JPH02105126A - Stroboscope incorporated camera - Google Patents

Abstract

PURPOSE:To achieve stroboscopic photographing at short time intervals by judging whether or not voltage information indicates a voltage level at which stroboscopic flash is possible or not under appropriate exposure. CONSTITUTION:A voltage discriminating circuit outputs voltage information, which is inputted from a terminal (g) to its terminal (i), to an arithmetic control circuit after converting the voltage information into information equivalent to a guide number; the guide number is obtained by properly setting a combination of terminals (o), (t), and (u), all of which switch a voltage level from HIGH to LOW and vice versa, at resistances R1, R2, Ro, Rt, or Ru. At the same time the metering information of an object obtained by the actuation of an AF circuit is inputted to the arithmetic control circuit in order to be judged whether proper exposure is possible or not according to the exposure F value, stored in advance, of a photographing lens; with a charged voltage which has reached the value, a signal is sent to a shutter driving circuit in order to release a release lock, and a stroboscope flashes in synchronization with shutter actuation. This shortens waiting time until the stroboscope is charged, and achieves stroboscopic photographing where proper exposure is quickly obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a camera with a built-in strobe that can take pictures while reducing the charging time of the strobe.

[Background of the invention]

Strobe light emitting devices built into small cameras generally have a guide number of GNo or IO and have a small capacity, but those that regularly use alkaline manganese batteries as a power source take about 10 seconds to reach the specified charging voltage. It is normal to need it.

Therefore, when using a strobe to take pictures continuously within a short period of time, a photo opportunity may be missed due to the charging time.

Recently, cameras have been introduced that replace alkaline manganese batteries with built-in lithium batteries, which are smaller, have a lower internal resistance, can draw more current, and have a longer lifespan, and their rapid charging characteristics can shorten the charging time of strobes by a considerable amount. ing.

[Problem that the invention seeks to solve]

However, although it is said to have been shortened, it is still longer than the operating time for one cycle of photographing operation, ie, a series of operations such as film winding, shutter setting, etc., and therefore the waiting time for charging has not yet been eliminated.

As a result of solving this problem and improving the present invention, the release lock is released when the charging voltage reaches a point at which the appropriate exposure amount can be obtained from a practical standpoint, taking into consideration the subject distance, and the release lock is released at an extremely short interval. The purpose of this invention is to provide a camera with a built-in strobe that enables photography using strobe light.

[Structure of the invention]

The above purpose is to provide a strobe charging circuit, a voltage detection means for detecting the strobe charging voltage and outputting the voltage information, a distance measuring means for measuring the subject distance and outputting the distance information, and a distance measuring means from the distance measuring means. and a judgment in which voltage information from the voltage detection means is inputted, and it is judged whether or not the voltage information is information indicating a voltage level that allows strobe light emission to perform proper exposure, and a judgment level is determined based on the distance measurement information. This is accomplished by a camera with a built-in strobe.

[Detailed description of the invention]

As is well known, the guide number GNo of a strobe is expressed as the product of the distance to the subject and the brightness F of the photographic lens.
On the other hand, when the charging capacity of the strobe capacitor is 01 and the charging voltage is V, it can also be expressed empirically by the following equation.

G No, = 2.42X 10-' x J Cx
V therefore L X F -2,42X 10"x J"CXV
If the following relationship is established, and if the capacitor used is constant and the photographic lens is always used at the maximum aperture ratio, proper exposure will be achieved if flash photography is performed when the charging voltage V corresponding to the distance is reached. This will be obtained.

On the other hand, the power supply voltage V is 3V, and the capacitor capacity C is 225μ.
When looking at a camera with a built-in strobe of about 12 and G No. F, the charging curve of the capacitor exhibits characteristics as shown in FIG. 4, and the charging voltage V is the peak. For example, charging is completed when the voltage reaches 330V, and the shirt release is unlocked only at this time.

As a result, depending on the distance to the subject, the battery may be charged more than necessary, which not only wastes power but also requires a long charging time before the shutter can be operated.

To deal with this problem, in the present invention, the shirt release is unlocked when a charging voltage corresponding to the subject distance is obtained, and when the charging voltage further increases, the aperture control is performed to ensure proper exposure at all times. The structure was designed so that

〔Example〕

An embodiment of the present invention is shown in FIGS. 1-3.

Figure 1 shows the charging and charging of the strobe built into the camera of this embodiment.
Figure 2 shows the circuit configuration of each part of the light emitting block circuit diagram (
A) to FIG. 2(F).

That is, Fig. 2 (A) shows the booster circuit, Fig. 2 (B) shows the voltage detection circuit, Fig. 2 (C) shows the light emitting circuit, Fig. 2 (D) shows the trigger signal generation circuit, and Fig. 2 (E) shows the voltage detection circuit. is the shutter drive circuit,
FIG. 2(F) shows each voltage discrimination circuit.

The camera of the present invention is characterized by an arithmetic control circuit consisting of a voltage discrimination circuit shown in FIG. 2 (F) and a well-known microcomputer shown in FIG. In particular, the charging voltage is set to obtain appropriate exposure based on the calculation result of the charging voltage information from the voltage detection circuit of FIG. 2(B) which is the charging voltage detection means and the distance information from the AF circuit which is the distance measuring means. This is because a determining means is provided which determines whether or not the voltage level reaches a certain voltage level, and determines a determination level as to whether or not the shirt release can be unlocked based on the result.

When the main switch MS shown in FIG. 1 is turned on due to an operation such as pop-up of a strobe light emitter, the transformer of the booster circuit oscillates and charging of the main capacitor of the light emitting circuit begins.

On the other hand, press the first step of the shirt release, that is, switch S.
When t (FIG. 1) is turned on, power is applied to the voltage discrimination circuit, arithmetic control circuit, AF circuit, and aperture control circuit, and each function enters an operating state.

The voltage discrimination circuit receives voltage information from the voltage detection circuit and inputs the charging voltage of the main capacitor into four voltage levels to the arithmetic control circuit.

In other words, the voltage discrimination circuit receives the voltage information input from the terminal g of the voltage detection circuit to its terminal l, and connects the combination of three terminals o, t, and U whose voltage level can be switched to HIGH or LOW as shown in Table 1 with a resistor. Rl, R2
By appropriately setting +Ro, Rt, and Ru, information equivalent to a guide number is output to the arithmetic control circuit.

Table 1 At the same time, distance measurement information of the subject due to the operation of the AF circuit is input to the arithmetic control circuit, and a judgment is made as to whether or not proper exposure is possible using the pre-stored aperture f-number of the photographic lens. If the voltage reaches that level, a release lock release signal is sent to the shutter drive circuit. That is, by setting the terminal V to LOW, a two-stage press of the shirt release, that is, turning on the switch S2, causes a current to flow through the magnet to operate the shutter, and by turning on the X contact, a strobe light is emitted in synchronization with the shutter operation.

Therefore, for example, when the aperture f-number of the photographic lens is 4, and the distance to the subject is 2.5 m, the release lock release signal is output when the charging voltage of the main capacitor reaches GNo. 10, and the switch sl is turned on. This also stops charging the main capacitor.

On the other hand, if it is determined as a result of the arithmetic processing that the charging voltage has not yet reached the level at which proper exposure can be obtained, the arithmetic control circuit maintains the above-mentioned shirt release rotor signal as it is, and at the same time outputs the voltage information from the voltage discrimination circuit as 0. By repeatedly inputting t and u, charging of the main capacitor is continued until voltage information for obtaining proper exposure is obtained.

Further, when the switch Sl is turned on while charging the main capacitor continues for a long time, the electrical current discrimination circuit 6
The electrical signals from the 1.
Since the charging voltage corresponding to 2 is stored, in that case, the shutter lock is naturally released by turning on the switch Sl, and if necessary, the aperture control circuit 9 acts to change the F value of the photographic lens to the above-mentioned value. After narrowing down the image according to the formula, the shutter is operated.

The level of the guide number GNo is determined by the resistances R1 and R2 of the voltage detection circuit and the resistances Ro and Rt of the voltage discrimination circuit.
, Ru can be set to any value corresponding to the strobe capacity.

FIG. 3 shows the front external appearance of the camera with a built-in strobe according to this embodiment.

〔Effect of the invention〕

According to the present invention, the waiting time for strobe charging is greatly shortened, making it possible to perform strobe photography with guaranteed proper exposure within a short period of time.As a result, even general users can fire strobes without missing a photo opportunity. A camera with a built-in strobe that can shoot continuously and consumes little power is now available.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of a strobe of a camera according to the present invention.
Figure 2 (A) to Figure 2 (F) are circuit diagrams of the main parts,
FIG. 3 is a front view of the camera, and FIG. 4 is a charging characteristic curve diagram of the main capacitor of the strobe. Applicant Konica Corporation Figure 2 (A) Figure 2 (C) Figure 2 (D) Figure 12 (B)

Claims (1)

[Claims] A strobe charging circuit, a voltage detection means for detecting the strobe charging voltage and outputting the voltage information, a distance measuring means for measuring a subject distance and outputting distance information, and distance measurement information from the distance measuring means and the voltage detection. A determining means receives voltage information from the means, determines whether or not the voltage information is information indicating a voltage level at which strobe light can be emitted to perform proper exposure, and determines the determination level based on the ranging information. Camera with built-in strobe.