Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
308 words
An electrical exposure control device for a single lens reflex camera, comprising: a power source having positive and negative terminals; a constant current generating circuit for generating current proportional to absolute temperature and including: a resistance consisting of a first resistor, one terminal of which is connected to said positive terminal, and a second resistor connected in series to said first resistor, a first NPN transistor having a collector connected to said second resistor, an emitter connected to said negative terminal, and a base connected to the junction of said first and second resistors, a second NPN transistor having a base connected to the collector of said first NPN transistor and an emitter connected through a third fixed resistor to said negative terminal, a first transistor circuit consisting of a PNP transistor having an emitter connected through a fourth resistor to said positive terminal, and a third PNP transistor having a base connected to a collector of said PNP transistor, a collector connected to the emitter of said PNP transistor and an emitter connected to the collector of said second NPN transistor, a second transistor circuit having a circuit connection equivalent to said first transistor circuit and consisting of a PNP transistor having a base connected to the base of the PNP transistor of said first transistor circuit and an emitter connected through a fifth resistor to said positive terminal, and an NPN transistor; a compression circuit including light receiving elements connected to an emitter of the NPN transistor of said second transistor circuit and which produces a potential proportional to the logarithm of light on the receiving surfaces of said light receiving elements; means for storing an output of said compression circuit; and a timing circuit including a fourth NPN transistor having a base for receiving the voltage of said compression circuit at the time of exposure.
Claim 2
Dependent Claim
308 words
An electrical exposure control device for a single lens reflex camera, comprising: a power source having positive and negative terminals; a constant current generating circuit for generating current proportional to absolute temperature and including: a resistance consisting of a first resistor, one terminal of which is connected to said positive terminal, and a second resistor connected in series to said first resistor, a first NPN transistor having a collector connected to said second resistor, an emitter connected to said negative terminal, and a base connected to the junction of said first and second resistors, a second NPN transistor having a base connected to the collector of said first NPN transistor and an emitter connected through a third fixed resistor to said negative terminal, a first transistor circuit consisting of a PNP transistor having an emitter connected through a fourth resistor to said positive terminal, and a third PNP transistor having a base connected to a collector of said PNP transistor, a collector connected to the emitter of said PNP transistor and an emitter connected to the collector of said second NPN transistor, a second transistor circuit having a circuit connection equivalent to said first transistor circuit and consisting of a PNP transistor having a base connected to the base of the PNP transistor of said first transistor circuit and an emitter connected through a fifth resistor to said positive terminal, and an NPN transistor; a compression circuit including light receiving elements connected to an emitter of the NPN transistor of said second transistor circuit and which produces a potential proportional to the logarithm of light on the receiving surfaces of said light receiving elements; means for storing an output of said compression circuit; and a timing circuit including a fourth NPN transistor having a base for receiving the voltage of said compression circuit at the time of exposure.
Claim 3
Dependent Claim
179 words
An electrical exposure control device for a single lens reflex camera as in claim 1, further comprising: a third transistor circuit in said constant current generating circuit and connected equivalently to said first transistor circuit, and consisting of a PNP transistor having a base connected to the base of the PNP transistor of said first transistor circuit and an emitter connected through a sixth resistor to said positive terminal, and an NPN transistor; a fifth NPN transistor in said compression circuit for producing a voltage proportional to the logarithm of illumination on the light receiving surfaces of said light receiving elements, said fifth NPN transistor having a similar temperature characteristic to that of said fourth NPN transistor; a variable resistor having one terminal connected to an emitter of said fifth NPN transistor and connected to the emitter of the NPN transistor of the third transistor circuit of said constant current generating circuit and another terminal is connected to said negative terminal, and the resistance of said variable resistor varying in accordance with the diaphragm aperture and film speed settings.
Claim 4
Dependent Claim
88 words
An electrical exposure control device for a single lens reflex camera as in claim 1, wherein said timing circuit includes a first capacitor connected to the collector of said fourth NPN transistor, and a second capacitor in parallel with said fourth NPN transistor and said first capacitor, said second capacitor and said series connected first capacitor and said fourth NPN transistor being selectively connected through a first change-over switch to a second variable resistor the resistance of which varies according to the diaphragm aperture and film speed settings.
Claim 5
Dependent Claim
91 words
An electrical exposure control device for a single lens reflex camera as in claim 3, further comprising: a second change-over switch for establishing either automatic exposure control or manual exposure control; a level detection circuit connected through said second change-over switch to one terminal of either of said first capacitor or said second capacitor for detecting the voltage of either of said first and second capacitors, to thereby generate a signal when said voltage reaches a predetermined level; and an electromagnet for terminating exposure and actuated by said level detection circuit.
Claim 6
Dependent Claim
64 words
An electrical exposure control device for a single lens reflex camera as in claim 4, wherein said means for storing includes a capacitor for storing the output voltage of said compression circuit and a fixed resistor connected to said capacitor and said negative terminal to thereby compensate for a voltage drop of said power source which results from the current flow to said electromagnet.
Claim 7
Dependent Claim
68 words
An electrical exposure control device for a single lens reflex camera as in claim 5, further comprising a delay circuit connected between an output terminal of said level detection circuit and an input terminal of said operating circuit to compensate for the time interval representing the OVERLAP between a trailing edge of a first curtain and a leading edge of a second curtain at the cocked position thereof.
Claim 8
Dependent Claim
103 words
An electrical exposure control device for a single lens reflex camera as in claim 3, further comprising: a fourth transistor circuit connected equivalently to said first transistor circuit in said constant current generating circuit and consisting of a PNP transistor having a base connected to the base of the PNP transistor of said first transistor circuit and an emitter connected through a resistor to said positive terminal, and an NPN transistor; and a meter circuit to which the output voltage of said compression circuit is fed and to which the emitter current of said NPN transistor of said fourth transistor circuit is fed.