# US 8,542,169 B2 · DC/DC converter and liquid crystal display > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,169 B2 - Document ID: US8542169B2 - Status: Granted - Kind: B2 - Application number: 11/929,282 - Filed: 2007-10-30 - Published: 2008-06-12 - Granted: 2013-09-24 - Earliest claimed: 2006-12-07 - Assignees: Samsung Display Co., Ltd. - Applicants: Michiru Senda - Inventors: Michiru Senda - Web page: https://patentgrep.com/patent/US8542169B2 ## CPC - H02M 3/073: {Charge pumps of the Schenkel-type} - G02F 1/13306: {Circuit arrangements or driving methods for the control of single liquid crystal cells (G02F1/132, G02F1/133382 take precedence)} - G09G 3/3696: {Generation of voltages supplied to electrode drivers} - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) ## Abstract A DC/DC converter of a liquid crystal display includes a charge pump having a thin film transistor, a capacitor and a diode. The thin film transistor is formed on an insulating substrate. A first main electrode of the thin film transistor is connected to an output terminal and a control electrode of the thin film transistor receives a control signal. The thin film transistor includes a non-monocrystal semiconductor. The capacitor has a first electrode connected to a second main electrode of the thin film transistor and a second electrode receiving a variable voltage. The diode is electrically connected between the second main electrode of the thin film transistor, the first electrode of the capacitor, and a power terminal in series. The diode includes a mono-crystal semiconductor. ## Claims ### Claim 1 A DC/DC converter comprising: a charge pump, wherein the charge pump comprises: a thin film transistor formed on an insulating substrate, having a first main electrode connected to an output terminal outputting an output voltage and a control electrode receiving a control signal, and comprising a non-monocrystal semiconductor; a capacitor having a first electrode directly connected to a second main electrode of the thin film transistor and a second electrode receiving a variable voltage; and a first diode electrically connected between the second main electrode of the thin film transistor, the first electrode of the capacitor, and a power terminal in series, and comprising a mono-crystal semiconductor, wherein the first main electrode is distinct from the second main electrode. ### Claim 2 (depends on 1) The DC/DC converter of claim 1, wherein the thin film transistor comprises one of polycrystal silicon and amorphous silicon. ### Claim 3 (depends on 2) The DC/DC converter of claim 2, wherein the first diode is an external connection device. ### Claim 4 (depends on 3) The DC/DC converter of claim 3, further comprising: a first external connection terminal disposed on the insulating substrate, and electrically connected between the second main electrode of the thin film transistor and the first electrode of the capacitor; and a second external connection terminal disposed on the insulating substrate, and connected to the power terminal, wherein terminals of the external connection device are connected to the first and second external connection terminals, respectively. ### Claim 5 (depends on 4) The DC/DC converter of claim 4, wherein the external connection device is mounted on the insulating substrate in a chip-on-glass structure. ### Claim 6 (depends on 1) The DC/DC converter of claim 1, wherein the charge pump comprises a voltage drop charge pump to receive a circuit grounding voltage from the power terminal and output a voltage that is obtained by dropping the circuit grounding voltage through the output terminal. ### Claim 7 (depends on 6) The DC/DC converter of claim 6, wherein the first diode comprises an anode area electrically connected to the second main electrode of the thin film transistor and a cathode area electrically connected to the power terminal. ### Claim 8 (depends on 1) The DC/DC converter of claim 1, wherein the charge pump comprises a voltage boost charge pump to receive a circuit driving voltage greater than a circuit grounding voltage from the power terminal and output a voltage, which is obtained by boosting the circuit driving voltage, through the output terminal. ### Claim 9 (depends on 8) The DC/DC converter of claim 8, wherein the first diode comprises a cathode area electrically connected to the second main electrode of the thin film transistor and an anode area electrically connected to the power terminal. ### Claim 10 (depends on 9) The DC/DC converter of claim 9, further comprising a second diode having a cathode area electrically connected in parallel between the first main electrode of the thin film transistor and the output terminal, and an anode area electrically connected to the power terminal. ### Claim 11 (depends on 1) The DC/DC converter of claim 1, further comprising a timing controller generating a clock signal such that a rising time and a falling time of the control signal input to the control electrode do not overlap with a rising time and a falling time of the variable voltage applied to the second electrode of the capacitor. ### Claim 12 (depends on 1) The DC/DC converter of claim 1, wherein the rising time of the control signal input to the control electrode of the thin film transistor is later than the rising time of the variable voltage applied to the second electrode of the capacitor, and the falling time of the control signal is faster than the falling time of the variable voltage. ### Claim 13 (depends on 1) The DC/DC converter of claim 1, further comprising a level shifter supplying a signal having an enlarged amplitude to the charge pump and the timing controller. ### Claim 14 (depends on 1) The DC/DC converter of claim 1, wherein the charge pump and the timing controller are supplied with a boosted circuit driving voltage. ### Claim 15 A liquid crystal display comprising: an insulating substrate having a first area and a second area adjacent to the first area; a pixel array formed in the first area of the insulating substrate; a driver formed in the second area of the insulating substrate to drive the pixel array; and a DC/DC converter formed in the second area of the insulating substrate to supply a driving voltage to the driver, wherein the DC/DC converter comprises a charge pump comprising: a thin film transistor formed in the second area of the insulating substrate, having a first main electrode connected to an output terminal outputting an output voltage, and a control electrode receiving a control signal, and comprising a non-monocrystal semiconductor; a capacitor having a first electrode directly connected to a second main electrode of the thin film transistor and a second electrode receiving a variable voltage; and a first diode electrically connected between the second main electrode of the thin film transistor, the first electrode of the capacitor, and a power terminal in series, and comprising a mono-crystal semiconductor, and wherein the first main electrode is distinct from the second main electrode. ### Claim 16 (depends on 15) The liquid crystal display of claim 15, further comprising: an opposite substrate facing the first area of the insulating substrate; and a liquid crystal interposed between the first area of the insulating substrate and the opposite substrate, wherein the first diode is provided in the second area of the insulating substrate, and does not overlap with the opposite substrate. ### Claim 17 (depends on 16) The liquid crystal display of claim 16, wherein the first diode of the DC/DC converter is an external connection device. ### Claim 18 (depends on 17) The liquid crystal display of claim 17, further comprising: a first external connection terminal formed in the second area of the insulating substrate, and electrically connected between the second main electrode of the thin film transistor and the first electrode of the capacitor; and a second external connection terminal formed in the second area of the insulating substrate, and connected to the power terminal, wherein terminals of the external connection device are connected to the first and second external connection terminals, respectively. ### Claim 19 A liquid crystal display comprising: an insulating substrate including a first area and a second area adjacent to the first area; a pixel array formed in the first area of the insulating substrate; a driver driving the pixel array; a DC/DC converter formed in the second area of the insulating substrate to supply a driving voltage to the driver; and a flexible printed wiring substrate adjacent to the insulating substrate, wherein the DC/DC converter comprises a charge pump comprising: a thin film transistor formed in the second area of the insulating substrate, having a first main electrode connected to an output terminal outputting an output voltage, and a control electrode receiving a control signal, and comprising a non-monocrystal semiconductor; a capacitor having a first electrode directly connected to a second main electrode of the thin film transistor and a second electrode receiving a variable voltage; and a first diode disposed on the flexible printed wiring substrate, electrically connected between the second main electrode of the thin film transistor, the first electrode of the capacitor, and a power terminal in series, and comprising a mono-crystal semiconductor, wherein the first main electrode is distinct from the second main electrode. ### Claim 20 A liquid crystal display comprising: an insulating substrate including a first area and a second area adjacent to the first area; a pixel array formed in the first area of the insulating substrate; a driver driving the pixel array; a DC/DC converter formed in the second area of the insulating substrate to supply a driving voltage to the driver; and a printed circuit board controlling the pixel array, the driver, and the DC/DC converter, wherein the DC/DC converter comprises a charge pump comprising: a thin film transistor formed in the second area of the insulating substrate, having a first main electrode connected to an output terminal outputting an output voltage, and a control electrode receiving a control signal, and comprising a non-monocrystal semiconductor; a capacitor having a first electrode directly connected to a second main electrode of the thin film transistor and a second electrode receiving a variable voltage; and a first diode disposed on the printed circuit board, electrically connected between the second main electrode of the thin film transistor, the first electrode of the capacitor, and a power terminal in series, and comprising a mono-crystal semiconductor, and wherein the first main electrode is distinct from the second main electrode.