first thermal head which is so provided as to be brought into contact with one side of a paper, a second thermal head which is so provided as to be brought into contact with the other side of the paper, and a controller. The first thermal head energizes a plurality of heater elements to print dot image data on one side of the paper. The second thermal head energizes a plurality of heater elements to print dot image data on the other side of the paper. The controller is configured to shift the energization times between the first thermal head and second thermal head.

Abstract: A method and apparatus for transferring an image of predetermined length onto a substrate by selective energization of a row of printing elements in a printhead of a printing apparatus. The printing apparatus may be arranged with a print ribbon located between the printhead and the substrate such that ink is selectively transferred from the ribbon to the substrate as a result of energizations of the printing elements. The image to be printed is rendered in memory as a series of rows of pixels and the apparatus is set up to download the rendered rows of pixels to the printhead successively. The relative positioning of successively printed rows of pixels on the substrate is determined by relative displacement between the printhead and the substrate. The apparatus is set up to control the positioning of the rows of pixels by controlling the delay between successive energizations of the printing elements.

Abstract: The present invention is and includes a conversion circuit for allowing a printer controller to send a different set of control signals for dot history control to an integrated circuit driver other than those which the integrated circuit driver is designed to receive. The conversion circuit includes a plurality of driver circuits coupled to a plurality of strobe signals from at least one strobe signal generator, wherein each of the plurality of driver circuits comprises a plurality of gating groups respectively coupled to the plurality of strobe signals, wherein each of the plurality of gating groups includes a plurality of gate units respectively coupled to a plurality of heating elements wherein at least one gate unit controls at least one coupled heating element according to a corresponding strobe signal.

Abstract: One or more arrays of heating elements are configured with insulating regions to prevent the dissipation of heat to unintended regions of a thermochromic substrate. Methods include printing and arranging impressions on a two-sided substrate avoiding bleeding and other problems more-commonly associated with traditional two-sided thermal printing techniques. A simple and reliable thermal printing system is provided for use in ballot marking, including several mechanisms for receiving and detecting the orientation of a substrate within a thermal printing apparatus.

Abstract: When printing is performed by dividing a thermal printer head into segmented blocks, the number of dots to be printed in one line is changed, depending on the case, high-speed printing with a small division number of the segmented blocks, or low-speed printing with a large division number of the segmented blocks. When the division number of the segmented blocks is large and printing is performed at a low speed, paper feeding within one line is performed by multiple pitches to prevent the paper sheet from halting in one line, and energization is performed for each pitch to prevent occurrence of gaps between dots and between lines, by increasing the number of dots to be printed in one line. In the multiple pitches in one line, the ratio of energization amount to be fed in each pitch is changed to reduce a difference in density among pitches in one line.

Abstract: A thermal printer includes a first thermal head which is so provided as to be brought into contact with one side of a paper, a second thermal head which is so provided as to be brought into contact with the other side of the paper, and a controller. The first thermal head energizes a plurality of heater elements to print dot image data on one side of the paper. The second thermal head energizes a plurality of heater elements to print dot image data on the other side of the paper. The controller is configured to shift the energization times between the first thermal head and second thermal head.

Abstract: An element substrate for a recording head includes groups of heating resistors that are disposed next to one another in each group; logic circuits configured to time-divisionally drive the heating resistors in units of one block; a heat enable signal line common to the groups of heating resisters, the heat enable signal line supplying a heat enable signal to each of the groups of heating resisters; and delay circuits connected to the heat enable signal line at positions between the groups of heating resisters. A signal output from each delay circuit to the next group is inverted.

Abstract: A printing apparatus includes a thermal head in which a plurality of heating elements are provided in a width direction of paper, an analyzing unit which analyzes whether an input print layout contains any bar code, a calculating unit which calculates a print ratio of a bar code portion in the paper for each line of the print layout in the case where the analyzing unit analyzes that at least the print layout contains a bar code, a setting unit which sets a printing velocity corresponding to the print ratio for one line in the bar code portion calculated by the calculating unit in the case where the analyzing unit analyzes that the print layout contains the bar code and a changing unit which changes a velocity at which the thermal head performs printing on the paper for one line to the printing velocity set by the setting unit.

Abstract: An ink jet printer has an ink jet head comprising a nozzle that discharges an ink droplet toward a print medium, and an actuator that makes the nozzle discharge the ink droplet when a pulse signal is applied to the actuator. An applying device can apply at least two kinds of pulse signals to the actuator. The pulse width of each kind of pulse signal mutually differs. A first storage stores at least two kinds of base pulse widths. Each kind of base pulse width mutually differs and corresponds with a different kind of pulse signal. An inputting device inputs a predetermined value which is stored in the second storage. The applying device determines a pulse width of each kind of pulse signal by multiplying the corresponding base pulse width stored in the first storage by the predetermined value stored in the second storage.

Abstract: A method and apparatus for transferring an image of predetermined length onto a substrate by selective energisation of a row of printing elements in a printhead of a printing apparatus. The printing apparatus may be arranged with a print ribbon located between the printhead and the substrate such that ink is selectively transferred from the ribbon to the substrate as a result of energisations of the printing elements. The image to be printed is rendered in memory as a series of rows of pixels and the apparatus is set up to download the rendered rows of pixels to the printhead successively. The relative positioning of successively printed rows of pixels on the substrate is determined by relative displacement between the printhead and the substrate. The apparatus is set up to control the positioning of the rows of pixels by controlling the delay between successive energisations of the printing elements.

Abstract: To provide a technology which facilitates positioning of a document to a document table even in a condition of a vertically placed image reading apparatus and by which operability was improved. It is configured in such a manner that, in case that a document cover 6 was opened to an apparatus main body 1 in the vertically placed condition, (a distance c between a document table glass 2 of an apparatus main body 1 and an end portion 57 of a lowermost portion of a press-contact sheet 8)<(a step (a height from the document table glass 2) d of a step 58a) is realized.

Abstract: A thermal head has plural heat generating elements arrayed therein in a main scanning direction to form a heat generating element row, causes the respective heat generating elements to generate heat while conveying a recording medium in a sub-scanning direction, and forms plural dot lines in the main scanning direction on the recording medium to record an image. A plurality of the heat generating element rows are arrayed in the sub-scanning direction. Respective nth (n is a natural number) heat generating elements among the heat generating elements in the respective heat generating element rows can sharingly form a dot in the same position in an identical dot line according to independent driving for each of the heat generating element rows.

Abstract: A thermal transfer printing method and apparatus. The thermal transfer printing method of printing each main line in a unit of a block comprises uniting a plurality of critical data, which exists in the same order in each of the blocks in each of the main lines composing a unit page, to one another, storing the uniting results as a plurality of sub-line data and printing the plurality of stored sub-line data, wherein each of the plurality of critical data is data obtained by dividing data included in each of the blocks by the number of critical dots and each of the plurality of critical data has a number of dots less than or equal to the number of critical dots.

Abstract: An fluid ejection device includes nozzles and includes firing resistors which correspond to the nozzles. Each firing resistor and corresponding nozzle are located in zones on the fluid ejection device where each zone has at least one firing resistor and corresponding nozzle. Addressable select logic responsive to a select address couples fire pulses to the firing resistors in the zones so that each firing resistor in each zone is coupled to the same fire pulse.

Abstract: The present invention provides a printing apparatus that selects a suitable speed, thereby enabling a rapid printing operation with printing quality maintained. In the printing apparatus, the number of heating elements for every printing line is counted. A printing constant speed is determined based upon the dividing number of a thermal head selected from the counting result. When the printing constant speed is changed, a corresponding numerical table is selected and set from a printing speed accelerating table and a printing speed decelerating table stored in a ROM and set for every printing constant speed.

Abstract: Printhead structured such that printing elements are divisionally driven in unit of plural blocks, comprises: an input terminal to which printing data and encoded block data are serially inputted; a shift register sequentially shifting and storing one bit at a time the data serially inputted from the input terminal; a latch temporarily storing the data stored in the shift register; a decoder decoding the block data stored in the latch; and an AND circuit. The decoder outputs a signal in which encoded block data is partially decoded, and the AND circuit determines blocks to be driven based on the partially decoded signal. This structure enables to reduce an area of a printhead substrate, thereby enabling cost reduction of a printhead.

Abstract: An fluid ejection device includes nozzles and includes firing resistors which correspond to the nozzles. Each firing resistor and corresponding nozzle are located in zones on the fluid ejection device where each zone has at least one firing resistor and corresponding nozzle. Addressable select logic responsive to a select address couples fire pulses to the firing resistors in the zones so that each firing resistor in each zone is coupled to the same fire pulse.

Abstract: An inkjet printhead assembly includes at least one inkjet printhead having nozzles and firing resisters. The inkjet printhead assembly includes fire pulse generator circuitry responsive to a start fire signal to generate fire signals, each having a series of fire pulses. The fire pulse generator circuitry generates the fire signals by controlling the initiation and duration of the fire pulses. The fire pulses control timing and activation of electrical current through the firing resisters to thereby control ejection of ink drops from the nozzles. One embodiment of the inkjet printhead assembly includes multiple printheads disposed on a carrier to form a wide-array inkjet printhead assembly.

Abstract: This invention provides an image printing apparatus in which, when the printhead temperature rises in driving the printhead at a high speed, the ink discharge amount is optimized in accordance with the temperature rise to achieve high-quality, high-efficiency printing. For this purpose, in an image printing system using a time division simultaneous driving method of grouping a predetermined number of printing elements into a plurality of blocks every predetermined number of printing elements and driving printing elements belonging to the same block at the same driving timing, if the printhead falls within a predetermined temperature range, droplets are discharged using all blocks to print an image. To the contrary, if the printhead reaches the predetermined temperature or higher, blocks to be used are restricted in accordance with the printhead temperature, the total number of droplets is decreased, and the amount of one droplet is increased to print an image.

Abstract: This invention is to provide a printhead capable of printing at a higher speed even when the number of printing elements is large, a printing apparatus using this printhead, a printhead cartridge, and a printing element substrate. For this purpose, print signals necessary for driving M printing elements belonging to each of N divisional blocks and a select control signal necessary for block selection are transferred by inputting print signals corresponding to L (L<M) printing elements serially from a first signal line by using a clock signal and inputting print signals corresponding to the remaining (M−L) printing elements and a corresponding select control signal serially from a second signal line by using the same clock signals.

Abstract: This invention discloses a printing apparatus and printing method for shortening the print data transfer time in thinning and driving nozzles in high-speed printing, multipass printing, or the like. In thinning and driving nozzle blocks, a printer main body transmits data representing a print mode, and print data corresponding to nozzles to be used. In a printhead, a shift clock generator generates a shift clock shortened in period in accordance with the thinning ratio, and a shift register stores the print data in correspondence with the clock. Print data corresponding to the printing elements to be used are repetitively stored in areas corresponding to printing elements not to be used.

Abstract: A method is provided for providing the same amount of energy to each print head element in a thermal printer during each print head cycle used to print an image, regardless of the number of print head elements that are active during each print head cycle. The desired amount of energy may be provided to a plurality of print head elements that are active during a print head cycle by delivering power to the plurality of print head elements for a period of time whose duration is based in part on the number of active print head elements. The period of time may be a portion of the print head cycle.

Abstract: A method of controlling a temperature of a print chip of a printhead in an ink jet printer includes providing a memory device within the printer. Ink is emitted from the printhead. Temperature data associated with the print chip during the emitting step is recorded. A thermal resistance value associated with the printhead and/or a thermal capacitance value associated with the printhead is calculated. The calculating is dependent upon the recorded temperature data. The thermal resistance value associated with the printhead and/or the thermal capacitance value associated with the printhead is stored in the memory device. A temperature of the print chip at a future point in time is estimated based upon a number of ink drops to be emitted by the printhead before the future point in time, and the thermal resistance value associated with the printhead and/or the thermal capacitance value associated with the printhead.

Abstract: A wide-array inkjet printhead assembly includes a carrier and N printheads and a module manager disposed on the carrier. The module manager receives a serial input data stream and corresponding input clock signal from a printer controller located external from the inkjet printhead assembly. The module manager demultiplexes the serial data stream into N serial output data streams. The module manager provides the N serial output data streams and N corresponding output clock signals based on the input clock signal to the N printheads.

Abstract: A thermal line printer drive method and a thermal line printer devised to prevent occurrence of a white gap during printing. A plurality of heating elements arranged on a line perpendicular to a sheet feed direction are separated into a plurality of blocks, and the heating elements in each block are driven separately from those in other blocks to perform thermal recording on a heat-sensitive sheet. A drive pulse is applied to each heating element in each block a certain number of times by being divided.

Abstract: To provide a thermal line printer and a method of driving the thermal line printer, which may suppress the degradation in printing quality such as non-uniformity in density caused by the sticking phenomenon. A method of driving a thermal line printer for performing thermal recording onto thermal paper to be fed by a drive of a stepping motor with a thermal line head where a plurality of heating resistors are arranged in a linear manner on a line perpendicular to a paper feeding direction, includes the following steps of: dividing the thermal resistors of the thermal line head into n blocks (where n is an integer not smaller than one), and further constituting m groups (where m is an integer not smaller than zero) by the n blocks; and driving each of the groups in order, and driving the stepping motor after each drive to thereby perform a paper feed less than one dot.

Abstract: There will be provided a printing method for block copy film and a block copy printer capable of adjusting printing density as occasion arises as well as making joints between print lines inconspicuous. A predetermined mount of conveyance of transparent resin film P will be set to 1/N (N is an integer of 2 or more) of a predetermined printing width, which is a line-up width of the exothermic elements, and printing at a predetermined printing width will be repeated after the transparent resin film P is conveyed in the predetermined amount of conveyance.

Abstract: Every time after a cyan ink and a magenta ink are transferred to form respective color dots of a line with a length L2 in a sub-scanning direction, an ribbon cassette RC is returned to a start position of the transference of the cyan and magenta inks and moved by half of a pitch of a print dot of the cyan and magenta inks in the sub-scanning direction by a carriage moving mechanism CH. Subsequently, an yellow ink is transferred to form yellow color dots of a first column. Every time after the ribbon cassette RC is moved by a pitch P1 each in the sub-scanning direction, the yellow ink is transferred to form dots of one column until dots of all columns in the length L2 of a line are formed.

Abstract: The invention provides a current supply control method used for a line thermal head that is capable of reducing the irregular color and jitter easily and surely. The method is characterized in that heating elements served for divided driving are controlled so as to be different for each color served for printing.

Abstract: A multi-gradation recording method wherein the recording energy in high density region can be reduced, and the rough appearance in low density region or high density region and notchy appearance in profile or line of the image can be reduced while maintaining the level of reproduction of intermediate tones obtained by the conventional recording method using the zigzag pattern or the stripe pattern is provided which comprises: using a printer of the type wherein each one pixel is formed by using each one recording element and the optical density of the pixel formed is represented by the magnitude of the area of the pixel, dividing input data into two or more groups with respect to the data corresponding to pixels to be arranged in principal scanning direction, correcting the data of each group on the basis of the corresponding &ggr; correction data, the &ggr; correction data for the respective groups being different from each other, and performing recording on the basis of the corrected data wherein the pixels

Abstract: A thermal head has plural heating elements arranged in line in a main scan direction. The heating elements are supplied with a train of drive pulses while the thermosensitive recording sheet is conveyed in a sub scan direction crosswise to the main scan direction, for thermal recording to the recording material by one line. The heating elements are grouped into first and second groups. The drive pulse train for the first group of the heating elements is determined by starting the drive pulse train at a start of the one line. The drive pulse train for the second group of the heating elements is determined by ending the drive pulse train at an end of the one line.

Abstract: An ink jet recording apparatus comprises a recording head having ink ejection orifices, and a common ink chamber communicating with the ink ejection orifices to supply the ink to the ink ejection orifices, a driver for non-simultaneously causing at least one of adjacent ones of the ejection orifices of the recording head to eject the ink, and a driving controller for changing an order of ejection performed by the driver.

Abstract: A substrate for a recording head has a plurality of recording elements, a plurality of functional elements electrically connected to the recording elements, and a common electrode electrically connected to the recording elements and selectively feeding a driving signal to the recording elements on a base boad. Also, the common electrode is prepared as a layer by the same step as that of forming a conductor electrode layer to be electrically connected to a semiconductor layer constituting the functional elements arranged in the substrate. Therefore, the recording apparatus, can be prepared by the process including the step of forming the recording elements and simultaneously connecting these elements to reduce the number of film forming operations.

Abstract: A recording head system for an ink jet recording apparatus having a full-line recording head. The recording head is divided into a variable number of blocks. The recording ratio of each block (that is, the ratio of the number of ink ejecting elements to be driven in a block in accordance with recording data to the total number of the ink ejecting elements in the block) is compared with a reference recording ratio. When the recording ratio is greater than the reference recording ratio, the interval between the drive timing of a block and that of the next block is lengthened, or vise versa. This is performed by controlling the enable timing of each block by D-flip-flops, AND gates and delay circuits. Unevenness of recorded images resulting from the fluctuation in periodic ink pressure can be ameliorated.

Abstract: A thermal transfer recording apparatus for performing recording of data on a recording medium by transferring ink of an ink sheet on said recording medium comprises conveying means for conveying said ink sheet and recording medium, recording means for effecting said ink sheet to record image data on said recording medium, and control means for counting time after image recording by said recording means and driving said recording means when the next image recording is not performed in a predetermined time period.

Abstract: In an inventive method of driving a thermal head including heating resistors corresponding to a line of dots, the heating resistors are grouped into blocks consisting of the same number of heating resistors. After producing main printing data for one line of printing, such blocks where the ratio of the number of heating resistors in which the printing data is inputted to the number of all the heating resistors in each block is smaller than a preset ratio, are detected as target blocks. Then, auxiliary printing data for preheating such heating resistors in each target block to which the main printing data is inputted, is produced. When the total number of the heating resistors in all the blocks to which the main printing data is inputted is larger than a preset number, the auxiliary strobe signal is inputted to the heating resistors to preheat the heating resistors in the target blocks. By this preheating, the shortage of energy due to voltage drop of a power source will be compensated.

Abstract: When a recording mode of a printer is changed to a resolution expansion mode when an internal temperature of a recording head falls or by an external indication, the number of divided blocks is changed so that the overlap of on time zones of block sub-division signals is prevented in order to assure that heaters of the recording head are energized for a sufficient time period. Thus, the heater energization time period for each block is extended without extending the total recording time.

Abstract: Both a method and apparatus are provided for sizing and operating enable groups of thermal elements in a thermal printer to allow the printer to be operated by power sources having outputs too small to operate all of the thermal elements simultaneously. Prior to the printing operation, the maximum number of thermal elements that can be actuated by the output of the power source is determined, and then divided into the total number of thermal elements. Next, the resulting quotient is rounded up into the nearest integer in order to ascertain the number of enable groups. The number of enable groups is then divided into the total number of thermal elements to determine the size of each enable group.