JPS61228832A - Ct apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an xHcr device.

[Technical background of the invention and its problems]

In an X-ray device in which an X-ray tube that generates X-rays directed toward the subject and a detector that detects the X-rays that have passed through the subject are rotated about the center of the subject, there are a fixed part and a rotating part. The signal pulse and start flag signal must be transmitted independently from each other using two slip ring channels. Of course, there is a system that does not use a slip ring for the start flag, but in that case, in the XWACT system that uses a slip ring, two channels are required to use the slip ring. is expensive, and the transmission reliability due to the slip ring is greatly reduced. Of course, a method that does not use a slip ring to transmit the start flag signal is superior in that respect, but as mentioned above, it is necessary to provide a start flag mark and a detector to detect it on both the fixed part and the rotating part. Must be. Therefore, cost reduction cannot necessarily be expected.

Furthermore, there is a problem that it is difficult to synchronize the start timings between the two, and adjustments have to be made individually for each of the two, and there is also the problem that drift occurs due to the detector, which is not preferable.

[Purpose of the invention]

The present invention reduces the number of slip rings to one channel and converts the gradation pulse and start flag signal into one channel.
The purpose is to enable transmission using a channel slip ring, eliminate the start timing difference between the rotating part and the fixed part, and realize the synchronization ratio without adjustment.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides a synthesis circuit that synthesizes a gradual pulse signal and a start flag signal detected in either one of a fixed part and a rotating part to obtain one signal; a one-channel slip ring that transmits the output signal of the combining circuit from one of the fixed part and the rotating part to the other; A gradation pulse signal or a signal indicating its timing.

The present invention is characterized in that it includes at least a separation circuit that restores the original start flag signal or its timing signal.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an X-ray CT apparatus according to the present invention. In the figure, reference numeral 1 denotes a fixed part of the CT apparatus frame, and 2 denotes a rotating part that rotates on the fixed part 1. The rotating part 2 is provided with a gratacule mark and a start flag mark. Reference numeral 3 denotes a slip ring for transmitting signals from a differential driver 8 to the rotating section 2, which will be described later. , 4 is a detector provided on the fixed part 1, which detects both the gratecule mark and the start flag mark. Reference numeral 5 denotes a signal synthesis circuit which synthesizes the gratecule mark detection signal and the start flag mark detection signal from the detector 3 into one signal. The output signal of the signal synthesis circuit 5 is transmitted to the fixed part 1 via the signal separation circuit 6A on the one hand, and is transmitted to the differential of the rotating part 2 via the differential driver 7° slip ring 3 on the other hand. It is transmitted to receiver 8. The signal received by the differential receiver 8 is separated by the signal separation circuit 6A and then transmitted to the fixed part 1 for use.In the same way, the signal is separated by the signal separation circuit 6B in the rotating part 2C2. The reason why these are used separately is to match the start timings of both the fixed part 1 and the rotating part 2 as much as possible.

FIG. 2 is a block diagram showing the internal structure of the signal synthesis circuit 5, and FIG. 3 is a time chart for explaining the operation of the signal synthesis circuit 5.

The signal synthesis circuit 5 consists of a circuit 5a and a circuit 5b. The circuit 5a uses the input signals GRAT and 5TART as a system clock of 5CLK (for example, typically 50 to 100 nS).
The signal 5TART is extended by, for example, 2.5 periods of the signal GRAT, like 5STT. Incidentally, the signal GRAT input to the circuit 5a is obtained by reading the grateicule mark 10 formed on the mark forming body 9 shown in FIG. In a normal scan, T changes from 100 to about 800 μs, and a variation of about Ilo% occurs due to the rotation of the rotating unit 2 and the like. Further, the signal 5TART input to the circuit 5a is obtained by reading the start flag mark 11 formed on the mark forming body 9 using the detector 4C. The mark forming body 9 is made of glass or metal, and the gratacule mark 10 and the start flag mark 11 are formed by printing in the case of glass and etching in the case of metal. The start flag mark 11 is made thicker than the gratacule mark 10.

By the way, the signal 5S which is synchronously ratioed with one circuit 5a (:ta)
TT and 8GRT are combined in circuit 5b (:). Signal C8G is a signal obtained by circuit 5b.
In some cases, C8G' having a complex waveform including a component representing the period of the original GRAT signal may be obtained instead of C8G. Specifically, this signal C8G' is designed to rise in synchronization with each rising edge of the GRAT signal, based on the same concept as, for example, a cutting pulse of a synchronizing signal of television broadcasting.

FIG. 5 shows the signal separation circuit 6A (6B and 6A have the same configuration). The signal separation circuit 6A
are the sampling circuit 6a, the integration and comparator circuit 5
b, 5e and a flip 70 and a knob 6d. This can be said to be a digital version of the synchronization separation circuit in television receivers and the like. FIG. 6 shows this signal separation circuit 6A (
6B) is a time chart showing the operation of FIG.

The signal CGS to be separated is input to the sampling circuit 6a, and the clock is gated only while the signal CGS is @1'' to become UPC, and the clock is gated only while the signal CGS is @0'' to become DNC. The clock period of the two signals UPC and DNC obtained from this signal CGS is 50
It is ns to 100ns. Signal UPC is the product 1 of circuit 6b
It is input to the division circuit section and integrated there. Specifically, this integrating circuit section consists of a simple up counter that counts clock pulses, and the signal UITG is an integral waveform. The up counter is counted up by the signal UPC in this way, and the integrator circuit section (1 circuit 6C) (
It is reset by the output UCLR of the up counter that counts the DNC clock.

The integrating circuit section of the circuit 6C also consists of an up counter, and counts the clock of the signal DNC, and when the count value by the integrating circuit section reaches a predetermined threshold value Kd, the signal UCLR falls due to the action of the comparator section. It looks like this.

This UCLR is formed by a flip 70 tube and rises when the above signal UPC arrives (at the beginning of UPC). This signal UCLR resets the integrator circuit section 1 up counter of circuit 6b as described above.

Now, the comparator circuit section of the integration and comparator circuit 6b outputs the signal SSP when the output of the integration circuit section, that is, the signal UITG crosses the threshold value Ku. This signal S
SP is input to the flip 70 knob 6d and raises its output signal R8TART. Then, the signal R8TART raised by the signal SSP is brought down by the signal UCLR. In this way, the 5TART signal included in the signal CGS is separated as the R8TAR signal. Note that this signal R8TART is the original signal 5.
Although it is out of phase with TART, there is no problem because it is out of phase with the constant relationship determined by the threshold value Ku. That is, it is sufficient for a plurality of units to start their operations in response to the signal R8TART, and the operation start timing is the same as the original signal R8.
There is no need for it to match TART; the above signal R8TART, i.e. the start signal, is normally used to clear the grateicule counters and ensure that the values of the grateicule counters are all the same between the units involved. It is. Then, if you program in advance the values of the counter, such as opening the shutter, emitting X-rays, and resetting the DAS, the X-rays will be automatically activated.
Line diagnosis can be performed.

Note that the signal C8G is obtained by adding a cutting pulse to the signal C8G.
' is effective to give 7 rerun periods of the analog integrator of the DAS. That is, it is usually preferable that the DAS is always integrated in accordance with the period of the gratecule signal, and the period is also preferably within the normal range. Therefore, the signal C8G includes the period of the grateicule signal.
It creates SG'. The DAS normally controls the analog integrator at the rising edge of the gratecule signal (in this embodiment, it is the rising edge, but it may also be the falling edge), and the signal CS
For example, the rising edge of G' is used to control the integrator. Note that when the signal synthesis circuit 5 generates the signal C8G', the separation circuits 6A and 6B generate the signal C8G'.
The threshold value 1 is set so that it will operate correctly even if
(You just need to set d.

Note that there are usually a plurality of scan times, such as 28.48, and the period of the gradient signal changes accordingly. Therefore, it is necessary to have a means to change the threshold values Ku, This can be accomplished without any problems.

[Effects of the Invention] As described above, according to the present invention, one signal is created by synthesizing the two signals, the Gratique pulse signal and the start flag signal, and the one signal is passed through the slip ring. The signal is transmitted from one of the rotating part and the fixed part (e.g., the fixed part) to the other (e.g., the rotating part), and the gradation pulse signal and the start flag signal are separated from the combined signal in the other part. Therefore, only one slip ring is required. Therefore, it is possible to reduce costs, reduce maintenance, and improve reliability. and.

If you leave a spare channel of the slip ring that is no longer needed, you can expect an increase in the degree of freedom in responding to future design changes.

[Brief Description of the Drawings] The drawings are for explaining one embodiment of the present invention.
Figure 2 is a block diagram showing the outline of the device, Figure 2 is a block diagram showing the internal configuration of the signal synthesis circuit, Figure 3 is a time chart showing the operation of the signal synthesis circuit, Figure 4 is a plan view of the Grateicle, i@5 is a block diagram showing the internal configuration of the separation circuit, and FIG. 6 is a time chart showing the operation of the separation circuit. DESCRIPTION OF SYMBOLS 1... Fixed part, 2... Rotating part, 3... Slip ring, 4... Detector, 5... Signal synthesis circuit, 6... Signal separation circuit.

Claims (1)

[Claims] a synthesis circuit that combines a Gratique pulse signal and a start flag signal detected in either the fixed part or the rotating part to obtain one signal; a one-channel slip ring for transmitting from one side to the other; a signal received through the slip ring from the synthesis circuit and indicating the original gradient pulse signal or its timing; A CT device characterized by having at least a separation circuit for restoring the original start flag signal or its timing signal.