Display unit for luminous data of a single lens reflex camera

Claim 2

A display system for object illumination data in a single lens reflex camera of the type comprising a taking lens for passing an image of an object being photographed into the camera; a movable reflecting mirror for reflecting said image after passage by said taking lens; a focussing screen located at a position conjugate to a photographic film disposed within the camera and on which said image is focussed; a finder for said focussing screen; and a light receiving element disposed within the light path of said finder for effecting photometry of the focussed image on said focussing screen, wherein the improvement comprises a memory circuit means for storing illumination data obtained by the light-receiving element; means for producing an end-of-photometry signal; means for conducting said signal to cut off the storage of said data in said memory circuit means; and a light-emitting display means disposed within the light path of the finder for displaying an indication of the production of an end-of-photometry signal when said signal is produced.

Claim 3

A display system for object illumination data in a single lens reflex camera of the type comprising a taking lens for passing an image of an object being photographed into the camera; a movable reflecting mirror for reflecting said image after passage by said taking lens; a focussing screen located at a position conjugate to a photographic film disposed within the camera and on which said image is focussed; a finder for said focussing screen; and a light receiving element disposed within the light path of said finder for effecting photometry of the focussed image on said focussing screen wherein the improvement comprises: a memory circuit means for storing illumination data obtained by the light-receiving element; means operatively connected to said memory circuit means for producing an end-of-photometry signal which cuts off the storage of said data in said memory circuit means; a light-emitting display means disposed within the light path of the finder for displaying an indication of the illumination data; means for converting the illumination data from the light-receiving element into a digital quantity for storage in said memory circuit means; and means for operating the display means only after the production of an end-of-photometry signal.

Claim 4

A display system for object illumination data in a single lens reflex camera of the type comprising a taking lens for passing an image of an object being photographed into the camera; a movable reflecting mirror for reflecting said image after passage by said taking lens; a focussing screen located at a position conjugate to a photographic film disposed within the camera and on which said image is focussed; a finder for said focussing screen; and a light receiving element disposed within the light path of said finder for effecting photometry of the focussed image on said focussing screen wherein the improvement comprises: a memory circuit means for storing illumination data obtained by the light-receiving element; means operatively connected to said memory circuit means for producing an end-of-photometry signal which cuts off the storage of said data in said memory circuit means; a light-emitting display means disposed within the light path of the finder for displaying an indication of the illumination data; means for converting the illumination data from the light-receiving element into a digital quantity for storage in said memory circuit means; and means for operating the display means only after the production of an end-of-photometry signal.

Claim 5

A system as in claim 1 wherein said means for producing an end-of-photometry signal comprises a first delay circuit.

Claim 6

A system as in claim 3 further comprising a second delay circuit connected between the output of said first delay circuit and said display means.

Claim 7

A system as in claim 2 further comprising means for operating said display means after the production of an end-of-photometry signal in response to the readout of said digital quantity from said memory circuit means and means for varying the intensity of illumination of the display means in accordance with the magnitude of said digital quantity to indicate the brightness of the object being photographed.

Claim 8

A system as in claim 5 wherein the means for varying the intensity of illumination comprises a plurality of Schmitt circuits having different threshold values connected in parallel with each other and a plurality of constant current sources respectively connected in series with said plurality of Schmitt circuits.

Claim 9

A system as in claim 2 wherein the means for converting the illumination data comprises: oscillator means for producing pulses of a fixed frequency; gating means for passing the output of said oscillator means to said memory circuit means; D-a converter means for receiving the output of said memory circuit means; and comparator means for receiving the outputs of said D-A converter means and said light-receiving element and controlling said gating means.

Claim 10

A system as in claim 7 wherein said means for producing an end-of-photometry signal comprises said comparator means.

Claim 11

A system as in claim 8 further comprising means for operating said display means after the production of an end-of-photometry signal in response to the readout of said digital quantity from said memory circuit means.

Claim 12

A system as in claim 9 further comprising means for varying the intensity of illumination of the display means in accordance with the magnitude of said digital quantity to indicate the brightness of the object being photographed.