JPH0336989Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device that displays exposure information of a camera using a plurality of light emitting elements, such as seven segment LEDs (light emitting diodes), in the viewfinder of a camera.

Conventionally, as a display device for displaying camera exposure information in the viewfinder of a camera, a display device as shown in the viewfinder field diagram of FIG. 1 has already been proposed. In FIG. 1, F indicates a photographing field frame, and _I1 indicates display information indicating the exposure mode of the camera. _I2 is shooting information determined by shooting conditions, for example, the aperture value of the shooting lens is displayed as "5.6" by a two-digit seven-segment LED.

In the viewfinder display as shown in FIG. 1, there is a limit to the size of the pentaprism, so only the range shown by the dashed-dotted line can be seen through the pentaprism. Therefore, a display with a large width such as the photographing information _I2 needs to be placed as close as possible to the photographing field frame F. By the way, when the photographing field frame F and the photographing information _I2 are placed close to each other, if the brightness within the photographing field frame F is very bright, the two-digit value of the photographing information _I2 may be distorted due to flare caused by diffused reflection of the funda optical system. A phenomenon occurs in which the first digit of the seven-segment LEDs, that is, the LED of the digit closer to the photographing field frame F, appears darker than the second-digit seven-segment LED. In order to solve this problem, a method has been considered in which a large current is passed through the seven-segment LED and the LED is turned on at maximum brightness, but this method requires a large amount of current consumption, and the camera battery is small and has a small capacity. Therefore, the battery life is extremely shortened and the burden on the user is increased. Also, in the above method, the seven segment LED in the second digit is better than the seven segment LED in the first digit.
It looks brighter than LED, and the display becomes unbalanced.

SUMMARY OF THE INVENTION An object of the present invention is to provide an in-viewfinder display device for a camera that eliminates the above-mentioned drawbacks.

In order to achieve the above object, the present invention has a plurality of light emitting elements arranged outside the penta roof prism, which allow the emitted light to enter the penta roof prism and guide it to a position adjacent to the photographing field frame within the viewfinder for visual recognition. and a light emitting element of the plurality of light emitting elements that is guided to a position closer to the viewing frame and is visible is predicted to have a higher luminance than a light emitting element that is guided to a farther position and is visible. The present invention is characterized by a display device in the viewfinder of a camera equipped with a display circuit that sets a luminance ratio to bring the visible luminances of both light emitting elements close to each other.

Hereinafter, embodiments of the present invention will be described based on the drawings.

First, Figure 2 is a layout diagram of the optical system of a single-lens reflex camera to which the present invention is applied.
13 is a rotating mirror, 13 is a focusing plate, 14 is a pentagonal roof prism, and 15 is an eyepiece lens. Subject light passing through the photographing lens 11 is reflected by the rotating mirror 12, and then focused on the focusing plate 13. As is well known, the object image formed on the focus plate 13 is reflected by the pentagonal roof prism 14 and then observed through the eyepiece 15 as a viewfinder field image. 16 is a condensing Fresnel lens, 17 is a light receiving element, and these light receiving systems include a penta roof prism 1.
This is a photometry section disposed above the eyepiece lens 15 toward the exit surface 14b of No. 4. A is an information display body,
A display film 18 of the information display body A is disposed to face the lower side of the bottom surface 14a of the pentagonal roof prism 14.

FIG. 3 is an enlarged exploded perspective view of one embodiment of the information display body A shown in FIG. 2 of the display device according to the present invention.

In the figure, information display symbols 18a, 18b, 18c, and 18d are drawn on the display film 18, such as information display symbols 18a, 18b, 18c, and 18d. Dot LEDs (light emitting diodes) 19a, 19b, 19c, and 19d are bonded on the substrate 20 facing the information display symbols 18a, 18b, 18c, and 18d, respectively. 2
1 is dot LED 19a, 19b, 19c, 19
Information display symbol 18 to which each light of d corresponds
This is a shielding plate provided around each LED to prevent leakage other than LEDs a, 18b, 18c, and 18d. A diffusion tape 22 is provided between the display film 18 and the shielding plate 21, and is used to uniformly illuminate the corresponding information display symbols 18a to 18d with light from the dot LEDs 19a to 19d. Reference numeral 23 denotes a monolithic LED having two digits of seven segments and one dot, which is bonded onto the substrate 20. The shielding plate 21 has a hole 21a in a portion corresponding to the light emitting portion of the LED 23, and is also shielded to prevent light from the LED 23 from leaking toward the display film 18. For this purpose, the display film 18 and the diffusion tape 22 are arranged avoiding the hole 21a. Also, 24 is
LED driver IC for lighting LEDs 19a to 19d and 23 in a timely manner, 25 is a board 20
This is a flat cable for connecting the camera to other circuits (not shown).

The display effect of this embodiment with the above configuration will be explained.

As a shooting mode selected according to shooting conditions,
For example, when shutter priority mode is selected, the LED
19b emits light, the light is restricted by the shielding plate 21 and diffused by the diffusion tape 22, and the light is transmitted to the display film 1.
The display information light from the display symbol 18b enters from the bottom surface 14a of the pentagonal roof prism 14 and passes through the same optical path as the photographing field light, and is then illuminated uniformly. As shown in the viewfinder field diagram, the display information "T" is displayed on the side of the photographing field frame F as display information _I1 .

In addition, as shooting information determined by shooting conditions, for example, the aperture value of the shooting lens is determined by the electronic circuit described later, and the 7-segment LED 23 emits and displays "5.6", and the light from the LED 23 is transmitted through the penta roof prism as described above. 14 bottom 14
As shown in Fig. 1, the shooting field frame F
"5.6" is displayed below the display information I ₁ on the side of the display information I ₂ .

On the other hand, when the aperture priority mode is set using an external operation member (not shown), the LED 19c lights up and illuminates the display symbol 18c "A" on the display film 18 in the same way as described above, and the subject brightness is measured by the light receiving element 17, which will be described later. As a result of calculation using the electric circuit, if the shutter time is between 2 seconds and 1/90 seconds, the calculated value of the shutter time will be displayed every 0.5 steps with a 7-segment LED 2.
Displayed at 3. In the case of high-speed seconds of 1/125 seconds or more, 1/125 seconds, 1/180 seconds, and 1/250 seconds are "HL", and 1/350 seconds, 1/500 seconds, and 1/750 seconds. , 1/1000
When seconds are indicated, an abbreviation such as "HH" is displayed on the 7-segment LED 23.

Next, one embodiment of an electric circuit for operating such a display device will be described with reference to the block diagram shown in FIG.

In the figure, 30 is a photometric circuit that measures the brightness of the subject through a lens, prism, etc.
Photoelectric conversion is performed by a light receiving element such as a cell). 31 is an A/D converter that repeatedly converts the photometric output voltage of the photometric circuit 30 into a digital pulse number at a predetermined period. 32 is a film sensitivity (ISO) information pulse code plate which outputs a pulse code corresponding to the film sensitivity set with an ISO dial (not shown).
33 is a lens aperture F-number information pulse code plate which outputs a pulse code corresponding to the aperture F-number of the lens attached to the camera. 34 is a shutter speed information pulse code plate which outputs a pulse code corresponding to the shutter speed set with a shutter dial (not shown). 35 is the shooting mode setting switch,
Consists of a 2-bit switch, manual M,
Switch and select shooting modes such as aperture priority A and shutter priority T. 36 is an APEX calculation circuit, A/D
Information necessary for the shooting mode set by the shooting mode setting switch 35 is digitally calculated based on the subject brightness information from the converter 31 and each setting information of the pulse code plates 32, 33, 34 and the aperture pulse code plate 46 (to be described later). ,Output. A decoder 37 decodes the 2-bit information of the setting switch 35 and selects one output line corresponding to the set photographing mode from among the 4-bit output lines. 39 is
In the LED drive circuit, the display dot LEDs 38a, 3
Supply current to 8b, 38c, and 38d to light them. The display dot LEDs 38a, 38b, 38
c and 38d are dot LEDs 19a and 38d shown in FIG.
19b, 19c, and 19d, respectively. 4
0 is a digital memory circuit, APEX calculation circuit 3
6 is temporarily stored at predetermined intervals. 41 is a data selector, and a digital memory circuit 40
The information (calculated value) from the APEX calculation circuit 36 via the shutter speed information pulse code board 34 settings or the aperture settings information of the aperture pulse code board 46 are sent to the _Av register 42 and shutter speed information according to the shooting mode. For example, in the shutter priority shooting mode, the shutter time information (T v ) from the shutter time information pulse code board 34 and the calculation information (E _{v )} of the APEX calculation circuit 36 are sent to the T _v register 43, respectively. It is sent to the A _v register 42 and the T _v register 43. The _Av register 42 and the _Tv register 43 store pulses corresponding to the aperture value information and shutter time information from the data selector 41, respectively, and also when the subject brightness is dark, the aperture value and shutter time are When each goes out of the control range, both output overflow. 44 is an OR gate which outputs a high level when an overflow output is received in either the A _v register 42 or the T _v register 43, and sends the signal to the LED drive circuit 39. 45
is a coincidence circuit which sends a signal to the aperture control circuit 47 when the digital values of the _Av register 42 and the aperture pulse code plate 46 match.

The aperture pulse code plate 46 outputs a pulse corresponding to the aperture value of the lens, and the aperture control circuit 47 outputs a pulse that corresponds to the aperture value of the lens, and the _aperture control circuit 47 outputs a pulse that corresponds to the aperture value of the lens. When the contents of the pulse code plate 46 match, the aperture control magnet 48 is controlled based on the signal from the matching circuit 45. Further, when manual photography is selected by the photographing mode setting switch 35, the aperture control circuit 47 is deactivated by a signal from the decoder 37, and the aperture is manually adjusted.

49 is a release sequence circuit, which activates the aperture pulse code plate 46 when the release switch 50 is turned on.
In addition to instructing the sliding of the camera and the operation of the aperture control circuit 47, it also sequentially controls each part of the camera (not shown). The release switch 50 is linked to the pressing of the second stroke of a release button (not shown).The aperture control magnet 48 is controlled by the aperture control circuit 47 as described above, and stops the sliding of the aperture pulse code plate 46. , make the aperture value of the lens match the calculated value. 51 is a clock pulse oscillator which outputs a reference pulse. Reference numeral 52 denotes a dividing period, which divides the clock pulse from the clock pulse oscillator 51 into a predetermined frequency. 53 is a shutter seconds expansion circuit which expands the digital value of the Tv _register 43 to shutter seconds based on the output of the frequency divider 52. Reference numeral 54 denotes a shutter control circuit which controls a shutter driving magnet 55 using the output of the shutter speed expansion circuit 53. The shutter drive magnet 55 controls a shutter (not shown). 56
a and 56b are decoders that output the digital values (2) of the A _v register 42 and T _v register 43, respectively.
It converts the 7-segment display code of the 7-segment LED 58, and its operation is controlled by the anode voltage of the LED 38c.
The decoder 56 only when the anode voltage is at a high level.
b is activated, and when the level is low, the decoder 56a is activated. 57 is an LED drive circuit, and a decoder 56a
and 7 segment LED5 based on the output of 56b
Supply current to 8 and display the lighting. The 7-segment LED 58 is the 7-segment LED shown in FIG.
23, the aperture value, shutter seconds, and abbreviations corresponding to the shutter seconds are displayed. 59 is an inverter whose output controls the operation of the decoder 56a.

The operation of the electric circuit configured as above will be explained.

By pressing the first stroke of a shutter button (not shown), current is supplied from the power supply to each predetermined part, and a voltage corresponding to the subject brightness is output from the photometry circuit 30. The voltage is repeatedly A/D converted at a predetermined period by the A/D converter 31, and the voltage is converted into a number of pulses. In other words, as an APEX value
The number of pulses corresponding to B _v −A _v0 is output. This number of pulses is calculated by the APEX calculation circuit 36 from the film sensitivity information pulse code plate 32 and the lens opening F-number information pulse code plate ₃₃ , respectively.
It is calculated as A _v0 , (B _v −A _v0 ) + S _v + A _v0 , i.e.
E _v is calculated, and this E _v is further calculated with the signal T _v of the shutter time information pulse code plate 34 or the signal A _v of the aperture pulse code plate 46 depending on the photographing mode. For example, when shooting with shutter priority, this
E _v and the signal T _v of the shutter time information pulse code plate 34 are calculated (E _v −T _v =A _v ), and a pulse corresponding to A _v is output from the APEX calculation circuit 36 .

The above-mentioned calculation contents according to the photographing mode are determined by the photographing mode setting switch 35. The pulses output from the APEX calculation circuit 36 according to the shooting conditions and shooting mode are sent to the digital memory circuit 40.
and is transmitted to the data selector 41 based on the stored value. For example, in the shutter priority shooting mode, the shutter second information pulse code plate 3
The number of pulses corresponding to the signal T _v from 4 is sent to the T _v register 43 via the data selector 41, and the number of pulses corresponding to A _v calculated from the subject brightness, film sensitivity, and shutter speed is sent to the APEX calculation circuit 3.
6→digital memory circuit 40→data selector 41→ _Av register 42.
Here, the values of registers 42 and 43 are shutter seconds,
If the aperture value is outside the control range, the register 42,
An overflow output is generated from either or both of the gates 43 and sets the OR gate 44 to a high level.

By the way, the dot LEDs 38a, 38b, 38
Regarding the display consisting of c and 39d, an output is output from one output line selected from the decoder 37 according to the shooting mode set by the shooting mode setting switch 35, and the signal causes the dot LED 38 to be output.
The LED drive circuit 39 operates so that one of the lights a to 38c lights up. For example, when the shutter priority shooting mode is selected, the LED 38b lights up, and when the aperture priority shooting mode is selected, the LED 38c lights up. Also, as mentioned above, when the shutter speed or aperture value is outside the control range, the high level signal of the OR gate 44 is
Applied to the LED drive circuit 39, the LEDs 38a to 3
The LED drive circuit 39 operates so that the LED 38d lights up as a warning in addition to one of the LEDs 8c lighting up.

Next, the aperture control will be explained. When the release switch 50 is turned on in conjunction with pressing the second stroke of the release button, the release sequence circuit 49 instructs the aperture control circuit 47 to operate. In accordance with the command, the aperture control magnet 48 is energized, and at the same time, the aperture of the lens moves, for example, from the open side to the small aperture side, and in conjunction with this, the number of pulses on the aperture pulse code plate 46 changes. The aperture pulse code plate 46 corresponds to the aperture value of the lens, so when the number of pulses matches the number of pulses in the _Av register 42, the matching circuit 45 detects this and sends the aperture control circuit 47 to the magnet 48. When the magnet 48 is de-energized, the aperture of the lens stops moving and is fixed at that aperture value.

Regarding shutter time control, the number of pulses in the Tv _register 43 is expanded by a shutter time expansion circuit 53 based on the output of a frequency divider 52 which divides the reference clock pulse from a clock pulse oscillator 51.
A shutter driving magnet 55 is driven by the expansion signal via a shutter control circuit 54, and a shutter (not shown) is controlled.

Regarding the display of the 7-segment LED 58, if shutter priority or manual shooting mode is selected by setting the shooting mode setting switch 35, no current flows to the dot LED 38c, and therefore the output of the inverter 59 becomes a high level. . Therefore, the decoder 56a connected to the output side of the inverter 59 operates, and A _v
7 segment LED for binary code of register 42
58 to a 7-segment display code, and the value, that is, the calculated aperture value, is sent to the LED drive circuit 57.
is displayed on the 7-segment LED 58. However, the decoder 56b does not operate at that time.

Next, when the aperture priority shooting mode is selected using the shooting mode setting switch 35, the dot LED 38c
lights up and its anode terminal becomes high level, so the decoder 56b operates and the inverter 59
The output of the decoder 56a becomes low level and the decoder 56a becomes inactive. By operating the decoder 56b,
The contents of the binary code of the T _v register 43 are converted into a 7-segment display code of the 7-segment LED 58, and the converted value is displayed on the 7-segment LED 58 via the LED drive circuit 57.

The display content is that the T _v register 43 is 2.
If the number of pulses corresponds to a shutter time of ~1/90 seconds, the value is displayed every 0.5 steps on the 7-segment LED5.
8, and if the number of pulses corresponds to the shutter speed of 1/125 seconds, 1/180 seconds, or 1/250 seconds, the abbreviation "HL" will be displayed on the 7-segment LED 58, and 1/350 seconds will be displayed.
If the number of pulses corresponds to seconds, 1/500 seconds, 1/750 seconds, or 1/1000 seconds, use the abbreviation "HH" in 7 segments.
Display on LED58.

The circuit for displaying the 7-segment LED 58 will be explained using the electric circuit shown in FIG.

In FIG. 5, the A _v register 42 consists of 4 bits, and the T _v register 43 consists of 5 bits.
The decoder 56a consists of a 4-bit decoder _56a1 that operates only when its EN terminal is at a high level, and a display matrix decoder, and the decoder 56b consists of a 5-bit decoder _56b1 that operates only when its EN terminal is at a high level, and a display matrix decoder. It consists of a Tux decoder. The circles on these display matrix decoders indicate where the vertical and horizontal lines are conductive, and the output lines Sa, Sb, Sc, Sd, Se, Sf,
Sg, Sh, Si, Sj, Sk, Sl, Sm, Sn, So are LEDs
7 segments each via the drive circuit 57
Segments a, b, c, d, e, f of LED58,
Connected to g, h, i, j, k, l, m, n, and o. 56b ₂ inputs three of the 5-bit decoder 56b ₁ : 1/125 seconds, 1/180 seconds, and 1/250 seconds.
OR gate, 56b ₃ is 1/350 second, 1/500 second,
This is an OR gate that inputs four values: 1/700 second and 1/1000 second.

In the shutter priority or manual shooting mode, as described above, the input of the inverter 59 is at a low level, so the EN terminal of the 5-bit decoder _56b1 becomes a low level, and the decoder _56b1 becomes inactive.
Since the output of the inverter 59 becomes high level, the EN terminal of the 4-bit decoder _56a1 also becomes high level.
The decoder _56a1 is activated, decodes one aperture value corresponding to the aperture value from the 4-bit binary code of the _Av register 42, and sets its output line to a high level. For example, if the _Av register 42 outputs a code corresponding to F5.6, the 4-bit decoder 5
6a ₁ sets only the output line of F5.6 to high level, and displays 7 segment LED58 in the display matrix decoder.
Segments a, c, d, f, g, h, i, j,
Light up k, n and o.

During aperture priority, the input to the inverter 59 is at a high level, so the 4-bit decoder _56a1 is inactive and the 5-bit decoder _56b1 is active.
One shutter second corresponding to the shutter second is decoded from the 5-bit binary code of the _Tv register 43, and its output line is set to high level. For example, when the _TV register 43 outputs a code corresponding to 1/30 second, the 5-bit decoder _56b1 sets only the 1/30 second output line to high level, and the display matrix decoder outputs the segment c of the 7-segment LED 58. , d, e, f, g, h, i, j, k, l, and m. Also, T _v register 43 is 1/125
When a code corresponding to a second, 1/180 second, or 1/250 second is output, the OR gate _56b2 outputs a high level, and the display matrix decoder selects segments a and b of the 7-segment LED 58. ,d,
Light up e, g, h, i, j and o and press "HL"
Display. Also, the T _v register 43 is 1/350 seconds,
If a code corresponding to 1/500 second, 1/750 second, or 1/1000 second is output, OR gate 56
b ₃ outputs a high level, and the display matrix decoder selects segments a and 7 of the 7-segment LED 58.
Light up b, d, e, g, h, i, k, l, n and o to display "HH".

When lighting each segment of the 7-segment LED 58, segments a to o are not lit at once, but the signal lines Sa to So are dynamically scanned, and when one segment of the 7-segment LED 58 is lit, the other segments are All segments are configured so that they are not lit, and the brightness of the LED 58 does not change depending on the number of segments a to o that are lit.

Further, the current control circuit in the LED drive circuit 57 is configured as shown in FIG. In Figure 6,
The output lines Sa to So in Figure 5 are transistors Tra to Tro.
are connected to their respective bases.

60 is a constant voltage circuit, which includes transistors Tr ₁ to _{Tr 3}
and a semi-fixed resistor _R1 constitute a constant current circuit.

7 segments by transistors Tr ₁₁ to Tr ₁₄
The current supplied to segments a to g of the LED 58 is controlled, and the transistors Tr ₁₅ to _{Tr 17} control the current supplied to segments h to o.
The current to the segment is controlled.

The ratio of the amount of current supplied to segments a to g and the amount of current supplied to segments h to o is as follows: transistors Tr ₁₁ to _{Tr 14} are connected to transistors Tr ₁₅ to Tr ₁₇ as shown in the figure. Therefore, the ratio is 4:3, and the setting is made so that the current supplied to the segments a to g is larger than that of the segments a to g.

As a result, segments a to g of the 7-segment LED 58, that is, the photographing field frame F (see Fig. 1)
Segments a to g forming the display digit closest to are set to have higher luminance than segments h to o.

So, for example, if the Av register 42 is
Output the code corresponding to F5.6 and 7 segments
Segments a, c, d, f, g, h of LED58,
When i, j, k, n, and o are lit, the display digit on the side of the photographing field frame F, that is, the number "5" has higher brightness than the number "6" on one display digit.

Therefore, even if the photographer looks through the viewfinder when the field of view is very bright, the visible brightness of the number "5" has been brought closer to the visible brightness of the number "6", so a well-balanced display inside the viewfinder can be achieved. This is something that can be provided. Also, the above number “6” forming the shooting information (the one farther from the shooting field frame F)
Since the 7-segment LED does not flow a large current, the life of the power battery can be extended.

In the above embodiment, the photographic information has two digits, but it goes without saying that the present invention can also be applied to cases where the number of digits is four or more.

Furthermore, although the above embodiment was an example of a display device using a 7-segment LED, when a liquid crystal display device is used as the display device, a light emitting element, such as a light emitting diode ( The above purpose can be achieved by setting the LED of the digit closest to the photographing field frame among the LEDs to have the maximum brightness, and decreasing the brightness of the LED of each digit as the distance from the photographing field frame increases.

As explained above, the present invention directs light emitted from a plurality of light emitting elements through the penta roof prism to a position close to the photographing field frame in the viewfinder to which the subject image reflected by the penta roof prism is guided. Also in the viewfinder display device, the luminance ratio is set in advance so that the luminance of the first light emitting element that is visible at a position close to the photographic field frame is higher than that of the second light emitting element that is visible at a far position. is set so that the visible brightness of both light-emitting elements is close even when the shooting field frame is bright, making it possible to provide a well-balanced display in the viewfinder, and also consume less current than conventional methods. This makes it possible to extend the life of the power supply battery.

[Brief explanation of the drawing]

Figure 1 is a viewfinder view of a conventional camera using 7-segment LEDs, Figure 2 is a layout diagram of the optical system of a single-lens reflex camera according to the present invention, and Figure 3 is an enlarged exploded perspective view of the information display shown in the second figure. 4 is a block diagram of an electric circuit for operating the information display of the camera display device shown in FIG. 2, FIG. 5 is a circuit diagram for a 7-segment LED display, and FIG. FIG. 2 is a circuit diagram of an embodiment of the dot LED driving circuit in the electric circuit shown in the figure. In the figure, 57...LED drive circuit, 58...
...7 segment LED, Tr ₁₁ ~ Tr ₁₇ , Tra ~ Tro...
...It's a transistor.

Claims (1)

[Scope of Claim for Utility Model Registration] In a camera viewfinder display device for displaying exposure information in close proximity to a photographing field frame in a viewfinder to which a subject image reflected by a penta-roof prism is guided, the display device is arranged outside the penta-roa prism. a first light-emitting element arranged outside the penta-roof prism to make the emitted light enter the penta-roof prism and guide it to a position adjacent to the photographing field frame in the viewfinder for viewing; Injecting light into the pentagonal roof prism and guiding the emitted light to a position adjacent to the visible position of the light of the first light emitting element within the viewfinder and further away from the field frame for visual recognition. a plurality of light emitting elements having at least a second light emitting element; a brightness ratio is set in advance so that the luminance of the first light emitting element is greater than that of the second light emitting element; 1. A display device in a viewfinder of a camera, characterized in that a display circuit is provided in which the visible brightness of a first light emitting element and a second light emitting element are brought close to each other.