GB2133564A

GB2133564A - Illumination arrangement for information indication in single lens reflex cameras

Info

Publication number: GB2133564A
Application number: GB08325147A
Authority: GB
Inventors: Rolf Jurenz; Hans-Joachim Bohm
Original assignee: Pentacon Dresden VEB
Current assignee: Pentacon GmbH Foto und Feinwerktechnik
Priority date: 1982-12-31
Filing date: 1983-09-20
Publication date: 1984-07-25
Also published as: FR2538922B1; DD213310A1; GB8325147D0; GB2133564B; DE3339071A1; FR2538922A1

Abstract

An illumination arrangement is provided for information indication in single-lens relex (SLR) cameras where the indicators (4) are arranged on the edge of the field lens (2) between field lens and pentahedral roof prism (1) and illuminated with direct transmitted light. On the field lens (2) in the region of the indicator (4) there is provided an oblique face (3) dimensioned for optimum transmitted light illumination, by way of which the light of at least one additional light source (5) is reflected in the direction of the transmitted light ray path, through the indicators. <IMAGE>

Description

SPECIFICATION Illumination arrangement for information indication in single lens reflex cameras The invention relates to an illumination arrangement for the information indication in SLR cameras where the indicators are arranged at the edge of the field lens, between field lens and pentahedral roof prism, and illuminated with direct transmitted light.

Scales, symbols and the like arranged on the image edge are presented in the viewfinder image plane preferably in the same light as a rule as the viewfinder image itself. In the case of unfavourable light conditions, that is if the information is hardly or no longer recognisable, the use of additional lighting would be necessary.

Devices of this kind for transmitted light indicators arranged in the viewfinder image plane are hitherto unknown. Only in special reflection ray paths for indicators are additional light sources used and/or window openings provided in the cover cap of the camera. Optimum lighting conditions are achieved with these measures.

By the use of the invention the recognisability of information on the image edge of the viewfinder image plane is improved in SLR cameras.

The problem of the invention consists in producing a lighting arrangement for the information indication which supplies optimum conditions both for normal transmitted light illumination and for additional illumination, without additional optical components.

In accordance with the invention the problem is solved in that on the field lens in the region of the indicator there is provided an oblique face dimensioned for optimum transmitted light illumination, by way of which the light of at least one additional light source is reflected in the direction of the transmitted light ray path. For optimum and uniform illumination of the indicator area the oblique face is preferably polished, ground or made with parts in each of the two variants.

Furthermore it is proposed in accordance with the invention that the additional light source is arranged near the pentahedral roof prism or laterally beside the field lens, in order to reflect the light into the transmitted light illumination ray path. For reflection by multiple reflection, mirrors or partially mirrorcoated surfaces are provided expediently on the indicator. Furthermore for the generation of a sharply defined luminous area on the oblique face, reproducing optical components can be used in accordance with the invention between indicator and additional light source.

The invention will be explained in greater detail below by reference to examples of embodiment. In the accompanying drawings: Figure la shows a form of embodiment according to the invention of an illumination arrangement, Figure ib shows a part of the viewfinder image plane with reflected-in flash symbol, Figures 2 and 3 show illumination arrangements with differently arranged light sources and Figure 4 shows an illumination arrangement with interposed reproduction system.

According to Fig. 1 a an indicator carrying the information to be displayed is arranged between pentahedral roof prism 1 and field lens 2 on a narrow side of the field lens 2. In the region of the information to be displayed the field lens 2 possesses an oblique face 3 on the edge on to which the light of an additional light source 5 falls. The additional light source 5 is for example a miniature incandescent lamp or a light-emitting diode and is situated beside the pentahedral roof prism 1, obliquely over the indicator 4. Light emitted by the additional light source 5 is reflected on the oblique face 3 partially into the fixed transmitted light illumination direction. The oblique face 3 is here so dimensioned that for the through-passing ray path an optimum illumination of the information takes place from the middle of the exit pupil of the objective lens.According to Fig. 1 b, which shows one half of the viewfinder image plane, by way of example the reflected-in flash symbol is additionally illuminated. In order to achieve special light guidance effects, for example a sharply defined luminous area in the region of the information to be displayed (flash readiness and the like), a reproduction system 6 (see Fig. 4) is arranged between light source 5 and indicator 4. The luminous area of the light source 5 is then reproduced directly on the oblique face 3 of the field lens 2, directly beneath the information. The indicator 4 is especially a liquid crystal component or another transparent information carrier, for example a scale mask.

Figs. 2 and 3 represent another expedient arrangement of the additional light source 5.

Here utilisation of multiple reflection takes place by means of mirrors or mirror-coated surfaces on the indicator 4.

The advantages of the illumination arrangement according to the invention by means of an oblique surface on the field lens consist in that two illumination tasks are fulfilled optimally at the same time and no additional optical components are required. Optical aids are necessary only in order to achieve special light guidance effects.

1. Illumination arrangement for information indication in SLR cameras where the indicators are arranged on the edge of the field lens between field lens and pentahedral roof prism and illuminated with direct transmitted light, characterised in that on the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Illumination arrangement for information indication in single lens reflex cameras The invention relates to an illumination arrangement for the information indication in SLR cameras where the indicators are arranged at the edge of the field lens, between field lens and pentahedral roof prism, and illuminated with direct transmitted light. Scales, symbols and the like arranged on the image edge are presented in the viewfinder image plane preferably in the same light as a rule as the viewfinder image itself. In the case of unfavourable light conditions, that is if the information is hardly or no longer recognisable, the use of additional lighting would be necessary. Devices of this kind for transmitted light indicators arranged in the viewfinder image plane are hitherto unknown. Only in special reflection ray paths for indicators are additional light sources used and/or window openings provided in the cover cap of the camera. Optimum lighting conditions are achieved with these measures. By the use of the invention the recognisability of information on the image edge of the viewfinder image plane is improved in SLR cameras. The problem of the invention consists in producing a lighting arrangement for the information indication which supplies optimum conditions both for normal transmitted light illumination and for additional illumination, without additional optical components. In accordance with the invention the problem is solved in that on the field lens in the region of the indicator there is provided an oblique face dimensioned for optimum transmitted light illumination, by way of which the light of at least one additional light source is reflected in the direction of the transmitted light ray path. For optimum and uniform illumination of the indicator area the oblique face is preferably polished, ground or made with parts in each of the two variants. Furthermore it is proposed in accordance with the invention that the additional light source is arranged near the pentahedral roof prism or laterally beside the field lens, in order to reflect the light into the transmitted light illumination ray path. For reflection by multiple reflection, mirrors or partially mirrorcoated surfaces are provided expediently on the indicator. Furthermore for the generation of a sharply defined luminous area on the oblique face, reproducing optical components can be used in accordance with the invention between indicator and additional light source. The invention will be explained in greater detail below by reference to examples of embodiment. In the accompanying drawings: Figure la shows a form of embodiment according to the invention of an illumination arrangement, Figure ib shows a part of the viewfinder image plane with reflected-in flash symbol, Figures 2 and 3 show illumination arrangements with differently arranged light sources and Figure 4 shows an illumination arrangement with interposed reproduction system. According to Fig. 1 a an indicator carrying the information to be displayed is arranged between pentahedral roof prism 1 and field lens 2 on a narrow side of the field lens 2. In the region of the information to be displayed the field lens 2 possesses an oblique face 3 on the edge on to which the light of an additional light source 5 falls. The additional light source 5 is for example a miniature incandescent lamp or a light-emitting diode and is situated beside the pentahedral roof prism 1, obliquely over the indicator 4. Light emitted by the additional light source 5 is reflected on the oblique face 3 partially into the fixed transmitted light illumination direction. The oblique face 3 is here so dimensioned that for the through-passing ray path an optimum illumination of the information takes place from the middle of the exit pupil of the objective lens.According to Fig. 1 b, which shows one half of the viewfinder image plane, by way of example the reflected-in flash symbol is additionally illuminated. In order to achieve special light guidance effects, for example a sharply defined luminous area in the region of the information to be displayed (flash readiness and the like), a reproduction system 6 (see Fig. 4) is arranged between light source 5 and indicator 4. The luminous area of the light source 5 is then reproduced directly on the oblique face 3 of the field lens 2, directly beneath the information. The indicator 4 is especially a liquid crystal component or another transparent information carrier, for example a scale mask. Figs. 2 and 3 represent another expedient arrangement of the additional light source 5. Here utilisation of multiple reflection takes place by means of mirrors or mirror-coated surfaces on the indicator 4. The advantages of the illumination arrangement according to the invention by means of an oblique surface on the field lens consist in that two illumination tasks are fulfilled optimally at the same time and no additional optical components are required. Optical aids are necessary only in order to achieve special light guidance effects. CLAIMS

1. Illumination arrangement for information indication in SLR cameras where the indicators are arranged on the edge of the field lens between field lens and pentahedral roof prism and illuminated with direct transmitted light, characterised in that on the field lens (2) in the region of the indicator (4) there is provided an oblique face (3) dimensioned for optimum transmitted light illumination, by way of which the light of at least one additional light source (5) is reflected in the direction of the transmitted light ray path.

2. Illumination arrangement according to Claim 1, characterised in that the oblique face (3) is polished, ground or made with parts in each of the two variants.

3. Illumination arrangement according to Claim 1, characterised in that the additional light source (5) is arranged near the pentahedral room prism (1) or laterally beside the field lens (2).

4. Illumination arrangement according to Claims 2 and 3, characterised in that reproducing optical components (6) for the generation of a sharply defined luminous area on the oblique face (3) are insertable between indicator (4) and additional light source (5).

5. Illumination arrangement according to Claim 4, characterised in that mirrors or partially mirror-coated surfaces are provided on the indicator (4).

6. Illumination arrangement for single lens reflex cameras substantially as described with reference to any one of the examples shown respectively in Fig. la, Fig. 2, Fig. 3 and Fig.