DE2438362A1 - Microfilm projector for interchangeable film media - allows viewing with different magnification and intensity - Google Patents

Abstract

Microfilm projector allowing different degrees of magnification comprises interchangeable films mounted in a film carrier capable of sliding in its own plane. For each objective there is a separate illuminating device, of which the projection lamps may be switched on and off reciprocally or adjusted separately with respect to intensity. The objectives which lie parallel to the film carrier may have vertical axes and project onto a common screen via deflection mirrors. The objective support is pref. connected to a shaft which is mounted rotatably in bearing blocks so that one objective is always located on the film carrier during projection. A common deflecting mirror with reflective surfaces on both sides may be used, which can pivot into position.

Description

PROJEKTI ONSEI NRI CIXTUNG FOR Ml KROFI LMGERAT The invention relates a projection device for microfilmers with several, widely spaced Magnifications, suitable for exchangeable ones held between transparent holding plates Film media, which are arranged displaceably in a plane.

There are microfilm devices well known in which by insertion new lenses or by switching lenses in nosepiece different Magnifications can be set. The lighting system must be used for each lens can be changed so that the image of the lighting lamp filament designed by the condenser lenses comes to lie at the place of the lens diaphragm, so that a flawless Illumination of the screen is guaranteed. This change in the lighting system for lenses with different focal lengths for different magnifications generally takes place by additionally pivoting in further condenser lenses or due to axial movement of the projection lamp.

It is obvious that these devices are mechanically very complex and require an exact adjustment. With the axial movement of the A further disadvantage of the projection lamp is the additional vibration of the lamp which reduces the life of the lamp. The above Have facilities furthermore the disadvantage that they are responsible for large differences in the magnification factors are unsuitable because they represent optical compromises and therefore the illumination strongly deviate from each other in the different measurements.

When working with microfilm readers, however, in practice showed that it is very important to always have the same brightness to the eye at enlargement to offer to reduce fatigue due to changes in the pupil of the eye to reduce.

PROJECTIONSEINRI ~ IzTONti FR Mlis RO RCvriLMGERAT The invention lay the task is to create a projection device for microfilm devices, with which z. B. various film media such as the microfilm punch card and the COM microfiches can be viewed with very different magnification factors.

The illumination properties for each enlargement should be optimal and correspond to one another in their brightness values. To quickly from an enlargement To be able to switch to the other must be the mechanical effort of switching be largely reduced and the focus adjustment with the different Larger sizes are largely omitted.

To solve the problem were 2 independent, each on the overlying lenses created coordinated lighting systems, which by electrically switching on the respective projection lamp via an adjacent, The upper condenser lens system and the objectives each have different magnifications of the film in the same film carrier with the same optical path. Included the strong enlargement expediently anyway with "Aufsitzendeml lens" should be worked, the other lenses with the same one Frame connected and rigidly adjusted to this lens, so that a pin of focus development could largely be omitted.

The main advantage of this arrangement is that any mechanical There is no need to switch optical parts and work can therefore be carried out quickly. Furthermore, the brightness of the screen can be reduced by the separately working optical systems corrected to the same extent.

The slight center offset of the two parallel optical axes is a nuisance Hardly at work, as mentioned above, with different film media for the different magnifications is being worked on.

In Figure 1, the projection device is partly an example shown.

Figure 2 shows the installation of the projection device in a microfilm device and the beam path of the device. PROJECTION DEVICE FOR MICROFILE READERS The objectives (2 and 3) are held in a carrier (1) with the aid of retaining screws (4 and 5) and the pressure screws (6) are adjustable so that their optical axes (7 and 8) run parallel and perpendicular to the film carrier plate (9 and 10). Between A film piece (11) is held on these transparent film base plates (9 and 10). It is easy to see in the drawing that a section of the film (11) under the lens (3) is illuminated by an illumination device, which consists from the projection lamp (12), the concave mirror (13), the heat absorption filter (14), a condenser lens (15), the deflecting mirror (16) and the double condenser (17).

Similarly, a piece of film (11) is placed under the lens (2) by a projection system consisting of the projection lamp (18), concave mirror (19), heat absorption filter (20), condenser lens (21), deflection mirror (22) and the upper condenser lens (23), illuminated. Both lighting systems can be optimally adjust to the lenses above and in their brightness controlled by a potentiometer.

The optical axes (7 and 8) of the objectives (2 and 3) run parallel to the deflecting mirror (23), from there further reflected in parallel via the deflecting mirror (24) to the screen (25).

It is now easily visible that both the lens (2) and above the lens (3) can produce an image of the film (11) on the same screen (25) is.

By switching on the lighting assigned to the respective lens (12 or 18) the magnification adjusted for the objectives can be viewed on the screen so that mechanical switching of optical parts is not necessary is.

It has proven to be useful that the lens has a shorter focal length (3) - (for the high magnification) - when moving the film carrier (9 and 10) on the upper glass plate (9) so that the PROJ EKT I ONSEI NRI CHTING FOR Ml KROFI LMG ERS sharpness for all positions of the film carrier is unchangeably the same.

In order to ensure that it is easy to rest on, the carrier (1) was also included a transverse shaft (26) which is rotatably mounted in the bearing blocks (27). It is also evident that if there are small differences in the magnification factors of the objectives (2 and 3) the rear condenser section, consisting of projection lamp, Concave mirror, heat absorption filter and rear condenser lens (12, 13, 14, 15) can be the same for both lenses. Only the upper condenser lenses (17th or 23) must be matched to the respective lenses. In this case it could be worked with a lighting system, the deflection mirror (16) for Deflection mirror (22) must be arranged in parallel and for the illumination of the under the lens (2) located film image is swiveled out of the way.

It is also obvious that instead of 2 mirrors (16 and 22) a mirror is used which is pivoted to the respective projection position and which must be appropriately mirrored on both sides.

Claims (8)

PAT DISCLAIMER (9 Projection device for microfilming device with several, from each other different magnifications and interchangeable film pieces (11) in a film carrier (9 and 10), which can be moved in its plane, characterized in that that a separate lighting device is provided for each lens (2 and 3) is. 2.) Projection device according to claim 1, characterized by ge-markzei chnet, that the projection lamps (12 and 18) of the lighting device alternate can be switched on and off. 3.) Projection device according to claim 1, d a d u r c h 9 e k e n z e i chnet that the brightnesses of the projection lamps (12 and 18) are separated are adjustable. 4.) Projection device according to claim 1, characterized marked chnet, that the objectives (2 and 3) parallel to the film carrier (9) perpendicular axes and via the deflection mirrors (23 and 24) on the common screen (25) can project. 5.) Projection device according to claim 1 and 4, characterized e i c h ne t that the carrier (1) of the lenses is connected to a shaft (26), which is rotatably mounted in the bearing blocks (27) so that the lens (3) on the film carrier (9) is always seated during the projection. 6.) Projection device according to the preceding claims, characterized gek e n n n z e i c h ne t that for the lighting device the common, bilateral Surface mirrored deflection mirror (16) is used, which is in the position (22) can be folded. 7.) Projection device according to claim 6, characterized in that it is marked, that by folding down the mirror, the respective projection lamp is switched on will. 8.) Projection device for microfilm device with several, from each other different magnifications, exchangeable films (11) in a film carrier (9 and 10), which can be moved in the plane of this carrier, characterized in that that several lenses (2 and 3), projection lamp 12, concave mirror (13), heat absorption filter (14) and condenser lens (15) are provided and the deflecting mirror (22) to the deflecting mirror (16) is parallel in such a way that either a piece of film via the deflecting mirror (16) a piece of film under the lens (3) or by folding up the mirror (16) the lens (2) is exposed. Blank page