Display system

display system

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.

In traditional small and medium-sized thin film transistor liquid crystal displays (TFT-LCDs), as the size of the screen becomes larger, the current consumed by the screen becomes larger and larger. At this time, if the charge pump circuit is used. The driving circuit end disposed on the thin film transistor liquid crystal display is limited by the resistance of the Indium Tin Oxide (ITO) film, and the voltage conversion efficiency thereof becomes worse and worse.

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, the charging pump circuit must be able to support different multiples (for example, 1.5 times, 2 times or 3 times) The voltage conversion ratio is used to provide the desired output voltage. If the charge pump circuit is moved from the drive circuit end on the thin film transistor liquid crystal display to a flexible printed circuit board end, it is necessary to consider how to control the behavior and operation of the charge pump circuit on the flexible printed circuit board end.

Accordingly, it is an object of the present invention to provide a display system to solve the above problems.

The invention discloses a display system comprising a display device, a driving circuit, a flexible printed circuit board and a charging pump 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 according to an input voltage.

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.

Please refer to FIG. 1. FIG. 1 is a schematic diagram of a first embodiment of a display system 100 according to the present invention. The display system 100 includes, but is not limited to, a display device 110, a panel 120, a drive circuit 130, 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 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 to the driving circuit 130 according to an input voltage. In this embodiment, the charge pump circuit 160 generates two output voltages VSP, VSN according to the input voltage VCI, wherein the input voltage VCI is supplied from one of the external system terminals of the display system 100, and the output voltages VSP, VSN It will then be passed to the drive circuit 130 for its use.

In addition, the charge pump circuit 160 has at least one control line, and the control line is coupled to the drive circuit 130 for receiving a control signal generated by the drive circuit 130. In the present embodiment, the charge pump circuit 160 has two control lines for receiving two control signals SC1 and SC2, respectively, and the charge pump circuit 160 sets a pumping factor PF1 according to the control signals SC1 and SC2. Details of the drive circuit 130 and the charge pump circuit 160 and their associated operations will be described in further detail in the following figures and embodiments.

As can be seen from FIG. 1, the charge pump circuit 160 is disposed on the flexible printed circuit board 150 instead of the drive circuit 130 of the display device 110, that is, because it does not receive the indium tin oxide resistor R. The limitation can therefore greatly improve the voltage conversion efficiency of the charge pump circuit 160. In addition, only two control signals SC1 and SC2 are required (note that the number of control signals is not limited), and the voltage conversion ratio of the charge pump circuit 160 can be controlled, so that the number of pins of the charge pump circuit 160 can be reduced. To the minimum to achieve the purpose of reducing costs.

Please note that the above display device 110 can be a thin film transistor liquid crystal display device (TFT-LCD), and the driving circuit 130 can be a driving film of a thin film transistor liquid crystal display, but the invention is not limited thereto. Moreover, the number of control lines is also not a limitation of the present invention.

Please refer to FIG. 2, which is a schematic diagram of a second embodiment of a display system 200 of the present invention. As shown in FIG. 2, the architecture of the display system 200 is similar to that of the display system 100 of FIG. 1, and the difference between the two is that the driving circuit 230 of the display device 210 shown in FIG. 2 further includes an input voltage detection. The unit 240, an output voltage detecting unit 250 and a control logic unit 260. The input voltage detecting unit 240 is coupled to the charging pump circuit 160 for detecting the input voltage VCI of the charging pump circuit 160 to generate a first result SR1. The output voltage detecting unit 250 is also coupled to the charging pump circuit 160. It is used to detect the output voltages VSP, VSN of the charge pump circuit 160 to generate a second result SR2. The control logic unit 260 is coupled to the input voltage detecting unit 240 and the output voltage detecting unit 250 to generate the control signals SC1 and SC2 according to the first result SR1 and the second result SR2. In other words, the driving circuit 230 can provide the control signals SC1, SC2 to the charge pump circuit 160 by detecting the input voltage VCI and the output voltages VSP, VSN to set the pump multiple PF1. In this way, the charge pump circuit 160 can support different conversion ratios (for example, 1.5 times, 2 times, or 3 times) to provide a desired output voltage VSP/VSN.

Please refer to FIG. 3, which is a schematic diagram of an example of the driving circuit 230 shown in FIG. In the embodiment, the input voltage detecting unit 240 and the output voltage detecting unit 250 are respectively implemented by using a comparator. The input voltage detecting unit 240 includes a first comparator COMP1 for comparing the input voltage VCI and the first reference voltage V._REF1To generate a first result SR1, the output voltage detecting unit 250 includes a second comparator COMP2 for comparing the output voltage VSP/VSN and the second reference voltage V._REF2To generate the second result SR2, finally, the control logic unit 260 generates the control signals SC1, SC2 according to the first result SR1 and the second result SR2.

It should be noted that the above-described embodiments are merely illustrative of the technical features of the present invention and are not intended to limit the scope of the present invention. However, it will be appreciated by those skilled in the art that various changes in the drive circuit are possible without departing from the spirit of the invention, which is also within the scope of the invention. In addition, the first reference voltage V_REF1And a second reference voltage V_REF2It is not a fixed value and can be adjusted according to actual needs.

Please refer to FIG. 4, FIG. 4 (including FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D) for explaining an exemplary embodiment in which the charge pump circuit 160 shown in FIG. 2 has different pump multiples. As shown in FIG. 4A, the charge pump circuit includes seven switches SW11-SW17 and two capacitors C11 and C12, and the seven switches SW11-SW17 and the two capacitors C11 and C12 are connected as shown in FIG. 4A. For the sake of brevity, it will not be repeated here. In the present embodiment, the input voltage VCI is 4V and the output voltage VSP is 6V, so the pumping multiple PF1 is equal to 1.5. In a charging phase, the first switch SW11, the second switch SW12, and the seventh switch SW17 are in an on state, and at this time, the third switch SW13, the fourth switch SW14, the fifth switch SW15, and the sixth switch SW16 are turned off. status. In a pumping phase, the third switch SW13, the fourth switch SW14, the fifth switch SW15, and the sixth switch SW16 are in an on state, and at this time, the first switch SW11, the second switch SW12, and the seventh switch SW17 are Is off state. It is assumed that the size of the first capacitor C11 is equal to the size of the second capacitor C12. Therefore, as can be seen from FIG. 4A, in the charging phase, the first capacitor C11 and the second capacitor C12 can be respectively charged to 2V; Medium, the output voltage VSP can be pumped to 6V.

As shown in FIG. 4B, the charge pump circuit includes seven switches SW21 to SW27 and two capacitors C21 and C22, and the connection manner of the seven switches SW21 to SW27 and the two capacitors C21 and C22 is as shown in FIG. 4B. For the sake of brevity, it will not be repeated here. In the present embodiment, the input voltage VCI is 2V and the output voltage VSP is 6V, and the pumping multiple PF1 is equal to 3. In a charging phase, the first switch SW21, the second switch SW22, the third switch SW23, and the fourth switch SW24 are in an on state, and at this time, the fifth switch SW25, the sixth switch SW26, and the seventh switch SW27 are turned off. status. In a pumping phase, the fifth switch SW25, the sixth switch SW26, and the seventh switch SW27 are in an on state, and at this time, the first switch SW21, the second switch SW22, the third switch SW23, and the fourth switch SW24 are Is off state. It is also assumed that the size of the first capacitor C21 is equal to the size of the second capacitor C22. Therefore, as can be seen from FIG. 4B, in the charging phase, the first capacitor C21 and the second capacitor C22 can be respectively charged to 2V; In the phase, the output voltage VSP can be pumped to 6V.

As shown in FIG. 4C, the charge pump circuit includes four switches SW31-SW34 and one capacitor C3, and the four switches SW31-SW34 are connected to the capacitor C3 as shown in FIG. 4C. For the sake of brevity, Let me repeat. In the present embodiment, the input voltage VCI is 3V and the output voltage VSP is 6V, and the pumping multiple PF1 is equal to 2. In a charging phase, the first switch SW31 and the second switch SW32 are in an on state, and at this time, the third switch SW33 and the fourth switch SW34 are in a closed state. In the pumping phase, the third switch SW33 and the fourth switch SW34 are in an on state, and at this time, the first switch SW31 and the second switch SW32 are in a closed state. Therefore, as can be seen from FIG. 4C, in the charging phase, the capacitor C3 can be charged to 3V; and in the pumping phase, the output voltage VSP can be pumped to 6V.

As shown in FIG. 4D, the charge pump circuit includes four switches SW41-SW44 and one capacitor C4, and the four switches SW41-SW4 are connected to the capacitor C4 as shown in FIG. 4D. For the sake of brevity, Let me repeat. In the present embodiment, the output voltage VSP is 6V and the other output voltage VSN is (-6V), and the pumping multiple PF1 is equal to (-1). In a charging phase, the first switch SW41 and the second switch SW42 are in an on state, and at this time, the third switch SW43 and the fourth switch SW44 are in a closed state. In the pumping phase, the third switch SW43 and the fourth switch SW44 are in an on state, and at this time, the first switch SW41 and the second switch SW42 are in a closed state. Therefore, as can be seen from FIG. 4D, in the charging phase, the capacitor C4 can be charged to 6V; and in the pumping phase, the output voltage VSN can be pumped to (-6V).

It can be seen from Fig. 4 that when the input voltage VCI is between 2.0V and 4V, the charge pump circuit can select different pump multiples (for example, 1.5 times, 3 times or 2 times) to generate the same output voltage. VSP (such as 6V). In addition, the charge pump circuit disclosed in the present invention can be easily implemented by using simple logic circuits, capacitors, and switches, and other complicated circuits such as a bandgap reference circuit, an operational amplifier, and a clock. A circuit such as a generating circuit can be placed at the driving circuit end, that is, the circuit can be easily implemented with a small cost. And the value of the pump multiple PF1 is not limited, and can be adjusted according to the actual design.

The embodiments described above are only intended to illustrate the technical features of the present invention and are not intended to limit the scope of the present invention. As apparent from the above, 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. In this way, the voltage conversion efficiency of the charge pump circuit 160 can be greatly improved without being limited by the Indium Tin Oxide (ITO) film resistance. In addition, only two control signals SC1, SC2 are required 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. By detecting the input voltage and the output voltage to set different pump multiples, the charge pump circuit can support voltage conversion ratios of different magnifications (for example, 1.5 times, 2 times or 3 times) to provide a desired output voltage. In addition, the charge pump circuit disclosed in the present invention can be easily implemented by simply using a simple logic circuit, a capacitor, and a switch, and the cost can be effectively controlled.

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.

<p>100, 200. . . display system</p><p>110, 210. . . Display device</p><p>120. . . panel</p><p>130, 230. . . Drive circuit</p><p>150. . . Flexible printed circuit board</p><p>160. . . Charge pump circuit</p><p>VCI. . . Input voltage</p><p>VSP, VSN. . . The output voltage</p><p>SC1, SC2. . . Control signal</p><p>PF1. . . Pump multiple</p><p>R. . . Indium tin oxide resistor</p><p>240. . . Input voltage detection unit</p><p>250. . . Output voltage detection unit</p><p>260. . . Control logic unit</p><p>SR1. . . First result</p><p>SR2. . . Second result</p><p>COMP1. . . First comparator</p><p>COMP2. . . Second comparator</p><p>V_REF1. . . First reference voltage</p><p>V_REF2. . . Second reference voltage</p><p>SW11~SW17, SW21~SW27, SW31~SW34, SW41~SW44. . . switch</p><p>C11, C12, C21, C22, C3, C4. . . capacitance</p>

Figure 1 is a schematic illustration of a first embodiment of a display system of the present invention.

2 is a schematic view of a second embodiment of a display system of the present invention.

Fig. 3 is a view showing an example of a driving circuit shown in Fig. 2.

Fig. 4 (comprising Figs. 4A, 4B, 4C and 4D) is a schematic view showing an exemplary embodiment in which the charge pump circuit shown in Fig. 2 has different pump multiples.