Device for a portable automatic syringe

The disclosure relates to a safety device for a portable automatic syringe. On injection for a diabetic this new device can not only prolong the injection time, but also timely and favorably control the injection amount. Furthermore it is so compact that a patient can carry along in safety. In other words, it is an insulin automatic syringe developed in a particular way, especially for use by a diabetic. Generally speaking, if a patient employs this device, he is in a position to easily manage himself and assure injection of the insulin injection which is prescribed. This device is provided with fixed number switches as a safety feature to prevent excess injection. At the same time, the device is also provided with a control unit which protects against repetitive injection even if he inadvertently performs a repetitive injection.

An automatic syringe published as a laying-open application for utility 
model series No. 52-3292 in Japan has been introduced into the world. 
However, this device is of the so-called analogue type which can only 
allow intermittently adjusting the required amount of injection by means 
of manually operating the variable resistor. 
The analogue type automatic syringe has inherent disadvantages in allowing 
neither accurate injections as needed nor automatic adjustments of 
injection amount. The new device of the present invention has two 
oscillators, one of which is for timers and the other is for counter units 
that work regularly or intermittently to adjust the most favorable amount 
of injection by means of digitally setting them in advance. Therefore, 
this can be called a type of portable automatic-syringe device. 
Since this device is used for injections to cure a disease of the human 
body and requires high accuracy and safety in terms of medicine, it is 
provided with fixed number switches for safety, control units against 
repetitive injection, and an excess-injection preventitive unit.

Referring to FIG. 2, oscillator (1) connects to timer (2) and the output of 
digital comparator (3) connects to the timer (2), counter (6) and 
flip-flop (9). Another oscillator (5) connects to the counter (6), AND 
gate (10)(11) and counter (13). The output of digital comparator (14) 
resets the flip-flop (9) and the output of the digital comparator (14) 
resets the flip-flop (16). A control unit against repetitive injection 
(17) is provided between manual infusion switch (12) and the counter (13). 
The output of the control unit (17) connects to the counters (13) and (21) 
and the flip-flop (16). The output of digital comparator (22) connects to 
a step motor driver (19) to stop step motor (20). The output of the 
flip-flop (16) is an input to the AND gate (11) which connects to OR gate 
(18). 
The step motor driver (19) is used for driving the step motor (20). 
Each of the fixed number switches (4), (8), (15) and (25) has five 
protruding insert bars and adaptors as indicated in FIG. 3. 
As best seen in FIG. 5, several holes (26) are made through the gear plate. 
A gear shaft (27) is fitted on the gear plate. And the piston plate is 
movably fitted in the gear shaft (27), the most part of which is screwed. 
A innovative combination of a light source (24) and a photo sensor (23) is 
attached to the lower and upper parts of a fixture as shown in FIG. 5. 
The overall assembly is shown in FIG. 1, wherein the following symbols are 
used: "G" for gear, "M" for motor, "I" for syringe and "N" for injection 
needle. 
The following explanation will make more understandable the functions and 
the effectiveness of the operation process with the new device of this 
invention. 
Referring again to FIG. 2, the digital comparator (3) compares the output 
of the timer (2) with the value of the fixed number switch (4) in which 
the prescribed period of time has been set in advance on the basis of the 
physical condition of a patient. The timer (2) counts pulses from the 
system oscillator (1) e.g. progressing by sixties at every second. When 
the output of the timer (2) and the value of the fixed number switch (4) 
coincide, one pulse comes out of the digital comparator (3) for resetting 
the timer (2) and setting the flip-flop (9). 
The counter (6) counts pulses from the oscillator (5) which has been 
designed for oscillating slower than the oscillator (1) on the decimal 
system. The digital comparator (7) compares the output of the counter (6) 
with the value of the fixed number switch (8) in which the prescribed 
amount of injections has been set in advance on the basis of the physical 
condition of the patient. When the output of the counter (6) and the value 
of the fixed number switch (8) coincide, one pulse comes out of the 
digital comparator (7) for resetting both counter (6) and flip-flop (9). 
If the flip-flop (9) sets, the AND gate (10) enables the pulse signals from 
the oscillator (5) to pass through to the OR gate (18) and if the 
flip-flop (9) resets, the AND gate (10) disables thepulse signals from 
passing through the OR gate (18). 
The combined circuit of the counter (13), the digital comparator (14) and 
the fixed number switch (15) is connected similarly to the above mentioned 
combination of the counter (6), digital comparator (7) and the fixed 
number switch (8). However, in this case the amount of injections preset 
by the fixed number switch (15) is normally greater than the amount set by 
the fixed number switch (8) to give more insulin injections at special 
times, for instance, meal time. In this connection, when a patient pushes 
the manual infusion switch (12), the counter (13) resets and the flip-flop 
(16) sets, so that the step motor starts through the OR gate (18) and the 
AND gate (11) which receives the pulse signals from the oscillator (5). 
Explaining the control unit against repetitive injection, (see FIG. 4), an 
AND gate (28), a flip-flop (29) and a timer (30) are added between the 
manual infusion switch (12) and the above mentioned systems such as (11) 
(12) (13) (14) (15) (16), which is referred to herein as the increased 
amount injection system. When a patient pushes the manual infusion switch 
(12), the AND gate (18) immediately sets the flip-flop (29) and resets the 
timer (30) at the same time. 
The flip-flop (29) is only allowed to reset after a prescribed period of 
time which is counted by the timer (30) so that repetitive-injections are 
prevented even if the manual infusion switch (12) is untimely pushed by 
the patient's mistake in the interval during the prescribed period of 
time. 
A step motor (20) is connected with the transmission gears, one of which is 
a cog gear mounted on a screw gear shaft of the syringe (I). When this cog 
gear shaft is driven by the step motor (20), the piston plate led along 
with the screw pushes the piston downward to dispense the prescribed 
amount of injection to the human body. The fixed number switches (4), (8), 
(15) and (25) are different from existing thumb wheel switches, which are 
rotary types. Ech of the fixed number switches has five protruding insert 
bars (a) (b) (c) (d) (e) and adaptors (a') (b') (c') (d') (e') as 
mentioned. These five protruding insert bars are internally connected to 
form various combinations of connections. The female adaptors are 
installed into the case of the automatic syringe. Accordingly, since the 
fixed number switches cannot be easily disassembled and changed, it can be 
seen that the prescribed amount of injection can be assuredly give to the 
patient. 
The photo sensor (23) is aimed to receive intermittent beams of light from 
source (24) which come through the several holes (26) on the gear plate. 
When the number of pulses counted by the counter (21) through this photo 
sensor (23) is greater than the value of fixed number switch (25), a 
signal comes out of the digital comparator (22) to interrupt the step 
motor driver (19) with an alarm. Accordingly, excess injection can be 
safely prevented by the above configuration.