JP3460886B2 - Camera with date imprint function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera with a date imprinting function, and more particularly to a camera with a date imprinting function capable of adjusting an exposure amount at the time of imprinting a date.

[0002]

2. Description of the Related Art In general, a camera with a date imprinting function of this kind, when imprinting a shooting date on each frame, records an appropriate density (ie, , A fixed standard date imprint exposure amount) is used to imprint the date.

[0003]

However, when the brightness of the subject is low and the image is out of the strobe range,
Although underexposure occurs, the density of the date imprinted by the date imprinting device is constant.Therefore, such an underexposed negative film is electrically detected and the exposure amount on the photographic paper is automatically adjusted. If the subject is printed with appropriate brightness, the date becomes too bright, resulting in a photograph with the date emphasized.

The present invention has been made in view of the above circumstances, and a camera with a date imprinting function capable of imprinting a date having a proper density on the brightness of a photograph even when the exposure is insufficient. The purpose is to provide.

[0005]

In order to achieve the above object, the present invention is a date imprinting means for imprinting a photographing date on a frame for each frame photographing, and an exposure amount when the date is imprinted. Adjustable date imprinting means and str
Measuring means for measuring underexposure during robo photography, and when the measuring means measures underexposure, the exposure amount by the date imprinting means is adjusted so as to be smaller than the standard date imprinting exposure amount. It is characterized by having an adjusting means.

[0006]

According to the present invention, the underexposure during flash photography is measured, and when the underexposure is measured, the exposure amount by the date imprinting means is adjusted to be smaller than the standard date imprinting exposure amount. I am trying to do it. As a result, even if the underexposed negative film is printed on the photographic paper so that the subject has an appropriate brightness, the date does not become too bright and the brightness of the photograph and the brightness of the date are balanced. I am trying.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a camera with a date imprinting function according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of the circuit configuration of a camera with a date imprinting function according to the present invention. The circuit of this camera is mainly composed of a central processing unit (CPU) 10, a power source 12 connected to the CPU 10 and an exposure control circuit 1.
4, a film feeding control circuit 16, a photometry circuit 18, a strobe circuit 20, a distance measurement circuit 22, a date imprinting circuit 24 and the like.

The CPU 10 determines the shutter speed and diaphragm based on the values of the subject brightness and the film sensitivity input from the photometry circuit 18 at the time of shooting, and outputs an output signal for driving the exposure control circuit 14. The exposure control circuit 14 controls the determined shutter speed and aperture, and the film feeding control circuit 16
Controls film feeding and film rewinding after shooting.

The CPU 10 has a strobe circuit 20,
A distance measuring circuit 22 including a focus sensor is connected, the strobe circuit 20 controls the light emission of the strobe based on a command from the CPU 10, and the distance measuring circuit 22 controls the focus adjustment of the photographing lens. Further, the CPU 10 is connected with a date imprinting circuit 24 for imprinting the date of photographing on the film,
As will be described later, the date is imprinted on the film according to a command from the CPU 10.

FIG. 2 shows a cartridge chamber 26, a film winding chamber 28, and an aperture (screen frame) on the rear surface of the camera body shown in FIG.
It is explanatory drawing which showed the positional relationship with 30. As shown in FIG. 2, a light emitting element (LED) 24A of a date imprinting circuit 24 for recording the date on the film surface is provided on the side of the aperture 30 inside the camera. LED24A
Displays the date in dot matrix format on the shooting screen in synchronization with the film feeding. That is, the LED 24A is
Based on the film feed amount detected by the film feed amount detection circuit 16A, light emission is controlled in a predetermined recording pattern to imprint the date. Also, the light emission time of the LED 24A is
As will be described later, it is controlled so that a predetermined date imprint exposure amount can be obtained.

Next, the operation of the CPU 10 will be described in detail with reference to the flowchart shown in FIG. First, when the power switch is turned on, initial processing such as clearing the memory built in the CPU 10 and setting the I / O port is performed (step S10). Then, the process waits until one of the various operation switches is activated (step S12). The switches include a self-timer switch and a zoom switch in addition to the shutter button. When any switch is activated (step S14), which switch is activated is detected (step S16), and in the case of a switch other than the shutter button, processing for each switch is performed.

When it is detected in step S16 that the shutter button is half-pressed (signal SP1), the remaining amount of the power supply battery is checked (step S18). continue,
A signal from the CPU 10 is given to the photometric circuit 18, and the photometric circuit 18 measures the external light luminance within the photographing field (step S20). Further, the signal from the CPU 10 is given to the distance measuring circuit 22, and the distance measuring circuit 22 measures the distance to the subject (step S22). And step S
The apex value (BV) of the external light luminance and the apex value (SV) of the film sensitivity obtained in 20 are substituted into the following equation,
An exposure value EV, which is a shutter control value, is calculated (step S24).

EV = SV + BV ... By the calculation of the EV value, the combination of the shutter speed and the aperture value for obtaining the exposure amount necessary for photographing is determined. Next, in step S26, the exposure time and the like at the time of date imprinting are determined according to the flowchart shown in FIG.

That is, in step S261 of FIG. 4, the aperture value AV is obtained by the following equation: AV = GV + SV + DV-5. In this equation, SV represents the film sensitivity, and DV and GV are obtained by substituting the distance (D) to the subject into the following equation and the guide number (GNo.) Into the following equation, respectively.

DV = -2log ₂ D ... GV = 2log ₂ GNo. Next, it is determined whether or not the aperture value AV obtained in step S261 is smaller than the maximum aperture value (AV0) (step S262). If AV <AV0, the aperture value AV 'is determined to be AV0. Yes (step S263).

Subsequently, the apex value BV of the external light luminance obtained in step S20 is compared with the apex value BV0 indicating a low luminance in which the subject luminance almost depends on the stroboscopic light (step S264). If BV <BV0 , The difference between the aperture value AV obtained by the equation and the maximum aperture value AV0 is obtained by the following equation: dAV = AV−AV0 ... (Step S265). In this case,
dAV has a negative value.

By the way, when dAV takes a negative value,
Since the exposure is insufficient, the date imprinting circuit 2 is used in the present invention.
The exposure amount by 4 is also adjusted so as to be smaller than the standard date imprinting exposure amount. That is, assuming that the standard date imprint exposure amount is Hd0, the exposure amount Hd by the date imprinting circuit 24 is adjusted to be the following expression, Hd = Hd0 × 2 ^dAV . Here, the exposure amount may be adjusted by adjusting the light emission amount (luminance) or adjusting the exposure time. In the present embodiment, the exposure time T _DATE is ^calculated by the following equation: T _DATE = T ₀ × 2 ^dAV Is calculated (step S266), and the exposure amount is adjusted according to the calculated exposure time T _DATE . In the equation, T ₀ is the exposure time required to obtain the standard date imprint exposure amount.

On the other hand, in step S262, AV ≧
If AV0, it is determined whether AV> AV (MAX) (step S267). If AV> AV (MAX), then
The aperture value AV 'is determined to be AV (MAX) (step S26).
8). If AV ≧ AV0, or BV ≧ BV0
In this case, T ₀ is set as the exposure time T _DATE (step S269).

Next, in FIG. 3, it is detected that the shutter button is half-pressed (signal SP1) (step S2).
8) Furthermore, the shutter button is fully pressed (signal
When SP2) is detected (step S30), the shutter is opened / closed and strobe light is emitted to take a picture (step S32). Then, the film is fed for feeding one frame and the date is imprinted (step S34). That is, as shown in the flow chart of FIG. 5, it is determined whether or not the energization of the motor is started to feed one frame (step S341), and the signal indicating the feed amount of the predetermined pitch required for date imprinting is detected. Yes (step S342).

Here, when the feed amount signal is detected, it is judged whether or not one frame feed is completed (step S34).
3) If the one-frame feed is not completed, it is further determined whether or not the date imprinting is completed (step S3).
44). If the date imprinting is not completed, the LED 24A of the date imprinting circuit 24 is turned on (step S345), and it is determined whether or not a predetermined exposure time T _DATE (see FIG. 4) has elapsed (step S346). ).

When the exposure time T _{DATE has} elapsed, the LED2
4A is turned off (step S347), and step S342.
Then, the feed amount signal is detected again here. In this way, the date of the dot matrix system is imprinted on the photographing screen in synchronization with the film feeding. Then, it is determined that the date imprinting is completed (step S34).
4) If it is further determined that the one-frame feeding is completed (step S343), the power supply to the motor is terminated (step S348).

Thereafter, as shown in FIG. 3, the strobe is charged (step S36), and in step S38,
When the shutter button is returned (that is, when the half-pressing of the shutter button (signal SP1) is not detected), the process returns to step S12 for performing the standby process. In this embodiment, the exposure amount at the time of imprinting the date is adjusted by controlling the exposure time by the LED, but the present invention is not limited to this, and the light emission amount (luminance) may be adjusted. Good. Further, the date imprinting means is not limited to one in which LEDs are arranged in a line, and date imprinting may be performed via, for example, a segment type liquid crystal display unit.

[0023]

As described above, according to the camera with the date imprinting function of the present invention, when the negative film is underexposed, the density of the date printed on the negative film is also lower than the normal density. Therefore, even if the underexposed negative film is printed on the photographic paper so that the subject has an appropriate brightness, the date will not be too bright and the balance between the brightness of the photo and the brightness of the date I am trying to get it.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a circuit configuration of a camera with a date imprinting function according to the present invention.

2 is an explanatory diagram showing a positional relationship between an aperture portion of the camera of FIG. 1 and a date imprinting device.

FIG. 3 is a flowchart used to explain the operation of the CPU of FIG.

FIG. 4 is a flowchart showing details of a process of calculating an exposure time in FIG.

FIG. 5 is a flowchart showing details of a process of performing film feeding and date imprinting in FIG.

[Explanation of symbols]

10 ... Central processing unit (CPU) 16 ... Film feeding control circuit 16A ... Film feed amount detection circuit 18 ... Photometric circuit 20 ... Strobe circuit 22 ... Distance measuring circuit 24 ... Date imprinting circuit 24A ... LED

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-20838 (JP, A) JP-A-61-59438 (JP, A) JP-A-7-120830 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03B 17/24

Claims (3)

(57) [Claims] 1. A date imprinting means for imprinting a photographing date on each frame for each frame photographing, the date imprinting means capable of adjusting an exposure amount at the time of imprinting the date, and a stroboscopic photographing mode at the time of stroboscopic photographing. Measuring means for measuring the underexposure, when the underexposure is measured by the measuring means, an exposure amount adjusting means for adjusting the exposure amount by the date imprinting means to be less than the standard date imprinting exposure amount, A camera with a date imprint function that is equipped with. 2. The measuring means sets the aperture value set by the strobe guide number and the subject distance to AV when the subject luminance is low depending on the strobe light.
The date imprinting function according to claim 1, wherein when the open aperture value is AV0, the difference dAV is obtained by the following equation: dAV = AV-AV0, and is measured as underexposure when the dAV becomes negative. With camera. 3. The exposure amount adjusting unit sets the exposure amount Hd when the standard date imprint exposure amount is Hd0 so that the exposure amount Hd when the dAV becomes negative is expressed by the following equation: Hd = Hd0 × 2 ^dAV. The camera with a date imprinting function according to claim 2, wherein the camera is adjusted.