Peristaltic pump with rotary encoder

• US 5,279,556 A
• Filed: 05/07/1992
• Issued: 01/18/1994
• Est. Priority Date: 04/28/1989
• Status: Expired due to Term

• Current Assignee: Baxter International Inc., Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Baxter International Inc., Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Goi, Nobuaki, Matthews, Joseph B., Bowman, George A.
• Primary Examiner(s): Hirsch, Paul J.
• Application Number:
  US07/879,357
• Time in Patent Office: 621 Days
• Field of Search: 604/65, 604/67, 128/DIG. 12, 128/DIG. 13, 417/18
• US Class Current: 604/67
• CPC Class Codes: A61M 2205/33 Controlling, regulating or measuring
• CPC Class Codes: A61M 5/14212 Pumping with an aspiration and an expulsion action
• CPC Class Codes: G01D 5/36 Forming the light into pulses
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

A rotary encoder comprises a rotary plate having a plurality of primary slits defined in the rotary plate in a circular row coaxial with the axis of rotation of the rotary plate. The rotary plate also has at least one reference slit defined therein at a position radially of the circular row of the primary slits. A primary photoelectric detector including a source of light and a photo-sensor positioned one above the other with the circular row of the primary slits intervening therebetween is used to detect the passage of the primary slits therethrough while an auxiliary photoelectric detector including a source of light and a photo-sensor positioned one above the other with the path of travel of the reference slit intervening therebetween is used to detect the passage of the reference slit therethrough.

Claims

1. A parenteral solution infusion pump comprising:

a peristaltic pump infusing a flow of fluid along a piping from a source of fluid to a destination;

a rotary encoder for controlling said pump said rotary encoder including,

(a) a rotary plate having a plurality of primary slits defined therein in a circular row coaxial with an axis of rotation of the rotary plate, said rotary plate also having at least one reference slit defined therein at a position radially of the circular row of the primary slits;

(b) a primary detector aligned with the circular row of the primary slits detecting the presence of one of said primary slits as the rotary plate rotates; and

(c) an auxiliary detector physically separate from said primary detector positioned along the path of travel of the reference slit detecting the reference slit as the rotary plate rotates;

(d) drive means for controlling the speed of the peristaltic pump and thereby rotational speed of said rotary plate;

(e) memory means for storing a plurality of parameters indicating the total number of primary slits for a given time during one revolution of said rotary disc corresponding to a particular pump speed;

(f) a counter for counting the total number of primary slits detected by said primary detector, said counter initiating counting upon detection of said reference slit by said auxiliary detector;

(g) comparator means for comparing the total number of primary slits with a selected one of said parameters stored in said memory means and for causing the drive means to increase the speed of the peristaltic pump if the total number of primary slits counted is less than the corresponding parameter, thereby maintaining a constant fluid flow within the piping.

2. A parenteral solution infusion system comprising:

peristaltic means including a stack of finger members adapted to be sequentially driven to operatively engage a piping to sequentially squeeze said piping while producing at least one moving zone of occlusion along said piping for infusing a fluid from a source of fluid towards a destination;

drive means for driving said peristaltic means to sequentially drive the finger members;

a rotary encoder electrically coupled with the drive means and including;

(a) a rotary plate having a plurality of primary slits defined therein in a circular row coaxial with an axis of rotation of the rotary plate, said rotary plate also having at least one reference slit defined therein at a position radially of the circular row of the primary slits and coinciding with the timing at which one of the finger members positioned on a most upstream side with respect to the direction of flow of the fluid from the fluid source is driven to squeeze the piping;

(b) a primary photoelectric detector including a primary source of light and a primary photo-sensor positioned one above the other with the circular row of the primary slits intervening therebetween, said primary photoelectric detector generating a primary signal each time any one of the primary slits traverses an optical path between the primary light source and the primary photo-sensor; and

(c) an auxiliary photoelectric detector physically separate from said primary photoelectric detector and including an auxiliary source of light and an auxiliary photo-sensor positioned one above the other with the path of travel of the reference slit intervening therebetween, said auxiliary photoelectric detector generating an auxiliary signal indicative of a passage of the reference slit across an optical path between the auxiliary light source and the auxiliary photo-sensor; and

control means for applying one of at least two drive control signals to said drive means and including;

(a) a first storage means storing a first parameter representative of the number of primary slits which would be counted during a period subsequent to the timing at which said one of the slits squeezes the piping and prior to the timing at which a first predetermined one of the remaining finger members squeezes the piping;

(b) a counting means for counting, and generating a count signal indicative of, the number of the primary signals generated from the primary photoelectric detector subsequent to a detection of the passage of the reference slit by said auxiliary photoelectric detector; and

(c) a first comparing means for comparing the count signal with the first parameter, said first comparing means causing the control means to generate said one of the drive control signals, in the event that said count signal coincides with the first parameter, thereby to accelerate said drive means for a predetermined length of time.

3. The parenteral solution infusion system as claimed in claim 2, wherein said control means further includes;

(d) a second storage means storing a second parameter representative of the number of primary slits which would be counted during a period subsequent to the timing at which said one of the slits squeezes the piping and prior to the timing at which a second predetermined one of the remaining finger members squeezes the piping, said second predetermined one of the remaining finger members being positioned downstream of said first predetermined finger member with respect to the direction of flow of the fluid; and

(d) a second comparing means for comparing the count signal with the second parameter, said second comparing means causing the control means to generate the other of the drive control signals, in the event that said count signal coincides with the second parameter, thereby to cause said drive means to assume an initial speed.