APPARATUS FOR MEASURING CONCENTRATION RATIOS OF A MIXTURE OF MATERIALS

• US 3,802,381 A
• Filed: 05/05/1971
• Issued: 04/09/1974
• Est. Priority Date: 07/30/1968
• Status: Expired due to Term

• Current Assignee: John B. Kennedy Jr, Roger M O'Neill
• Original Assignee: John B. Kennedy Jr, Roger M O'Neill
• Inventors: Kennedy, John B. Jr., O'Neill, Roger M.
• Primary Examiner(s): Stein, Mervin
• Assistant Examiner(s): Millstein, Leo
• Application Number:
  US05/140,573
• Time in Patent Office: 1,070 Days
• Field of Search: 118/7,9,637 324/34,61
• US Class Current: 399/30
• CPC Class Codes: G01R 27/02 Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant by measuring phase angle only G01R25/00
• CPC Class Codes: G03G 15/0851 the concentration being measured by electrical means
• CPC Class Codes: G03G 15/0853 the concentration being measured by magnetic means

Abstract

An apparatus for measuring the ratio of carrier particles to toner particles in an electrostatic printing operation is disclosed herein. The apparatus includes the employment of the electrical properties dependent upon the ratio of carrier to toner particles in a carrier-toner mix to determine the suitability of that ration for an electrostatic printing operation. Variations in magnetic permeability, dielectric permittivity, electrical conductivity or combinations of these three parameters are employed to indicate variations in the ratio of carrier to toner. An electric or magnetic field is established in the area of a quantity of mix and a measurement of one or more of the aforementioned parameters is employed to indicate the need for a greater or lesser percentage of toner or carrier in the mix. Apparatus for indicating the carrier-toner ratio includes provisions for establishing an electric or magnetic field in a quantity of mix and provisions for providing an output signal representative of one or more of the aforementioned parameters exhibited by the quantity of mix. A trough located in the path of movement of mix within an electrostatic printing device provides a build-up of mix in which the aforementioned fields may be established.

Claims

1. An electrostatic printing or coating device employing a developer mix of dry carrier particles having first electrical properties and smaller dry toner particles having second electrical properties differing from said first electrical properties, said toner particles adhering to said carrier particles by triboelectric forces, comprising means for transporting a portion of said mix from a depository into the application area;

means for applying toner particles from said mix in said application area to a substrate;

means for moving mix, including unused toner particles, from said application area along a return path toward said depository;

means disposed along said return path for facilitating the addition of toner particles to said mix to compensate for the toner particles applied to said substrate;

a collection trough disposed in the path of said mix moving along said return path, said collection trough being spaced from said application area and comprising means for accommodating a generally constant volume of said mix while said mix moves along said return path, means for establishing a field within said volume of said mix within said trough;

means responsive to variations in said field resultant from variations in at least one of the properties of dielectric permittivity, electrical conductivity and magnetic permeability caused by changes in the ratio of carrier and smaller toner particles which adhere thereto to indicate the reduction of toner particles in said mix through application thereof to said substrate and to indicate the need for additional toner to said mix.

2. An electrostatic printing or coating device according to claim 1 including means responsive to an output from said means responsive to variations in said field for controlling said means for facilitating the addition of toner particles to said mix prior to introducing said mix into the printing or coating zone.

3. An electrostatic printing or coating device according to claim 1 wherein said means for establishing a field is a magnetic means for establishing a magnetic field.

4. An electrostatic printing or coating device according to claim 1 wherein said means for establishing a field is a means for establishing an electrical field, and said means responsive to variations in said field are responsive to variations in dielectric permittivity.

5. An electrostatic printing or coating device according to claim 1 wherein said means for establishing a field is a means for establishing an electrical field including a current path, and said means responsive to variations in said field are responsive to variations in electrical conductivity.