JPS62257030A - Photometric apparatus of camera - Google Patents

Abstract

PURPOSE:To enhance response while reducing the capacity possessed by a photodiode, by setting the thickness of the I-layer of the photodiode to a predetermined value or more. CONSTITUTION:A photodiode is used as a photometric element for performing the photometry of an image pickup surface and the photometry of the light reflected from the surface of a photographic film or shutter film. This photodiode is a PIN type one having such a structure that a transparent electrode 2, a P-layer 3 made of P-type a-Si : H, an I-layer 17 made of a-Si : H showing an intrinsic semiconductive characteristic, a N-layer 5 made of N-type a-Si : H and a metal electrode 6 made of Al or the like are successively laminated to a transparent substrate 1 and the thickness of the I-layer 17 is set to 10,000 Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a photometric device for a camera, in particular a photometric device for a single-lens reflex camera using a photodiode with an amorphous hydrogenated or fluorinated silicon layer. [R view of the invention] Conventionally, amorphous hydrogenated silicon (hereinafter referred to as a-8i:)
i) or fluorinated silicon (hereinafter referred to as a-8i:F)'! ! - The photodiode used had a transparent electrode 2 made of ITO, SnO, etc. on a transparent substrate 1 as shown in FIG.
2 layers consisting of 3, a-8i indicating intrinsic semiconductor %Note: H
1 layer 4 consisting of (a-8i:F), n-type a-8i:
A structure in which a single layer 5 made of H(a-st:F);bh, a metal electrode 6 made of At or the like is stacked on J@, or a structure in which i(P)@3 on a metal substrate 7 as shown in FIG. 114.1 layer 5,
Structures in which transparent electrodes are laminated in 2t-order t order and structures using Schottky barriers have been proposed, and among these, the pin-type photodiode shown in Figures 5 and 6 is widely used in solar cells and optical sensors. The first layer 4 of the pin-type photodiode, into which light enters from the transparent electrode 2 side, has carriers generated by optical excitation.
This is a region that drifts due to the electric field caused by the difference in Fermi energy between P+'1lj3 and 1st layer 5, and is usually 4
A thickness of 000 to 7000^ is considered optimal for such applications.

By the way, such a Pin type 7 photodiode has the following characteristics: 1) The spectral sensitivity & is close to the ratio tA'; Ef, and when used as a visible light sensor, an infrared cant filter is unnecessary.

1i) As a result of i), the sensitivity is greater than that of the crystalline silicon photodiode with an infrared cut filter, which is used for the side light of the camera.

jll) Can be formed on transparent materials, and can also be patterned with 8
It is an easy thin film.

1) Due to its advantages such as being cheaper than crystalline silicon, it has been proposed to be used as a photometric element in cameras.

Conventional Pan type a-8i: u(a-6i
:F) The photodiode has a memory type that controls the exposure amount by adjusting the photometry before taking a photo, since each junction of the photodiode is weak and the response is slow in the photometry circuit of the compression type shown in Figure 7. Although it can be used for photometry, it has been difficult to use it for direct photometry, which controls the amount of exposure by measuring the reflected light of a 7-point curtain or photographic film at the same time as shooting. In other words, the thickness of the i-layer of such a conventional photodiode is optimized for efficient extraction of power, and the thickness of the i-layer of such a conventional photodiode is optimized for efficient extraction of power. It's not necessarily optimal.

[Purpose of the invention]

The present invention reduces the capacity of a photodiode consisting of a-8i:)i or a-8i:F, and significantly improves the photometry of the O-S company. It is an object of the present invention to provide a photometry device for a camera that is inexpensive and can be miniaturized by using a single photodiode.

[Summary of the invention]

The camera photometry device according to the invention has at least 1000
A photodiode with a single layer of amorphous hydrogenated or fluorinated silicon formed on a 4-layer film with a diameter of 0 Å or more, and is characterized by being able to measure the light from the photographing surface and the light reflected from the photographic film surface or shutter curtain. That is.

[Embodiments of the invention]

The present invention will now be described in detail based on embodiments shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of the photometric device according to the present invention, in which 8 is a photographing lens, 9 is a quick return mirror consisting of a half-midgee or partially transparent pattern mirror, 10 is a small mirror, and 11 is a A photometric optical system, 12 is a photometric element, 13 is a focusing plate, 14 is a pentaprism, 15 is an eyepiece lens, and 16 is a photographic film, and is arranged as shown in the figure.

The light beam t from the photographic object that passes through the photographic lens 8 gold reaches the quick return mirror 9 before photographing, and a part of the light beam tζ is reflected and guided to the focusing plate 13, pentaprism 14, and eyepiece lens 15. , other luminous flux t,
is transmitted. Light flux transmitted through quick return mirror 9 1. is reflected from the small mirror 10Vc, and the photometric optical system 11
Then, when the 1-1 period (H type light) is incident on the 1:1 optical element 12, photometric information is outputted from the photometric element 1 or to a memory-type photometric circuit (not shown).

On the other hand, if something happens during photography, the quick return mirror 9 and the small mirror 10 will move as shown by the broken lines in the figure, causing the luminous flux t.
reaches the photographic film 16 and photography is performed. At this time, the light beam 4 reflected by the photographic film 16 passes through the photometric optical system 11 and enters the photometric element 12, and the photometric information necessary for direct photometry is output from the photometric element 12 to a direct-side optical circuit (not shown). Ru.

As shown in FIG. 2, the photometric element 12 has a transparent electrode 2, a P-type a-8i: )l, Sl, 2 layers 3, and an intrinsic semiconducting rest 4 on a transparent substrate 1, as shown in FIG. a-8i: f (i layer 17 consisting of ``W &Si;) 17) - n +75, metal electrode 6 consisting of AM Sae, horizontally 1
This is a pin-type photodiode made by Yuzukuri, which has an IJ
The thickness of the i layer 17 is tlooooA.

Photometric element used in this example (thickness of i-layer: 1000
0A) 12, a conventional Pin7ji 7, and a t diode (i-layer thickness: s o o o A) are connected to the circuit shown in Fig. 7, which is normally used for Camilla photometry, and the direct output from this circuit is The time from irradiation to stabilization, that is, the response speed to light, was measured. As the irradiation light source, a yellow low LED f with an illuminance through which a short-circuit photocurrent of 5×10 A flows was used. As a result, 1
The response speed of a photometric element with a layer thickness of 10000 Å is 5.6
The response speed of a μ-type photometric element with a single layer thickness of 500 OA was 10 μm.

That is, by setting the thickness of the i-layer to 10,000 Å, the response speed became approximately twice as fast.

Further, the spectral sensitivity characteristics change in addition to the value of K due to the i-layer 'k10000A, but as shown in FIG. 4, there is no significant change.

As described above, according to this embodiment, the i of the photometric element 12 is
The layer is made 10,000 Å thick to reduce the capacitance and speed up the response time, so it reduces the memory side light before shooting and during shooting ((
This makes it possible to perform direct photometry using the same photodiode.

In addition, since this type of photodiode can be formed on a continuous member, it is possible to take advantage of the features of diodes, such as dividing the photometric surface into a large number of photometric regions and easily forming them into various shapes. It's a monkey.

Note that the photometric element 12 is not limited to the above embodiment, and as shown in FIG.
It may be a structure in which i 417, n im 5, and transparent electrode 2 are laminated in order, or amorphous hydrogenated silicon y
(a-6t:H) may be replaced with amorphous fluorinated silicon (a-8i:F)t-.

Further, a-8i:H2C may be used for P and @3, and microcrystallized St may be used for nl-5.

〔Effect of the invention〕

According to the present invention, by setting the photodiode's Irm to 4, which is more than 1000OA in total, the capacity of the photodiode becomes smaller and the response becomes faster. This has the effect of making it possible to perform both photometry and photometry using the same photodiode.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of a photometric device according to the present invention, FIGS. 2 and 3 are cross-sectional views of a photodiode used in the present invention, FIG. 4 is a chart showing spectral sensitivity characteristics, and FIG. 6 is a sectional view of a conventional photodiode, and FIG. 7 is a circuit diagram showing a logarithmic compression circuit. 8...Photographing lens 9...Quick return mirror 10...Small mirror 11...Photometry optical system 12
...Photometering element 13...Focusing plate 14...
Pentaprism 15... Eyepiece 16... Photographic film. Figure 111 Figure 2 Figure 3 Figure 4 -1 (nm) Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] A photodiode in which an amorphous hydrogenated or fluorinated silicon i-layer is formed to a thickness of at least 10,000 Å, and is capable of measuring the light of the photographic screen and the light reflected from the photographic film surface or the shutter curtain. Photometering device for cameras.