EP0414504A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Densitometer for measuring developability
Assignee: Xerox Corp
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Filing: 1990-08-21
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Granted: —
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Expires: 2010-08-21
Abstract
Abstract An infrared densitometer which measures the reflectivity of a selected region on a moving photoconductive belt (10) covered at least partially with marking particles. Collimated light rays are projected onto the selected region of the moving photoconductive member with or without marking particles thereon. The light rays reflected from the selected region of the moving photoconductive member are collected and directed onto a photodiode array (106). The photodiode array generates electrical signals proportional to the diffuse component of the total reflectivity of the selected region of the photoconductive member with and without marking particles thereon. Circuitry determines a control signal as a function of the difference in electrical signals.
Inventors
- 👤 Michael D. Borton
- 👤 Fred F. Hubble Iii
- 👤 James P. Martin
- 👤 Theresa K. Mattioli
- 👤 Ralph A. Shoemaker
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 21:40
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/55; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/0822; G03G15/0848; G03G15/0849; G03G15/0855; G01N2021/559; G01N21/84; G01N21/8422; G01N2021/8427; G01N21/47; G01N21/4738; G03G15/50; G03G15/5033; G03G15/5041
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
100 words
An apparatus for measuring the reflectivity of a selected region of a surface (10) covered at least partially with particles; including: means for generating a first signal (VD ct ) proportional to the diffuse component of the total reflectivity of the selected region of the surface covered at least partially with particles and a first reference signal (VD pr ) proportional to the diffuse component of the total reflectivity of a region of the surface without particles thereon; and means for determining a control signal as a function of the difference between the first signal and the first reference signal.
Claim 2
Independent Claim
100 words
An apparatus for measuring the reflectivity of a selected region of a surface (10) covered at least partially with particles; including: means for generating a first signal (VD ct ) proportional to the diffuse component of the total reflectivity of the selected region of the surface covered at least partially with particles and a first reference signal (VD pr ) proportional to the diffuse component of the total reflectivity of a region of the surface without particles thereon; and means for determining a control signal as a function of the difference between the first signal and the first reference signal.
Claim 3
Dependent Claim
136 words
An apparatus according to claim 1, wherein: said generating means generates a second reference signal (VS pr ) proportional to the specular component of the total reflectivity of the region of the surface without particles thereon, a third reference signal (VS bt ) proportional to the specular component of the total reflectivity of the selected region of the surface with black particles thereon, and a fourth reference signal (VD bt ) proportional to the diffuse component of the total reflectivity of the selected region of the surface with black particles thereon; and said determining means determines a constant of proportionality GD as a function of the first reference signal, the second reference signal, the third reference signal and the fourth reference signal with the control signal being determined as a function of the constant of proportionality.
Claim 4
Dependent Claim
20 words
An apparatus according to claim 1 or claim 2, wherein said generating means includes means (102) for illuminating the surface.
Claim 5
Dependent Claim
15 words
An apparatus according to claim 3, wherein said illuminating means includes a light emitting diode.
Claim 6
Dependent Claim
28 words
An apparatus according to claim 3 or claim 4, further including means (104) for measuring and controlling the intensity of the light being emitted from said illuminating means.
Claim 7
Dependent Claim
36 words
An apparatus according to claim 5, wherein said measuring and control means includes a control photosensor positioned adjacent said illuminating means to detect the variation in intensity of the light being emitted from said illuminating means.
Claim 8
Independent Claim
37 words
An apparatus according to any one of claims 3 to 6, further including a first condenser lens (116) interposed into the light path of said illuminating means so that collimated light rays are projected onto the surface.
Claim 9
Independent Claim
28 words
An apparatus according to any one of the preceding claims, wherein said generating means (106) includes means for detecting the total reflectivity and the diffuse component of reflectivity.
Claim 10
Dependent Claim
27 words
An apparatus according to claim 8, further including a condenser lens (114) interposed between said detecting means and the surface for receiving the light rays reflected therefrom.
Claim 11
Dependent Claim
17 words
An apparatus according to claim 8 or claim 9, wherein said detecting means includes a photosensor array.
Claim 12
Dependent Claim
49 words
An apparatus according to claim 10, wherein said photosensor array includes: a central photosensor (126) positioned to receive specularly-and diffusely-reflected light rays from the surface; and at least one edge photosensor (128, 130) positioned about the periphery of said central photosensor to receive diffusely-reflected light rays from the surface.
Claim 13
Dependent Claim
12 words
An apparatus according to claim 11, wherein: each photosensor comprises a photodiode.
Claim 14
Dependent Claim
43 words
An electrophotographic printing machine, including a movable photoconductive member and measuring apparatus as claimed in any one of the preceding claims for measuring the reflectivity of a selected region of the surface of the photoconductive member covered at least partially by marking particles.
Claim 15
Dependent Claim
52 words
A machine as claimed in claim 13, including developer apparatus operable to deposit marking particles on the surface of the photoconductive member, in which the control signal from the said measuring apparatus is applied to the developer apparatus to regulate the rate at which marking particles are deposited on the said surface.
Claim 16
Dependent Claim
176 words
A densitometer for measuring the reflectivity of a selected region of a moving photoconductive member (10) covered at least partially with marking particles, including a collimating lens (116); a light source (102) positioned to project light rays through said collimating lens onto the moving photoconductive member with or without marking particles thereon; a collector lens (114) positioned to receive the light rays reflected from the moving photoconductive member; a photosensor array (106) positioned to receive the light rays transmitted through said collector lens and operable to generate a first signal (VD ct ) proportional to the diffuse component of the total reflectivity of the selected region of the photoconductive member with marking particles covering at least a portion thereof and a first reference signal (VD pr ) proportional to the diffuse component of the total reflectivity of a region of the photoconductive member without marking particles thereon; and control circuitry, electrically connected to said photosensor array, for determining a control signal as a function of the difference between the first signal and the first reference signal.
Claim 17
Dependent Claim
176 words
A densitometer for measuring the reflectivity of a selected region of a moving photoconductive member (10) covered at least partially with marking particles, including a collimating lens (116); a light source (102) positioned to project light rays through said collimating lens onto the moving photoconductive member with or without marking particles thereon; a collector lens (114) positioned to receive the light rays reflected from the moving photoconductive member; a photosensor array (106) positioned to receive the light rays transmitted through said collector lens and operable to generate a first signal (VD ct ) proportional to the diffuse component of the total reflectivity of the selected region of the photoconductive member with marking particles covering at least a portion thereof and a first reference signal (VD pr ) proportional to the diffuse component of the total reflectivity of a region of the photoconductive member without marking particles thereon; and control circuitry, electrically connected to said photosensor array, for determining a control signal as a function of the difference between the first signal and the first reference signal.
Claim 18
Independent Claim
197 words
A method of measuring the reflectivity of a selected region of a photoconductive member (10) covered with diffusely reflecting marking particles, including the steps of: generating reference voltages (VS pr , VD pr , VS bt , VD bt ) proportional to the specular and diffuse components of the total reflectivity of the selected region of the photoconductive member without marking particles thereon and when covered at least partially with black marking particles; determining a constant of proportionality (GD) as a function of the said reference voltages and the diffuse reflectivity (RD bt ) of black marking particles; generating a diffuse output voltage (VD ct ) proportional to the diffuse component of the total reflectivity of the selected region of the photoconductive member with diffusely reflecting particles covering at least a portion thereof; and determining the portion (b) of the selected region of the photoconductive member that is covered with diffusely reflecting marking particles as a function of the constant of proportionality (GD), the diffuse output voltage (VD ct ) and the reference voltage (VD pr ) proportional to the diffuse component of the total reflectivity of the region of the photoconductive member without marking particles thereon.
Claim 19
Independent Claim
197 words
A method of measuring the reflectivity of a selected region of a photoconductive member (10) covered with diffusely reflecting marking particles, including the steps of: generating reference voltages (VS pr , VD pr , VS bt , VD bt ) proportional to the specular and diffuse components of the total reflectivity of the selected region of the photoconductive member without marking particles thereon and when covered at least partially with black marking particles; determining a constant of proportionality (GD) as a function of the said reference voltages and the diffuse reflectivity (RD bt ) of black marking particles; generating a diffuse output voltage (VD ct ) proportional to the diffuse component of the total reflectivity of the selected region of the photoconductive member with diffusely reflecting particles covering at least a portion thereof; and determining the portion (b) of the selected region of the photoconductive member that is covered with diffusely reflecting marking particles as a function of the constant of proportionality (GD), the diffuse output voltage (VD ct ) and the reference voltage (VD pr ) proportional to the diffuse component of the total reflectivity of the region of the photoconductive member without marking particles thereon.
Claim 20
Dependent Claim
77 words
In a electrophotographic printing machine, the method of regulating the density of marking particles deposited on the photoconductive member, the method including the step of measuring the reflectivity of a selected portion of the photoconductive member by a method as claimed in claim 16, generating a control signal in dependence on the size of the determined portion (b) and using the control signal to regulate the rate at which marking particles are deposited on the photoconductive member.
References Cited (Backward Citations)
No citation records indexed.
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