EP0292130B1 - Toner concentration detection - Google Patents

Toner concentration detection Download PDF

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Publication number
EP0292130B1
EP0292130B1 EP88303863A EP88303863A EP0292130B1 EP 0292130 B1 EP0292130 B1 EP 0292130B1 EP 88303863 A EP88303863 A EP 88303863A EP 88303863 A EP88303863 A EP 88303863A EP 0292130 B1 EP0292130 B1 EP 0292130B1
Authority
EP
European Patent Office
Prior art keywords
toner concentration
diode
voltage
circuit
differential transformer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88303863A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0292130A3 (en
EP0292130A2 (en
Inventor
Shiro Nakagawa
Taisuke Domon
Takehiro Imai
Eiji Takahashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TDK Corp
Original Assignee
TDK Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TDK Corp filed Critical TDK Corp
Publication of EP0292130A2 publication Critical patent/EP0292130A2/en
Publication of EP0292130A3 publication Critical patent/EP0292130A3/en
Application granted granted Critical
Publication of EP0292130B1 publication Critical patent/EP0292130B1/en
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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/0822—Arrangements for preparing, mixing, supplying or dispensing developer
    • G03G15/0848—Arrangements for testing or measuring developer properties or quality, e.g. charge, size, flowability
    • G03G15/0849—Detection or control means for the developer concentration
    • G03G15/0853—Detection or control means for the developer concentration the concentration being measured by magnetic means

Definitions

  • the present invention relates to means for detecting toner concentration in a two component type developer for an electrostatic copying machine or other apparatus which is designed to produce copies in accordance with the principle of the electrostatic photography. More particularly, the present invention relates to toner concentration detecting means of a type which contain a differential transformer.
  • a so-called two component type developer for developing a latent image includes a carrier in the form of particles of a magnetic material and colour toner powder. To maintain the quality of the copies to be produced, it is required to maintain the concentration of the toner in the developer within a desired range.
  • US-A-4,592,645 proposes a toner concentration controlling apparatus which uses a differential transformer. According to this proposal the differential transformer has a primary winding and a pair of secondary windings which are wound in opposite senses around a core. The primary winding and one of the secondary windings provide a detection transformer which is arranged to be placed adjacent to the developer in the developer container and produce a detection signal representing the toner concentration in the developer.
  • the primary winding and the other of the secondary windings form a reference transformer which is arranged to provide a reference signal.
  • the detection and reference transformers have outputs which are connected with a phase detection circuit which is arranged to detect the difference in the phase of the outputs of the detection and reference transformers.
  • a similar toner concentration detection device is also disclosed in JP-A-60-154275.
  • a toner concentration detecting means includes differential transformer means including primary coil means and secondary coil means for producing a differential output representing the concentration of a toner in a developer, variable capacitance means connected between the primary coil means and the secondary coil means, and drive means for applying an oscillating signal to the differential transformer means, characterised in that the variable capacitance means comprises a variable capacitance diode and capacitor means connected between the primary coil means and the secondary coil means in series with the diode and in that the detecting means also includes means for applying a voltage to the diode and mean for changing the voltage applied to the diode.
  • An advantage of the present invention is that the adjustment of the coupling coefficient can be readily made without any adverse effect.
  • the means for adjusting the coupling coefficient are compact and reliable and have a high heat resistance. Also the means for adjusting the coupling coefficient of the differential transformer can be located at a readily accessible place without any problem of high frequency noise.
  • the capacitance of the diode means is controlled through an adjustment of the voltage applied to the diode so that the coupling coefficient is adjusted.
  • the phase of the voltage applied from the primary coil means to the secondary coil means being changed due to the adjustment because the voltage is changed through the adjustment of the capacitance of the diode.
  • no problem will be produced such as the setting drift as experienced in the case of using a ceramic variable capacitor. It is therefore possible to carry out a precise and accurate adjustment.
  • the means for applying the voltage to the diode can be constituted as a DC circuit so that it can be made separate from the high frequency circuit having the variable capacitance diode. Therefore, it is possible to locate the voltage adjusting means at any place which is readily accessible.
  • FIG. 4 is a circuit diagram showing an example of such arrangement.
  • the conventional toner concentration detecting device shown therein includes a differential transformer 1 including a primary winding 101, a reference secondary winding 102 and a detection secondary winding 103.
  • the primary winding 101 has opposite ends which are connected with capacitors C1 and C2.
  • the primary winding 101 is connected with a driving circuit 2 which constitutes an oscillating circuit together with the primary winding 101 and the capacitors C1 and C2.
  • the reference secondary winding 102 has one end which is grounded. The other end of the reference secondary winding 102 is connected with one end of the detecting secondary winding 103.
  • the other end of the detecting secondary winding 103 is connected with a processing circuit 3 which may be a phase detection circuit of a conventional type.
  • the driving circuit 2 is also connected with the processing circuit 3 to provide the processing circuit 3 with a reference signal.
  • the secondary windings 102 and 103 are wound around a core 104 in an opposite polarity so that a differential output E0 is produced on the detection secondary winding 103.
  • the processing circuit 3 functions to compare the phase of the differential output E0 with the phase of the reference signal supplied from the driving circuit 102 to produce an output signal corresponding to the phase difference.
  • the ends of the secondary windings 102 and 103 which are connected together are also connected with one end of the primary winding 101 through a variable capacitor V c so that the secondary windings 102 and 103 are applied with a voltage which is determined by the capacitance of the capacitor V c .
  • V c the capacitance of the variable capacitor V c
  • a ceramic variable capacitor is preferable in that it is compact and has a high heat resistant property.
  • it has an inherent disadvantage of a setting drift wherein the capacitance of the capacitor changes after a certain time period due to a change in the thickness of the silicon oil film which is provided between the rotor and the stator of the capacitor. Therefore, it is difficult to carry out an accurate adjustment with the use of the ceramic variable capacitor.
  • Other types of capacitors are not preferable because they are generally bulky and do not have satisfactory heat resistance.
  • a further problem in using a variable capacitor is that when it is desired to locate the variable capacitor in a readily accessible position it is required to provide an extension of a high frequency wiring. Such a high frequency wiring can cause noises which may lead to an unreliable operation of the detecting device. Therefore, it is difficult to locate the variable capacitor in a readily accessible place.
  • a toner concentration detecting device which includes a differential transformer 1 having a primary coil 101, a reference secondary coil 102 and a detecting secondary coil 103.
  • capacitors C1 and C2 are connected between the opposite ends of the primary coil 101.
  • a driving circuit 2 and a phase detecting circuit 3 are provided and connected with the differential transformer 1 as in the conventional system shown in Figure 4.
  • the detecting coil 3 is located adjacent to a developer 4 containing a toner.
  • the developer 4 is contained in a developer container which is not shown but may be constituted as shown in Figure 1a or 1b of the U.S. patent 4,592,645.
  • the toner concentration detecting device comprising the differential transformer 1, the driving circuit 2 and the phase detecting circuit 3 may be positioned as shown in the above U.S. patent.
  • a variable capacitance diode V CD and a capacitor C c are connected in series between the primary coil 101 and the secondary coil 102 of the differential transformer 1.
  • a variable voltage applying circuit 5 which includes a variable resistor V R connected at one end with a DC voltage source V cc . The other end of the variable resistor V R is grounded.
  • a slider S of the variable resistor V R is connected through a resistor R1 between the diode V CD and the capacitor C c .
  • the DC voltage is thus applied through the variable resistor V CD and the resistor R1 to determine the capacitance of the diode V CD . It is therefore possible to determine the voltage applied from the primary coil 101 to the secondary coil 102.
  • the differential transformer 1 comprises a pair of primary coils 101a and 101b which are connected in an opposite polarity.
  • the transformer 1 further includes a secondary coil 102 which is connected with the phase detecting circuit 3. Between one ends of the primary coils 101a and 101b, there are connected capacitors C1 and C2.
  • the arrangements are the same as those in the previous embodiment. Therefore, further descriptions will be omitted by showing corresponding parts by the same reference numerals as in Figure 1.
  • the driving circuit 2 is in the form of an oscillating circuit constituted by the aforementioned capacitors C1 and C2, an exclusive OR circuit 21 and a resistor R2.
  • the output of the oscillating circuit is connected with the primary coil 101 of the differential transformer 1 to drive the transformer 1.
  • the oscillating circuit has an output connected with a phase detecting circuit 32 which constitute a part of the processing circuit 3.
  • the phase detecting circuit 32 may be constituted by an exclusive OR circuit.
  • the processing circuit 3 includes an amplifier 31 provided with a negative feedback resistor R3 and connected through a capacitor C4 with the detecting coil 103 of the differential transformer 1.
  • a capcitor C3 is further connected between the detecting coil 103 and the capacitor C4.
  • the phase detecting circuit 32 has an output resistor R4 and a smoothing capacitor C5.
  • the phase of the output of the differential transformer 1 is a function of the toner concentration in the developer so that the toner concentration can be detected by detecting the change in the phase of the output of the differential transformer 1 by the phase detecting circuit 32.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
EP88303863A 1987-05-19 1988-04-28 Toner concentration detection Expired - Lifetime EP0292130B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP74869/87 1987-05-19
JP1987074869U JPH0633484Y2 (ja) 1987-05-19 1987-05-19 トナ−濃度検出装置

Publications (3)

Publication Number Publication Date
EP0292130A2 EP0292130A2 (en) 1988-11-23
EP0292130A3 EP0292130A3 (en) 1989-06-14
EP0292130B1 true EP0292130B1 (en) 1992-12-30

Family

ID=13559768

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88303863A Expired - Lifetime EP0292130B1 (en) 1987-05-19 1988-04-28 Toner concentration detection

Country Status (3)

Country Link
EP (1) EP0292130B1 (US07655688-20100202-C00086.png)
JP (1) JPH0633484Y2 (US07655688-20100202-C00086.png)
DE (1) DE3877054T2 (US07655688-20100202-C00086.png)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5648514A (en) * 1994-12-29 1997-07-15 Allergan Substituted acetylenes having retinoid-like biological activity
JP5721365B2 (ja) * 2010-08-23 2015-05-20 キヤノン株式会社 磁性体粉濃度検知装置及びこの検知装置を用いた画像形成装置

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56120045A (en) * 1980-02-16 1981-09-21 Nippon Air Brake Co Detector
JPS5813013A (ja) * 1981-07-17 1983-01-25 Nippon Technical Co Ltd 同調回路
JPS5836018A (ja) * 1981-08-27 1983-03-02 Mitsubishi Electric Corp Ｆｍ受信機
WO1984002202A1 (en) * 1982-11-29 1984-06-07 Hitachi Metals Ltd Apparatus for controlling toner concentration in developer
JPS59141817A (ja) * 1983-02-03 1984-08-14 Nippon Technical Co Ltd 同調器
JPS60154275A (ja) * 1984-01-24 1985-08-13 Hitachi Metals Ltd トナ−センサ−
JPS61149859A (ja) * 1984-12-24 1986-07-08 Tdk Corp 磁気的検知装置
JPS61149858A (ja) * 1984-12-24 1986-07-08 Tdk Corp 磁気的検知装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 9, no. 329 (P-416)(2052), 24 décembre 1985 ; & JP-A-60154275 (HITACHI KINZOKU), 13.08.85 *

Also Published As

Publication number Publication date
JPH0633484Y2 (ja) 1994-08-31
JPS63187160U (US07655688-20100202-C00086.png) 1988-11-30
DE3877054D1 (de) 1993-02-11
EP0292130A3 (en) 1989-06-14
DE3877054T2 (de) 1993-04-29
EP0292130A2 (en) 1988-11-23

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