JP2001305600A - Film unit with lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film unit with a lens which is equipped with a stroboscopic circuit having at least either an automatic light control circuit or an automatic light emission circuit and in which reflected light from a subject is securely made incident in a short distance and the reflected light is securely made incident even when the subject looks small in a long distance. SOLUTION: The light receiving range of a photodetector receiving the light from the subject in a horizontal direction is made equal to >=40% and <=85% of the length in the horizontal direction of a photographing scene with the center of a photographing range as the center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens-equipped film unit having a flash circuit having at least one of an automatic light control circuit and an automatic light emission circuit.

[0002]

2. Description of the Related Art Conventionally, a large number of film units with a lens having a built-in strobe have been sold, and it is possible to easily enjoy photography at night or the like.

[0003]

In a film unit with a lens, the aperture remains open even during flash photography and the photography lens has a fixed focus, so that the exposure amount is adjusted according to the photography distance. Can not do. Therefore, there is only one shooting distance at which proper exposure is performed in flash shooting, and overexposure occurs when the shooting distance is shorter than the shooting distance. The overexposure is compensated for by the latitude of the film or photographic paper. However, there is a limit to how much it can be compensated for by latitude, and if the distance is as short as about 1 m, the photograph becomes overexposed considerably, and a satisfactory photograph cannot be obtained.

Therefore, studies have been made to incorporate an automatic light control strobe into a film unit with a lens, and a proposal has been made in a patent publication. What is an automatic flash control flash?
The strobe light reflected by the subject is received by a light-receiving element such as a phototransistor, photoelectrically converted, and the photocurrent is stored in the capacitor of the control unit. When the capacitor is stored to a certain level, an emission stop signal is issued immediately. To stop light emission of the discharge tube. Therefore, when the distance is short, light emission is stopped early because the amount of reflected light is large, and when the distance is long, light emission is stopped late because the amount of reflected light is small. As a result, the amount of light emitted from the strobe changes according to the shooting distance, and the exposure is always properly adjusted.

Further, the film unit with a lens does not have a photometric function for measuring the luminance of a subject.
For this reason, even if the strobe is built in, the user does not know how dark the strobe should be fired, and the user simply depends on intuition. As a result, there is a case where a photograph is taken without firing the flash even though it is dark, resulting in a photograph with insufficient exposure.

Therefore, it has been studied to incorporate an automatic flash in a film unit with a lens, and a proposal has been made in a patent publication. What is an automatic flash?
The brightness of the subject is measured using a light receiving element such as a Cds cell,
When the brightness is equal to or higher than a preset brightness, the strobe is not fired, and when the brightness is lower than the brightness, the strobe is automatically fired. This eliminates the need for the user to determine how dark the strobe should be fired, reducing the number of underexposed photos.

The present invention relates to a lens-equipped film unit having a built-in automatic light control strobe and an automatic light emission strobe.
It is an object of the present invention to propose a film unit with a lens capable of obtaining better printed photographs.

[0008]

The above object is achieved by any of the following means.

In a film unit with a lens provided with a strobe circuit having at least one of an automatic light control circuit and an automatic light emission circuit, a light receiving element for receiving light from a subject in a horizontal direction is defined as a photographing range. 40 of the horizontal length of the shooting screen centered on the center of
%. A film unit with a lens, wherein the film unit is set to be equal to or more than 85%.

In a film unit with a lens provided with a strobe circuit having at least one of an automatic light control circuit and an automatic light emission circuit, a plurality of light receiving elements for receiving light from a subject are provided, and a plurality of light receiving elements for adjacent light receiving elements are provided. A film unit with a lens characterized by overlapping light receiving ranges.

In a film unit with a lens provided with a strobe circuit having at least one of an automatic light control circuit and an automatic light emission circuit, a light receiving element for receiving light from a subject has a relative sensitivity at a wavelength of 600 nm or more. Is not more than 20% of the peak value.

In a film unit with a lens provided with a strobe circuit having at least one of an automatic dimming circuit and an automatic light emitting circuit, a wavelength of 600 nm or more is provided in front of a light receiving element for receiving light from a subject. A film unit with a lens, comprising a filter having a relative sensitivity of 20% or less of a peak value.

In a film unit with a lens provided with a strobe circuit having an automatic light control circuit, when a subject at a distance of 1 m is photographed, an appropriate strobe light amount determined by the subject distance and the aperture is 0 to 0.5 EV. A film unit with a lens, characterized in that the strobe light amount is controlled to be small in the range of.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a film unit with a lens according to the present invention will be described with reference to the drawings.

First, a flash circuit having an automatic light control circuit will be described with reference to FIG.

[0016] When you turn on the main switch S ₁ by an external operation, turns on in conjunction also Flash Off switch S _2, transistor T _R to flow to start oscillation current of the battery B via a resistor R _1, The secondary side of the oscillation transformer T is boosted to a high voltage. By rectifying the current on the secondary side by the diode D, a DC high voltage of 300 to 350 V is obtained.
The main capacitor C _M and the trigger capacitor C _T connected in series with the resistor R ₃ are charged. Main capacitor C _M
There Once charged to a predetermined voltage, the resistor R ₂ connected in series with the light emitting diodes D _L is lighted.

At the time of photographing, the trigger switch _ST is turned on in conjunction with the opening operation of the shutter blade. Thereby, the trigger capacitor C _T , the trigger switch S _T ,
Primary winding of the trigger transformer T _C, and a closed circuit the Flash Off switch S ₂ connected in series are formed, electric charges charged in the trigger capacitor C _T is discharged to the primary side of the trigger transformer T _C. As a result, a further high voltage is generated on the secondary side of the trigger transformer T _C and applied to the trigger electrode of the discharge tube Xe, so that the ionized xenon atoms in the discharge tube Xe are ejected from the cathode. is excited by the collision, the discharge tube Xe with the discharge of the main capacitor C _M emits light.

Further, when the trigger switch S _T is turned on, flowing through the resistor R ₁₁ becomes current i ₁ part of the charge of the main capacitor C _M flows through the primary side and the trigger switch S _T of the trigger transformer T _C . Further, after the trigger capacitor C _T is discharged, through the resistor R ₁₁ and a part of the main capacitor charge becomes current i ₂ so as to charge the trigger capacitor C _T. Since in this embodiment the Zener diode D ₁₁ to the side of the resistor R ₁₂ and a cathode connected to the resistor R _11, R ₁₂ in series, the zener diode D ₁₁ and a current i ₁ and the current i ₂ The added current i flows.

[0019] Here, is connected flash light reflected by a subject in series to the phototransistor P _T and the capacitor C _P for receiving each other, further connected in parallel with the Zener diode D ₁₁ to which they are connected to the anode of the diode D Have been. Connection portion between the phototransistor P _T and the capacitor C _P is connected to the base of transistor T _RP via a resistor R _13, the emitter of the transistor T _RP is connected to the gate of the thyristor Th _1. Thyristor Th ₁ is connected to the choke coil C _C series with bypass, which are connected in parallel with the discharge tube Xe.

[0020] Therefore, when the thyristor Th ₁ is turned on, the electric charge of the main capacitor C _M than the current flowing through the discharge tube Xe with a large current a current flows through the choke coil C _C is rapidly consumed, light emission of the discharge tube Xe Is to be stopped.

The current i flows through the Zener diode D _11,
If both ends of the Zener voltage of the Zener diode D ₁₁ is generated, a current flows through the phototransistor P _T in accordance with the reflected light of the subject. Strobe light shooting distance reflected by the subject if short distance becomes stronger, the current increases flowing in the phototransistor P _T, the charging of the capacitor C _P is faster. Meanwhile, the shooting distance is flash light reflected by the subject if long distance is weakened, the current flowing through the phototransistor P _T decreases, the charging of the capacitor C _P is delayed.

[0022] Consequently, if the short-range, transistor T _RP early from turning on, because the thyristor Th ₁ also fast to turn on, quickly charges the main capacitor C _M is in the middle light emission of the discharge tube Xe It is consumed by the choke coil C _C, the light emission of the discharge tube Xe is stopped early. On the other hand, if the distance is long, the transistor T _RP is turned on late and the thyristor Th ₁ is also turned on late, so that the discharge tube Xe stops emitting light later. Therefore, even if the aperture is fixed, the reflected light from the subject changes in accordance with the shooting distance and the total light emission amount of the strobe changes, so that a substantially constant exposure amount can be obtained even when the shooting distance changes.

[0023] Incidentally, chattering occurs when the trigger switch S _T is turned on, since the operation becomes unstable, the thyristor Th ₂ is provided for this prevention.

Next, a flash circuit having an automatic light emitting circuit will be described with reference to FIG. In FIG. 2, the portion surrounded by a broken line is an automatic light emitting circuit, which replaces the portion surrounded by a broken line in FIG.
Is the same as Therefore, the description of the same circuit will be omitted, and only the automatic light emitting circuit will be described.

In FIG. 2, a CdS cell Cd and a resistor R
₃₁ and are connected in series, one end of the CdS cell Cd is connected to the high voltage side of the main capacitor C _M, one end of the resistor R ₃₁ is connected with the trigger capacitor C _T.

The subject brightness when the high brightness, the current resistance of the CdS cell Cd flows decreases increases, the electric charge charged in the trigger capacitor C _T is discharged.
Therefore, even if the trigger switch _ST is turned on, the discharge tube Xe
Does not emit light.

On the other hand, when the subject brightness is low, Cd
The resistance of the S cell Cd increases and the flowing current decreases,
Never charges charged in the trigger capacitor C _T is discharged.

Therefore, when the subject brightness is high, the discharge tube Xe does not emit light, and when the subject brightness is low, the discharge tube Xe emits light.

Here, FIG. 3 is a diagram of the phototransistor, and FIG. 4 is a diagram of the light receiving sensitivity of the phototransistor.

For the light receiving sensitivity, a strobe unit is fixed to a fixed base, a point light source that moves in the X and Y directions is placed at a position 1 m away, and the point light source is moved in the X and Y directions.
This is obtained by measuring the output signal from the phototransistor _{PT at} that time. The sensitivity decreases from the center to the periphery.

Here, a light receiving sensitivity of 50% or more is regarded as a sensitivity effective for automatic light control. The light receiving range d is 40% or more and 85% or more of the length of the photographing screen with the center of the photographing screen as the center.
It is desirable to make the following. In the shooting screen of FIG. 5, when the film unit with the lens is horizontal, that is, the light receiving range d is 40% of the long side dimension L of the shooting screen.
As mentioned above, it is 85% or less. The same applies to the vertical dimension.

If such a light receiving range is set to 40% or more, especially in a short distance where automatic light control is to be performed accurately,
The reflected light from the subject will surely enter. Further, even if the subject becomes small at a long distance, the reflected light can be surely incident. If the light receiving range is set to 85% or less, reflected light from an object outside the screen, which is not a subject, can be reliably prevented from entering.

Note that such a light receiving range is the same for the CdS cell in the automatic light emission strobe, so that the brightness of the subject can be properly measured without measuring the background subject.

Next, an embodiment using a plurality of phototransistors of an automatic light control strobe and CdS cells of an automatic light emission strobe will be described.

FIG. 6 is a circuit diagram in which two phototransistors of an automatic light control strobe are provided and two sets of circuits related thereto are provided. As a result, the phototransistors _PT1 , _PT2
The capacitor C connected to the one with the larger current flowing in
The charge of _P1 and _CP2 is accelerated, and the light emission of the discharge tube Xe stops accordingly. That is, when the reflected light from tend short distance subject overexposed is incident on either of the phototransistor P _T1, P _T2, light emission of the discharge tube Xe is stopped.

FIG. 7 is a circuit diagram in which two CdS cells of an automatic light emission strobe are provided. Thus, when low-brightness light is incident on any of the CdS cells Cd ₁ and Cd ₂ , the strobe automatically emits light.

As described above, the phototransistor and the CdS
By providing two sets of light receiving elements such as cells, even a light receiving element having a narrow light receiving range has a wide light receiving range as a whole and can reliably receive light. In this case, also in this case, the light receiving range d by the plurality of light receiving elements
As described above, the light receiving range d is desirably set to 40% or more and 85% or less with respect to the longitudinal direction of the photographing screen with the center of the photographing screen as the center as described above.

In addition, since the main subject is generally located at the center, it is desirable to overlap the light receiving ranges of the adjacent light receiving elements in order to reliably receive the light of the central subject. FIG. 8 shows an example in which the light receiving range is widened by providing two light receiving elements in this manner.

In particular, in the case of an automatic light control strobe, if the subject is not close to the center at a short distance, the reflected light from the subject cannot be received. By providing two sets of phototransistors, light can be reliably received.

Further, as shown in FIG. 9, by using three sets of light receiving elements and increasing the degree of overlap in the center than in the periphery, the light of the center subject can be more reliably received.

When a plurality of light receiving elements are provided, the light receiving range of each light receiving element is 9% or more with respect to the photographing screen.
% Is desirable. Further, it is desirable that the overlapping range be 10 to 50% for each light receiving element. As a result, it is possible to more reliably receive the reflected light of the subject in a wide range, and it is possible to obtain better printed photographs.

Next, the spectral sensitivity of a phototransistor used for an automatic light control strobe will be described.

When a bright fluorescent lamp is turned on when photographing indoors, the automatic light emitting circuit may determine that strobe light is unnecessary. However, since the film unit with a lens has a built-in daylight type film, green color fogging occurs when photographing with fluorescent light. Therefore, it is desirable to always use flash photography under fluorescent light illumination.

FIG. 10 is a graph showing the spectral sensitivity of a general phototransistor. At this spectral sensitivity, light from a fluorescent lamp is also received. Therefore, if a phototransistor that receives only a wavelength of 700 nm or more as shown in FIG. 11 so that the relative sensitivity at a wavelength of 600 nm or less is 20% or less of the peak sensitivity is used, the influence of the fluorescent lamp is eliminated. The above problem is solved.

A filter is arranged in front of the phototransistor having the spectral sensitivity shown in FIG. 10 so that the relative sensitivity at a wavelength of 600 nm or less is 20% or less of the peak sensitivity, for example, as shown in FIG. You may make it sensitivity.

The same applies to Cds of an automatic flash. In addition, for example, when an automatic light control strobe capable of obtaining an appropriate exposure up to a distance of 3 m is used, the exposure amount for a normal shooting distance is shown by a solid line in FIG. 12 with the appropriate exposure amount as a reference (0EV). On the other hand, it is said that a negative film incorporated in a film unit with a lens has an allowance of about 1.7 EV on the underexposure side. Therefore, instead of intentionally setting the light control level of the automatic light control strobe to 0EV of a proper exposure, the face of a subject at a short distance at which overexposure is likely to occur, that is, a person at a distance of 1 m, specifically, a person at a distance of 1 m, is specifically determined. When one person is photographed so as to be in the center, the light is adjusted so that the exposure becomes insufficient by 0 to 0.5 EV. This is, for example, 0 to 0.5 as shown by the broken line in FIG.
In the range of EV, preferably in the range of 0.1 to 0.5 EV, light control is performed by shifting to the underexposure side. In this way, even if the flash light is emitted with a smaller amount of light than the proper light amount, the exposure is corrected at the time of printing, so that the dark background will be corrected in the direction of less underexposure at the time of printing and printed. become. Accordingly, a brighter photograph can be obtained not only of the main subject photographed with the flash, but also of the background.

[0047]

According to the film unit with the lens according to the first aspect, the reflected light from the subject can be reliably incident particularly at a short distance where the automatic light control is to be performed accurately, and the subject can be projected at a long distance. Even if the size becomes smaller, reflected light can be surely incident, and further, reflected light from an object outside the screen that is not a subject can be reliably prevented from entering.

According to the film unit with the lens according to the second to fourth aspects, it is possible to reliably receive the light of the subject in the screen.

According to the film unit with the lens according to the fifth and sixth aspects, it is possible to prevent the occurrence of green color fogging by photographing under illumination under a fluorescent lamp.

According to the film unit with the lens according to the seventh aspect, a photograph in which the background subject is brighter during printing can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a flash having an automatic light control circuit.

FIG. 2 is a circuit diagram of a strobe having an automatic light emitting circuit.

FIG. 3 is a diagram of a phototransistor.

FIG. 4 is a diagram of the light receiving sensitivity of a phototransistor.

FIG. 5 is a diagram showing a shooting screen and a light receiving range.

FIG. 6 is a circuit diagram in which two phototransistors of an automatic light control strobe are provided and two sets of circuits related thereto are provided.

FIG. 7 is a circuit diagram in which two CdS cells of an automatic light emission strobe are provided.

FIG. 8 is a diagram in which two light receiving elements are provided and light receiving ranges are overlapped.

FIG. 9 is a diagram in which three sets of light receiving elements are provided and light receiving ranges are overlapped.

FIG. 10 is a graph of spectral sensitivity of a general phototransistor.

FIG. 11 is a graph of the spectral sensitivity of a phototransistor that receives only a wavelength of 700 nm or more.

FIG. 12 is a graph of an exposure amount with respect to a shooting distance when an automatic light control strobe is used.

[Explanation of symbols]

Xe discharge tube P _T, P _T1, P _T2 phototransistor C _P, C _P1, C _P2 capacitors Cd, Cd _1, Cd ₂ Cds cell

Claims (7)

[Claims] In a film unit with a lens provided with a strobe circuit having at least one of an automatic light control circuit and an automatic light emitting circuit, a horizontal light receiving range of a light receiving element for receiving light from a subject is defined as: 40 of the horizontal length of the shooting screen centered on the center of the shooting range
%. A film unit with a lens, wherein the film unit is set to be equal to or more than 85%. 2. A lens-equipped film unit having a strobe circuit having at least one of an automatic light control circuit and an automatic light emission circuit, wherein a plurality of light receiving elements for receiving light from a subject are provided. A film unit with a lens, wherein light receiving ranges of the elements are overlapped. 3. A plurality of light receiving elements such that a horizontal light receiving range of the plurality of light receiving elements is equal to or more than 40% and equal to or less than 85% of a horizontal length of a shooting screen centered on a center of the shooting range. 3. The film unit with a lens according to claim 2, wherein the light receiving elements are arranged adjacent to each other, and the degree of overlap between the adjacent light receiving elements is larger in the central part than in the peripheral part. 4. The film unit with a lens according to claim 2, wherein the light receiving range in the horizontal direction of each of the light receiving elements corresponds to 9% or more and 57% or less of the photographing screen. . 5. In a film unit with a lens provided with a strobe circuit having at least one of an automatic light control circuit and an automatic light emission circuit, a light receiving element for receiving light from a subject has a wavelength of 600 nm or more. A film unit with a lens, wherein the relative sensitivity is 20% or less of the peak value. 6. In a film unit with a lens provided with a strobe circuit having at least one of an automatic light control circuit and an automatic light emitting circuit, a wavelength of 600 nm or more is provided in front of a light receiving element for receiving light from a subject. Wherein a filter having a relative sensitivity of not more than 20% of a peak value is disposed. 7. In a film unit with a lens provided with a strobe circuit having an automatic light control circuit, when a subject at a distance of 1 m is photographed, a value of 0 to 0 is set based on an appropriate strobe light amount determined by the subject distance and the aperture. A film unit with a lens, wherein the strobe light amount is controlled to be small in a range of 0.5 EV.