Power supply voltage converting circuit, control method thereof, display apparatus, and portable terminal

• US 20050184943A1
• Filed: 04/20/2005
• Published: 08/25/2005
• Est. Priority Date: 12/06/2000
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Nakajima, Yoshiharu
• Granted Patent: US 7,336,273 B2
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• CPC Class Codes: H02M 1/0012 Control circuits using digital or numerical techniques in DC/DC converters H02M3/157, H02M3/33515; in DC-AC converters H02M7/53873
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/071 adapted to generate a negative voltage output from a positive voltage source
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

In a power supply voltage converting circuit using a charge pump circuit having a switch device (Nch MOS transistor Qn(12) and Pch MOS transistor Qp(12)) in an output unit, a first clamp circuit (13) diode-clamps a switching pulse voltage (control pulse voltage) for the switch device at the time of starting the power supply voltage converting circuit, and a second clamp circuit (16) clamps the switching pulse voltage at a ground level (negative side circuit power supply potential) on the basis of a clamp pulse obtained by using an output voltage Vout at the time of an end of the starting process. A sufficient driving voltage is thereby provided for the Pch MOS transistor Qp(12) in particular. Thus, a power supply voltage converting circuit that can obtain a high current capacity on a small-area circuit scale, a control method thereof, a display apparatus having the power supply voltage converting circuit as a power supply circuit, and a portable terminal having the display apparatus are provided.

Claims

1-33. -33. (canceled)

34. A portable terminal characterized by using, as an output display unit, a display apparatus having a power supply voltage converting circuit, said power supply voltage converting circuit, being formed by using a charge pump circuit having a switch device in an output unit, comprising:

a first clamp circuit for diode-clamping a control pulse voltage for said switch device at the time of a start; and

a second clamp circuit for clamping said control pulse voltage at a circuit power supply potential on the basis of a voltage outputted through said switch device at the time of an end of the start process.

35. A portable terminal as claimed in claim 34, wherein said power supply voltage converting circuit is formed integrally with a display area unit of said display unit on an identical substrate.

36. A portable terminal as claimed in claim 34, wherein said display apparatus is a liquid crystal display apparatus.

37. A portable terminal as claimed in claim 34, wherein said display apparatus is an electroluminescence display apparatus.

38. A portable terminal characterized by using a display apparatus as an output display unit, said display apparatus comprising:

a display area unit formed by arranging pixels each having an electrooptic device in a matrix manner;

a vertical driving circuit for selecting the pixels of said display area unit by a unit of a row;

a horizontal driving circuit for supplying an image signal to each of the pixels of the row selected by said vertical driving circuit; and

a power supply voltage converting circuit for converting a single direct-current voltage into a plurality of direct-current voltages of different voltage values and then supplying the plurality of direct-current voltages to said vertical driving circuit and said horizontal driving circuit;

wherein at least a transistor circuit forming said power supply voltage converting circuit is formed by using an identical process with that of said display area unit on an identical substrate of said display area unit.

39. A portable terminal as claimed in claim 38, wherein said display apparatus is a liquid crystal display apparatus using a liquid crystal cell as said electrooptic device.

40. A portable terminal as claimed in claim 38, wherein said display apparatus is an electroluminescence display apparatus using an electroluminescence device as said electrooptic device.

41. A portable terminal characterized by using a display apparatus as an output display unit, comprising:

a display area unit formed by arranging pixels each having an electrooptic device in a matrix manner;

a vertical driving circuit for selecting the pixels of said display area unit by a unit of a row;

a horizontal driving circuit for supplying an image signal to each of the pixels of the row selected by said vertical driving circuit; and

a power supply circuit for converting a single direct-current voltage into a plurality of direct-current voltages of different voltage values and then supplying the plurality of direct-current voltages to at least said vertical driving circuit and said horizontal driving circuit, a current supply capacity of said power supply circuit being reduced at the time of a power saving mode.

42. A portable terminal as claimed in claim 41, wherein said power supply circuit is a charge pump type power supply voltage converting circuit.

43. A portable terminal as claimed in claim 41, wherein said display apparatus is a liquid crystal display apparatus using a liquid crystal cell as said electrooptic device.

44. A portable terminal as claimed in claim 41, wherein said display apparatus is an electroluminescence display apparatus using an electroluminescence device as said electrooptic device.

45. A portable terminal characterized by using a display apparatus as an output display unit, comprising:

a display area unit formed by arranging pixels each having an electrooptic device in a matrix manner;

a vertical driving circuit for selecting the pixels of said display area unit by a unit of a row;

a horizontal driving circuit for supplying an image signal to each of the pixels of the row selected by said vertical driving circuit; and

a power supply circuit for converting a single direct-current voltage into a plurality of direct-current voltages of different voltage values and then supplying the plurality of direct-current voltages to at least said vertical driving circuit and said horizontal driving circuit, said power supply circuit operating on the basis of a synchronizing signal in synchronism with a video signal displayed on said display area unit.

46. A portable terminal as claimed in claim 45, wherein said power supply circuit is a charge pump type power supply voltage converting circuit that performs switching operation on the basis of said synchronizing signal.

47. A portable terminal as claimed in claim 45, wherein said synchronizing signal is a horizontal synchronizing signal, a vertical synchronizing signal, or a clock signal serving as a basis for operation of said vertical driving circuit.

48. A portable terminal as claimed in claim 47, wherein said power supply circuit operates on the basis of the horizontal synchronizing signal or the vertical synchronizing signal immediately after power is turned on, and operates on the basis of the clock signal serving as a basis for operation of said vertical driving circuit after passage of a certain period.

49. A portable terminal as claimed in claim 45, wherein said display apparatus is a liquid crystal display apparatus using a liquid crystal cell as said electrooptic device.

50. A portable terminal as claimed in claim 45, wherein said display apparatus is an electroluminescence display apparatus using an electroluminescence device as said electrooptic device.