JPH0659310B2 - Infusion amount detection device in infusion device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an infusion amount detection device in an infusion device used in the medical field and the like.

[Conventional technology]

In the infusion device used in the medical field, etc., as a method of measuring the infusion amount of the liquid to be injected into the human body, conventionally, the method of counting the number of drip of the infusion set or the mechanical displacement applied to the tube is used. The method of counting the number of times is used. In this method of counting the number of infusions, a nurse or the like generally counts them visually. Also,
In the method of counting the number of mechanical displacements described above, the number of peristaltic movements of the finger in the peristaltic movement mechanism, the rotation number of the roller in the drive mechanism by the roller, etc. are detected, and the infusion volume is mechanically measured. There is.

Furthermore, in JP-A-59-166816, a droplet is regarded as a sphere, by calculating the volume of the droplet in accordance with V = 4πr ^3/3 have been disclosed.

[Problems to be Solved by the Invention]

The above-mentioned conventional technique has the following problems.

That is, in the method based on the number of drip described above, the first
In some cases, the infusion set used to determine the set value of the infusion device does not exactly correspond to the infusion set actually used, and this mismatch causes an error in the infusion volume. Secondly, the difference in the size of the liquid droplet due to the difference in the viscosity of the liquid causes an error in the infusion volume. Third
In addition, the difference in the size of the liquid drop due to the variation in the thickness of the drip needle of the infusion set or the variation in the thickness of the infusion tube causes an error in the infusion volume. Fourth, an error in the infusion volume occurs due to fluctuations in the blood pressure of the patient, detachment of the injection needle, and the like. Fifthly, an error in the infusion amount occurs due to the restoring force of the infusion tube being attenuated or changed due to long-term use or use environment temperature.

In addition, in the method of counting the number of mechanical displacements described above, a dedicated infusion tube is attached to the infusion device, but it is difficult to maintain a large number of infusion tubes in a homogeneous state for a long period of time. Even with a dedicated infusion tube, there is currently an error in the infusion volume of about ± 10%.

In this type of infusion device, the amount of infusion per hour is usually set, but it is desirable to set it in minutes or seconds depending on the type of drug solution.

An object of the present invention is to use an inexpensive infusion set, to adjust the viscosity of the liquid, variations in the thickness of the infusion tube and the thickness of the drip needle, attenuation of the restoring force of the infusion tube due to long-term use, patient It is an object of the present invention to provide a transfusion amount detection device in a transfusion device capable of accurately detecting a transfusion amount without being affected by fluctuations in blood pressure, detachment of an injection needle, and the like.

[Means for Solving the Problems]

The infusion amount detection device according to the present invention for achieving the above-mentioned object is an infusion device configured to supply a droplet to be dropped from a drip needle to a predetermined supply point. The droplet sensor unit that receives the irradiation light changed by the above and outputs an electrical signal corresponding to this irradiation light, and the peak value of the output signal of this droplet sensor unit is detected and the peak detection signal corresponding to this peak value. a peak detecting means for outputting v _i , a time width detecting means for detecting a waveform width of the output signal of the droplet sensor unit and outputting a time width detecting signal v _w corresponding to the waveform width, and a half of the sine curve Volume of a rotating body obtained by rotating a wave component (however, its wave height is the peak detection signal v _{i and} its waveform width is the time width detection signal v _w ) around the reference line of this sine curve. The real To the above expression, the peak detection signal v
_i and each detection value of the time width detection signal v _w are substantially substituted, and the calculation means for calculating the volume V of the droplet is provided.

〔Example〕

An embodiment of the infusion device according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing a liquid drop sensor unit (optical system) of the infusion amount detecting device in the above infusion device, FIG. 1 (a) showing its front view, and FIG. 1 (b) showing its plane. The figure is shown.

1 is a drip tube of an infusion set. Infusion bottle 10 (4th
The liquid flowing out of the drawing) reaches the drip tube 1 through the infusion tube 3, and becomes a droplet 4 from the lower end of the drip needle 2 protruding inside the drip tube 1 toward the lower part of the drip tube 1. Drop it. The liquid accumulated in the lower part of the drip tube 1 is supplied to the patient side through the infusion tube 5.

On the other hand, the light emitting unit 6 irradiates the droplet 4 to be dropped with the irradiation light 7 from a direction substantially perpendicular to the dropping direction. As the irradiation light 7, a vertical cross section in a direction substantially orthogonal to the traveling direction is a line shape or a slit shape, and as a whole, a strip shape substantially orthogonal to the dropping direction (that is, extending substantially horizontally). It is possible to use a laser beam having a thickness of 1 mm and a width of 10 mm. The band-shaped irradiation light 7 passes through the drip tube 1 and is received by the light receiving unit 9 as passing light 8. The light receiving unit 9 has a slit-shaped window and receives the band-shaped passing light 8. Then, the light receiving unit 9 supplies an electric signal corresponding to the received transmitted light 8 to the amplification unit 12 (see FIG. 4).

The electric signal supplied to the amplification unit 12 changes as the droplet 4 crosses the strip-shaped irradiation light 7 that extends substantially horizontally. This is because the irradiation light 7 is temporarily shielded by the droplet 4 in the drip tube 1. In addition, in FIG. 1B, the irradiation light 7 in the drip tube 1 is indicated by a broken line arrow in order to show a light shielding state.

FIG. 2 is a curve diagram showing a light attenuation (blocking) amount L of the passing light 8 caused by being blocked by the droplet 4. In FIG. 2, the vertical axis represents the light attenuation amount L of the irradiation light 7, and the horizontal axis represents the time t. As can be seen from FIG. 2, when the lower end of the droplet 4 reaches the time point t ₁ by the belt-shaped irradiation light 7 made of laser light and extending substantially horizontally, the light attenuation amount L increases. Then, the light attenuation amount L changes by substantially drawing a half-wave waveform of the sine curve, and when the upper end of the droplet 4 passes at the time point t ₂ , the attenuation amount L returns to the same level as at the time point t ₁ . In this case, the peak value R of the sine waveform corresponds to the maximum size of the bulging portion of the droplet 4.

Incidentally, t _w in FIG. 2 shows the time difference between time t ₂ and time t _1.

Here, a method of calculating the volume of the droplet in the droplet sensor unit shown in FIG.

According to the experiments conducted by the present inventors, the actual outer shape of the droplet 4 is almost the same as the light attenuation amount shown in FIG. That is, the third
As shown in the figure, when the actual bulge of the outer shape from the vertical center line of the droplet 4 is plotted, a half-wave waveform of the sine curve is almost drawn. In FIG. 3, the vertical axis represents the value of the waveform function f (x), and the horizontal axis represents the position x in the vertical direction.

Therefore, the general formula for calculating the volume of the liquid droplets is that the curve shown in FIG.
As the volume of the rotating body obtained by rotating π,
You can ask. In the text, the “reference line of the sine curve” means a straight line connecting points where the crest value (that is, amplitude) is zero in the sine curve (that is, a center line along the waveform width direction of this sine curve). )
Say. That is, the starting point of the waveform function f (x) in FIG.
_If the end point of f (x) is x _2, and the minute value from a certain value x on the horizontal axis is dx, the volume V is expressed by the following equation.

Since the waveform function f (x) draws a sine waveform, it can be expressed by the following equation.

Here, k is a constant determined by the measurement system (that is, various states of the infusion device).

Further, the dropping speed (droplet speed) v of the droplet 4 is equal to the drip needle 2
At the lower end position of v, v = 0. When the distance from the lower end position of the drip needle 2 to the irradiation position of the irradiation light 7 (light attenuation amount detection point by laser) is h, the droplet velocity v at the detection point is It is represented by. Here, g is the gravitational acceleration.

Now, when the general formula (1) for obtaining the droplet volume is applied to the optical attenuation amount L shown in FIG. 2, the time t _w (= t ₂ −t ₁ ) of the output waveform of the light receiving unit 9 and an arbitrary time t And a small time dt, and also above equations (2), (3) and x = v
By substituting t, the volume V is expressed by the following equation.

In the above formula (4), π and g are constants, and h
Since and k are constants determined by the measurement system, the volume of the droplet V
Is obtained by detecting the peak value R of the light attenuation amount L and the time t _w . Then, the peak value R is obtained by processing the output signal of the light receiving unit 9 by an electronic circuit,
It can be easily obtained as the voltage v _i . Therefore,
R in the equation (4) can be replaced with v _i . Also,
Time t _w can be by a counter (timer) which stops at the start and the time t ₂ at time t _1, it can be readily and electrical signals (data).

Next, an infusion device to which the infusion amount detecting method according to the formula (4) is applied will be described.

FIG. 4 is a block diagram showing the configuration of the whole infusion device in one embodiment of the present invention. In FIG.
The same parts as those in FIG. 1 are designated by the same reference numerals.

In FIG. 4, the infusion set includes an infusion bolt 10 for containing the liquid 11, an infusion tube 3 connected to the infusion bottle 10, an infusion tube 1 having an infusion needle 2 connected to the infusion tube 3, and an infusion tube. 5, 5 '(in practice these tubes 5 and 5'may consist of one tube as a whole). The infusion tube 5'is connected to the patient side. Also,
The light emitting unit 6 and the light receiving unit 9 constitute a drip sensor unit as described with reference to FIG. The light emitting unit 6 is driven by the arithmetic control unit 16 and emits the band-shaped irradiation light 7. The light receiving unit 9 supplies an electric signal corresponding to the received transmitted light 8 to the amplifier 12.

The amplifier 12 amplifies the electric signal supplied from the light receiving unit 9 and outputs an output signal having a voltage proportional to the optical attenuation amount L as shown in FIG. 2 to the voltage peak detection unit 13 and the voltage waveform width detection unit 18. And supply to. The voltage gain of the amplifier 12 is adjusted by the gain signal supplied from the arithmetic control unit 16. The reason why the voltage gain is adjusted in this way is that, when the drip tube 1 becomes cloudy due to the temperature, the irradiation light 7 attenuates entirely and reaches the light receiving portion 9, so that the overall attenuation of this light quantity is compensated. Is.

The voltage peak detection unit 13 may include a peak hold circuit and a clock generation circuit that generates a clock when the peak hold circuit holds the peak value. Then, the voltage peak detection unit 13 supplies the peak voltage v _i (voltage corresponding to R in FIG. 2) of the output signal of the amplifier 12 to the analog-digital (A / D) conversion unit 14 and latches the clock 15 To the signal line (the signal line is not shown).

The A / D conversion unit 14 converts the peak voltage v _i supplied from the voltage peak detection unit 13 into a digital signal and supplies the digital signal to the latch 15. The latch 15 includes the voltage peak detector 13
The output signal of the A / D conversion unit 14 is latched according to the clock supplied from. Then, the latch 15 supplies the arithmetic control unit 16 with a digital signal corresponding to the peak voltage v _i .

On the other hand, the voltage waveform width detection unit 18 includes a comparator, a counter that counts a predetermined pulse supplied from the pulse oscillator 17 according to the output of the comparator, and a clock and an interrupt signal when the count of the counter is completed. It may be composed of a digital circuit or the like for sequentially generating and. Then, when the output voltage from the amplifying unit 12 becomes zero or more at the time point t ₁ in FIG. 2, the voltage waveform width detecting unit 18 starts counting the pulses supplied from the pulse oscillator 17. When the output signal from the amplifier 12 returns to zero at time t ₂ , counting is stopped and the count value (value corresponding to t _w in FIG. 2) and the clock are supplied to the latch 19.

The latch 19 latches the count value (time width detection signal v _w ) supplied from the voltage waveform width detection unit 18 by the clock similarly supplied. And the latch 19
Supplies the latched count value to the arithmetic control unit 16. After that, the voltage waveform width detection unit 18 supplies the interrupt signal to the arithmetic control unit 16. When the operation control unit 16 is supplied with the interrupt signal from the voltage waveform width detection unit 18, the calculation control unit 16 receives the latch 15
The data v _i corresponding to R in the equation (4) is read from, and the data v _w corresponding to t _w in the equation (4) is read from the latch 19. After that, the arithmetic control unit 16 resets the voltage peak detection unit 13, the latch 15, the voltage waveform width detection unit 18, and the latch 19 almost at the same time (the signal line is not shown).

The arithmetic control unit 16 may be composed of a microcomputer or the like, and receives the data v _i , v obtained from the latches 15, 19.
The volume V of the droplet 4 is calculated by calculating _w based on the equation (4).
To calculate. Then, the infusion flow rate per unit time is calculated from the sum of the volumes V of the droplets 4 per unit time, and the infusion integration amount is calculated from the time from the start of the infusion. Also,
The calculation control unit 16 compares the calculated value of the infusion rate with the set value of the infusion rate supplied from the infusion rate setting unit 20 (a value relating to the reference value of the volume of the droplet 4 and the period of the droplet). Further, the calculated value of the infusion solution integrated amount is compared with the set value of the infusion solution integrated amount supplied from the infusion solution integrated amount setting unit 21.

If no abnormality is found in the comparison results, the arithmetic control unit 16 supplies the speed control signal set to a predetermined value based on the calculated value to the motor drive control unit 25. The motor drive control unit 25 controls the infusion drive unit 26 based on the supplied speed control signal. Infusion drive unit 2
Reference numeral 6 denotes a peristaltic movement mechanism in this embodiment, which is composed of a motor (not shown) and three or more fingers (not shown) that perform a peristaltic movement as a whole by the motor. These fingers selectively clamp the infusion tube portion between the infusion tubes 5 and 5 '(in fact, these tubes 5 and 5'may consist of one tube as a whole). It is configured to sequentially move the clamping position.

In other words, the motor drive control unit 25 controls the motor of the infusion drive unit 26 to control the infusion flow rate. Then, the volume of the droplet 4 changes according to the operating state of the infusion drive unit 26. Therefore, closed-loop control is achieved in the infusion control system in this infusion device, so that accurate control of the infusion volume can be realized.

Next, a case where an abnormality is recognized in the above comparison result in the arithmetic control unit 16 will be described. The case where an abnormality is recognized means that the calculated value of the volume V is zero even though the droplet 4 is generated, or that the droplet is inevitably determined according to the calculated value of the volume V. Period (This droplet period is
This may be the case where the calculation cycle is calculated by the calculation control unit 16 based on the set value supplied from the infusion flow rate setting unit 20) and the actually detected dropping period of the droplet 4 is significantly different.

When such an abnormality is recognized, the arithmetic control unit 16
Supplies a signal indicating the occurrence of an abnormality to the liquid proper cycle abnormality alarm unit 27. The droplet cycle abnormality alarm unit 27 turns on a lamp (not shown) and sounds a buzzer (not shown) by this signal to generate an alarm sound. Also,
A stop signal, which is a part of the signal supplied to the droplet cycle abnormality alarm unit 27, is supplied to the motor drive control unit 25. When this stop signal is supplied, the motor drive control unit 25 stops the motor of the infusion drive unit 26. Therefore, the fingers of the infusion drive unit 26 stop the peristaltic movement, and the infusion ends.

The infusion start switch 22 is a switch that supplies a signal instructing the start of infusion to the arithmetic control unit 16. When the infusion start switch 22 is turned on,
The arithmetic control unit 16 supplies the speed control signal to the motor drive control unit 25 with a set value of zero or more. The infusion stop switch 23 is a switch that supplies a signal for instructing the infusion stop to the arithmetic and control unit 16. When the infusion stop switch 23 is turned on, the arithmetic control unit 16
Supplies the motor drive control unit 25 with the speed control signal set to zero (substantially the same signal as the stop signal).

In addition, the infusion flow rate / integrated amount display unit 24 is provided in the calculation control unit 16
Display the actual infusion flow rate and infusion infusion data supplied from. This actual infusion flow rate is represented by the sum of the volumes V of the droplets 4 dropped per unit time. Further, the actual infusion volume is represented by the sum total of the volumes V of the dropped droplets 4 from the start of infusion.

Next, the outline of the operation of the infusion device shown in FIG. 4 will be described based on FIG.

FIG. 5 is a general flow chart showing the operation of the infusion device. In FIG. 5, when the infusion device of FIG. 4 is powered on, the arithmetic control unit 16 is operated in step S1.
Performs initialization (initialization setting). By this initialization, the arithmetic control unit 16 drives the light emitting unit 6. For this reason, the light emitting section 6 is provided with a band-shaped irradiation light (laser light)
Emits light. Further, the arithmetic control unit 16 sets the speed control signal to zero and supplies it to the motor drive control unit 25 to maintain the infusion stop state and reset the infusion flow rate / integrated amount display unit 24 and the like.

Next, in step S2, the arithmetic and control unit 16 reads the set value of the infusion flow rate set in the infusion solution flow rate setting unit 20 and the set value of the infusion solution integration amount set in the infusion solution integration setting unit 21. Then, the arithmetic control unit 16 enters a standby state waiting for an ON signal from the infusion start switch 22.

Next, in step S3, when the infusion start switch 22 is turned on and the ON signal is supplied to the arithmetic control unit 16, the arithmetic control unit 16 sets the speed control signal to a predetermined value and sets the motor drive control unit. Supply to 25. Therefore, the motor drive control unit 25 drives the motor of the infusion drive unit 26,
By driving the motor, the finger starts the peristaltic movement, so that the infusion is performed.

Next, since the light emitting unit 6 emits the irradiation light 7 when the power is turned on (at the time of initialization), the light receiving unit 9 generates a signal according to the dropping of the droplet 4 in step S4. That is, droplet detection is performed. Then, since the output signal of the light receiving section 9 is supplied to the amplifying section 12, the digital signal (corresponding to R in FIG. 2) corresponding to the peak voltage v _i is calculated from the latch 15 as described above in step S5. In addition to being supplied to the control unit 16, the count value (corresponding to t _w in FIG. 2) corresponding to the time width detection signal v _w is supplied from the latch 19 to the arithmetic control unit 16. That is, the voltage waveform width of the output voltage of the amplifier 12 and the peak voltage are detected.

Next, in step S6, the arithmetic control unit 16 calculates the volume V of the droplet 4 based on the equation (4), and calculates the total sum of the volume V per unit time to obtain the actual infusion flow rate. Is calculated, and the volume V of the droplet 4 from the time when the infusion is started is calculated to calculate the actual infusion integrated amount. Then, in step S7, the calculated actual infusion flow rate and its set value are compared, and
The calculated actual infusion volume and the set value are compared.

Next, in step S8, the arithmetic control unit 16 determines an abnormality in the droplet cycle based on the comparison result in step S7. Then, if there is no abnormality, the process proceeds to step S9, and if there is an abnormality, the process proceeds to step S12. In step S <b> 9, the actual infusion flow rate and infusion infusion amount data calculated in step S <b> 6 is supplied from the arithmetic control unit 16 to the infusion flow rate / integration amount display unit 24. As a result, the infusion flow rate / integrated amount display unit 24 displays the infusion flow rate and the infusion calculation amount.

Next, in step S10, the arithmetic control unit 16 supplies to the motor drive control unit 25 a speed control signal whose value is set based on the calculated infusion volume and infusion volume.
The motor drive control unit 25 drives and controls the infusion drive unit 26.

Next, in step S11, the arithmetic and control unit 16 determines the signal supplied from the infusion stop switch 23. If the signal of the infusion stop switch 23 is in the off state,
Returning to step S4, a series of processes is repeated again. If the signal of the infusion stop switch 24 is in the ON state,
The arithmetic control unit 16 supplies the speed control signal with the value set to zero to the motor drive control unit 25, and after the infusion is stopped, the process returns to step S2.

On the other hand, if an abnormality is determined in step S8, the process proceeds to step S12 as described above. And
In step S12, the arithmetic control unit 16 supplies the droplet cycle abnormality alarm unit 27 with a signal indicating that an abnormality has occurred.
Therefore, the droplet cycle abnormality alarm unit 27 turns on the lamp and sounds the buzzer to generate an alarm sound. Then, in step S13, the stop signal is supplied to the motor drive controller 25. As a result, the motor drive control unit 25 stops the motor of the infusion drive unit 26, so that the infusion is stopped. After the processing of step S13, the process proceeds to the next process routine, but the description thereof will be omitted.

Next, the characteristics of the droplet volume of one droplet brought about by the infusion control system of the above infusion device will be described with reference to FIG.

In FIG. 6, the horizontal axis represents the infusion flow rate [ml / h], and the vertical axis represents the volume of one droplet [ml]. A high-viscosity liquid is used as the infusion liquid, and the infusion set is a commonly used one for 15 drops (a liquid drop set configured to have about 15 drops per minute). The dashed line in the figure shows the actual measurement data (true value), the solid line shows the calculated value of the volume of the droplet 4 by the formula (4), and the broken line shows the conventional example in which the volume of the droplet 4 is calculated as spherical (the above-mentioned example). Japanese Patent Laid-Open No. 59-1668
No. 16) shows the calculated value.

As can be seen from FIG. 6, when the volume V of the droplet 4 is calculated based on the above equation (4), the actual measurement data is obtained more than when the volume is calculated by regarding the droplet 4 as a spherical shape. near.

Further, the characteristic of the difference between the measured value (data) and the calculated value of the droplet volume, which is brought about by the infusion control system of the above infusion device, will be described with reference to FIG.

In FIG. 7, the horizontal axis represents the flow rate [ml / h] of the infusion solution, and the vertical axis represents the difference [ml] between the measured value and the calculated value of the droplet volume per droplet. Then, physiological saline is used as the infusion solution, and the infusion set is for the same 15 drops as that used in the case of FIG. The solid line in the figure shows the case of the volume value of the droplet 4 according to the formula (4), and the broken line shows the case of the calculated value of the conventional example in which the volume of the droplet 4 is calculated as a spherical shape.

As can be seen from FIG. 7, when the volume of the droplet 4 is calculated based on the equation (4), the difference from the actual measurement data is smaller.

In the above-described embodiment, the light emitting unit 6 emits the laser light as the irradiation light 7, but if a band-shaped light beam is similarly obtained, it does not matter if it is not the laser light. In addition, in order to obtain a band-shaped light beam, the light emitting unit 6 is provided through a plurality of optical fibers whose emission ends are arranged in a line.
It is also possible to guide the irradiation light 7 from the drip tube 1 to the drip tube 1.

Further, in the above-described embodiment, the light receiving unit 9 has a slit-shaped window, but instead of having such a slit-shaped window, a line-shaped optical sensor (line sensor) can be used to receive light. .

Further, in the above-described embodiment, the infusion drive unit 26 is composed of a peristaltic movement mechanism, but it may be a drive mechanism of a roller, or a clamp mechanism simply composed of a plunger and an ampule (bulging portion). It may be. Further, the installation location of the infusion drive unit 26 is in the rear position of the drip tube 1 (between the drip tube 1 and the patient), but in front of the drip tube 1 (between the infusion bottle 10 and the drip tube 1). Infusion drive unit 26
Can also be installed.

〔The invention's effect〕

According to the present invention described in detail above, an inexpensive infusion set can be used, the viscosity of the liquid, the variation in the thickness of the infusion tube and the thickness of the drip needle, the restoration of the infusion tube by long-term use. It is possible to accurately detect the infusion volume without being affected by the attenuation of force, the fluctuation of blood pressure of the patient, the detachment of the injection needle, and the like.

[Brief description of drawings]

The drawings show an embodiment of an infusion device according to the present invention, and FIGS. 1 (a) and 1 (b) are schematic views of a droplet sensor section of an infusion amount detection device used in the above infusion device. 2 is a curve diagram showing the optical attenuation of the passing light in the droplet sensor unit in FIG. 1, and FIG. 3 is a diagram showing the droplets in the droplet sensor unit in FIG. Fig. 4 is a curve diagram showing the actual outline, and Fig. 4 is a block diagram of the whole infusion device.
FIG. 5 is a general flow chart showing the operation of the infusion device of FIG. 4, FIG. 6 is a curve diagram showing measured and calculated values of the volume of one droplet, and FIG. 7 is a droplet per droplet. It is a curve figure which shows the difference of the measured value of volume, and a calculated value. In the reference numerals used in the drawings, 1 ... Drip tube 2 ... Drip needle 4 ... Droplet 6 ... Light emitting part 7 ... Irradiating light 8 ... Passing light 9 ... Light receiving part 13 ... Voltage peak detection Section (peak detection means) 16 ... arithmetic control section (calculation means) 18 ... voltage waveform width detection section (time width detection means) 26 ... infusion drive section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Terumi Matsubara 2-2-1, Dojo, Urawa-shi, Saitama Atom Co., Ltd. Urawa factory (72) Inventor Kazuo Matsubara 3--18-15 Hongo, Bunkyo-ku, Tokyo Atom Co., Ltd.

Claims (3)

[Claims] 1. An infusion device adapted to supply a liquid drop dripping from a drip needle to a predetermined supply location, and receives irradiation light irradiated to the liquid drop and changed by the existence of the liquid drop, and irradiating the irradiation light. the droplet sensor section that outputs an electric signal corresponding to the light, a peak detection means for detecting a peak value of the output signal of the droplet sensor section outputs a peak detection signal v _i corresponding to this peak value, the Time width detection means for detecting the waveform width of the output signal of the droplet sensor unit and outputting the time width detection signal v _w corresponding to this waveform width, and a half wave portion of the sine curve (however, the wave height is detected as the peak above. Signal v _{i and} its waveform width as the time width detection signal v _w ) is rotated about the reference line of this sine curve to substantially express the volume of the rotating body, and the peak detection is added to the expression. signal _{v i} By substantially substituting the detected values of the time width detection signal v _w and, infusion amount detection apparatus characterized by comprising a calculating means for calculating the volume V of the droplet, respectively. 2. An equation that substantially represents the volume of a rotating body is (Where, k is a constant determined by the state of the infusion device, g is gravitational acceleration, and h is the distance from the lower end of the drip needle to the light attenuation amount detection point of the liquid drop). Infusion volume detection device. 3. An infusion device is provided with an infusion driving means for controlling a dropping state of a droplet dropped from a drip needle, and a computing means has a driving state of the infusion driving means according to a computation result of a volume V of the droplet. The infusion volume detection device according to claim 1 or 2, which controls the infusion rate.