FR2778001A1 - Astronomical camera - Google Patents

Abstract

The metal plate (3) in the back of the camera (1), against which the film (16) is applied, is coated with a thermal paste and stuck to a Peltier module (4). The warm face (22) of the latter is also coated with the thermal paste and stuck to a six-sided copper-plated cooling reservoir (5).- DETAILED DESCRIPTION - The assembly is attached to the back of the camera by four spring-loaded screws (13) to give it flexibility, and is covered by an opaque plastic housing to prevent the penetration of any light that could damage the film

Description

The device consists, from a simple photographic camera, of

  reduce the cause to the law of reciprocity of a film for astronomical use. by cooling it, on its back,

by a Peltier module.

  In a general way. during an astronomical snapshot, the amateur astronomer has three options to solve his problems of loss of sensitivity over time: - Either build or buy a sealed tank, hosting carbon dioxide snow but which remains unstable in its regulation of the cold . costly to use and unable to achieve

only one shot at a time.

  - Either hypersensitize the entire film in a vacuum tank filled with 80% hydrogen. and 20% nitrogen for sixty hours at sixty degrees celcius, with

  a shelf life limited to 5 days in the refrigerator.

  - Or else, go directly to the particularly expensive electronic cilicon sensor (C.C.D.), forgetting there. everything to do with gelatin and its

basic characteristics.

  There are therefore few tools that are easy to use, inexpensive and autonomous, marketed today4 to promote

the astronomy of the cold domain.

  The invention therefore aims to offer, at a lower cost to amateur astronomers, an interchangeable system of universal rear door of camera, all brands combined without any other modification of the original housing, integrated with a Peltier module producing cold, electrically regulated to the nearest 1 by an LM 338 and connected by a

12 volt battery.

  The device thus becoming autonomous in all circumstances, it can have as many views. that commercial films

can provide it.

  The Practice of such a technique allows its user to reduce the cause to the law of reciprocity, but also in parallel, to avoid a significant Brownian movement, to tend to a decrease in ionic recombination, to make more stable the "seeds" of latent images. The effectiveness is all the more appreciable on all uncorrected films, for example: slides. There is no increase in the background and in

  color film the spectral balance is balanced.

  All the apparatus, producing cold, on the back of the film, is based on the use of a Peltier module. The latter works according to the inverted principle of the thermocouple effect. It is a ceramic support which, when subjected to an electric flow, emitted by an LM 338 regulator, creates a cold face and a hot face. It should be understood that the more the electric intensity will increase and the more the hot surface will be suitably cooled, the more the cold face will decrease in temperature. In the configuration which will be detailed here, the cooling system will be limited to 5 C. Thus avoiding that too quickly frost arises on the film, also causing a rupture at the time of a change of view or that of

the mist is placed on the lens.

  Anyway, in the invention, there is provided a pump which will convey by simple piping to the first lens inside the camera, ambient air, which will allow dry any fogging by simple thermal difference. The principle could also be envisaged with an inverted refrigerator compressor, this time removing air from the appliance, providing a

  drying instead of ventilation.

  The heat energy released on the hot side of the Peltier module can be eliminated in several different ways: - by air, with the principle of an ambient or electrically ventilated radiator, - by water or any other effective co-carrying liquid. It is also possible to envisage the installation of Peltier modules placed in stages. This arrangement makes it possible to obtain a particularly large cold face, the film plane being able to easily reach -45 ° C. to -50 ° C. In this

  In this case, the camera must be more complex.

  It is compulsory for the enclosure where the film will be located to be under vacuum or to contain an inert gas, with a device of heating filaments on the objective (internal lens) or of double walls of optical glass totally avoiding the installation of

mist and frost.

  This ceramic module opens a wide range of configuration by its ease of installation, its multiple sizes. For example, we can consider cooling by Peltier module on 6 X 6 plates by

  the combination of 4 modules placed behind it.

  More precisely, this rear door (2) of a camera (1). shown in Figure I in axial section, comprises a metal support (3) applying the negative on the film plane (16). What we find elsewhere on any box. It is covered with a thermal paste promoting temperature exchanges and then bonded with a specific product which accepts large thermal differences without deteriorating. Peltier module (4), front side

cold (21).

  In turn. the latter is covered with the same so-called paste and glue to be applied to the rectangular tank with six copper faces for water cooling (5) 4 c6té hot face (22). The whole being fixed on the whole of the door (2) thanks to four screws with springs (13) giving flexibility to the system and covered with an opaque plastic case (15), avoiding any penetration of light harmful to the

negative (16).

  The interior of the tank (5) is designed so as to make the water arrive directly on the hot face to be cooled (22), by a 90 ° coppered elbow (6). The exit being done

  to her normally on side (7).

  The system (5) being composed of springs (13) therefore flexible. the water inlet and outlet (11) will be mounted with a support for flexible plastic pipes (8) fixed at their ends by screwed metal rings (9). connected to more rigid copper pipes (11) which will be. in turn, screwed by rings of

  plumbing (10) to the plastic housing (15).

  The latter (15) will have on its top a digital thermometer (14) with a probe (20) placed on the support for maintaining the film plane (3), indicating the temperature to the nearest tenth of degrees. It will also have a female plug (12) for the supply of power to the module

Peltier (4).

  The power supply, in a separate case, will consist of an LM 338, five amps. actuated by a potentiometer displayed by a voltmeter, allowing a gradual and smooth descent of the temperature, avoiding any thermal shock on the negative (16). The water inlets and outlets (11) will be connected to a 5-liter tank, also separate, comprising a pump supplied with 12 volts. A thermal probe will indicate the temperature of the coolant and this in a concern of constant cold, produced by the module

Peltier (4).

  We can fix on the back of the 5 liter tank, an air or vacuum pump, to ventilate by ambient air, or 1l dry by suction, through a flexible plastic pipe (19), the first inner lens or the camera body, thanks to a

  hole (17) at the front of the camera.

  Of course, the invention is not limited to the modes of execution previously described. Thus, for example, in order to avoid the excessive bulk of the reservoir (5) at the rear of the Peltier module (4), it may be envisaged an opaque plastic bag (perfusion type) particularly thin and flexible. thermo-welded on the hot face (22) of the Peltier module (4). The thickness would not exceed one centimeter approximately, instead of five to six centimeters for the prototype

state here.

  There would therefore be no more gene for the reflex aim of the camera and the production cost of this

  fact can be greatly reduced.

Claims (9)

  1) Universal camera door with Peltier effect intended to reduce the cause to the law of reciprocity. of a film for astronomical use, characterized in that a metal support (3) applying the negative on the film plane (16) will be coated with a thermal paste and bonded to the   Peltier module (4). cold side (21).   2) Universal effect camera door   Peltier according to claim i characterized in that.   the hot side (22) of the Peltier module (4) will itself be coated with thermal paste and bonded to the reservoir of   rectangular water cooling of six copper-colored faces (5).   3) Universal effect camera door   Peltier according to claims 1 and 2 characterized in that,   the assembly (3) (4) and (5) are fixed to the door of the camera (2) by means of four spring-loaded screws (13) giving flexibility to the system and covered with an opaque plastic housing (15) avoiding any penetration of harmful light to the movie.   4) Universal Peltier effect camera door   according to claims 1 to 3 characterized in that   the interior of the tank (5) is designed so as to make the water arrive directly on the hot face to be cooled (a22) by a copper-colored elbow at 90 (6); the exit being done   as for it normally on the side (7).   5) Universal effect camera door   Peltier according to Claims 1 to 4, characterized in that   the system (5) mounted on springs (13) will be connected with flexible plastic pipes (8), fixed at their ends by 7-screw metal rings (9) then fitted to more rigid copper pipes (11) which will be, in turn, screwed by plumbing rings (10) on the sides of the plastic case opaque (15).   6) Universal effect camera door   Peltier according to Claims 1 to 5, characterized in that   on the housing (15) there will be a digital thermometer (14) with a probe (20) placed on the support for holding the film plane (3), indicating the temperature. It will also have a female plug (12) for the supply of power of the Peltier module (4).   7) Universal effect camera door   Peltier according to Claims 1 to 6, characterized in that   the power supply, apart from the camera (1) will be provided with a LM 338 regulator, five amps, maximum 12 volts, actuated by a potentiometer and displayed by a voltmeter allowing a gradual decrease in the temperature of the Peltier module (4), avoiding any thermal shock on the negative (16) and connected to a 12-volt battery allowing the autonomy of the whole system.   8) Universal effect camera door   Peltier according to Claims 1 to 7, characterized in that   the water inlets and outlets (11) will be connected to a five-liter tank, apart from the camera (1), comprising a pump supplied with 12 volts. A thermal probe will indicate the temperature of the coolant. We can fix on the back of the tank, an air or vacuum pump to ventilate by ambient air or dry by suction, through a flexible plastic pipe (19), the first inner lens or the enclosure of the housing photographic and this thanks to an orifice (17) in   the front of the camera.   9) Universal effect camera door   Peltier according to claims i a B characterized in that   that there is the possibility of changing the reservoir (5) by an opaque plastic bag of the perfusion type, particularly thin and flexible, having an inlet an outlet,   thermo-welded on the hot face (22) of the Peltier module (4).   The thickness would not exceed one centimeter approximately not annoying   plus the reflex sight of the camera (1) ,.   at the same time considerably reducing the cost of production.