JPS6021324B2 - Light receiving device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light receiving device including an additional light source passed through, for example, a camera.

Generally, light from an object has a wide wavelength range, and a light receiving element such as a silicon photodiode has a spectral sensitivity characteristic as shown by EI in FIG.

However, the wavelength range that is actually felt by the eye is from 40km to 70km. For this reason, the subject's light is directly focused on the subject's neck. When exposed to light, the influence of the infrared light region becomes very large, making it impossible to obtain proper exposure. Therefore, by providing a filter for correcting spectral sensitivity in front of the light-receiving element, the secondary structure cuts the influence of infrared light on the light-receiving element and corrects the spectral characteristics to be close to the human eye sensitivity characteristics. .

However, in a storage optical circuit that uses a secondary photovoltaic optical box conversion element as a light receiving element, since a high input impedance operational multiplier equipped with an FET at the input stage is connected to the light receiving element, it is difficult to turn on the power. The capacitance present at the gate of the FET,
Unnecessary charging of stray capacitance such as the junction capacitance of the photodetector and the capacitance generated in the printed wiring steel occurs instantaneously, and it takes a considerable amount of time to discharge this unnecessary charge. The circuit is stable and strong. This is particularly noticeable when weak light is emitted because the photocurrent is small. Furthermore, in the secondary side optical circuit, in a dark state, the photocurrent to the logarithmic conversion diode inserted in the negative feedback circuit is cut off, so negative feedback is no longer applied to the high input impedance operational amplifier, and the output of the amplifier is is either high level or low level depending on the direction of the diode.

That is, the intensifier will be latched. For this reason, when taking the next photograph, it takes time to release the latch of the arithmetic intensifier, and the amount of light varies depending on the amount of incident light. This deteriorates the followability of the optical circuit. The present invention has been made in view of the above circumstances, and a filter for spectral sensitivity correction is provided in front of the light receiving element, and between the filter and the light receiving element, the filter is located within the sensitivity wavelength range of the light receiving element but outside the transmission wavelength range of the filter. By arranging a light emitting light source for bias light supply having a spectral emission energy characteristic of The present invention aims to provide a light-receiving device that avoids this problem.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows the spectral characteristics of the light receiving element, spectral sensitivity correction filter, and light source. In the figure, EI indicates the spectral sensitivity characteristic when a photovoltaic silicon photodiode is used as the light receiving element. E2 is the spectral transmission characteristic of the spectral sensitivity correction filter, E3 is the spectral energy distribution characteristic when a light emitting diode is used as an infrared light source, and E4 is the spectral sensitivity characteristic necessary as a light receiving element for a camera. When the characteristic EI is multiplied by the spectral characteristic E2, the spectral sensitivity characteristic of the silicon photodiode as a whole becomes E4, which is suitable as a light receiving element for a camera.

On the other hand, the spectral energy distribution characteristic E3 is within the region of the spectral characteristic EI, but not within the region of the spectral characteristic B2.

Here, FIG. 2 shows a light receiving device of a camera that utilizes the relationship of spectral characteristics shown in FIG. 1, and 1 is a photographing lens system;
2 is an aperture, 3 is a lens shutter, 4 is a film, 5 is a silicon photodiode as a light receiving element having spectral sensitivity characteristics shown by EI in FIG. 1, and 6 is a spectral transmission characteristic of E2 in FIG. 1. 7 is a light emitting diode as a light source having a spectral energy distribution characteristic of E3 in FIG. 1; 8 is a silicon photodiode 5;
A light-shielding tube 8 is provided with a filter 6 attached to the front surface of the light-shielding tube 8, and a light-emitting diode 7 is provided inside the oblique light tube 8.

FIG. 3 shows an exposure control circuit of the camera shown in FIG. 2, and the same parts as in FIG. 2 are designated by the same reference numerals and will be explained.
10 is a high input impedance operational intensifier with a silicon photodiode 5 connected between its input terminals, 11 is a logarithmic conversion element for logarithmically compressing the photocurrent of the silicon photodiode 5, and 12 and 13 are operational intensifiers. Various stray capacitances present at the inverting input terminal of 10 (for example, the capacitance of a field effect transistor in the input stage of the arithmetic multiplier 10, the junction capacitance of the silicon photodiode 5, the capacitance when the circuit is mounted, etc.), 14 is the arithmetic multiplier a logarithmic expansion transistor connected to the output terminal of the capacitor 10; 15 a second time integration capacitor connected to the transistor; 16 a count switch; 17 a Schmitt trigger circuit for detecting the voltage level between the terminals of the capacitor 5; 18 is a shirt starter control magnet whose conduction is controlled when it is detected that the Schmitt trigger circuit 17 has reached a predetermined level; 19 is a main switch which is closed when the shirt starter button is depressed in the first step; 20 and 21
2 is a power supply battery; 22 is a switch that is momentarily turned on in conjunction with the second press of the shirt button; a light emitting diode 7 is connected in series to the switch 22;
The light-emitting diode 7 is turned on only for a moment by turning on the light emitting diode 2 for a moment.

Next, the operation of the above configuration will be explained.

When the main switch 19 is turned on by pressing down the first step of the shirt button, the spotlight circuit system converts the capacitance of the field effect type transistor in the input stage of the arithmetic intensifier through the logarithmic conversion element 11 etc. in a transient state. Stray capacitance12,13
Unnecessary charging is performed.

Then, when the switch 22 is momentarily turned on in conjunction with the second depression of the shirt button, the light emitting diode 7 emits light momentarily and irradiates the silicon photodiode 5, thereby eliminating unnecessary charges to the stray capacitance. The light current is momentarily discharged by the photocurrent of the diode 5, and the spotlight circuit becomes stable. At the same time, when the shirt cover 3 is opened, the subject light is reflected by the film 4 surface through the photographing lens 1, and this reflected light reaches the silicon photodiode 5 through the spectral sensitivity characteristic correction filter 6. Therefore, the spectral sensitivity characteristic of the silicon photodiode 5 with respect to the subject light becomes a spectral sensitivity characteristic suitable for a camera exposure meter, as shown by E4 in FIG. Further, although the light from the light emitting diode 7 is irradiated onto the silicon photodiode 5, the light is not irradiated onto the film 4 because a filter 6 is interposed therebetween, so that the film 4 is not affected at all. Therefore, when the count switch 16 is turned off at the same time as the trigger switch 3 is opened, the capacitor 15 is charged according to the output of the arithmetic multiplier 10, and when the capacitor 15 reaches a predetermined value after a certain time, the Schmitt trigger circuit 17 is reversed. Then, the magnet 18 becomes de-energized and the shirt sleeve 3 is closed.
Although the above embodiments have been described with reference to the case where a lens shutter is used, the present invention is not limited thereto, and can be implemented similarly when a focal plane shutter 3' is used as shown in FIG.

In this case, the light-receiving element 5 includes the shirt cover 3' surface and the film 4.
The light reflected from the surface is irradiated through the filter 6, and the light emitting diode 7 is connected to the main switch 19 and the switch 22, which are closed by the first operation of the shirt button.
It is also a good idea to open it. In addition, the light receiving device of the present invention is not only designed to instantly eliminate unnecessary charges to stray capacitance, but also to replace the switch 22 with a variable resistor 23 as shown in FIG. If the brightness of the light emitting diode 7 is set to a predetermined value, it can also be used as an IJ transmitter for shutter speed.

In other words, if the variable resistor 23 is set so that the brightness of the light emitting diode 7 is set to 1/6 of the shutter speed, then if the subject light is brighter than the set value, the shutter speed will change accordingly. Control is performed, and if the subject light is darker than the set value, the light intensity is simply controlled to 1/6 current.

If this set value is set as the camera shake limit value, camera shake will be prevented. Since this camera shake limit value differs depending on the type of lens (wide-angle, standard, telephoto), a variable resistor is used to adjust the light intensity of the light emitting diode 7. By adjusting 23 automatically or manually depending on the type of lens, camera shake can be prevented in any case. As described in detail above, according to the present invention, a spectral sensitivity correction filter is provided in front of the light receiving element, and between the filter and the light receiving element there is a wavelength within the sensitivity wavelength range and outside the transmission wavelength range of the filter. By arranging a light emitting light source for supplying bias light having spectral emission energy characteristics, light from the outside is irradiated onto the light receiving element through the filter, and light from the light source is irradiated onto the light receiving element and is not transmitted to the outside of the filter. By constructing a light receiving device that does not leak and using this light receiving device in a camera, it is possible to instantly eliminate unnecessary charges to stray capacitance that occur in the light circuit without causing any adverse effects on photosensitive materials such as film. It is possible to provide a light-receiving device that has effects such as being able to be used as an IJ mittator during shutter speeds.

It goes without saying that the light receiving device of the present invention can be applied not only to cameras but also to various other applications without departing from the scope of the invention.

[Brief explanation of the drawing]

Fig. 1 is a spectral characteristic diagram of a light receiving element, a spectral sensitivity correction filter, and an additional light source, Fig. 2 is a block diagram showing an embodiment of a camera using the light receiving device of the present invention, and Fig. 3 is a diagram showing the spectral characteristics of the additional light source. 4 is a configuration diagram of the camera shown in FIG. 2 using a focal plane shutter, and FIG. 5 is a configuration diagram of the camera shown in FIG. FIG. 3 is an exposure control circuit diagram of the camera in this case. 3...Lens shirt evening, 3'...Focal plane shutter, 4...Film, 5...Silicon photodiode, 6"""filter, 7"""light emitting diode,
10... Arithmetic multiplier, 11... Logarithmic compression diode, 12, 13... Stray capacitance, 22... Switch. Fig. 1 Fig. 2 Inferior Fig. 4 Fig. 5

Claims (1)

[Claims] 1. A filter for spectral sensitivity correction is provided in front of the light receiving element, and between the filter and the light receiving element, a filter for supplying bias light having spectral emission energy characteristics within the sensitivity wavelength range of the light receiving element and outside the transmission wavelength range of the filter is provided. A light receiving device characterized in that by arranging a light emitting light source, external light is irradiated onto a light receiving element through the filter, and light from the light source is irradiated onto the light receiving element so as not to leak to the outside of the filter. Device.