1. A distance measuring apparatus, comprising:
a transmitter, configured to transmit first one-frame signals from an antenna via radio waves having three or more different carrier frequencies, each of the first one-frame signals being composed of a request signal and a continuous carrier wave;
a receiver, configured to receive second one-frame signals generated when the first one-frame signals are reflected by a reflector while being modulated, each of the second one-frame signals having a frequency corresponding to a frequency of an associated one of the first one-frame signals;
a phase information acquirer, configured to calculate a phase change amount between the first one-frame signals and the second one-frame signals for each of the carrier frequencies; and
a distance calculator, configured to calculate a distance between the antenna and the reflector by high-resolution spectrum analysis, on the basis of the carrier frequencies and the phase change amount calculated for each of the carrier frequencies.
2. The distance measuring apparatus as set forth in claim 1, wherein:
the distance calculator is configured to perform a MUSIC (Multiple Signal Classification) method as the high-resolution spectrum analysis, in which the second one-frame signals are used as an input, a MUSIC evaluation function is obtained by using a mode vector as a function of the distance, and the distance is calculated by obtaining peak values of the MUSIC evaluation function.
3. The distance measuring apparatus as set forth in claim 2, wherein:
the distance calculator is configured to determine the distance as a minimum one of distances corresponding to the peak values.
4. The distance measuring apparatus as set forth in claim 1, wherein:
the distance calculator is configured to calculate the distance also on the basis of an intensity of each of the second one-frame signals received by the receiver.
5. The distance measuring apparatus as set forth in claim 1, further comprising:
a reception controller, configured to acquire information of a data section included in each of the second one-frame signals, and to output the distance while associating with the information of the data section.
6. The distance measuring apparatus as set forth in claim 1, wherein:
the distance calculator is configured to determine a direction that the reflector is located on the basis of the second one-phase signals.
7. The distance measuring apparatus as set forth in claim 1, wherein:
the distance calculator is configured to calculate the distance by analyzing a signal in a preamble section of each of the second one-frame signals.
8. A distance measuring method, comprising:
transmitting first one-frame signals from an antenna via radio waves having three or more different carrier frequencies, each of the first one-frame signals being composed of a request signal and a continuous carrier wave;
receiving second one-frame signals generated when the first one-frame signals are reflected by a reflector while being modulated, each of the second one-frame signals having a frequency corresponding to a frequency of an associated one of the first one-frame signals;
calculating a phase change amount between the first one-frame signals and the second one-frame signals for each of the carrier frequencies; and
calculating a distance between the antenna and the reflector by high-resolution spectrum analysis, on the basis of the carrier frequencies and the phase change amount calculated for each of the carrier frequencies.
9. The distance measuring method as set forth in claim 8, wherein:
the distance is calculated by performing a MUSIC (Multiple Signal Classification) method as the high-resolution spectrum analysis, in which the second one-frame signals are used as an input, a MUSIC evaluation function is obtained by using a mode vector as a function of the distance, and the distance is calculated by obtaining peak values of the MUSIC evaluation function.
10. The distance measuring method as set forth in claim 9, wherein:
the distance is determined as a minimum one of distances corresponding to the peak values.
11. The distance measuring method as set forth in claim 8, wherein:
the distance is calculated also on the basis of an intensity of each of the second one-frame signals received by the receiver.
12. The distance measuring method as set forth in claim 8, further comprising:
acquiring information of a data section included in each of the second one-frame signals; and
outputting the distance while associating with the information of the data section.
13. The distance measuring method as set forth in claim 8, further comprising:
determining a direction that the reflector is located on the basis of the second one-phase signals.
14. The distance measuring method as set forth in claim 8, wherein:
the distance is calculated by analyzing a signal in a preamble section of each of the second one-frame signals.
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 printing apparatus comprising:
a main tank for containing ink;
a sub tank for containing ink supplied from the main tank and supplying ink to a print head;
a detection unit configured to detect an ink amount in the sub tank; and
an ink filling unit configured to perform an ink filling operation to the sub tank by driving a driving unit for supplying ink from the main tank to the sub tank,
wherein the ink filling unit performs a first ink filling operation when the main tank is mounted to the printing apparatus and performs a second ink filling operation in which the driving unit is driven longer drive time than that in the first ink filling operation, in a case where the detection unit detects the ink amount less than a first predetermined amount.
2. The printing apparatus according to claim 1, wherein the ink filling unit performs the second ink filling operation in which the driving unit is driven at lower drive speed than that in the first ink filling operation.
3. The printing apparatus according to claim 1, wherein the ink filling unit performs the second ink filling operation after the detection unit detects the ink amount less than the first predetermined amount.
4. The printing apparatus according to claim 1, wherein the ink filling unit performs the second ink filling operation after the detection unit detects the ink amount less than the first predetermined amount and thereafter a predetermined amount of ink in the sub tank has been consumed.
5. The printing apparatus according to claim 1, wherein the ink filling unit performs the second ink filling operation after the detection unit detects the ink amount less than the first predetermined amount and thereafter when the detection unit detects the ink amount less than a second predetermined amount that is less than the first predetermined amount.
6. The printing apparatus according to claim 1, wherein the ink filling unit performs the second ink filling operation after the detection unit detects the ink amount less than the first predetermined amount and thereafter when the main tank is detached from the printing apparatus.
7. The printing apparatus according to claim 1, wherein the ink filling unit determines whether to perform the second ink filling operation based on at least one of an ink supply amount, a type of ink, environmental temperature and environmental humidity at time when an ink remaining amount in the main tank is less than a predetermined amount, and performs the second ink filling operation according to a result of the determination.
8. An ink amount control method for an ink tank in an ink jet printing apparatus that performs printing using the ink tank for containing ink and supplying ink to a print head, the method comprising:
a step of performing an ink discharge operation that discharges ink from the ink tank by driving a driving unit,
wherein the ink discharge operation is performed by driving the driving unit longer drive time than that in an ink discharge operation performed when the ink tank is mounted to the ink jet printing apparatus.