1. A handheld mobile communications device comprising:
a support structure;
radio signal processing circuitry positioned on the support structure and configured to receive and transmit radio signals;
audio signal processing circuitry positioned on the support structure and operatively connected to the radio signal processing circuitry;
image processing circuitry positioned on the support structure and operatively connected to the radio signal processing circuitry; and
a receptacle for receiving a detachable printing mechanism having a non-traversing printhead, the receptacle including an interface enabling connection of the printing mechanism to the image processing circuitry, thereby enabling images processed by the image processing circuitry to be printed by the printhead of the printing mechanism onto print media in a single pass when it is operatively positioned within the receptacle.
2. A communications device as claimed in claim 1, in which the printhead of the printing mechanism is a pagewidth printhead and an ink distribution unit mounted on the printhead to supply ink to the printhead.
3. A communications device as claimed in claim 2, in which the printhead includes a printhead chip that spans a print media pathway, the printhead chip defining a plurality of ink inlets for the supply of ink to the printhead chip.
4. A communications device as claimed in claim 3, in which the ink distribution unit defines a number of discrete ink supply chambers and a plurality of ink pathways interposed between the ink supply chambers and said ink inlets, the ink pathways converging towards the ink inlets so that each ink inlet is supplied with ink from a respective ink pathway.
5. A communications device as claimed in claim 1, in which the radio signal processing circuitry is configured to process radio signals of the type transmitted and received by a mobile telephone.
6. A communications device as claimed in claim 1, in which the audio signal processing circuitry is configured to process audio signals of the type generated and received by a mobile telephone.
7. A communications device as claimed in claim 1, in which the image processing circuitry is configured to process images of the type generated by a digital camera device.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A constant power LED drive circuit comprising:
a switch-mode power supply;
a current sensor providing a signal proportional to an LED current;
an integrator taking the signal from the current sensor and combining the signal from the current sensor with a signal proportional to the duty cycle and forming an output, which determines a relative amount of time for a transistor switch in an on configuration and an off configuration; and
wherein the integrator comprises a series resistor and a parallel capacitor, wherein the time constant of the resistor-capacitor circuit is a multiple of the inverse of the switching frequency of the switch-mode power supply, and wherein the multiple of the inverse of the switching frequency of the switch-mode power supply is approximately 3 to 10 times longer than a complete switching period of the transistor switch.
2. A constant power LED drive circuit as set forth in claim 1, wherein the current sensor is a resistor.
3. A constant power LED drive circuit as set forth in claim 1, wherein the current sensor is a transformer.
4. A constant power LED drive circuit as set forth in claim 1, wherein the switch-mode power supply is a buck-derived converter.
5. A constant power LED drive circuit as set forth in claim 1, wherein the switch-mode power supply is power-factor corrected.
6. A constant power LED drive circuit as set forth in claim 1, wherein the switch-mode power supply comprises an input power source, an inductor, a diode, and a transistor switch.
7. A constant power LED drive circuit as set forth in claim 1, further comprising at least one LED.
8. An LED driver circuit, the driver circuit comprising:
a power supply including an inductor and a switching transistor, the power supply configured to supply power with a first duty cycle and a switching frequency;
a current sensor configured to sense an LED current;
an integrator configured to combine a first signal based on the sensed LED current with a second signal based on the first duty cycle to form an output signal;
wherein the integrator comprises a series resistor and a parallel capacitor, a time constant of the resistor-capacitor circuit is a multiple of the inverse of the switching frequency of the power supply, and the multiple of the inverse of the switching frequency of the power supply is 3 to 10 times longer than a complete switching period of the power supply.
9. The LED driver circuit of claim 8, wherein the second signal is proportional to the first duty cycle.
10. The LED driver circuit of claim 8, wherein the current sensor is a resistor configured to convert the LED current into a voltage signal.
11. The LED driver circuit of claim 8, wherein the current sensor is a transformer.
12. The LED driver circuit of claim 8, wherein the power supply is a switch-mode power supply.
13. The LED driver circuit of claim 12, wherein the switch-mode power supply comprises a buck converter.
14. The LED driver circuit of claim 12, wherein the switch-mode power supply is power-factor corrected.
15. The LED driver circuit of claim 8, wherein the power supply comprises an inductor, a diode, and a transistor switch.
16. The LED driver circuit of claim 8, further comprising at least one LED.
17. An LED driver circuit, the driver circuit comprising:
at least one LED;
a power supply electrically connected to the at least one LED, the power supply comprising an indicator and a switching transistor configured to supply power at a duty cycle and a switching frequency;
a current sensor configured to sense a current of the at least one LED;
an integrator configured to combine a first signal based on the sensed current with a second signal based on the duty cycle of the power supply to form an output signal;
wherein the power supply is further configured to change the duty cycle based on the output signal; and
wherein the integrator comprises a series resistor and a parallel capacitor, a time constant of the resistor-capacitor circuit is a multiple of the inverse of the switching frequency of the power supply, and the multiple of the inverse of the switching frequency of the power supply is 3 to 10 times longer than a complete switching period of the power supply.