Patent US3924948A successfully refreshed from Google Patents.
US3924948A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Densitometer for use in quantitative thin layer chromatographic analysis
Assignee: Kontes Glass Co
•
Filing: 1973-12-17
•
Granted: 1975-12-09
•
Expires: 1993-12-17
Abstract
Abstract A densitometer for use in quantitative analysis of spots on a thin layer chromographic plate includes a movable plate support to permit scanning of the plate by a head assembly positioned above the support. For reflectance mode operation the head assembly contains a source of visible light for illuminating the plate with light which is subsequently reflected by the plate back towards the head assembly. For transmittance mode operation a source of ultraviolet light is situated below the support. The support is provided with a frame portion for contacting only the peripheries of the plate and an opened portion aligned with the spotted areas of the plate such that the spotted areas of the plate may be exposed to light from below by the ultraviolet light source during transmittance mode operation. Exposure to ultraviolet light causes the spots on a properly prepared plate to fluoresce thus emitting visible light. In both operational modes the light from the plate is detected by a sensing means located in the head assembly. The active portion of the head assembly is vertically movable by means of a solenoid between an operational position adjacent the plate and a position remote therefrom. In order to prevent head damage, the active portion is automatically moved to its remote position when the power to the densitometer is removed. In order to eliminate output transients from the sensing means due to vertical movement of the head assembly, the sensing means is energized only when the head assembly is in the operational position. The sensing means circuitry drives a balance meter and incorporates a damping circuit which regulates the meter sensitivity to make the meter less sensitive at the peripheries of the meter range. The head positioning solenoid is provided with a high voltage transient pulse generating circuit to enhance the efficiency thereof. Spring-loaded plate hold-down means are provided to releasably secure the plate to the support and the head assembly is provided with a pointer extending therefrom to identify the spotted area being scanned.
Inventors
- 👤 John Thoden
- 👤 Theodore Wagner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:55
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/59; G01N21/5907; G01N21/5911; G01N30/00; G01N30/90; G01N30/95
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
95 words
A densitometer for use in quantitative analysis of spots on a thin layer chromographic plate comprising a plate support, a head assembly positioned above said support, said assembly comprising a first source of light and means for sensing light from the plate, a second source of light situated below said support, said support having a frame portion for contacting the outer portion of the plate and an open portion aligned with the spotted areas of the plate such that the spotted areas of the plate may be exposed to light from said second light source.
Claim 2
Dependent Claim
95 words
A densitometer for use in quantitative analysis of spots on a thin layer chromographic plate comprising a plate support, a head assembly positioned above said support, said assembly comprising a first source of light and means for sensing light from the plate, a second source of light situated below said support, said support having a frame portion for contacting the outer portion of the plate and an open portion aligned with the spotted areas of the plate such that the spotted areas of the plate may be exposed to light from said second light source.
Claim 3
Dependent Claim
32 words
The densitometer of claim 1 wherein said head assembly has an active portion which is movable between an operative position adjacent the plate and an inoperative position relatively remote from the plate.
Claim 4
Dependent Claim
46 words
In the densitometer of claim 2, a power supply for said densitometer, and means operatively connected between said power supply and said active portion of said head for moving said active portion from said operative to said inoperative position when the densitometer power is turned off.
Claim 5
Dependent Claim
39 words
The densitometer of claim 2 further comprising indicating means operatively connected to said active portion of said head and movable adjacent said plate support for indicatinG the location of said active portion relative to the spots on the plate.
Claim 6
Dependent Claim
27 words
The densitometer of claim 4 wherein said indicating means comprises a pointer mounted on said head assembly adjacent said active portion and extending over the plate support.
Claim 7
Dependent Claim
122 words
The densitometer of claim 1 wherein said head assembly comprises a container portion wherein said first light source is located and an active portion wherein light from said first source is directed onto the plate and means for transferring light from said container portion to said active portion, said transferring means comprising a base within which said first light source is situated, a cylindrical cover member having a first opening in one end adapted to receive said base and a second opening in the other end, a fibre optic bundle having a light input end and a light output end, said light input end situated within said second opening and said light output end situated in said active portion of said assembly.
Claim 8
Dependent Claim
28 words
The densitometer of claim 6 further comprising means for supporting a filter, said filter support means situated within said cover member between said first and said second opening.
Claim 9
Dependent Claim
27 words
The densitometer of claim 1 wherein said plate support further comprises means for releasably engaging the plate such that the plate is secured to said frame portion.
Claim 10
Dependent Claim
64 words
The densitometer of claim 8 wherein said engaging means comprises an elongated member rotatably mounted to said frame for movement in a plane perpendicular to the plane of the plate and a bias spring, said spring exerting a force on said member tending to cause said member to rotate to a position such that the plate is secured between said member and said frame.
Claim 11
Dependent Claim
44 words
The densitometer of claim 1 further comprising means for indicating the quantity of light detected by said sensing means, said indicating means comprising a meter having a scale and means for controlling the sensitivity of said meter of different portions along said meter scale.
Claim 12
Dependent Claim
33 words
The densitometer of claim 10 wherein said sensing means comprises photosensitive signal generating means and wherein said sensitivity controlling means comprises a damping circuit connected between said signal generating means and the meter.
Claim 13
Dependent Claim
39 words
The densitometer of claim 11 wherein said meter is a balance meter and wherein said damping circuit comprises two oppositely oriented diodes each of which is connected in parallel with a series circuit comprising a resistor and said meter.
Claim 14
Dependent Claim
27 words
The densitometer of claim 2 further comprising means for deactivating said sensing means except when said active portion of said head assembly is in said operational position.
Claim 15
Dependent Claim
175 words
The densitometer of claim 13 wherein said deactivating means comprises a capacitor, an output terminal first and second switching devices, first and second voltage sources and a logic circuit, said sensing means being operably connected to said terminal, said capacitor being connected in parallel with the output circuit of said first device, said second source being connected to said terminal, the output circuit of said second device being connected between said terminal and ground, said logic circuit being effective to render both of said devices conductive when said active portion is in said inoperative position thereby preventing activation of said sensing means and to render said first device nonconductive when said active portion is in said operative position, the output circuit of said first device being connected between said first voltage source and ground such that the nonconductivity thereof permits said capacitor to charge to a given voltage, said given voltage being effective to cause said logic circuit to render said second device nonconductive thus permitting said second voltage source to activate said sensing means.
Claim 16
Dependent Claim
16 words
The densitometer of claim 14 wherein said logic circuit is a pair of cross-coupled NOR gates.
Claim 17
Dependent Claim
70 words
The densitometer of claim 2 further comprising means for moving said active portion between said operAtive and inoperative positions, said moving means comprising a solenoid having a plunger operably connected to said head assembly and a high voltage transient pulse generating circuit connected to the coil of said solenoid whereby the pulling force of said coil on said plunger is enhanced during the period of initial activation of said solenoid.
Claim 18
Dependent Claim
88 words
The densitometer of claim 16 wherein said transient pulse generating circuit comprises a voltage source, a capacitor and a voltage doubler circuit connected between said voltage source and said capacitor for charging same, said capacitor being connected in parallel with said coil when said solenoid is activated to provide a pulse across said coil to initiate movement of said plunger, and means for causing the voltage across said coil to maintain a steady state value sufficient to provide the necessary pull on said plunger to complete movement thereof.
Claim 19
Dependent Claim
20 words
The densitometer of claim 17 wherein said active portion is retained in said operative position when said solenoid is activated.
Claim 20
Dependent Claim
24 words
The densitometer of claim 18 further comprising balancing means effective to move said active portion to said inoperative position when said solenoid is deactivated.
Claim 21
Dependent Claim
29 words
The densitometer of claim 1 wherein said first source of light emits light in the visible range and said second source of light emits light in the ultraviolet range.
Claim 22
Dependent Claim
103 words
A densitometer for use in quantitative analysis of spots on a thin layer chromographic plate comprising a plate support, a head assembly positioned above said support, a source of light and means for sensing light from the plate at least one of which is carried by said head assembly, said head assembly being movable between an operative position adjacent the plate and an inoperative position relatively remote from the plate, and means operatively connected between said power supply and said active portion of said head assembly for moving said active portion to said inoperative position when the densitometer power supply is turned off.
Claim 23
Dependent Claim
103 words
A densitometer for use in quantitative analysis of spots on a thin layer chromographic plate comprising a plate support, a head assembly positioned above said support, a source of light and means for sensing light from the plate at least one of which is carried by said head assembly, said head assembly being movable between an operative position adjacent the plate and an inoperative position relatively remote from the plate, and means operatively connected between said power supply and said active portion of said head assembly for moving said active portion to said inoperative position when the densitometer power supply is turned off.
Claim 24
Dependent Claim
121 words
The densitometer of claim 21 wherein said head assembly comprises a container portion wherein said light source and said sensing means are situated, an active portion wherein light from said source is directed onto the plate and means for transferring light from said container portion to said active portion, said transferring means comprising a base within which said source is situated, a cylindrical cover member having a first opening in one end adapted to receive said base and a second opening in the other end, a fibre optic bundle having a light input end and a light output end, said light input end situated with said second opening and said light output end situated in said active portion of said assembly.
Claim 25
Dependent Claim
27 words
The densitometer of claim 21 wherein said plate support further comprises means for releasably engaging the plate such that the plate is secured to said frame portion.
Claim 26
Dependent Claim
27 words
The densitometer of claim 21 further comprising means for deactivating said sensing means except when said active portion of said head assembly is in said operational position.
Claim 27
Dependent Claim
70 words
The densitometer of claim 22 further comprising means for moving said active portion between said operative and inoperative positions, said moving means comprising a solenoid having a plunger operably connected to said head assembly and a high voltage transient pulse generating circuit connected to the coil of said solenoid whereby the pulling force of said coil on said plunger is enhanced during the period of initial activation of said solenoid.
Claim 28
Dependent Claim
118 words
A densitometer for use in quantitative analysis of spots on a thin chromographic plate comprising a plate support, a head assembly positioned above said support, a source of light and means for sensing light from said plate at least one of which is carried by said assembly, means to move said head assembly and said support relative to each other to align the head assembly transversely with respect to the plate and to scan the plate longitudinally, and meaNs operatively connected to said head assembly and movable adjacent said plate support for indicating the transverse location of the assembly relative to the plate, said means comprising a pointer mounted on said assembly and extending over the plate support.
Claim 29
Dependent Claim
118 words
A densitometer for use in quantitative analysis of spots on a thin chromographic plate comprising a plate support, a head assembly positioned above said support, a source of light and means for sensing light from said plate at least one of which is carried by said assembly, means to move said head assembly and said support relative to each other to align the head assembly transversely with respect to the plate and to scan the plate longitudinally, and meaNs operatively connected to said head assembly and movable adjacent said plate support for indicating the transverse location of the assembly relative to the plate, said means comprising a pointer mounted on said assembly and extending over the plate support.
Claim 30
Dependent Claim
121 words
The densitometer of claim 26 wherein said head assembly comprises a container portion wherein said light source and said sensing means are situated, an active portion wherein light from said source is directed onto the plate and means for transferring light from said container portion to said active portion, said transferring means comprising a base within which said source is situated, a cylindrical cover member having a first opening in one end adapted to receive said base and a second opening in the other end, a fibre optic bundle having a light input end and a light output end, said light input end situated with said second opening and said light output end situated in said active portion of said assembly.
Claim 31
Dependent Claim
27 words
The densitometer of claim 27 wherein said active portion is movable between an operative position adjacent the plate and an inoperative position relatively remote from the plate.
Claim 32
Dependent Claim
33 words
In the densitometer of claim 28 wherein said head assembly has an active portion which is movable between an operative position adjacent the plate and an inoperative position relatively remote from the plate.
Claim 33
Dependent Claim
110 words
A densitometer for use in quantitative analysis of spots on a thin chromographic plate comprising a plate support, a head assembly positioned above said support, a source of light and means for sensing light from the plate at least one of which is carried by said head assembly, means operatively connected to said sensing means for indicating the quantity of light detected thereby, said indicating means comprising a balance meter having a balance point along scale and means for controlling the sensitivity of said meter to provide a relatively low sensitivity for points on the scale relatively far from said balance point and a peak sensitivity at said balance point.
Claim 34
Dependent Claim
110 words
A densitometer for use in quantitative analysis of spots on a thin chromographic plate comprising a plate support, a head assembly positioned above said support, a source of light and means for sensing light from the plate at least one of which is carried by said head assembly, means operatively connected to said sensing means for indicating the quantity of light detected thereby, said indicating means comprising a balance meter having a balance point along scale and means for controlling the sensitivity of said meter to provide a relatively low sensitivity for points on the scale relatively far from said balance point and a peak sensitivity at said balance point.
Claim 35
Dependent Claim
33 words
The densitometer of claim 30 wherein said sensing means comprises photosensitive signal generating means and wherein said sensitivity controlling means comprises a damping circuit connected between said signal generating means and said meter.
Claim 36
Dependent Claim
31 words
The densitometer of claim 31 wherein said damping circuit comprises two oppositely oriented diodes each of which is connected in parallel with a series circuit comprising a resistor and said meter.
Claim 37
Dependent Claim
32 words
The densitometer of claim 32 wherein said head assembly has an active portion which is movable between an operative position adjacent the plate and an inoperative position relatively remote from the plate.
Claim 38
Dependent Claim
70 words
The densitometer of claim 33 further comprising means for moving said active portion between said operative and inoperative positions, said moving means comprising a solenoid having a plunger operably connected to said head assembly and a high voltage transient pulse generating circuit connected to the coil of said solenoid whereby the pulling force of said coil on said plunger is enhanced during the period of initial activation of said solenoid.
Claim 39
Dependent Claim
27 words
The densitometer of claim 33 further comprising means for deactivating said sensing means except when said active portion of said head assembly is in said operational position.
References Cited (Backward Citations)
US2406716A
Cited
US3208265A
Cited
US3406290A
Cited
US3480786A
Cited
US3473878A
Cited
US3462225A
Cited
US3600099A
Cited
US3712745A
Cited
US3734630A
Cited
US3762817A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |