1. A transceiver system providing for a transmission of packetized digital data wherein a packet consists of a data payload sharing common control information of the packet, the transceiver system comprising:
(a) a transmitter circuit:
(i) receiving a first data payload and a first rate map describing a desired transmission bit rate of the data payload, the desired transmission bit rate varying as a function of bit positions in the first data payload; and
(ii) transmitting the first data payload according to the first rate map together with control information in a first packet; and
(b) a receiver circuit:
(i) receiving a second packet including a second data payload and control information; and
(ii) decoding the second data payload according to a second rate map describing a transmission bit rate of the second data payload that varies as a function of bit positions in the second data payload.
2. The transceiver system of claim 1 wherein the transmitter circuit transmits the first rate map in the first packet and wherein the receiver receives the second rate map from the second packet.
3. The transceiver system of claim 1 wherein
the transmitter circuit includes:
an encoder circuit variably mapping payload data to transmission symbols according to the first rate map to produce a variable transmission bit rate; and
wherein the receiver includes:
a decoder circuit variably mapping received symbol data to payload data according to the second rate map to decode a transmitted second payload.
4. The transceiver system of claim 1 further including a statistical payload error table recording a statistical probability of errors as a function of bit position in a payload and wherein the rate map varies the bit rate of the first data payload according to the packet error table to reduce bit rates at bit positions having high statistical probability of error and to increase bit rate at bit positions having low statistical probability of errors.
5. The transceiver system of claim 1 wherein the transmitter and receiver are spread-spectrum transmitters and receivers.
6. The transceiver system of claim 1 further including an error detector detecting variation in error rates as a function of bit rate within a packet having different intra-packet bit rates and monitoring the function to deduce an improved error-corrected transmission rate and wherein the rate map encodes a payload according to the improved error-corrected transmission rate.
7. The transceiver system of claim 6 wherein the rate map varies the transmission bit rate within the first packet to provide transmission bit rates on either side of the improved transmission rate.
8. The transceiver system of claim 7 further including a statistical payload error table recording a statistical probability of errors as a function of bit position in a payload and wherein the rate map varies the transmission bit rate of the first data payload according to the packet error table to reduce bit rate at bit positions having high statistical probability of error and to increase bit rate at bit positions having low statistical probability of errors.
9. The transceiver system of claim 1 wherein the transmitter and receiver provide for a transmitted symbol constellation and the transmitter varies the transmission bit rate by using only a subset of symbols of the constellation, the subset size being a function of the desired transmission bit rate.
10. The transceiver system of claim 9 wherein the receiver further includes an error corrector re-mapping of data received at symbols outside of the subset to symbols within the subset.
11. The transceiver system of claim 10 wherein the re-mapping maps the symbols to a closest symbol within the subset.
12. A transceiver system providing for the transmission of packetized digital data, the transceiver system comprising:
(a) a transmitter circuit providing for the transmission of data using a modulation system having a constellation of a first set of symbols;
(b) a pre-processor connected to the transmitter circuit for receiving the first data to be transmitted by the transmitter circuit, the pre-processor variably mapping the data to be transmitted to a subset smaller than the first set of symbols according to the first rate map describing a desired transmission bit rate of the data and providing the mapped data to the transmitter circuit;
(c) a receiver circuit providing for the reception of data using a demodulation system having a constellation of the first set of symbols; and
(d) a post-processor connected to the receiver circuit for receiving data from the receiver circuit, the post-processor variably mapping the received data to a subset smaller than the first set of symbols according to a second rate map describing a transmission bit rate of the data received from the receiver that varies as a function of bit positions of the data received from the receiver.
13. The transceiver system of claim 12 wherein the transmitter and receiver work with data packets each consisting of a data payload sharing common control information of the packet, wherein further, the transmitter circuit transmits the first rate map as payload data of the first packet and wherein the receiver receives the second rate map from the control information of the second packet as payload data of the second packet.
14. The transceiver system of claim 12 wherein the pre-processor includes a statistical payload error table holding a statistical probability of errors as a function of bit
position in a payload and wherein the first rate map reduces bit rates at bit positions of the transmitted data having high statistical probability of error and increases bit rate at bit positions of the transmitted data having low statistical probability of errors.
15. The transceiver system of claim 14 wherein the transmitter and receiver are spread-spectrum transmitters and receivers.
16. The transceiver system of claim 12 wherein the post-processor includes an error detector detecting and monitoring error packets from the receiver to deduce an improved error-corrected transmission rate and wherein the pre-processor selects a first rate map according to the improved error-corrected transmission rate.
17. The transceiver system of claim 16 wherein the pre-processor varies the transmission bit rate to provide transmission bit rates on either side of the improved transmission rate.
18. The transceiver system of claim 17 wherein the pre-processor includes a statistical payload error table holding a statistical probability of errors as a function of bit position in a payload and wherein the first rate map reduces bit rates at bit positions of the transmitted data having high statistical probability of error and increases bit rate at bit positions of the transmitted data having low statistical probability of errors.
19. The transceiver system of claim 12 wherein the post-processor further includes an error corrector re-mapping data received at constellation points outside of the subset to constellation points within the subset.
20. The transceiver system of claim 19 wherein the re-mapping maps the symbols to the closest symbol of the subset.
21. A transceiver system providing for a transmission of packetized digital data wherein a packet consists of a data payload sharing common control information of the packet, the control information including a synchronization clock sequence containing predetermined data known to a potential receiver allowing the receiver to adjust its reception circuitry with respect to an incoming signal, the transceiver system comprising:
(a) a transmitter circuit:
(i) receiving a first data payload and a model of effective transmission rate of the first data payload as a function of bit position after the synchronization clock sequence; and
(ii) transmitting the first data payload with the insertion of augmenting synchronization clock sequences according to the model of effective transmission rate; and
(b) a receiver circuit:
(i) receiving a second packet including a second data payload and control information and augmenting synchronization clock sequences; and
(ii) decoding the second data payload to remove the augmenting synchronization clock sequences after synchronizing the receiver circuit with the augmenting synchronization clock sequences.
22. The transceiver system of claim 21 wherein the transmitter circuit inserts of augmenting synchronization clock sequences when a predicted gain in data transmission resulting from the introduction of an augmenting synchronization clock sequence exceeds a predicted loss in data resulting from the introduction of the augmenting synchronization clock sequence at the time of the introduction.
23. The transceiver system of claim 21 wherein the model of effective transmission rate is updated periodically during transmission of packets.
24. The transceiver system of claim 21 wherein the transmitter circuit further receives a rate map describing a desired transmission bit rate of the data payload, the desired transmission bit rate varying as a function of bit positions in the data payload and wherein the model of effective transmission rate is the received first rate map; and
wherein the transmitter transmits the first data payload according to the first rate map together with control information in a first packet.
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. An inkjet printing apparatus comprising:
at least one printhead comprising at least one ink chamber and a plurality of nozzles,
at least one ink container remote from the printhead,
an ink delivery system comprising a source of gas under pressure operable to supply ink from said remote ink container to said ink chamber on the printhead,
a priming device arranged to prime at least one printhead and comprising a connecting assembly to connect the source of gas under pressure to the printhead to be primed, and
a controller to control the flow of gas through said connecting assembly to provide upon demand gas under pressure to the printhead in order to cause a flow of ink from the ink chamber through the nozzles to prime the printhead,
wherein the priming device comprises at least one coupling member and a positioning unit operable to selectively position the coupling member in a priming position in which the coupling member engages a vent hole of an air chamber of the printhead, and an inactive position in which the coupling member is disengaged from the vent hole, whereby, in the priming position, the coupling member provides fluid communication between the source of gas under pressure and the air chamber of the printhead.
2. An apparatus as claimed in claim 1, wherein the air chamber comprises at least one variable volume air chamber which can expand inside the ink chamber, said air chamber being connected to ambient atmospheric pressure through the vent hole in the printhead, and said coupling member appropriate to sealingly engage the vent hole of the air chamber.
3. An apparatus as claimed in claim 2, wherein the connecting assembly of the priming device comprises at least one air conduit extending between the source of gas under pressure and said at least one coupling member.
4. An apparatus as claimed in claim 3, wherein the priming device comprises a positioning unit operable to selectively position said coupling member in and out of engagement with said vent hole.
5. An apparatus as claimed in claim 3, wherein the connecting assembly of the priming device comprises at least one control valve operable to selectively open or close the flow of gas through the air conduit.
6. An apparatus as claimed in claim 3, wherein the priming device comprises at least two coupling members arranged on a common support and the positioning unit operable to selectively position the common support and the coupling members in a priming position in which at least one coupling member engages a vent hole of an air chamber of a printhead, and an inactive position in which the coupling members are disengaged from the vent holes.
7. An apparatus as claimed in claim 6, wherein said positioning unit comprises an arm pivotably mounted on the printing apparatus and carrying said common support.
8. An apparatus as claimed in claim 7, wherein said common support is mounted with a degree of freedom on the distal end of said arm.
9. An apparatus as claimed in claim 8, wherein said degree of freedom is a linear movement.
10. An apparatus as claimed in claim 6, wherein each coupling member comprises a tubular housing fixed to the common support and an inner tube which can slide within said housing between a retracted position and an extended position, said inner tube having a seal attached at one of its ends and adapted to sealingly engage a vent hole of an air chamber of a printhead.
11. An apparatus as claimed in claim 1, wherein said at least one printhead is arranged on a carriage and the apparatus further comprises a service area in which is arranged at least part of said priming device, the carriage being adapted to position a printhead to be primed in correspondence with the priming device in the service area.
12. An apparatus as claimed in claim 11, wherein the service area comprises a spittoon arranged such that when a printhead is positioned in the service area in correspondence with the priming device the nozzles of the printhead are facing the spittoon.
13. An apparatus as claimed in claim 1, wherein the pressure of the gas provided to the printhead through said connecting assembly is equal to the pressure of the gas in the ink delivery system.
14. An apparatus as claimed in claim 1, wherein said connecting assembly is provided with at least one pressure regulating member.
15. An apparatus as claimed in claim 1, wherein the priming device is arranged to prime at least two printheads simultaneously.
16. A priming device for priming at least one printhead of an inkjet printing apparatus, comprising:
at least one coupling member adapted to sealingly engage a vent hole of a variable volume air chamber of a printhead,
a connecting assembly for connecting said coupling member to a source of gas under pressure associated to an ink delivery system of the printing apparatus, and
a positioning unit operable to selectively position said coupling member in a priming position in which said coupling member engages said vent hole, and an inactive position in which said coupling member is out of engagement with said vent hole,
wherein, in said priming position, said coupling member provides fluid communication between the source of gas under pressure and the air chamber of the printhead.
17. An inkjet printing apparatus comprising a priming device as claimed in claim 16.
18. A method for priming a printhead of an inkjet printing apparatus by causing a flow of ink through a plurality of nozzles of the printhead, comprising the steps of:
connecting a priming device to a source of gas under pressure which is associated to an ink delivery system of the printing apparatus for delivering ink to an ink chamber of a printhead;
selectively positioning a coupling member of the priming device in a priming position sealingly engaging a vent hole of a variable volume air chamber of a printhead to be primed, and an inactive position disengaged from the vent hole, whereby, in the priming position, the coupling member provides fluid communication between the source of gas under pressure and the air chamber of the printhead; and
causing gas under pressure to flow from said source of gas under pressure to the air chamber of said printhead which can expand inside the ink chamber, in order to cause a flow of ink through the nozzles.
19. A method as claimed in claim 18, wherein the priming device comprises at least two coupling members arranged on a common support, and the step of selectively positioning the coupling member comprises selectively position the common support and the coupling members in the priming position in which at least one coupling member engages a vent hole of an air chamber of a printhead, and the inactive position in which the coupling members are disengaged from the vent holes.
20. A method as claimed in claim 18, further comprising the step of positioning at least one printhead to be primed in a service area of the apparatus, before said step of sealingly engaging the coupling member to the vent hole of the air chamber.