KR101855658B1 - Trigger circuit of x-ray photographing device having trigger valid peroid - Google Patents

Abstract

The trigger circuit of the X-ray imaging apparatus in which the trigger valid time is set is posted. The trigger circuit of the X-ray photographing apparatus of the present invention generates an irradiation response signal having a voltage level corresponding to the received light, wherein the detection photodiode and the detection reset switch are used as a light ray sensing element, Wherein the detection reset switch changes the voltage level of the irradiation response signal in a second direction opposite to the first direction in response to activation of the detection reset signal, ; Wherein the final trigger signal is generated by generating a final trigger signal that is activated depending on the relationship of the voltage level of the irradiation response signal to the sense reference voltage, ; And a blocking signal generating block for generating the trigger blocking signal, wherein the trigger blocking signal has the blocking signal generating block activated by an elapse of a trigger effective time from activation of the sensing reset signal. The length of the trigger effective time depends on the ambient temperature. According to the trigger circuit of the X-ray imaging apparatus of the present invention, stability against temperature change is enhanced.

Description

(TRIGGER CIRCUIT OF X-RAY PHOTOGRAPHING DEVICE HAVING TRIGGER VALID PEROID)

The present invention relates to a trigger circuit of an X-ray imaging apparatus, and more particularly, to a trigger circuit of an X-ray imaging apparatus having a temperature change stability by setting a trigger effective time.

Typically, an x-ray imaging apparatus is composed of a light source for scanning an x-ray and a sensor for securing an image of the object from the scanned x-ray. At this time, it is important that the sensor is synchronized with the scanning of the X-ray from the light source to secure the image of the object. For this purpose, most x-ray imaging devices incorporate a trigger circuit that senses that the x-ray is scanned from the light source and generates the final trigger signal to be activated.

On the other hand, the trigger circuit of the X-ray photographing apparatus includes a light sensing element having a sensing photodiode and a sensing reset switch. That is, the X-ray to be scanned is converted into light by a scintillator, and the current flowing through the sensing photodiode toward the ground voltage increases with the intensity of the incident light. The trigger circuit senses that the amount of current flowing from the sensing photodiode to the ground voltage is increased by more than a certain amount, and activates the final trigger signal. At this time, the sense reset switch serves to supply current from the power source voltage to the sense photodiode of the light-sensing device in accordance with the activation of the sense reset signal.

However, the current flowing in the sensing grape diode increases as the ambient temperature rises. In this case, the trigger circuit of the X-ray imaging apparatus becomes unstable, and the final trigger signal can be activated even though the X-ray is not scanned.

Therefore, in the trigger circuit of the X-ray imaging apparatus, it is very important to have the stability of the temperature change by reducing the influence on the ambient temperature so that the final trigger signal is activated only when the X-ray is scanned.

An object of the present invention is to provide a trigger circuit of an X-ray imaging apparatus having a temperature validity by having a trigger effective time whose length is adjusted to reflect a change in ambient temperature.

In order to accomplish the above object, one aspect of the present invention relates to a trigger circuit of an X-ray imaging apparatus. A trigger circuit of an X-ray photographing apparatus according to an embodiment of the present invention generates an irradiation response signal having a voltage level according to a received light, wherein the detection photodiode and the detection reset switch are used as a light ray sensing element, Wherein the detection reset switch changes the voltage level of the irradiation response signal in a second direction opposite to the first direction in response to activation of the detection reset signal, Light sensing element; A sensing comparison block for generating a final trigger signal which is activated depending on the relationship of the voltage level of the survey response signal to the sensing reference voltage; And a blocking signal generating block for generating a trigger blocking signal. The final trigger signal is activated by activation of the trigger shutoff signal and the trigger shutoff signal is activated by the passage of a trigger valid time that is dependent on the ambient temperature from activation of the sense reset signal.

In the trigger circuit of the X-ray photographing apparatus of the present invention having the above-described structure, the trigger effective time is set in consideration of the phenomenon that the current flowing through the sensing photodiode of the light-sensing device varies with the change in the ambient temperature. As a result, according to the trigger circuit of the X-ray imaging apparatus of the present invention, stability against temperature change is enhanced.

A brief description of each drawing used in the present invention is provided.
1 is a block diagram schematically showing a trigger circuit of an X-ray imaging apparatus according to an embodiment of the present invention.
Fig. 2 is a timing chart for explaining the operation of the main signal of the trigger circuit of the X-ray imaging apparatus of Fig.
FIG. 3 is a view showing in detail the blocking signal generating block of FIG. 1; FIG.
4 is a diagram for explaining that the length of the trigger effective time depends on the ambient temperature in the trigger circuit of the X-ray imaging apparatus of FIG.

For a better understanding of the present invention and its operational advantages, and the objects attained by the practice of the present invention, reference should be made to the accompanying drawings, which illustrate preferred embodiments of the invention, and the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are being provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

It should be noted that, in understanding each of the drawings, the same members are denoted by the same reference numerals whenever possible. Further, detailed descriptions of known functions and configurations that may be unnecessarily obscured by the gist of the present invention are omitted.

Also, a plurality of expressions for each component may be omitted. For example, a plurality of switches or a plurality of signal lines may be expressed as 'switches', 'signal lines', or may be expressed in a single number, such as 'switch' or 'signal line'. This is because the switches operate in complementary manner and sometimes operate independently. In the case where the signal lines are formed of a plurality of signal lines, for example, data signals having the same property, It is also because there is no need to divide into plural. In this respect, such description is reasonable. Accordingly, similar expressions should be construed in the same sense throughout the specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing a trigger circuit of an X-ray imaging apparatus according to an embodiment of the present invention. Referring to FIG. 1, the trigger circuit of the present invention includes a light sensing element 110, a sensing comparison block 120, and a blocking signal generating block 130.

The light-sensing element 110 receives the received light LGT and generates an irradiation response signal XRSD. At this time, the voltage level of the irradiation response signal XRSP depends on the property of the received light (LGT) such as intensity.

The light sensing element 110 includes a sensing photodiode 111 and a sensing reset switch 113. The sensing photodiode 111 generates a positive diode current Ipd corresponding to the received light LGT. Accordingly, the voltage level of the irradiation response signal XRSD changes in the first direction (in this embodiment, from the power source voltage VDD side to the ground voltage VSS side). As a result, the voltage level of the irradiation response signal XRSD has a voltage level corresponding to the amount of the diode current Ipd flowing through the sensing photodiode 111. [ That is, the voltage level of the irradiation response signal XRSD corresponds to the intensity of the received light LGT.

At this time, the amount of current flowing in the sensing photodiode 111 of the light-sensing device 110 is increased as the ambient temperature rises.

The reference light LGT is incident on the sensing photodiode 111 of the light sensing element 110 through a scintillator X-ray (not shown) scanned from a light source (not shown) ).

The sensing reset switch 113 responds to the activation of the sensing reset signal XRTS by driving the voltage level of the sensing response signal XRSD in a second direction opposite to the first sensing direction VSS) to the power supply voltage VDD.

The detection comparing block 120 compares the voltage level of the irradiation response signal XRSD with the sensing reference voltage VRFS to generate a final trigger signal XTRGF.

In the present embodiment, during the trigger effective time (T_VA, see FIG. 2) during which the trigger cutoff signal XPTB provided in the blocking signal generation block 130 is deactivated to "H ", the final trigger signal XTRGF And becomes "H" when the voltage level of the irradiation response signal XRSD becomes lower than the detection reference voltage VRFS.

However, when the trigger interception signal XPTB is activated to "L ", the activation of the final trigger signal XTRGF is suppressed.

The sensing comparison block 120 specifically includes a sensing comparison unit 121 and a logic unit 123. [

The sensing and comparing unit 121 compares the voltage level of the inspection response signal XRSD with the sensing reference voltage VRFS to generate a preliminary trigger signal XTRGP. In the present embodiment, the preliminary trigger signal XTRGP is activated to "H" when the voltage level of the irradiation response signal XRSD is lower than the detection reference voltage VRFS.

At this time, the sensing reference voltage VRFS is set to an appropriate level in consideration of the configuration of the sensing reset switch 113 and the activation level of the sensing reset signal XRTS.

For reference, the sense reference capacitor CPS of FIG. 1 serves to store the charge of the probe response signal XRSD and is intentionally or unintentionally generated.

The logic unit 123 logic-operates the preliminary trigger signal XTRGP and the trigger interception signal XPTB to generate the final trigger signal XTRGF.

At this time, the final trigger signal XTRGF has an activation state according to the activation state of the preliminary trigger signal XTRGP during the trigger valid time T_VA (see FIG. 2). Then, activation of the final trigger signal XTRGF is suppressed by the trigger interception signal XPTB.

On the other hand, when the preliminary trigger signal XTRGP is directly used as a trigger for driving the sensor of the X-ray imaging apparatus, the X-ray imaging apparatus may malfunction.

For example, if the ambient temperature rises and the amount of current flowing through the sensing photodiode 111 increases, malfunction may occur. That is, the voltage level of the irradiation response signal XRSD is not limited to the detection reference voltage VRFS in the region PON where the light LGT exists, but also in the region POFF where the light LGT is not present. (See t11) is generated.

Thus, the preliminary trigger signal XTRGP is activated (t13, see Fig. 2) to "H" despite the absence of the received light LGT.

In order to solve the possibility of such a malfunction, the trigger circuit of the present invention is configured such that, in the state (t15, see Fig. 2) in which the trigger shutoff signal XPTB is activated to "L" , And the activation of the final trigger signal XTRGF is suppressed (t17, see Fig. 2).

At this time, the length of time during which the trigger shutoff signal XPTB maintains the inactivated state from the activation of the sense reset signal XRTS, that is, the length of the trigger effective time T_VA depends on the ambient temperature.

Thus, according to the trigger circuit of the present invention, the possibility of malfunction that may occur when the preliminary trigger signal XTRGP is used as a trigger for driving the sensor of the X-ray imaging apparatus is solved.

The blocking signal generating block 130 generates the trigger blocking signal XPTB. At this time, the trigger cutoff signal XPTB is activated by the elapse of the trigger effective time T_VA from the activation of the sense reset signal XRTS.

Preferably, the blocking signal generating block 130 includes a dark photodiode 131. The dark photodiode 131 has a shielding film on its surface and generates a dark reference current Idar. That is, preferably, the dark photodiode 131 generates the dark reference current Idar in a state in which the light is blocked due to the blocking film written on the surface. In other words, the dark reference current Idar corresponds to the current generated by the dark photodiode 131 itself.

The length of the trigger effective time (T_VA) depends on the amount of the dark reference current (Idar) of the dark photodiode (131).

For reference, the dark reference current Idar of the dark photodiode 131 tends to increase as the ambient temperature rises.

Next, the blocking signal generation block 130 of FIG. 1 will be described in more detail.

3 is a diagram specifically illustrating an example of the blocking signal generating block 130 of FIG. Referring to FIG. 3, the blocking signal generating block 130 includes the dark photodiode 131, the dark reset switch 133, and the dark comparing unit 135.

The dark photodiode 131 generates the dark reference current Idar which is positive depending on the ambient temperature as described above. According to the dark reference current Idar, the voltage level of the dark response signal XPRD changes in the first direction (in this embodiment, from the power supply voltage VDD side to the ground voltage VSS). As a result, the voltage level of the dark response signal XPRD has a voltage level corresponding to the amount of the dark reference current Idar flowing in the dark photodiode 131. [ That is, the voltage level of the dark response signal XPRD corresponds to the ambient temperature.

At this time, the dark reference current Idar of the dark photodiode 131 increases with the increase of the ambient temperature and decreases with the decrease of the ambient temperature.

The dark reset switch 133 outputs a voltage level of the dark response signal XPRD in a second direction opposite to the first direction in response to the activation of the dark reset signal XRTD VSS) to the power supply voltage VDD.

The dark comparison unit 135 compares the voltage level of the dark response signal XPRD with the dark reference voltage VRFD to generate a dark spare signal XPRD. In the present embodiment, the dark spare signal XPRD is activated to "H" when the voltage level of the dark response signal XPRD is lower than the dark reference voltage VRFD.

The dark reference voltage VRFD is set to an appropriate level in consideration of the configuration of the dark reset switch 133 and the activation level of the dark reset signal XRTD.

With the blocking signal generation block 130 having such a configuration, the dark spare signal XPRD is activated at a constant cycle. At this time, the period of the dark spare signal XPRD depends on the magnitude of the dark reference current Idar of the dark photodiode 131, that is, the ambient temperature. Again, the period of the dark spare signal (XPRD) is shortened when the ambient temperature rises.

For reference, the dark reference capacitor CPD of FIG. 3 serves to store the charge of the dark response signal XPRD and is intentionally or unintentionally generated.

In this embodiment, the activation of the dark reset signal XRTD is dependent on the activation of the dark preliminary signal XPRD. The length of the trigger effective time T_VA depends on the activation period of the dark spare signal XPRD.

Preferably, the blocking signal generating block 130 further includes a delay unit 136.

The delay unit 136 delays the dark spare signal XPRD to generate the dark reset signal XRTD.

Also, preferably, the blocking signal generating block 130 further comprises a counter 137.

The counter 137 generates the trigger interception signal XPTB which is activated by counting the dark spare signal XPRD (the falling end in this embodiment) from the activation of the sensing reset signal XRTS. Accordingly, as the activation period of the dark spare signal XPRD elapses from the activation of the sense reset signal XRTS to a certain number (in this embodiment, 5), the trigger shutoff signal XPTB Activated.

As a result, the length of the trigger effective time T_VA depends on the activation period of the dark spare signal XPRD, that is, the ambient temperature.

For example, when the ambient temperature is relatively low (CASE1, see FIG. 4), the period of the dark spare signal XPRD is relatively long. In this case, the period of the sensing reset signal XRTS is shorter than five times the activation period of the dark spare signal XPRD. As a result, in case of CASE1, the trigger cutoff signal XPTB maintains the inactive state of "H ", and the activation to the" L "

On the other hand, when the ambient temperature rises (CASE2, see Fig. 4), the period of the dark spare signal XPRD is shortened. In this case, the period of the sensing reset signal XRTS is longer than five times the activation period of the dark spare signal XPRD. As a result, in the case of CASE2, the trigger shutoff signal XPTB is set to "L" at the time t21 when the activation period of the dark spare signal XPRD has elapsed five times from the activation of the sense reset signal XRTS Activated. Accordingly, after the trigger effective time T_VA has elapsed, the trigger cut-off period T_PT is generated. Thereafter, the trigger cutoff signal XPTB is deactivated again in response to the activation (t22) of the sense reset signal XRTS in the next cycle.

In summary, in the trigger circuit of the X-ray imaging apparatus of the present invention, it can be seen that the setting of the trigger effective time (T_VA) and the adjustment of the length depend on the ambient temperature.

3, the blocking signal generating block 130 further includes a latch 138. The blocking signal generating block 130 includes a latch 138,

The latch 138 latches the dark spare signal XPRD and provides it as an input to the counter 137. By the latch 138, activation of the dark spare signal XPRD can be stably counted.

Also, preferably, the blocking signal generating block 130 further comprises a current source 139.

The current source 139 sourcing the current of the dark response signal XRDS. By the current source 139, the reflection of the ambient temperature to the length of the trigger effective time T_VA can be smoothly corrected.

In summary, in the trigger circuit of the X-ray imaging apparatus of the present invention, in consideration of the phenomenon that the current flowing in the detection photodiode 111 of the light-sensing element 110 changes in accordance with the change in ambient temperature, the trigger effective time T_VA ) Is adjusted. As a result, according to the trigger circuit of the X-ray imaging apparatus of the present invention, stability against temperature change is enhanced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (8)

In the trigger circuit of the X-ray imaging apparatus,
A light sensing element having a sensing photodiode and a sensing reset switch, the sensing photodiode generating a sensing signal having a voltage level according to the received light, the sensing photodiode having a voltage level of the sensing response signal in a first direction Wherein the detection reset switch changes the voltage level of the irradiation response signal in a second direction opposite to the first direction in response to activation of a detection reset signal;
A sensing comparison block for generating a final trigger signal which is activated depending on the relationship of the voltage level of the survey response signal to the sensing reference voltage; And
And a blocking signal generating block for generating a trigger blocking signal,
The final trigger signal
Activation is suppressed by activation of the trigger interception signal,
Wherein the trigger shut-off signal is activated upon elapse of a trigger effective time that is dependent on ambient temperature from activation of the sense reset signal.
2. The method of claim 1,
A detection comparing unit which generates a preliminary trigger signal which is activated depending on a relation of a voltage level of the irradiation response signal to the detection reference voltage; And
And a logic unit which is driven to generate the final trigger signal having an activation state according to an activation state of the spare trigger signal during the trigger valid time and to inhibit activation of the final trigger signal by activation of the trigger interception signal And the trigger circuit of the X-ray imaging apparatus.
2. The apparatus of claim 1, wherein the blocking signal generating block
And a dark photodiode having a shielding film on its surface to generate a dark reference current,
The trigger effective time is
Wherein the second reference current is dependent on the magnitude of the dark reference current.
4. The apparatus of claim 3, wherein the blocking signal generation block
The dark photodiode generating the dark reference current to change the voltage level of the dark response signal in the first direction;
A dark reset switch for changing a voltage level of the dark response signal in the second direction in response to a dark reset signal; And
And a dark comparison unit for generating a dark spare signal which is activated depending on the relationship of the voltage level of the dark response signal to the dark reference voltage,
The activation of the dark reset signal
Dependent on activation of the dark spare signal,
The trigger effective time is
And the activation period of the dark preliminary signal.
5. The apparatus of claim 4, wherein the blocking signal generation block
And a delay unit for delaying the dark spare signal to generate the dark reset signal.
5. The apparatus of claim 4, wherein the blocking signal generation block
Further comprising a counter for counting the dark spare signal from the activation of the detection reset signal to activate the trigger cutoff signal.
7. The apparatus of claim 6, wherein the blocking signal generation block
Further comprising a latch for latching the dark spare signal and providing it as an input to the counter.
5. The apparatus of claim 4, wherein the blocking signal generation block
Further comprising a current source for sourcing the current of the dark response signal.

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