TWI505616B - Display system - Google Patents

Description

display system

The present invention relates to a display system, and more particularly to a display system in which a charge pump circuit is disposed on a flexible printed circuit board outside of its display device to improve its voltage conversion efficiency.

The charge pump is a DC to DC converter that uses a capacitor as an energy storage element to create a voltage source with a higher output voltage or a lower output voltage. The charge pump can use some form of switching device to control the voltage-to-capacitor connection. In addition, based on the controller and circuit structure, the charge pump can generate double voltage, triple voltage, half voltage, reverse voltage, fractional product, and specific ratio. Voltage (such as x3/2, x4/3, x2/3, etc.) or any voltage. A conventional charge pump circuit includes a voltage source, one or more charge capacitors, a load capacitor, some circuit switches, and a clock generator having a fixed frequency and used to control the circuit switches. Taking a clock cycle as an example (for example, a doubled two phase circuit), in the first half cycle, the circuit-on relationship is used to connect the voltage source and the charging capacitor in parallel to charge the charging capacitor to A voltage level; in the second half cycle, the circuit-on relationship is used to connect the voltage source, the charging capacitor, and the load capacitor in series. After repeating a plurality of cycles, the voltage difference across the load capacitor is raised to a voltage level that is much higher than the voltage level of the voltage source from which the voltage was originally supplied.

In the conventional small and medium-sized Thin Film Transistor-Liquid Crystal Display (TFT-LCD) device, as the screen size becomes larger and larger, the current consumed by the screen is also increasing. When the charge pump circuit is disposed on the driving circuit end of the thin film transistor liquid crystal display device, the resistance of the Indium Tin Oxide (ITO) film is limited, and the voltage conversion efficiency thereof is deteriorated.

In addition, since the system side is expected to directly supply an input voltage of 2.0V to 4.8V to the driving circuit terminal on the thin film transistor liquid crystal display device, the charging pump circuit must be able to support different multiples (for example, 1.5 times, 2 times or 3) The voltage conversion ratio of the times) provides the desired output voltage. Therefore, how to install the charge pump circuit in the thin film transistor liquid crystal display device without being affected by the indium tin oxide resistance and controlling the charge pump circuit in this case has become an important research and development topic in the industry.

Accordingly, it is an object of the present invention to provide a display system that provides a charge pump circuit on a flexible printed circuit board external to its display device to solve the above problems.

The invention discloses a display system comprising a display device, a driving circuit, a flexible printed circuit board, a charging pump circuit and a control circuit. The driving circuit is disposed on the display device for driving the display device. The flexible printed circuit board is externally coupled to the display device. The charge pump circuit is disposed on the flexible printed circuit board for generating at least one output voltage to the drive circuit. The control circuit is disposed on the display device and coupled to the driving circuit for generating a control signal to control the charge pump circuit. The charge pump circuit has a control pin coupled to the control circuit for receiving the control signal generated by the control circuit.

Certain terms are used throughout the description and following claims to refer to particular elements. It should be understood by those of ordinary skill in the art that hardware manufacturers may refer to the same elements by different nouns. The scope of this specification and the subsequent patent application do not use the difference of the names as the means for distinguishing the elements, but the difference in function of the elements as the criterion for distinguishing. The term "including" as used throughout the specification and subsequent claims is an open term and should be interpreted as "including but not limited to". In addition, the term "coupled" is used herein to include any direct and indirect electrical connection. Therefore, if a first device is coupled to a second device, it means that the first device can be directly electrically connected to the second device or indirectly electrically connected to the second device through other devices or connection means.

In the embodiment of the present invention, the charge pump circuit is moved from the driving circuit of the thin film transistor liquid crystal display device to the flexible printed circuit board, so it is necessary to consider how to control the operation of the charge pump circuit provided on the flexible printed circuit board. . Please refer to FIG. 1. FIG. 1 is a schematic diagram of a display system 100 according to an embodiment of the present invention. The display system 100 includes, but is not limited to, a display device 110, a panel 120, a driving circuit 130, a control circuit 140, a flexible printed circuit board 150, and a charge pump circuit 160. The panel 120 is disposed on the display device 110, and the driving circuit 130 is also disposed on the display device 110 for driving the panel 120. The control circuit 140 is also disposed on the display device 110 and coupled to the driving circuit 130 for generating a control signal SC to control the operation of the charge pump circuit 160. The flexible printed circuit board 150 is externally coupled to the display device 110, and the charge pump circuit 160 is disposed on the flexible printed circuit board 150 for generating at least one output voltage according to the control signal SC generated by the control circuit 140. Drive circuit 130.

In the present embodiment, the charge pump circuit 160 includes a control pin 162, a charge pump unit 164, a separation circuit 166, and a processing unit 168. As shown in FIG. 1, the control pin 162 is coupled to the control circuit 140 for receiving the control signal SC generated by the control circuit 140. In other words, since the charge pump circuit 160 is provided with only a single pin, A control signal is received so that only one control signal is allowed to pass from control circuit 140 to charge pump circuit 160. The charge pump unit 164 is configured to generate the at least one output voltage to the drive circuit 130. The separation circuit 166 is coupled to the control pin 162 for obtaining a clock signal S _clock and a processing signal S _process from the received control signal SC, wherein the processing signal S _process can be a data signal S _data or a Command signal S _command . The processing unit 168 is coupled between the separation circuit 166 and the charging pump unit 164 for receiving the clock signal S _clock generated by the separation circuit 166 and the processing signal S _process , and according to the clock signal S _clock and the processing signal S _process To control the operation of the charge pump unit 164. The charge pump circuit 160 sets a pumping factor PF1 according to the control signal SC and generates two output voltages VSP, VSN, wherein the output voltages VSP, VSN are transmitted to the drive circuit 130 for use.

In addition, the separation circuit 166 in this embodiment includes a low pass filter 1662 and a high pass filter 1664. The low-pass filter 1662 is coupled to the control pin 162 for filtering the control signal SC to generate the clock signal S _clock, and the high-pass filter 1664 is also coupled to the control pin 162 for performing the control signal SC. Filtering to generate a processing signal S _process . Please note that in this embodiment, the separation circuit 166 uses two filters to obtain the clock signal S _clock and the processing signal S _process from the control signal SC, but this is not a limitation of the present invention, in other words, the separation circuit The 166 can also obtain the clock signal S _clock and the processing signal S _process from the control signal SC by other types of circuits according to actual design considerations. Details of the control circuit 140 and the charge pump circuit 160 and their associated operations will be described in further detail in the following figures and embodiments.

It is noted that the present invention is described in detail in conjunction with the drawings in order to make the present invention more obvious. However, this is not a limitation of the present invention. Please refer to FIG. 2 and FIG. 1 at the same time. FIG. 2 is a sequence diagram of a control signal SC, a clock signal S _clock and a processing signal S _process from top to bottom. The control circuit 140 generates a control signal SC according to the demand of the driving circuit 130 to control the operation of the charge pump circuit 160. In this embodiment, the control circuit 140 combines the processed signal S _process transmitted at a high frequency and the clock signal S _clock transmitted at a lower frequency into the control signal SC shown in FIG. 2, however, this is only The description of the examples is not intended to limit the invention.

The separation circuit 166 in the charge pump circuit 160 receives the control signal SC through the control pin 162, and the low pass filter 1662 and the high pass filter 1664 filter the received control signal SC to generate the second shown in FIG. The clock signal S _clock and the processing signal S _process . Next, the high pass filter 1664 in the separation circuit 166 selectively generates the data signal S _data or the command signal S _command according to the carrier position of the high frequency signal portion of the control signal SC. For example, if the high-frequency signal portion of the control signal SC is placed at the high level position of the _clock signal S _clock , it is regarded as the data signal S _data (for example, the logic value in the second figure "0110"); When the high frequency signal part of the signal SC is placed at the low level position of the _clock signal S _clock , it is regarded as the command signal S _command (for example, the logic value "1011" in Fig. 2). The charge pump circuit 160 can set the pump multiple PF1 according to the clock signal S _clock and the processing signal S _process and generate two output voltages VSP, VSN. For example, in the embodiment, the charge pump circuit 160 is based on the logic value. "1011" command signal S _command and the pump PF1 is set to a multiple of 3/2.

As can be seen from Fig. 1, the charge pump circuit 160 is disposed on the flexible printed circuit board 150 instead of the end of the drive circuit 130 of the display device 110, that is, since it is not exposed to indium tin oxide ( Indium Tin Oxide (ITO) limits the resistance R, thus greatly improving the voltage conversion efficiency of the charge pump circuit 160. In addition, only one control signal SC is needed to control the voltage conversion ratio of the charge pump circuit 160, so that the number of pins of the charge pump circuit 160 can be minimized to achieve cost reduction. Please note that the above display device 110 can be a thin film transistor liquid crystal display device, and the driving circuit 130 can be a thin film transistor liquid crystal display driving chip, but the invention is not limited thereto. In addition, all of the components in the charge pump circuit 160 can also be integrated into a single wafer (eg, a system single wafer), such that the charge pump unit 164 can provide a more accurate output voltage.

The above embodiments are only intended to illustrate the technical features of the present invention and are not intended to limit the scope of the present invention. In summary, the present invention provides a display system in which a charge pump circuit is disposed on a flexible printed circuit board outside the display device, which can greatly improve the voltage conversion efficiency of the charge pump circuit. The display system of the present invention only needs to control the charge pump circuit disposed on the flexible printed circuit board by using a control pin and a control signal. Therefore, the voltage conversion efficiency of the charge pump circuit in the display system of the present invention is not affected. Limitation of indium tin oxide resistance.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100‧‧‧Display system

110‧‧‧ display device

120‧‧‧ panel

130‧‧‧Drive circuit

140‧‧‧Control circuit

150‧‧‧Soft printed circuit board

160‧‧‧Charging pump circuit

162‧‧‧Control pins

164‧‧‧Charging pump unit

166‧‧‧Separation circuit

168‧‧‧Processing unit

1662, 1664‧‧‧ filter

Figure 1 is a schematic diagram of a display system in accordance with an embodiment of the present invention.

Figure 2 is a timing diagram of a control signal, a clock signal, and a processing signal.

100. . . display system

110. . . Display device

120. . . panel

130. . . Drive circuit

140. . . Control circuit

150. . . Flexible printed circuit board

160. . . Charge pump circuit

162. . . Control pin

164. . . Charge pump unit

166. . . Separation circuit

168. . . Processing unit

1662, 1664. . . filter

Claims (8)

A display system comprising: a display device comprising an Indium Tin Oxide (ITO) resistor; a driving circuit disposed on the display device for driving the display device; a flexible printed circuit board (flexible a printed circuit (FPC) coupled to the display device; a charge pump circuit disposed on the flexible printed circuit board for generating at least one output voltage to the driving circuit; and a control circuit The control device is coupled to the driving circuit for generating a control signal for controlling the charging pump circuit. The charging pump circuit has a control pin coupled to the control circuit. Receiving the control signal generated by the control circuit; and the charge pump circuit is disposed on the flexible printed circuit board and coupled to each of the drive circuit and the control circuit through the flexible printed circuit board And not directly connected to any one of the driving circuit and the control circuit, so as to avoid voltage conversion efficiency of the charging pump circuit being affected by the display Limit the resistance of these indium tin oxides. The display system of claim 1, wherein the charge pump circuit comprises: a charge pump unit for generating the at least one output voltage to the drive circuit; and a separate circuit coupled to the control pin For obtaining a moment from the control signal a signal signal and a data/command signal; and a processing unit coupled to the separation circuit and the charge pump unit for receiving the clock signal and the data/command signal generated by the separation circuit, and according to the time The pulse signal and the data/command signal control the charging pump unit. The display system of claim 2, wherein the separating circuit filters the control signal to generate the clock signal and the data/command signal. The display system of claim 3, wherein the separation circuit comprises: a low pass filter coupled to the control pin for filtering the control signal to generate the clock signal; A high pass filter is coupled to the control pin for filtering the control signal to generate the data/command signal. The display system of claim 4, wherein the high-pass filter selectively generates a data signal or a command signal according to a carrier position of the high-frequency signal portion of the control signal. The display system of claim 1, wherein the charge pump circuit comprises: a charge pump unit for generating the at least one output voltage to the drive circuit; and a separate circuit coupled to the control pin For obtaining a plurality of driving signals from the control signal; A processing unit is coupled to the separating circuit and the charging pump unit for receiving the driving signals generated by the separating circuit, and controlling the charging pump unit according to the driving signals. The display system of claim 6, wherein the separating circuit filters the control signal to generate the driving signals. The display system of claim 1, wherein the display device is a thin-film transistor liquid crystal display (TFT-LCD) device, and the driving circuit is a thin film transistor. The liquid crystal display drives the wafer.