Abstract: An apparatus and method for correcting printing characteristics of a full-line printhead, and producing a high-printing quality printhead at high manufacturing yield, a corrected printhead by this apparatus, and a printer employing this printhead are disclosed. According to this method, an image is printed on a printing medium by using double pulses obtained based on fluctuation of resistance of each printing unit of a printhead, and a reference OD value is determined from an OD value histogram of the printed image. A preheating pulse width is selected, based on OD values of n printed images obtained by changing the preheating pulse width n times and the reference OD value, such that an OD value on each printing element is equal or close to the reference OD value. For example, assuming that the reference value is 0.43, a preheating pulse width on printing element No. 3 is 0.875.mu. sec.

Abstract: A method and apparatus for automatically compensating for thermal conditioning of an ink jet print head are provided. The method and apparatus monitor the time during which the print head experiences various temperatures. The driving voltage supplied to the ink jet transducer is adjusted over time to compensate for thermal conditioning of the print head.

Abstract: A thermal printing method for printing an image line by line on a recording material by driving an array of heating elements of a thermal head while transporting the recording material relative to the thermal head. Heating data for recording a subject line to print is corrected in accordance with heat accumulation amounts of the heating elements. Surface temperatures of the respective heating elements are estimated on the basis of corrected heating data. A frictional force that will be generated between the thermal head and the recording sheet on recording the subject line is calculated on the basis of the estimated surface temperatures. The heating elements start being driven to record the subject line at a time shifted by a time shifting amount from a standard time. The time shifting amount is determined depending upon the frictional force so as to eliminate influence of fluctuations in transport speed of the recording sheet on the printed image.

Abstract: According to the improved method of correcting uneven densities in a thermal recording apparatus, on the basis of a preliminarily computed mathematical function that represents the relationship between the image data and the frictional force between the thermal recording material and the thermal head, a total sum of functional values corresponding to the image data of individual pixels in a present line, as well as a total sum of functional values corresponding to the image data of individual pixels in a preceding line are taken and the image data are corrected in accordance with the difference between the two total sums. This method can prevent effectively the occurrence of uneven densities due to the variation of recording density to provide for precise image recording.

Abstract: An improved thermal printer has circuits that are responsive to selected parameters of the printer and to the contents of a document to be printed to selectively enable the individual printing electrodes with printing impulses of varying energy depending upon when the electrode had printed. Other circuits cause the selective process to be responsive to whether electrodes adjacent a selected electrode had printed and how recently such printing took place. In different embodiments, circuits utilize not only the history of a selected electrode and its neighbors, the as yet unprinted portion of the document to be printed is utilized to aid in the selection of an appropriate printing impulse.

Abstract: A method and apparatus for maximizing print quality in a thermal printer uses a ribbon condition monitor to detect the condition of a multipass thermal ribbon. Data related to the condition of the thermal ribbon at each individual pixel is used to determine a custom energization signal for each thermal print element. In one embodiment, the system utilizes a history memory to track the prior heating history of each thermal print element and an ink memory to track the prior use of each location on the thermal print ribbon corresponding to the thermal print elements. The data from the history memory and the ink memory are combined to form an index to a table memory containing data corresponding to a plurality of energization signal levels for a particular print medium. The data in the table memory provides the custom energization signal for each of the thermal print elements. In an alternative embodiment, a light source and detector are used to determine the thickness of ink remaining on the thermal ribbon.

Abstract: A plurality of shift register groups 13a-13d each consisting of a plurality of registers are provided to store a next one of printing data, a current one of the printing data, a predetermined number of previous ones of the printing data and a predetermined number of previous ones of the printing data for an adjacent heating dot. A plurality of pattern discerning circuits 14a-14d are also provided to consecutively discern history patterns of respective heating dots and output corresponding driving data, so that the printing energy for a heating dot is made smaller when its next one of the printing data stored in the shift register group 13a-13d is "0" than when the next one of the printing data is "1".

Abstract: A thermal printer using a thermal head having a plurality of heating elements arranged in line, wherein the heating elements are driven for different power conduction times to record dots at different densities. According to the invention, the thermal printer is comprised of a first look-up table for converting original heating data into time data representative of a power conduction time corresponding to the original heating data; a correction circuit for correcting the time data to obtain a corrected power conduction time; a second look-up table for converting the corrected power conduction time into corrected heating data which corresponds to the corrected power conduction time; and a head driver for driving the heating elements in accordance with the corrected heating data.

Abstract: Accumulated heat correcting data of an Nth line to be printed is subtracted from original heat data of the Nth line. This corrected heat data of the Nth line is supplied to a head driver which drives a thermal head to record dots of one line on a recording sheet. The corrected heat data of the Nth line is multiplied by a coefficient K1 to obtain first data. The first data is added to the accumulated heat correcting data of the Nth line, and sum data of the addition is written in a line memory as second data. In printing the (N+1)th line, the second data is read from the line memory. The second data is multiplied by a coefficient K2 to obtain the accumulated heat correcting data of the (N+1)th line, which is used for accumulated heat correction of the original heat data of the (N+1)th line.

Abstract: In the disclosed thermal gradation printing apparatus, heat elements in a line-type thermal head are divided into a plurality of groups, and an accumulated heat amount in the substrate of the thermal head for each group is estimated based on the pulse width data applied to each heat element considering the influences by heat accumulations in the main-scanning direction and in the sub-scanning direction. Based on the group division estimated accumulated heat amounts and the temperature of the body portion of the thermal head, a correction value for the pulse width data to be applied to each heat element. Moreover, the correction value is applied to the pulse width data for each heat element, so as to output the corrected pulse width data to the thermal head.

Abstract: A method of controlling a thermal print head having a plurality of resistive heaters to compensate for the effects of latent heat from the resistive heaters is disclosed. The plurality of resistive heaters are arranged in a line on a substrate with each of the plurality of resistive heaters corresponding to a pixel position on a medium such as paper. A compensation value is determined for each pixel in a line such that the effects of latent heat from the corresponding heater and from adjacent heaters are compensated. A compensated gray level for each pixel of the line is calculated as a function of a desired gray level for the particular pixel in the line and as a function of the associated compensation value. Finally, the heaters are driven as a function of the compensated gray levels to print the corresponding pixels of the line.

Abstract: The past print data of plural heating resistance elements adjacently disposed are stored and latched in first latching circuit, the present print data is stored and latched in second latching circuit, and corresponding to the latched outputs of these first and second latching circuits, when the heating resistance elements have printed in the past and when the heating resistance elements adjacently to both sides of each heating resistance element are presently used in printing, it is controlled so as to shorten the driving time. As a result, blurring of the print due to excessive temperature rise of the heating resistance elements may be suppressed. Hence, the printing quality may be enhanced.

Abstract: A DEP device adapted for grey-scale printing comprising a back electrode (105), a printhead structure (106), an array of printing apertures (107) in the printhead structure (106) through which a particle flow can be electrically modulated by a control electrode (106a), a toner delivery means (101), at least one control means (111) for applying an electric field to the control electrodes, wherein:(i) the control means controls each single control electrode to enable the printing through each single printing aperture (107) of pixel dots (PD), each of the pixel dots intended to have a density D, and(ii) the control means controls the printing of the pixel dots through the each single printing aperture as a function of both the intended density (D.sub.intend) and the density (D.sub.prev) previously produced through the single printing aperture, i.e. the control means use "previous correction".

Abstract: In a thermal printing apparatus, three consecutive image data items in the main scanning direction is sequentially extracted. When all the three image data items are at level 0 (indicating that no dot is printed) and at level 1 (indicating that a dot is printed), a printing density is determined to be 0 (indicating that no dot is printed) and 3 (indicating that a dot of the highest printing density is printed), respectively. When one of the three image data items is at level 1, the printing density is determined to be 1 (indicating that a dot of the lowest printing density is printed) when the printing density of the preceding printed pixel is any value other than 0. When one or two of the three image data items is or are at level 1, the printing density is determined to be 1 or 2 (indicating that a dot of an intermediate printing density is printed) according to the printing density of the preceding printed pixel.

Abstract: In the disclosed thermal gradation printing apparatus, heat elements in a line-type thermal head are divided into a plurality of groups, and an accumulated heat amount in the substrate of the thermal head for each group is estimated based on the pulse width data applied to each heat element considering the influences by heat accumulations in the main-scanning direction and in the sub-scanning direction. Based on the group division estimated accumulated heat amounts and the temperature of the body portion of the thermal head, a correction value for the pulse width data to be applied to each heat element. Moreover, the correction value is applied to the pulse width data for each heat element, so as to output the corrected pulse width data to the thermal head.

Abstract: There is disclosed a method of successively forming and/or erasing images selectively in different portions of a recording layer of a recording medium which comprises a reversible thermosensitive recording material capable of recording images and erasing the same by reversibly changing the transparency or the color tone of the portions of the recording layer with the application of heat thereto, depending upon the temperature thereof, in such a manner that the same portion of the recording layer is not continuously used for image formation and/or erasure in excess of a predetermined number of times, thereby repeating the use of the recording medium for an extended period of time.

Abstract: A method and apparatus for controlling a thermal printhead. In response to a sequence of print commands, the method and apparatus generate an energization signal for each thermal print element in the printhead. In one embodiment, the energization is a function of at least the present print command and a future print command. In certain embodiments, the energization signal may also be a function of a past print command, print commands for at least one adjoining print element, and other parameters. Each print element in the printhead can, accordingly, be maintained at a proper temperature to ensure long printhead life and cause the printhead to generate sharp images.

Abstract: A system for controlling the temperature of the printing elements of a thermal printhead. The printhead is provided with a plurality of spaced apart temperature sensor that measure the temperature at various locations on the printhead. A processor receiving outputs from the sensors determines the approximate temperature of each printing element based upon its proximity to at least one temperature sensor and the temperature sensor outputs. The processor then uses the approximate temperature of the printing elements to formulate either a strobe signal or a serial data stream that is applied to the respective printing element. Each printing element thus receives a quantity of energy that is a function of whether the printing element will contribute to the printing of an image during a scan line as well as the approximate temperature of the printing element.

Abstract: A method of supplying an energization signal to a selected element in an array of print elements. Printing activity of the selected element and neighboring elements is determined, compressed and stored to memory. Based on the stored compressed printing activity data, an energization schedule for the selected element is determined using a look-up table technique. The data in the look-up table may also be compressed reducing the memory required by the energization data. Further reductions in memory are achieved by grouping portions of the printing activity data to identify common energization schedules for differing printing activities. The printing activity data may relate to temporal distributions and/or spatial distributions of printing activity of elements in the array. The method may be applied to linear or two-dimensional arrays of print elements.

Abstract: The present invention is intended to provide a method of controlling the printing condition of a thermal print head provided with a comparatively large number of heating elements, capable of controlling the printing condition of the thermal print head by using a heating element driving circuit having a comparatively simple configuration and of dealing with increase in both printing speed and dot density. The method corrects the energizing time for each heating element (2) of a plurality of heating elements (2) of the thermal head (1) by adjusting the amount of heat to be generated by the heating elements (2) through a procedure comprising determining a plurality of logical values on the basis of the mode of energization of each heating element in the preceding printing cycles, and sequentially providing the logical values at predetermined time intervals.

Abstract: A recording apparatus having a print head control apparatus containing an IC drive control circuit utilizes at least two shift registers having N single bit registers with respective data input terminals sequentially switched to receive print data wherein, at any one print cycle, one shift register is storage for current print data and the other shift register is storage for past print data so that, on the succeeding print cycle, the latter shift register receives new print data and the former shift register becomes the holder of past print data. When one of the shift registers provides output for the current print data to the thermal print head drivers, the other shift register is employed for referencing the past print data, i.e., comparing current and past print data. Thus, the function of shift registers are sequentially switched to control the drive data output to the thermal elements of the print head based on past print data history.

Abstract: A printer for printing serial bar codes on a web of record members with a thermal print head is shown. The thermal print head is driven by a series of pulses having a constant duty cycle for each row of information printed. However, the number of pulses in the series is varied from row to row, in accordance with the status of the current row being printed as a bar row or a space row; with the status of at least one row immediately preceding the current row and at least one row immediately succeeding the current row; and with the number of bar rows previously printed. By varying the number of pulses applied to the thermal print head and thus the amount of energy applied thereto, discontinuities in the serial bar code and any information, such as a human readable character, printed adjacent thereto are minimized.

Abstract: A drive control apparatus for a thermal head, capable of controlling application energy given to heater elements in the thermal head on the basis of not only history information of a present heater element but also print information including print history information of heater elements adjacent to the present heater element. A print information processing is carried out based on the print history information of the present heater element, the print information of the adjacent heater elements, and the print history information of the preceding and two times before print information of the adjacent heater elements. One example of this processing circuit includes an OR circuit for a logical sum of the preceding and two times before print information of the adjacent heater element, an AND circuit for a logical product of this OR output and a print speed signal, and an OR circuit for a logical sum of this AND output and the print information of the adjacent heater element.

Abstract: Disclosed herein is a thermal head driving circuit for energizing a plurality of thermal resistors corresponding to a plurality of dots to thereby control a thermal head for printing data on a heat-sensitive paper. The thermal head driving circuit is provided with a plurality of latch circuits each of which retains recorded information formed of respective dots on the present line, of the plurality of dots and previous recorded information and outputs a plurality of patterns indicative of these information on a time-series basis. A pulse signal generator outputs pulse signals so as to increase the number of pulses with respect to patterns each falling under a high level when patterns that the degrees of increases in temperatures of said thermal resistors by energization based on patterns falling under different levels, of the plurality of patterns, are the same, are selected. The thermal resistors are energized based on the outputted pulse signals.

Abstract: A printer for printing serial bar codes on a web of record members with a thermal print head is shown. The thermal print head is driven by a series of pulses having a constant duty cycle for each row of information printed. However, the number of pulses in the series is varied from row to row, in accordance with the status of the current row being printed as a bar row or a space row; with the status of at least one row immediately preceding the current row and at least one row immediately succeeding the current row; and with the number of bar rows previously printed. By varying the number of pulses applied to the thermal print head and thus the amount of energy applied thereto, discontinuities in the serial bar code and any information, such as a human readable character, printed adjacent thereto are minimized.