Display device with improved smooth tone display utilizing different sets of tone voltages converted from display data based on different conversion charateristics
View Patent ↗When one frame period of two consecutive frame periods is a frame A and a next frame period subsequent to the frame A is a frame B, a tone requested from an external system is displayed in each sub-pixel by displaying two tones during the two frame periods including the frame A and the frame B, display data of an image A displayed during a period of the frame A and display data of an image B displayed during a period of the frame B are display data generated based on the display data and a video line driving circuit supplies, as tone voltages corresponding to the display data, a first set of tone voltages to video lines during the period of the frame A and a second set of tone voltages to the video lines during the period of the frame B subsequent to the frame A.
1. A display device comprising:
a display panel having a plurality of sub-pixels and a plurality of video lines which input tone voltages to the sub-pixels,
a video line driving circuit which supplies, based on input display data, the tone voltage corresponding to the display data to each of the video lines, and
a tone voltage generating circuit which generates the tone voltages, wherein:
each frame period comprises a light frame period for a light frame and a dark frame period for a dark frame, subsequent to the light frame period, wherein, during the dark frame, a tone is displayed to reduce effects of animated-image blur on the display panel, and the sub-pixel displays one tone requested from an external system by displaying two tones during each frame period including the light frame and the dark frame period,
display data of an image A which is displayed during a period of the light frame and display data of an image B which is displayed during a period of the dark frame are display data which are generated based on display data which is input from the external system,
the video line driving circuit supplies, as the tone voltage corresponding to the display data, a first set of tone voltages to the video lines during the period of the light frame and a second set of tone voltages to the video lines during the period of the dark frame which is subsequent to the light frame,
the first set of tone voltages are converted from the display data of the image A displayed during the light frame based on a second conversion characteristic by the tone voltage generating circuit,
the second set of tone voltages are converted from the display data of the image B displayed during the dark frame based on a first conversion characteristic by the tone voltage generating circuit,
a tone reference voltage for the light frame is set to be different from a tone reference voltage for the dark frame so that the tone voltage during the light frame and the tone voltage during the dark frame are changed such that, at a same tone, an absolute value of the tone voltage of the second set of tone voltages is larger than an absolute value of the tone voltage of the first set of tone voltages, and
a viewing brightness is generated by combining the first set of tone voltages and the second set of tone voltages.
2. The display device according to claim 1 , wherein
when the tone requested from the external system is included on a side of a low tone among intermediate tones between a maximum tone and a minimum tone, the tone during the period of the light frame changes corresponding to the tone requested from the external system and the tone during the period of the dark frame is set to the minimum tone, and
when the tone requested from the external system is included on a side of a high tone among the intermediate tones, the tone during the period of the light frame is set to the maximum tone and the tone during the period of the dark frame changes corresponding to the tone requested from the external system.
3. The display device according to claim 2 , wherein
a boundary between the side of low tone and the side of high tone for the tone requested from the external system is a tone which is obtained by setting one of the two tones in the consecutive frame periods including the period of the light frame and the period of the dark frame as the minimum tone and setting the other of the two tones as the maximum tone.
4. The display device according to claim 1 , further comprising:
a frame memory which stores the display data which is input from the external system;
a first lookup table which converts display data which is input from the external system and which is stored in the frame memory into the display data of the image A;
a second lookup table which converts the display data which is input from the external system and which is stored in the frame memory into the display data of the image B; and
a selector which selects the display data of the image A which is converted by the first lookup table or the display data of the image B which is converted by the second lookup table, and which inputs the selected display data into the video line driving circuit.
5. The display device according to claim 1 , further comprising
a tone reference voltage generating circuit which generates a plurality of tone reference voltages, wherein
the video line driving circuit comprises a tone voltage generating circuit which generates a tone voltage based on a plurality of the tone reference voltages which are input from the tone reference voltage generating circuit,
the tone reference voltage generating circuit generates a first set of the plurality of the tone reference voltages during the period of the light frame and generates a second set of the plurality of the tone reference voltages during the period of the dark frame, and
the tone voltage generating circuit generates the first set of the tone voltages based on the first set of the plurality of tone reference voltages which are input from the tone reference voltage generating circuit and generates the second set of the tone voltages based on the second set of the plurality of tone reference voltages which are input from the tone reference voltage generating circuit.
6. The display device according to claim 5 , further comprising
a display controlling circuit, wherein
the tone reference voltage generating circuit sets, based on tone reference voltage data from the display controlling circuit, voltages for the first set of the plurality of tone reference voltages which are generated during the period of the light frame and voltages for the second set of the plurality of tone reference voltages which are generated during the period of the dark frame.
7. The display device according to claim 5 , wherein
the tone reference voltage generating circuit comprises a first tone reference voltage generating circuit which generates the first set of the plurality of tone reference voltages, a second tone reference voltage generating circuit which generates the second set of the plurality of tone reference voltages, and a selector which selects one of outputs of the first tone reference voltage generating circuit and of the second tone reference voltage generating circuit, and
the selector selects, during the period of the light frame, the first set of the plurality of tone reference voltages which are generated by the first tone reference voltage generating circuit and selects, during the period of the dark frame, the second set of the plurality of tone reference voltages which are generated by the second tone reference voltage generating circuit.
8. The display device according to claim 6 or 7 , wherein
absolute values of the second set of the plurality of tone reference voltages are larger than absolute values of the first set of the plurality of tone reference voltages at a same tone.