JPS581740B2 - Light-emitting drive device for blood leakage detectors, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light emitting drive device for a blood leakage detector or the like in an artificial kidney or the like.

Blood leakage detection in an artificial kidney requires rapid detection of a very small amount of leakage, about 0.001% diluted with a large amount of dialysate, and requires an extremely high degree of stability.

The main object of the present invention is to provide a light emitting drive unit for a blood leak detector or the like that can be put into use immediately after completion of preparatory work such as boiling water disinfection.

Another object of the invention is to provide a circuit arrangement that protects the light emitting diode from destruction despite the temperature increase of the measuring cell due to boiling water disinfection.

Still another object of the present invention is to provide a circuit configuration that visually indicates that preparation is in progress.

Still another object of the present invention is to provide a simple circuit configuration that achieves the above objects.

Therefore, the present invention provides a preparation state in which a smaller current is applied to the light emitting element than in the dialysis use state, and performs chemical disinfection, boiling water disinfection, and other preparatory work under this preparation state, and utilizes that time to conduct circuit equipment. The device is configured so that it can be used for dialysis immediately after the preparation work is completed.

Next, an embodiment in which the present invention is applied to a blood leak detector will be described.

FIG. 1 is a longitudinal sectional view of the optical device of this embodiment.

The measurement cell 1 is a cylindrical tube made of glass or the like, and a sample supplied from an inlet 2 flows through the measurement cell and flows out from an outlet 3.

A holder 4 made of an opaque material such as metal or rubber is fitted into the center of the measurement cell 1, and both ends of the holder 4 are sealed with O-ring packings 5 and 6.

Through holes are formed in the axially symmetrical positions of the measurement cell 1 of this holder 4, and a compound light emitting diode 7 with a condensing lens is attached to one of the holes, and a single photodiode 8 is attached to the other hole. A temperature compensating thermistor 9 is attached near the light emitting diode 1.

The light emitting diode 7 and thermistor 9 are shielded by a small box 10 and each lead wire is led out by a cable 11, and the photodiode 8 is shielded by a small box 12 and its lead wire is led out by a cable 13. .

Each of the above-mentioned parts constitutes the optical device 20.

The composite light emitting diode T has different wavelength characteristics, and
It consists of two types of electrically independent light emitting diodes.

The first light emitting diode D1 mainly emits green light having a wavelength of 520 nm to 600 nm, which is included in the absorption wavelength range of hemoglobin.

The second light emitting diode D2 mainly has a wavelength characteristic of 600 n, which is biased toward the longer wavelength side than that of the first light emitting diode.
It emits red light with a wavelength of m to 750 nm.

The photodiode 8 has wavelength characteristics that allow it to detect light emission from both the first light emitting diode and the second light emitting diode.

FIG. 2 is a diagram showing an embodiment of the electric circuit section of the present invention, in which the light emitting drive circuit section is particularly shown in a specific circuit diagram, and the other parts are shown in a block system diagram.

The reference signal generation circuit section 14 includes light emitting diodes D1 and D.
A circuit that generates the square wave signal A that defines the light emission time of No. 2, and is particularly stable and has excellent temperature characteristics and voltage characteristics.

The light emitting drive circuit section 15 drives the composite light emitting diode I according to the reference signal A, and the details will be described later, but in particular, the light intensity ratio between the first light emitting diode D1 and the second light emitting diode D2 is stable over a long period of time. are required to do so.

The AC amplification circuit section 16 receives the output signal B of the photodiode 8.
This is a circuit that amplifies only the alternating current component with high gain.

When there is no blood leakage in the measurement cell 1, the photodiode 8
Since the output signal B is a balanced electric signal due to two types of light generated by alternate light emission, no alternating current component appears.

When blood leakage occurs, absorption by hemoglobin becomes noticeable on the green light side, causing an imbalance in the electrical signals of the two types of light, and a square wave signal appears in the output signal B.

The phase detection circuit section 11 is a circuit for detecting the presence or absence of blood leakage and the amount of blood leakage without being affected by air bubbles, and uses the reference square wave signal A as a reference signal and detects the square wave output signal of the AC amplification circuit section 16. Detect the phase of C.

The output section 18 displays the phase detection output D or transmits it to the central processing unit.

Further, the alarm unit 19 issues a necessary alarm signal depending on the magnitude or duration of the blood leakage output signal.

The anode electrode of the first light emitting diode D1 has a resistor R1
The anode electrode of the second light emitting diode D2 is connected to the output line 22 via a resistor R2 and variable resistors VR1 and VR2.

Here, the variable resistor VR1 is for balancing the output signal B of the photodiode 8, and the variable resistor VR2 is for balancing the output signal B of the photodiode 8.
is for compensating for the difference in temperature characteristics between the two types of light emitting diodes through a parallel circuit with the thermistor 9, and resistors R1 and R2 are for determining the drive current of both light emitting diodes.

At both ends of the light emitting diodes DI and D2, the emitter and collector electrodes of the switching transistors TR1 and TR2 are maintained in the same direction as the corresponding light emitting diodes, respectively.
The square wave output signal A of the reference signal generation circuit section 14 is introduced into the base electrode B1 of the transistor TR1, and the base electrode B2 of the transistor TR2 is introduced into the base electrode B1 of the transistor TR1.
A complement signal of the square wave output signal A is introduced through an inverter circuit consisting of 3.

Therefore, when the transistor TRI is on and the transistor TR2 is off due to the square wave signal A, the terminal voltage of the first light emitting diode D1 is the threshold voltage, which is usually 0.6.
The second light emitting diode D2 does not emit light because the voltage is lower than about volts, and when the power supply voltage is applied to the terminal of the second light emitting diode D2, the second light emitting diode D2 emits light.

Next, the level of the square wave signal A is inverted and the transistor TR
When transistor TR2 is turned off and transistor TR2 is turned on, the first light emitting diode D1 emits light and the second light emitting diode D2 stops emitting light.

The power switch S uses a 3-circuit 3-contact switch.
The circuit includes a switch S1 of the power supply section 21 and a light emitting drive circuit section 1.
5, and switch S3 of the output section 18, and the three contacts switch between three states: "power off" (2), "preparation" (2), and "use" (2).

The power supply section supplies power in both the "preparation" and "use" states, and the output section displays blood leakage and alarm only in the "use" state.

In the light emitting drive circuit section, the monitor light emitting diode D
The first light emitting diode D1 only when D3 is in the "ready" state
is connected in parallel to form a shunt circuit.

For example, as a light emitting element, Sanyo Electric's Sanlumi Lamp S
When using the LP-751 composite light emitting diode and the silicon planar high-sensitivity light receiving diode OT22 manufactured by Oki Electric as the light receiving part, one way to balance the light intensity of green light and red light is to use the green light diode D1. A possible method is to set the drive current of the red light diode D2 to about 2 to 3 mA compared to the drive current of 20 mA, and increase the former by one order of magnitude.

In this case, a shunt circuit using the additional diode D3 is provided only on the D1 side where the driving current is large, and the shunt current of the additional diode D3 is selected to be, for example, about 15 mA, so that the current of the first diode D1 in the ready state is reduced to about 5 mA. By leaving the power switch in the ready state during boiling water disinfection, the light emitting diode will not be damaged during disinfection, and by immediately switching the switch to use after disinfection, it will be ready for stabilization. The blood leakage detector can be activated without any delay.

The value of the reduced drive current in the ready state is determined taking into account the characteristics of the light-emitting diode used, in particular the rated current of the diode at the temperature of the diode during scalding.

As other embodiments of the means for reducing the light emitting drive current of the present invention, two power output terminals corresponding to the use state and the ready state may be provided and configured to switch between them. For example, a resistive element may be inserted in series in the circuit from the power supply section output line to the light emitting element in the preparation state, or in parallel to this circuit in the use state.

Incidentally, it goes without saying that an operation switch for instructing the preparation state of the present invention is provided independently of the power switch.

As described above, according to the present invention, the measurement cell can be sterilized with boiling water without damaging the light emitting element, and dialysis treatment can be started immediately after the preparatory work such as boiling water sterilization is completed.

Also, if a light emitting diode is used as the shunt diode D3, the ready state will be displayed as is, but such a display can be done by using another circuit, for example, a fourth circuit for the pilot lamp in the power switch S. It goes without saying that you can also do things by making money.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an optical section of an embodiment of the present invention. FIG. 2 is a circuit diagram showing the electric circuit section of the embodiment of the present invention. 1...Measurement cell, 1...Composite light emitting element, S1, S2, S3...Operation switch circuit, Di, I)2...Light emission Diode, D3
・・・・・・Diode for shunting.

Claims (1)

[Scope of Claims] 1. In a device in which a light-emitting element is installed in close proximity to a translucent measurement cell that guides a sample such as a dialysate, an operation switch for setting the detection device in a ready state, and the preparation described above. A light emitting drive device, such as a blood leakage detector, comprising circuit means in which the current supplied to the light emitting element in a state is reduced compared to a state in which the device is in use. 2. In an apparatus having a translucent measurement cell for guiding a sample such as a dialysate, and first and second light emitting elements disposed in close proximity to each other so as to illuminate the inside of the measurement cell, the above-mentioned A shunt circuit consisting of an operation switch circuit and a series circuit of a resistor element for setting the detection device in a ready state is connected in parallel with the element with a larger driving current among the first and second light emitting elements, and the current state is set in the ready state. A light emitting drive device, such as a blood leakage detector, configured such that the drive current of the first or second light emitting element is reduced compared to the state of use.