Driving device for electro-optic device, display device using the driving device, driving method thereof, and weight determination method thereof

A display device, comprising:

• an electro-optic device including electro-optic elements capable of outputting R gradations of brightness (R being an integer not less than 2), the electro-optic elements being provided for each combination of a plurality of scanning lines and at least one data line;
• and
• a driving device for driving the electro-optic device including a driving section for supplying instruction data to the electro-optic elements corresponding to the scanning line currently selected among the plurality of scanning lines sequentially selected, the driving section supplying the instruction data to the electro-optic elements via the data lines corresponding to the electro-optic elements, the instruction data for controlling outputs of the electro-optic elements for a period until subsequent instruction data is supplied,
• the driving section (a) supplying instruction data P1 through PA (A being an integer not less than 2) in one frame period for each electro-optic element so as to control outputs thereof in the one frame period, (b) selecting the scanning lines so that each of the instruction data P1 through PA appears once in the instruction data to be sequentially supplied to the data line, (c) supplying gradation data of the electro-optic elements as the instruction data, and (d) supplying the instruction data such that at least one instruction data of the instruction data in each frame period is different from an immediately previously supplied instruction data and different from an immediately subsequently supplied instruction data, and
• weights of the instruction data contributing to the outputs in the one frame period being set to satisfy RA>B where B is a number of brightness levels displayable in the one frame period by a combination of A weights of instruction data being supplied to the electro-optic elements in the one frame period, wherein
• at least one of the instruction data to be supplied to the electro-optic element in the one frame period is set to 0 in the weight.

A display device of matrix-type including electro-optic elements capable of outputting R gradations (R being an integer not less than 2) aligned in a matrix manner,

• each of the electro-optic elements having A (A being an integer not less than 4) display state time periods in one frame period such that the electro-optic elements are capable of B-levels of display output over one frame period (B being an integer satisfying B>R), and
• the B levels of display output are represented by A bits of data, the bits of the A bits of data satisfying a relation of R0:R1:
• . . . Rm−n:
• . . . (m being an integer not less than 2, and n being an integer not less than 1),
• weights of the data contributing to the outputs in the one frame period are set such that RA>B where B is a number of brightness levels displayable in the one frame period by a combination of A weights of instruction data being supplied to the electro-optic elements in the one frame period, and
• each difference in brightness between adjacent brightness levels among the B brightness levels is the same.

A driving method for driving an electro-optic device including electro-optic elements capable of outputting R gradations of brightness (R being an integer not less than 2) provided for each combination of a plurality of scanning lines and at least one data line, the method comprising the step of:

• (a) driving the electro-optic device by supplying instruction data to the electro-optic elements corresponding to the scanning line currently selected among the plurality of scanning lines sequentially selected, via the data lines corresponding to the electro-optic elements, the instruction data for controlling outputs of the electro-optic elements for a period until subsequent instruction data is supplied,
• wherein:
• the outputs in one frame period are controlled by supplying instruction data, P1 through PA (A being an integer not less than 2), in the one frame period to each electro-optic element, in the step (a),
• the scanning lines are selected so that respective instruction data are applied to electro-optic elements corresponding to the selected scanning lines, in the step (a), and
• weights of the instruction data contributing to the outputs in the one frame period are set to satisfy RA>B where B is a number of brightness levels displayable in the one frame period by a combination of the A weights of instruction data being supplied to the electro-optic elements in the one frame period,
• each difference in brightness between adjacent brightness levels among the B brightness levels is the same, and
• the instruction data is supplied such that at least one instruction data of the instruction data in each frame period is different from an immediately previously supplied instruction data and different from an immediately subsequently supplied instruction data.

A driving method for driving a display device of matrix-type including electro-optic elements capable of outputting R gradations (R being an integer not less than 2) aligned in a matrix manner, the driving method comprising the step of:

• (a) driving the display device by setting the electro-optic elements to have A (A being an integer not less than 4) display state time periods in one frame period so that the electro-optic elements are capable of B levels of display output over one frame period (B being an integer satisfying B>R),
• wherein:
• the B levels of display output are represented by A bits of data, the bits of the A bits of data satisfy a relation of R0:R1:
• . . . Rm−n:
• . . . (m being an integer not less than 2, and n being an integer not less than 1), in the step (a),
• weights of the data contributing to the outputs in the one frame period are set such that RA>B where B is a number of brightness levels displayable in the one frame period by a combination of A weights of instruction data being supplied to the electro-optic elements in the one frame period, and
• each difference in brightness between adjacent brightness levels among the B brightness levels is the same.

A weight determination method in a driving device for driving an electro-optic device including electro-optic elements capable of outputting R gradations of brightness (R being an integer not less than 2) provided for each combination of a plurality of scanning lines and at least one data line,

• the driving device including a driving section for supplying instruction data to the electro-optic elements corresponding to the scanning line currently selected among the plurality of scanning lines sequentially selected, the driving section supplying the instruction data to the electro-optic elements via the data lines corresponding to the electro-optic elements, the instructions data for controlling outputs of the electro-optic elements for a period until subsequent instruction data is supplied,
• the driving section supplying instruction data P1 through PA (A being an integer not less than 2) in one frame period for each electro-optic element so as to control outputs in the one frame period performed as output operation of the electro-optic elements over the one frame period, and selecting the scanning lines so that each of the instruction data P1 through PA appears once in the instruction data to be sequentially supplied to the data line,
• the method comprising the steps of:
• (a) carrying out initialization by setting weights of the instruction data contributing to the one frame period so that a given bit data has a weight of R times of a weight of an immediately preceding bit data, when the instruction data are aligned in order of smaller to greater weight;
• and
• (b) providing a predetermined selection time as a selection time for starting the output period of a first instruction data in order of smaller to greater weight;
• (c) determining a length of the output period appropriate for the instruction data according to the weight of the instruction data, and providing the selection time for starting the output period of a next instruction data by using the selection time at a time when the output period is terminated, the step (c) being repeated until all of the instruction data are provided with the selection time;
• (d) judging whether or not the selection time thus provided to the next instruction data is identical to the selection time which has been provided before;
• and
• when it is judged that the selection time is the same as the selection time which has been provided before in the step (d),
• (e) adjusting the instruction data so that each of the instruction data, including the instruction data which have already been provided with the selection time and the instruction data which is to be provided with the selection time next, has a different selection time, by reducing the weight of the instruction data whose length of the output period has been determined in or before the step (c).

A display device comprising:

• electro-optic display elements arranged in a matrix, each electro-optic display element capable of outputting R gradation levels;
• and
• a driving section for writing data to the electro-optic display elements A times during a frame period in accordance with data having A bits, each bit having a corresponding weight indicative of a time for which that bit is written to the electro-optic elements, so that B equally spaced-apart gradation levels can be displayed by the electro-optic display elements,
• wherein R is an integer not less than 2, A is an integer not less than 2, B>R and RA>B, and
• wherein the bits are written to the electro-optic display elements such that the weight of
• at least one bit of the instruction data in each frame period is different from the weight of an immediately previous bit and different from the weight of an immediately subsequent bit.