JPH0562209U - Azimuth trigger converter - Google Patents

Abstract

(57) [Summary] [Object] To provide an azimuth trigger conversion device capable of changing the number of azimuth pulses during one rotation of a gantry, irrespective of the relationship between the scan algorithm and the mechanical portion. An azimuth trigger conversion device for changing the number of azimuth pulses of a CT gantry, including a counter 2 for counting azimuth pulses, a table 3 for designating a pulse interval according to the number of azimuth pulses counted by the counter 2, and a table 3. Pulse generating means 4 for generating an azimuth pulse in accordance with the pulse interval designated by
5 and.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an azimuth trigger conversion device that changes the number of azimuth pulses in a CT gantry.

[0002]

[Prior Art]

 The azimuth pulse (representing the rotation angle of the gantry) required by the DAS during one rotation of the gantry of the CT device is made up of a combination of a large pulley, a small pulley, and an encoder. This state is shown in FIG. In this figure, the azimuth pulse number is determined by the ratio of the diameters of the large pulley A and the small pulley C and the output pulse number of one rotation of the encoder.

The TGP shapes the azimuth pulse sent as the A phase and the B phase into one pulse train, but does not convert the frequency or the like. The TGP sends a signal to the DAS informing the start of scanning when the tube (TUBE) reaches the home position (0 degree) in synchronization with the azimuth pulse.

[0004]

[Problems to be solved by the device]

 In such a CT device, the number of azimuth pulses during one rotation of the gantry cannot be arbitrarily changed due to mechanical restrictions such as the gear ratio of the motor and the ratio of the diameters of the pulleys. For this reason, it was necessary to balance the scan algorithm with the mechanical part.

The present invention has been made to solve the above problems, and provides an azimuth trigger conversion device capable of changing the number of azimuth pulses during one rotation of the gantry regardless of the relationship with the mechanical portion. It is in.

[0006]

[Means for Solving the Problems]

 An azimuth trigger conversion device that changes the number of azimuth pulses in a CT gantry, a counter that counts azimuth pulses, a table that specifies pulse intervals according to the number of azimuth pulses counted by the counter, and an interval that is specified by the table. And pulse generating means for generating an azimuth pulse according to the above.

[0007]

[Action]

 When the number of azimuth pulses counted by the counter reaches a predetermined number, the address of the corresponding table is designated. Then, the time data corresponding to the address is output from the table. Furthermore, the azimuth pulse is output from the pulse generating means according to the time data.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Further, FIG. 2 is a waveform diagram showing signal waveforms of respective portions when the circuit having the configuration of FIG. 1 is in an operating state.

In this figure, a clock circuit 1 generates a clock signal based on an SPD signal (gantry rotation speed signal) given from the outside. The latch counter 2 counts by latching a trigger TGTRG given from the outside with a clock. The ROM 3 has a time table until the azimuth pulse DTRG is started. The counter 4 counts clocks, and outputs a trigger for starting DTRG at a time corresponding to the data given from the ROM 3. The pulse generator 5 receives the trigger from the counter 4 and changes the azimuth pulse DTRG from L to H for a certain period of time. The latch 6 latches TGENA supplied from the outside at the falling timing of the azimuth pulse DTRG. The switch 7 is a switch circuit that outputs TGENA and TGTRG as they are in the case of SC (scout scan).

The operation of the apparatus of this embodiment having the above configuration is as follows. It is assumed that TGENA as shown in FIG. 2A and TG TRG as shown in FIG. 2B are given from the outside. At this time, the latch counter 2 latches TGTR G with a clock and counts.

The ROM 3 receives the count value of the latch counter 2 and outputs time data until the azimuth pulse DTRG rises based on the internal table. The counter 4, which receives the time data output from the ROM 3, counts the clock and, when the given time data has elapsed, outputs a trigger for starting DTRG. The pulse generator 5 receiving this trigger generates DTRG of H level for a certain period (FIG. 2 (c)). Here, the latch 6 latches TGENA at the falling timing of DTR G.

As a result, the DTRG decimated at a predetermined interval from the TGTRG is output. In the above case, by changing the contents (time interval) of the table of the ROM 3, it is possible to arbitrarily change the cycle of DTRG regardless of the cycle of TGTRG.

FIG. 3 is a configuration diagram showing a specific configuration example of the latch / counter 2, ROM 3, and counter 4. Here, the case where 39040 pulses / revolution is converted to 2,0096 pulses / revolution is shown. In this figure, the 16-bit output of the 39040 counter 12 as a latch counter is given as the address of the ROM 13, and the output of this ROM drives the timer 14 to generate a rising trigger.

FIG. 4 is a waveform diagram showing a signal waveform. In this figure, TGTRG and DTRG are shown. In this example, in order to convert 39040 pulses / revolution to 2,0096 pulses / revolution, the pulse period T1 of TGTRG is 98 microseconds and the pulse period T2 of DTRG is 190.38 microseconds.

As described in detail above, according to the present embodiment, an azimuth / strength converter capable of arbitrarily changing the number of azimuth pulses during one rotation of the CT gantry is realized regardless of mechanical restrictions. You can do it.

Therefore, the number of azimuth pulses during one rotation of the gantry is not limited by mechanical constraints such as the gear ratio of the motor and the diameter ratio of the pulleys, and can be changed arbitrarily, and the scan algorithm and the mechanical portion can be adjusted. Becomes unnecessary.

[0017]

[Effect of the device]

 As described in detail above, according to the present invention, it is possible to realize an azimuth trigger conversion device capable of arbitrarily changing the number of azimuth pulses during one rotation of the CT gantry regardless of mechanical constraints. . For this reason, it is not necessary to adjust the scan algorithm and the mechanical section.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a waveform diagram showing a signal waveform of each part.

FIG. 3 is a configuration diagram showing a detailed configuration of a main part of the present invention.

FIG. 4 is a waveform diagram showing signal waveforms at various parts of the configuration shown in FIG.

FIG. 5 is a configuration diagram showing a configuration around a conventional CT gantry.

[Explanation of symbols]

 1 Clock Circuit 2 Latch Counter 3 ROM 4 Counter 5 Pulse Generator 6 Latch 7 Switch

Claims (1)

[Scope of utility model registration request] 1. A azimuth trigger conversion device for changing the number of azimuth pulses of a CT gantry, wherein a counter (2) for counting azimuth pulses and a pulse interval is designated according to the number of azimuth pulses counted by the counter (2). An azimuth trigger conversion device comprising a table (3) and pulse generation means (4, 5) for generating an azimuth pulse according to an interval designated by the table (3).