Intermittent charge pump, configuration method and display driving circuit

Abstract

The invention provides an intermittent charge pump, a configuration method and a display driving circuit, and belongs to the technical field of charge pumps. A charge pump controller is connected with a transfer capacitor and a stable capacitor through a switch group, and a voltage feedback circuit is connected with the output end of the stable capacitor; the comparator compares the reference voltage sent by the charge pump controller with the feedback voltage sent by the voltage feedback circuit and sends a comparison result to the charge pump controller, the charge pump controller counts the number of times of overturning of the comparator in a preset clock range according to the comparison result, and if the number of times of overturning reaches a preset value, the comparator is switched to the preset clock range. And judging that the output voltage of the charge pump reaches the preset voltage range, maintaining the clock parameter and the driving parameter of the charge pump, otherwise, adjusting the clock parameter and the driving parameter of the charge pump. According to the invention, the turning frequency of the comparator is taken as a judgment basis, and a non-comparison result is taken as a control signal for turning on and turning off the charge pump, so that ripples generated when the charge pump is turned on and turned off are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of charge pumps, and in particular to an intermittent charge pump, a configuration method and a display driving circuit. Background Art

[0002] Capacitance Sensing Analog Front-End is an electronic circuit used to measure capacitance values. It is usually used in touch screens, proximity sensors and other devices that need to detect capacitance changes. Its basic principle is to obtain the capacitance value by monitoring the charging and discharging process of the capacitor, thereby realizing the detection of the object being measured.

[0003] like Figure 1 As shown, in the capacitive touch chip, a boost circuit composed of a charge pump is usually used to increase the coding voltage by 2 to 3 times, so as to obtain more charge and transmit it to the capacitive detection analog front-end circuit. In this way, the capacitive detection analog front-end circuit can obtain a larger integrated voltage swing and a better signal-to-noise ratio.

[0004] The commonly used charge pump currently realizes the charge pump function by switching switches. During the charging and discharging process of the charge pump, the output voltage of the charge pump will produce ripples, which will affect the circuit accuracy. Summary of the invention

[0005] The present invention provides an intermittent charge pump, a configuration method and a display drive circuit, which solve the defect that the output voltage of the charge pump generates ripples during the charging and discharging process of the existing charge pump, thereby affecting the circuit accuracy.

[0006] In the first aspect, the present invention provides an intermittent charge pump, including a charge pump controller, a switch group, a transfer capacitor, a stabilizing capacitor, a voltage feedback circuit and a comparator; the charge pump controller is connected to the transfer capacitor and the stabilizing capacitor through the switch group, the voltage feedback circuit is connected to the output end of the stabilizing capacitor, and the output voltage of the charge pump is fed back to one of the input ends of the comparator, the other input end of the comparator is connected to the charge pump controller, the reference voltage sent by the charge pump controller and the feedback voltage sent by the voltage feedback circuit are compared, and the comparison result is sent to the charge pump controller, the charge pump controller is used to count the number of flips of the comparator within a preset clock range according to the comparison result, if the number of flips reaches a preset value, it is determined that the output voltage of the charge pump has reached the preset voltage range, and the clock parameters and drive parameters of the charge pump are maintained, otherwise the clock parameters and drive parameters of the charge pump are adjusted.

[0007] According to an intermittent charge pump provided by the present invention, the stable voltage is also connected to a capacitive load circuit, and correspondingly, the charge pump controller is also used to respond to a flip signal or a rising edge signal or a falling edge signal of the capacitive load circuit, and control the charge pump to start through the switch group, and after N charge pump cycles, control the charge pump to stop through the switch group, where N is a positive integer less than 10.

[0008] According to an intermittent charge pump provided by the present invention, the clock frequency of the capacitive load circuit is 100KHz to 500KHz, and the clock frequency of the charge pump is 1MHz to 10MHz.

[0009] According to an intermittent charge pump provided by the present invention, the capacitive load circuit is a display screen driving circuit or a touch sensor driving circuit, and correspondingly, the flip signal or rising edge signal or falling edge signal of the capacitive load circuit is the flip signal or rising edge signal or falling edge signal of the gate.

[0010] According to an intermittent charge pump provided by the present invention, the charge pump controller is further used to adjust the driving parameters of the charge pump according to the process characteristics and / or the operating voltage of the capacitive load circuit.

[0011] In a second aspect, the present invention further provides an intermittent charge pump configuration method, for configuring any one of the intermittent charge pumps described above, the method comprising:

[0012] Configure reference voltage, comparator filter time and charge pump cycle parameters, and turn on the charge pump clock signal;

[0013] adjusting a driving parameter of the charge pump according to the reference voltage, the comparator filtering time and the charge pump cycle parameter;

[0014] If the output voltage of the charge pump does not reach the preset voltage range, determine whether the charge pump reaches the charge pump cycle parameter, if so, return to the step of configuring the charge pump cycle parameter, otherwise, adjust the driving parameter of the charge pump;

[0015] If the output voltage of the charge pump reaches a preset voltage range, the clock parameters and driving parameters of the charge pump are maintained.

[0016] In a third aspect, the present invention further provides a display driving circuit, comprising any one of the intermittent charge pumps described.

[0017] The present invention provides an intermittent charge pump, configuration method and display driving circuit, the intermittent charge pump includes a charge pump controller, a switch group, a transfer capacitor, a stabilizing capacitor, a voltage feedback circuit and a comparator; the charge pump controller is connected to the transfer capacitor and the stabilizing capacitor through the switch group, the voltage feedback circuit is connected to the output end of the stabilizing capacitor, the output voltage of the charge pump is fed back to one of the input ends of the comparator, the other input end of the comparator is connected to the charge pump controller, the reference voltage sent by the charge pump controller and the feedback voltage sent by the voltage feedback circuit are compared, and the comparison result is sent to the charge pump controller, the charge pump controller is used to count the number of flips of the comparator within a preset clock range according to the comparison result, if the number of flips reaches a preset value, it is determined that the output voltage of the charge pump has reached the preset voltage range, the clock parameters and driving parameters of the charge pump are maintained, otherwise the clock parameters and driving parameters of the charge pump are adjusted. The present invention uses the number of flips of the comparator as a judgment basis, rather than directly using the comparison result output by the comparator as a control signal for opening and closing the charge pump, to avoid ripples generated when the charge pump is opened and closed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a circuit diagram of an existing capacitance detection analog front end.

[0020] Figure 2a is a circuit diagram of an existing charge pump. Figure 2b It is a timing control schematic diagram of an existing charge pump.

[0021] Figure 3 It is a circuit diagram of the intermittent charge pump provided by the present invention.

[0022] Figure 4 It is a schematic diagram of the timing control of the intermittent charge pump provided by the present invention.

[0023] Figure 5 It is a flow chart of the intermittent charge pump configuration method provided by the present invention.

[0024] Figure 6a is a circuit diagram of a display driving circuit provided by the present invention, Figure 6b yes Figure 6a A magnified view of one of the drive units in the . DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] It should be noted that in the description of the present invention, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "include one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements. The orientation or position relationship indicated by the terms "upper", "lower" and the like is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] The terms "first", "second", etc. in the present invention are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" means at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0028] All actions of acquiring signals, information or data in the present invention are performed in compliance with the corresponding data protection laws and policies of the location and with the authorization given by the owner of the corresponding device.

[0029] The circuit diagram of the commonly used charge pump is as follows Figure 2a As shown, the corresponding driving timing diagram is as follows Figure 2b As shown, the charge pump is composed of a transfer capacitor Cfly and a stabilizing capacitor Ctank. When φ1 is high, switches S11 and S21 are closed, and switches S12 and S22 are opened to charge the transfer capacitor Cfly. When φ2 is high, switches S11 and S21 are opened, and switches S12 and S22 are closed to pump charge to the stabilizing capacitor Ctank, and the output voltage increases. During the start-up of the charge pump, the voltage continues to increase. After the output voltage of the charge pump is stabilized, the voltage no longer increases, but each charge pumping will bring ripples on the output voltage. Among them, φ1 and φ2 are clock signals of the same frequency but different phases. By controlling the switch state, the transfer capacitor Cfly is continuously and periodically charged, and the charge is pumped to the stabilizing capacitor Ctank.

[0030] Existing charge pumps have the following problems: each charge and discharge consumes current, and under light load conditions, the efficiency of the charge pump will be greatly reduced; switching will cause ripples in the output voltage, affecting the accuracy of the analog circuit; the charge pump continuously draws current from the DC power supply VDD, which will generate electromagnetic interference and affect the performance of other components.

[0031] An intermittent charge pump, configuration method and display driving circuit provided by the present invention are described below in conjunction with the accompanying drawings.

[0032] Figure 3 is a circuit diagram of an intermittent charge pump provided by the present invention, Figure 4 Schematic diagram of timing control of the intermittent charge pump provided by the present invention, such as Figure 3 and Figure 4 As shown, the present invention provides an intermittent charge pump, including a charge pump controller, a switch group, a transfer capacitor, a stabilizing capacitor, a voltage feedback circuit and a comparator; the charge pump controller is connected to the transfer capacitor and the stabilizing capacitor through the switch group. The switch group includes a switch S11, a switch S12, a switch S21 and a switch S22, one end of the switch S11 is grounded, and the other end is connected to one end of the transfer capacitor with the switch S12 respectively, the common end of the switch S12 and the switch S21 is connected to a DC power supply VDD, the switch S21 is connected to the other end of the transfer capacitor and one end of the switch S22, the other end of the switch S22 is connected to one end of the stabilizing capacitor, the common end is the output voltage VPUMPOUT of the charge pump, and the other end of the stabilizing capacitor is grounded.

[0033] The voltage feedback circuit is connected to the output end of the stabilizing capacitor, and feeds back the output voltage of the charge pump to one of the input ends of the comparator. The other input end of the comparator is connected to the charge pump controller, and compares the reference voltage sent by the charge pump controller and the feedback voltage sent by the voltage feedback circuit, and sends the comparison result to the charge pump controller. The charge pump controller is used to count the number of flips of the comparator within a preset clock range according to the comparison result. If the number of flips reaches a preset value, it is determined that the output voltage of the charge pump has reached the preset voltage range, and the clock parameters and drive parameters of the charge pump are maintained. Otherwise, the clock parameters and drive parameters of the charge pump are adjusted.

[0034] according to Figure 3 and Figure 4 It can be seen that the charge pump provided by the present invention is a closed loop, and the number of flipping of the comparator can be used to detect whether the charge pump reaches the required output voltage range. Specifically, the number of flipping of the comparator within the preset clock range is counted, and if the number of flipping reaches a preset value, it is determined that the output voltage of the charge pump has reached the preset voltage range. Figure 4 If there are M TXCLKs that are clock signals of capacitive loads, within the time of a rising edge and a falling edge of TXCLK, the comparator will flip along with the output voltage. If the number of flipping times of the comparator reaches 0.98*M times, that is, the comparator flips frequently, it is determined that the output voltage of the charge pump has reached a preset voltage range. Usually, M is an integer greater than 100 and less than 200.

[0035] The existing charge pump will consume current when charging and discharging at K CPCLKs. The characteristic of the capacitive load is that once the charging is completed, the voltage will be maintained. Therefore, the present invention can meet the load requirements based on the driving capacity of N CPCLK cycles. The clock output is stopped from the N+1th to the Kth CPCLK cycles, and the charge pump stops working. No additional current consumption will be generated, reducing the current drawn from the DC power supply VDD. Among them, K is assumed that there are K CPCLK cycles in a TX rising cycle or falling cycle, K>N.

[0036] The switch switching timing of the charge pump of the present application is different from that of the prior art. The switch of the charge pump of the prior art is a continuous clock signal with a fixed frequency, such as Figure 2b In the embodiment of the present application, CPCLK stops after outputting N CPCLKs after the rising or falling edge of TX. The present application is obviously different from the continuous clock signal of the prior art, and can reduce the ripple caused by the uninterrupted switching in the prior art. In addition, high-precision signal measurement can be performed during the time period when CPCLK stops. High-precision signal measurement during the idle time period of the charge pump will not be interfered by the switching noise of the charge pump, and will not affect the circuit accuracy.

[0037] Optionally, the clock parameter of the charge pump refers to the number of clock cycles of the charge pump, the drive parameter (here the adjustable drive parameter is mainly the switch size). If the charge pump cannot reach the preset voltage range, first adjust the drive parameter of the charge pump, if the preset voltage range is still not reached after adjusting the drive parameter of the charge pump, then increase the number of clock cycles of the charge pump.

[0038] It can be understood that the output result of the comparator in the existing charge pump closed-loop structure is used as a stop signal of the charge pump clock signal CPCLK, and each flip of the comparator in the existing charge pump closed-loop structure will be responded to by the charge pump clock controller. The charge pump clock controller turns on or off the clock in response to the flip of the comparator, which brings a large ripple, and the ripple has an uncertain frequency, which will greatly affect the performance of the analog circuit, especially the integrator and ADC (the noise brought by the digital-to-analog converter during the CPCLK flip will affect the measurement accuracy of the analog signal). However, the present invention uses multiple flips of the comparator as the basis for judgment, and does not directly use the output of the comparator as a control signal for turning on and off the charge pump clock.

[0039] As an optional embodiment, the stable voltage is also connected to a capacitive load circuit, and correspondingly, the charge pump controller is also used to respond to the flip signal or rising edge signal or falling edge signal of the capacitive load circuit, control the charge pump to start through the switch group, and control the charge pump to stop through the switch group after N charge pump cycles, where N is a positive integer less than 10. Optionally, the clock frequency of the capacitive load circuit is 100KHz to 500KHz, and the clock frequency of the charge pump is 1MHz to 10MHz. According to the physical characteristics of the touch screen, it can be understood that due to the limitation of the touch screen RC, the clock frequency of the capacitive load circuit cannot be too high, usually 100KHz to 500KHz; similarly, the frequency of the charge pump is also determined by the transfer capacitor and the RC of the switch, and the frequency is 1M to 10MHz.

[0040] As an optional embodiment, the capacitive load circuit is a display screen driving circuit or a touch sensor driving circuit, and correspondingly, the flip signal or rising edge signal or falling edge signal of the capacitive load circuit is a flip signal or rising edge signal or falling edge signal of the gate.

[0041] The charge pump provided by the present invention is used in a display screen driving circuit or a touch sensor driving circuit. The display screen driving circuit or the touch sensor driving circuit usually adopts a gate to drive the charge pump to start and stop. After the charge pump clock is turned on, the charge pump clock stops after N charge pump cycles.

[0042] As an optional embodiment, the charge pump controller is further used to adjust the driving parameters of the charge pump according to the process characteristics and / or the operating voltage of the capacitive load circuit. Specifically, the present invention adjusts the driving parameters of the charge pump by adjusting the size of the driving switch tube of the charge pump to compensate for the process deviation and load changes, and adjusting the value of N to adapt to the load changes, such as increasing N as the load increases and decreasing N as the load decreases.

[0043] The present invention can automatically adjust the driving capability of the charge pump according to the process deviation and / or the operating voltage of different chips, reduce unnecessary charge consumption of the charge pump, and thus reduce the power consumption of the charge pump itself.

[0044] The intermittent charge pump configuration method provided by the present invention is described below. The intermittent charge pump configuration method described below and the intermittent charge pump described above can be referenced to each other.

[0045] Figure 5 FIG. 1 is a flow chart of the intermittent charge pump configuration method provided by the present invention, such as Figure 5 As shown, the present invention also provides an intermittent charge pump configuration method, which is used to configure any of the intermittent charge pumps described in any one of the above. The intermittent charge pump includes a charge pump controller, a switch group, a transfer capacitor, a stabilizing capacitor, a voltage feedback circuit and a comparator; the charge pump controller is connected to the transfer capacitor and the stabilizing capacitor through the switch group, the voltage feedback circuit is connected to the output end of the stabilizing capacitor, and the output voltage of the charge pump is fed back to one of the input ends of the comparator, and the other input end of the comparator is connected to the charge pump controller, and the reference voltage sent by the charge pump controller and the feedback voltage sent by the voltage feedback circuit are compared, and the comparison result is sent to the charge pump controller, and the charge pump controller is used to count the number of flips of the comparator within a preset clock range according to the comparison result. If the number of flips reaches a preset value, it is determined that the output voltage of the charge pump has reached the preset voltage range, and the clock parameters and drive parameters of the charge pump are maintained, otherwise the clock parameters and drive parameters of the charge pump are adjusted. The method includes the following steps.

[0046] S1, configure reference voltage, comparator filter time and charge pump cycle parameters, turn on the charge pump clock signal, turn on the charge pump clock signal to start the charge pump. The charge pump has the ability to pump charge, that is, it has load capacity. Configuring reference voltage, comparator filter time and charge pump cycle parameters specifically refers to using registers to control DAC to configure reference voltage according to system needs, comparator filter time is configured by counter, and charge pump cycle configuration register generates timing. Register configuration DAC can generate different voltages as reference voltages; comparator filter time is different through counter counting time length; charge pump configuration register outputs different N values.

[0047] S2, adjusting the driving parameters of the charge pump according to the reference voltage, the comparator filtering time and the charge pump cycle parameters.

[0048] S3, if the output voltage of the charge pump does not reach the preset voltage range, determine whether the charge pump reaches the charge pump cycle parameter, if so, return to the step of configuring the charge pump cycle parameter, otherwise, adjust the drive parameter of the charge pump.

[0049] S4: If the output voltage of the charge pump reaches a preset voltage range, the clock parameters and driving parameters of the charge pump are maintained.

[0050] It should be noted that the order of step S3 and step S4 can be adjusted, and the present invention is not limited to this.

[0051] As an embodiment, the stable voltage is also connected to a capacitive load circuit, and correspondingly, the charge pump controller is also used to respond to a flip signal or a rising edge signal or a falling edge signal of the capacitive load circuit, and control the charge pump to start through the switch group, and after N charge pump cycles, control the charge pump to stop through the switch group, where N is a positive integer less than 10.

[0052] As an embodiment, the clock frequency of the capacitive load circuit is 100 KHz to 500 KHz, and the clock frequency of the charge pump is 1 MHz to 10 MHz.

[0053] As an embodiment, the capacitive load circuit is a display screen driving circuit or a touch sensor driving circuit, and correspondingly, the flip signal or rising edge signal or falling edge signal of the capacitive load circuit is a flip signal or rising edge signal or falling edge signal of a gate.

[0054] As an embodiment, the charge pump controller is further configured to adjust driving parameters of the charge pump according to process characteristics and / or operating voltage of the capacitive load circuit.

[0055] The display driving circuit provided by the present invention is described below. The display driving circuit described below and the intermittent charge pump and the intermittent charge pump configuration method described above can be referred to each other.

[0056] Figure 6a is a circuit diagram of a display driving circuit provided by the present invention, Figure 6b yes Figure 6a An enlarged view of a drive unit in Figure 6a-6b As shown, the present invention also provides a display driving circuit, comprising any of the intermittent charge pumps described above. The intermittent charge pump is applied to a display driving circuit having a capacitive load (TX driver), a start signal is sent to the charge pump, and a start signal is executed. Figure 5 The intermittent charge pump configuration method shown enables the charge pump to achieve the function of positive boost or negative boost.

[0057] It can be understood that the display driving circuit provided by the present invention adopts the intermittent charge pump in the above embodiment, which can reduce the output ripple of the charge pump and improve the signal-to-noise ratio of the touch screen detection circuit; improve the performance of ADC and integrator, significantly improve the sensing accuracy of the chip, and improve image quality.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An intermittent charge pump, characterized in that: It includes a charge pump controller, a switch group, a transfer capacitor, a stabilizing capacitor, a voltage feedback circuit and a comparator; the charge pump controller is connected to the transfer capacitor and the stabilizing capacitor through the switch group, the voltage feedback circuit is connected to the output end of the stabilizing capacitor, and the output voltage of the charge pump is fed back to one of the input ends of the comparator, the other input end of the comparator is connected to the charge pump controller, the reference voltage sent by the charge pump controller and the feedback voltage sent by the voltage feedback circuit are compared, and the comparison result is sent to the charge pump controller, the charge pump controller is used to count the number of flips of the comparator within a preset clock range according to the comparison result, if the number of flips reaches a preset value, it is determined that the output voltage of the charge pump has reached the preset voltage range, and the clock parameters and drive parameters of the charge pump are maintained, otherwise the clock parameters and drive parameters of the charge pump are adjusted.

2. The intermittent charge pump according to claim 1, characterized in that: The stable voltage is also connected to a capacitive load circuit. Correspondingly, the charge pump controller is also used to respond to a flip signal or a rising edge signal or a falling edge signal of the capacitive load circuit, and control the charge pump to start through the switch group. After N charge pump cycles, the charge pump is controlled to stop through the switch group, where N is a positive integer less than 10.

3. The intermittent charge pump according to claim 2, characterized in that: The clock frequency of the capacitive load circuit is 100KHz to 500KHz, and the clock frequency of the charge pump is 1MHz to 10MHz.

4. The intermittent charge pump according to claim 2 or 3, characterized in that: The capacitive load circuit is a display screen driving circuit or a touch sensor driving circuit. Correspondingly, the flip signal or rising edge signal or falling edge signal of the capacitive load circuit is a flip signal or rising edge signal or falling edge signal of a gate.

5. The intermittent charge pump according to claim 2 or 3, characterized in that: The charge pump controller is further configured to adjust driving parameters of the charge pump according to process characteristics and / or operating voltage of the capacitive load circuit.

6. A method for configuring an intermittent charge pump, characterized in that: For configuring the intermittent charge pump according to any one of claims 1 to 5, the method comprising: Configure reference voltage, comparator filter time and charge pump cycle parameters, and turn on the charge pump clock signal; adjusting a driving parameter of the charge pump according to the reference voltage, the comparator filtering time and the charge pump cycle parameter; If the output voltage of the charge pump does not reach the preset voltage range, determine whether the charge pump reaches the charge pump cycle parameter, if so, return to the step of configuring the charge pump cycle parameter, otherwise, adjust the driving parameter of the charge pump; If the output voltage of the charge pump reaches a preset voltage range, the clock parameters and driving parameters of the charge pump are maintained.

7. A display driving circuit, characterized in that: Comprising the intermittent charge pump as described in any one of claims 1-5.

Images