Signal processing device for video printer

Claim 2

A signal processing device for a video printer for printing a two-dimensional multi-gradation image which is formed by a predetermined number of picture elements, said signal processing device comprising: means for receiving R, G and B image data; means for receiving control data for designating an operation mode; color conversion data forming means for processing said R, g and B image data to form color conversion data; a first memory for storing said color conversion data and gradation control data; a second memory for temporarily storing processed data during data processing; arithmetic means, coupled to said first and second memories, for performing an aperture correction operation and an addition operation selectively on said stored color conversion data, said corrected color conversion data stored in said second memory as said processed data; means for producing heat generating data for a plurality of blocks of a thermal head in accordance with said designated operation mode and said processed data; and means for generating clock signals and address data, coupled to said first and second memories, said arithmetic means, said means for producing heat generating data and said means for receiving control data, generating clock signals and address data in response to said designated operation mode to print each line for a period of time P t which is defined by P t =t s ×S×T×U where t s is a fundamental unitary time for heat generation control, S is a number of continuation of a fundamental unitary time, T is a block division number and U is a sub-line repeat number.

Claim 3

The signal processing device as claimed in claim 1, the multi-gradation printing of each picture element is carried out with a number of slots defined by the product of said number of continuation S and said sub-line repeat number U.

Claim 4

The signal processing device as claimed in claim 1, said sub-line repeat number U is selectively designated.

Claim 5

The signal processing device as claimed in claim 1, said block division number T is selectively designated.

Claim 6

The signal processing device as claimed in claim 1, said number of continuation S is selectively designated.

Claim 7

The signal processing device as claimed in claim 1, said stored color conversion data subjected to said aperture correction operation is comprised of ink density data.

Claim 8

The signal processing device as claimed in claim 1, said corrected color conversion data is subjected to an interpolation operation after said aperture correction operation.

Claim 9

The signal processing device as claimed in claim 7, said aperture correction operation and said interpolation operation are carried out in said second memory and said arithmetic means per line of said image data.

Claim 10

The signal processing device as claimed in claim 8, the type of said interpolation operation is selected according to said control data.

Claim 11

The signal processing device as claimed in claim 7, said image data and said interpolated corrected color conversion data are stored with said corrected color conversion data in said second memory.

Claim 12

The signal processing device as claimed in claim 1, one ink group is selected for printing from a plurality of ink groups according to said control data.

Claim 13

The signal processing device as claimed in claim 1, a printing mode is selected from one of a color printing mode and a monochrome printing mode according to said control data.

Claim 14

The signal processing device as claimed in claim 1, the necessity of said aperture correction operation is determined according to said control data.

Claim 15

The signal processing device as claimed in claim 1, said first and second memories have a common address bus and a common data bus.

Claim 16

The signal processing device as claimed in claim 14, further comprising means for subjecting said address data to a multiplex operation in a time-division mode, said means for subjecting coupled to said first and second memories and said means for generating clock signals and address data.

Claim 17

The signal processing device as claimed in claim 1, said fundamental unitary time for heat generation control ts includes at least a data transferring period of time for a thermal head of the video printer.

Claim 18

The signal processing device as claimed in claim 1, a minimum value of said sub-line number U is 4.

Claim 19

The signal processing device as claimed in claim 1, further comprising means for maintaining print density unchanged regardless of variation of said block division number T.

Claim 20

The signal processing device as claimed in claim 1, wherein said plurality of blocks of a thermal head have a common data transmission terminal.

Claim 21

A video signal processing means for preventing the occurrence of a white stripe, attributable to block division type drive of a thermal print head, in a printed image, comprising: image data means for receiving image data comprising R, G and B image data and control data; color conversion means, coupled to said image data means, for processing said R, G and B image data to generate color conversion data comprising minimum component data indicative of which component of said R, G and B image data is smallest, achromatic color data of said image data and selected color data in which said minimum component is eliminated; memory conversion means, coupled to said color conversion means, for storing gradation data, data generated during processing and said color conversion data and for generating partial color data and partial achromatic color data; arithmetic means, coupled to said memory conversion means, for adding said partial color data and said partial achromatic color data to generate printing ink density data and for performing an aperture correction operation on said printing ink density data, said aperture corrected printing ink density data thereafter stored in said memory conversion means as said processed data; and print head drive means, coupled to said memory conversion means, for generating head drive data in accordance with said gradation data and said processed data for driving a plurality of blocks of the thermal print head, based upon said image data, to produce a printed image in which the occurrence of a white strip attributable to block division type drive is prevented.

Claim 22

A video signal processing means for preventing the occurrence of a white stripe, attributable to block division type drive of a thermal print head, in a printed image, comprising: image data means for receiving image data comprising R, G and B image data and control data; color conversion means, coupled to said image data means, for processing said R, G and B image data to generate color conversion data comprising minimum component data indicative of which component of said R, G and B image data is smallest, achromatic color data of said image data and selected color data in which said minimum component is eliminated; memory conversion means, coupled to said color conversion means, for storing gradation data, data generated during processing and said color conversion data and for generating partial color data and partial achromatic color data; arithmetic means, coupled to said memory conversion means, for adding said partial color data and said partial achromatic color data to generate printing ink density data and for performing an aperture correction operation on said printing ink density data, said aperture corrected printing ink density data thereafter stored in said memory conversion means as said processed data; and print head drive means, coupled to said memory conversion means, for generating head drive data in accordance with said gradation data and said processed data for driving a plurality of blocks of the thermal print head, based upon said image data, to produce a printed image in which the occurrence of a white strip attributable to block division type drive is prevented.

Claim 23

The video signal processing means of claim 20, said print head drive means generates said head drive data in further accordance with operation modes designated by said control data, said operation modes indicate selection of printing dyes, color mode, monochromatic mode and recording width.

Claim 24

The video signal processing means of claim 20, further comprising: clock and address generating means, coupled to said memory conversion means, said arithmetic means and said print head drive means, for generating clock and address data in response to operation modes designated by said control data to print each line of said image data for a period of time which is defined as P t =t s ×S×T×U where t s is a fundamental unitary time for head generation control, S is a number of continuation of a fundamental unitary time, T is a block division number and U is a sub-line repeat number.

Claim 25

The video signal processing means of claim 20, said color conversion means comprising: minimum value calculation means, coupled to said image data means, for outputting said achromatic color data and for comparing said components of said R, G and B image data to select and output said minimum component data; a subtractor, coupled to said minimum value calculation means, for subtracting said achromatic color data from said R, G and B image data to generate difference color components; and selector means, coupled to said minimum value calculation means and said subtractor, for outputting said selected color data after eliminating said minimum component.

Claim 26

The video signal processing means of claim 20, said arithmetic means further comprising printing ink density data generating means comprising: first and second flip-flops, coupled to said memory conversion means, for respectively temporarily storing said partial color data and said partial achromatic color data; and a first full adder, coupled to said first and second flip-flops, for adding said partial color data and said partial achromatic color data to generate said printing ink density data.

Claim 27

The video signal processing means of claim 24, said arithmetic means further comprising aperture correction operation means comprising: third through sixth flip-flops, coupled to said memory conversion means, for respectively temporarily storing said printing ink density data corresponding to four immediately adjacent picture elements of a target picture element; first adding means, coupled to said third through sixth flip-flops, for adding said printing ink density data of said adjacent picture elements to generate adjacent density data; a seventh flip-flop, coupled to said memory conversion means, for temporarily storing said printing ink density data corresponding to said target picture element; second adding means, coupled to said seventh flip-flop, for adding said printing ink density data of said target picture element to a predetermined reference value to generate an adjusted target printing ink density data; an inverter, coupled to said first adding means, for inverting said adjacent density data; and third adding means, coupled to said inverter and said second adding means, for adding said inverted adjacent density data and said adjusted target printing ink density data to generate said