Current generating circuit, electro-optical apparatus, and electronic unit
View Patent ↗The invention provides a simple circuit configuration that can convert a current I 1 to a current I 2 having smooth, non-linear characteristics. The invention can include first and second resistors having one end of each of the resistors, whose resistances are different, connected to a power supply terminal to which a power supply voltage is supplied. The source of a first transistor can be coupled to the other end of the resistor, and is also connected to a gate in a saturating manner. The source of a second transistor is connected to the other end of the other resistor, and a gate of the second transistor is coupled to the gate of the first transistor, which is connected to a drain thereof in a saturating manner. The current I 2 flowing in a second transistor is a function equal to the square of the current I 1 flowing in the first transistor, thereby exhibiting smooth, non-linear characteristics.
1. An electro-optical apparatus, comprising:
pixel circuits disposed at intersections of a plurality of scanning lines and a plurality of data lines;
a scanning-line drive circuit that selects the scanning lines;
a data-line drive circuit,
the pixel circuits having a plurality of types of pixel circuits corresponding to a plurality of primary colors,
the data-line drive circuit being provided corresponding to the primary colors, and having a current generating circuit that supplies a current to a corresponding data line,
the current generating circuit comprising:
a power supply terminal having a power supply voltage applied thereto;
a first resistor and a second resistor, one end of each of the first resistor and the second resistor being coupled to the power supply terminal, and a resistance of the first resistor and a resistance of the second resistor being different;
a first transistor that allows a current corresponding to a voltage of a gate of the first transistor to flow between a first terminal and a second terminal of the first transistor, the first terminal being coupled to another end of the first resistor, and the second terminal and the gate being coupled with each other; and
a second transistor that allows a current corresponding to a voltage of a gate of the second transistor to flow between a first terminal and a second terminal of the second transistor, the first terminal being coupled to another end of the second resistor, and the gate of the second transistor being coupled to the gate of the first transistor; and
the electro-optical apparatus further comprising a setting circuit that sets individually a resistance of at least one of the first resistor and the second resistor for each of the primary color.
2. The electro-optical apparatus according to claim 1 , further comprising:
a plurality of current generating circuits, which include the current generating circuit, being dependently connected, a current that flows to the second transistor of one of the current generating circuits positioned in a front stage flowing to the first transistor of one of the current generating circuits positioned in a back stage.
3. The electro-optical apparatus according to claim 1 , further comprising a D/A conversion circuit that converts digital data into a current signal indicating a current corresponding to digital data and that allows the current signal to flow in the first transistor.
4. An electro-optical apparatus according to claim 1 ,
the pixel circuit having a capacitor device that stores electrical charge in accordance with the current flowing in the data line when the scanning line is selected by the scanning-line drive circuit; and an electro-optical device in which a current corresponding to an electrical charge stored in the capacitor device flows when selection of the scanning line is finished.
5. The electro-optical apparatus according to claim 1 ,
the pixel circuits corresponding to the same primary colors being arranged using the same data line.
6. The electro-optical apparatus according to claim 5 , further comprising:
a memory that stores digital data defining a grayscale of the electro-optical device;
a control circuit that reads the digital data from the memory; and
a D/A conversion circuit that converts the digital data read by the control circuit into a current signal indicating a current corresponding to the digital data, and for allowing the current signal to flow in the first transistor of the current generating circuit.
7. The electro-optical apparatus according to claim 5 , the electro-optical device being an organic electro luminescence device.
8. The electro-optical apparatus according to claim 1 ,
in the current generating circuit, the current flowing in the first transistor being converted into a non-linear current flowing in the second transistor.
9. The electro-optical apparatus according to claim 1 , further comprising a designation circuit that designates a resistance to be set by the setting circuit.
10. An electronic unit, in which the electro-optical apparatus as set forth in claim 1 is mounted.
11. An electro-optical apparatus, comprising:
pixel circuits disposed at intersections of a plurality of scanning lines and a plurality of data lines;
a scanning-line drive circuit that selects the scanning lines;
a data-line drive circuit,
the pixel circuits having a plurality of types of pixel circuits corresponding to a plurality of primary colors,
the data-line drive circuit being provided corresponding to the primary colors, and having a current generating circuit that supplies a current to a corresponding data line,
the current generating circuit comprising:
a first resistor and a second resistor, one end of each of the first resistor and the second resistor being connected to a power supply terminal, a resistance of the first resistor and a resistance of the second resistor being different, and at least one of the first resistor and the second resistor being a variable resistor;
a first transistor that allows a current corresponding to a voltage of a gate of the first transistor to flow between a first terminal and a second terminal of the first transistor, the first terminal being coupled to the other end of the first resistor, and the second terminal and the gate being coupled with each other; and
a second transistor that allows a current corresponding to a voltage of a gate of the second transistor to flow between a first terminal and a second terminal of the second transistor, the first terminal being coupled to the other end of the second resistor, and the gate of the second transistor being coupled to the gate of the first transistor; and
the electro-optical apparatus further comprising a setting circuit that sets individually a resistance of at least one of the first resistor and the second resistor for each of the primary colors.
12. The electro-optical apparatus according to claim 11 , only the first resistor of the first and second resistors is a variable resistor.
13. The electro-optical apparatus according to claim 11 , the variable resistor being configured such that a plurality of resistor devices having predetermined resistances are coupled in series with each other.
14. The electro-optical apparatus according to claim 11 , the variable resistor being configured such that a plurality of resistor devices having predetermined resistances are coupled in parallel with each other.
15. The electro-optical apparatus according to claim 11 , further comprising:
a plurality of current generating circuits, which include the current generating circuit, being dependently connected, a current that flows to the second transistor of one of the current generating circuits positioned in a front stage flowing to the first transistor of one of the current generating circuits positioned in a back stage.
16. The electro-optical apparatus according to claim 11 , further comprising a D/A conversion circuit that converts digital data into a current signal indicating a current corresponding to digital data and that allows the current signal to flow in the first transistor.