GB2148519A

GB2148519A - Camera display

Info

Publication number: GB2148519A
Application number: GB08420960A
Authority: GB
Inventors: Eiichi Tano
Original assignee: Asahi Kogaku Kogyo Co Ltd
Current assignee: Pentax Corp
Priority date: 1983-09-14
Filing date: 1984-08-17
Publication date: 1985-05-30
Also published as: DE3431264A1; JPS6060631A; DE3431264C2; FR2551893B1; FR2551893A1; GB8420960D0; GB2148519B

Abstract

A camera has means for manually setting film sensitivity data, means for automatically reading film sensitivity data when provided on a film cartridge, and means for automatically displaying the read film sensitivity data of the manually set film sensitivity data if no sensitivity data can be read. The display is digital. Manual setting may be with the aid of switches which increment or decrement a counter. The read data may be in the form of a pattern of conductive areas 3, 5 and 10. The display may indicate whether film sensitivity data can be read. Shutter speed and aperture may also be displayed. <IMAGE>

Description

SPECIFICATION Display device for camera The present invention relates to a display device for displaying the sensitivity of a film loaded iri a camera.

Heretofore, it has been the practice to provide a film sensitivity setting dial to set a film sensitivity in an analog mode or in a digital mode. In the analog mode, the film sensitivity setting dial is turned to set the resistance of a variable resistor, and film sensitivity data corresponding to the resistance thus set is applied to an exposure calculation control circuit. In the digital mode, the film sensitivity setting dial is turned to set the film sensitivity data in the form of a bit pattern (digital code) using switches, and the data thus inputted is supplied to the exposure calculation control circuit.

Recently, a film sensitivity reading device has been proposed which operates using the digital mode wherein the film sensitivity data is read from a bit pattern recorded on a film cartridge. This device is advantageous in that employment thereof completely eliminates the manual film sensitivity setting operation.

Moreover, the conventional device operating in the analog mode suffers from a difficulty that film sensitivities marked on the film sensitivity setting dial are rather difficult to read. In setting a film sensitivity, the photographer must turn the film sensitivity setting dial until the film sensitivity of the film being used is aligned with the index. For instance, if the camera is designed to accommodate film sensitivities in a range of 25 to 5000 with a step size of 1/3 EV, the number of steps is twenty-four, and therefore, the digits marked on the dial to represent the film sensitivities must necessarily be small.

In view of the foregoing, an object of the invention is to provide a display device for a camera in which the film sensitivity can be readily read by the photographer, not only when the film sensitivity is recorded on the film cartridge, but also when the film sensitivity is manually set.

According to this invention there is provided in a camera having manual setting means for manually setting a film sensitivity and reading means for reading film sensitivity data provided on a film cartridge, a display device comprising: means for discriminating whether film sensitivity data is recorded on a film cartridge loaded in said camera; a display unit for displaying digits according to said output selected by said selecting means; and drive circuit means for driving said display unit according to said output selected by said selecting means.This invention will now be described in more detail, by way of example, with reference to the drawings in which Fig. 1 is a diagram showing a film cartridge used with a display device according to the invention; Fig. 2 is a block diagram showing a first example of a display device according to the invention; Fig. 3 is a block diagram showing a second example of a display device according to the invention; Fig. 4 is a circuit diagram, partly as a block diagram, showing the second example of Fig.

3 in more detail; Fig; 5 is a table indicating film sensitivities with numerical data set for recording areas on a film cartridge; Fig. 6 is a table indicating aperture values with input signals to a ROM in Fig; 4; Fig. 7 is a table indicating shutter speeds with input signals to the ROM; and Fig. 8 is a table indicating film sensitivities with input signals to the ROM.

Fig. 1 is a schematic diagram showing a film cartridge used in the practice of the invention. The film cartridge has recording areas 1 through 1 2 in which a film sensitivity, number of frames and film latitude are recorded. The recording areas 1 through 1 2 are formed, for instance, by dividing an electrically conductive sheet into twelve areas, which are selectively coated with insulating material according to the data to be recorded.

In Fig. 1, the recording areas 3, 5 and 10 are coated with insulating material; The boundaries between the recording areas 1 through 1 2 are indicated by broken lines.

In this example, the recording areas 1 and 7 are exposed irrespective of the type of the film 1 3. The recording areas 2 through 6 form a film sensitivity recording section S, and are selectively coated with the insulating material according to the film sensitivity. More specifically, the recording areas 2 through 6 are coated with the insulating material selectively according to a table shown in Fig; 5; In Fig. 5, "1" represents that the respective recording area is not coated with insulating material, thus providing a logically high potential, and "0" represents that the respective recording area is coated with insulating material, thus providing a logically low potential.

The recording areas 8, 9 and 10 form a numberof-frames recording section N, and the recording areas 11 and 1 2 form the latitude recording section L.

Fig. 2 is a block diagram showing a first embodiment of a display device of the invention; In Fig. 2, a discriminating unit 14 operates to discriminate whether or not film sensitivity data is recorded on the film cartridge in use. The output signal of the discriminating unit 1 4 is applied to the control terminal CONT of a selector 1 6. A reading unit 1 5 operates to read the film sensitivity data on the film cartridge. The output signal of the reading unit 1 5 is supplied to an input terminal INI of the selector.The output signal of manual setting device 1 5a used to manually set in the film sensitivity is applied to an input terminal IN2 of the selector 1 6. The selector 1 6 operates to select as its output the output of one of the manual setting device 1 5a and the reading unit 1 5 according to the output of the discriminating unit 14.

The film sensitivity data outputted by the selector 1 6 is applied to an exposure calculation control circuit 1 7 and a drive circuit 1 8, the latter operating to cause a display unit 1 9 to display the film sensitivity. In other words, when the discriminating unit 14 detects the fact that film sensitivity data is recorded on the film cartridge, the film sensitivity data (2...6) is read by the reading unit 1 5 and outputted by the selector 1 6. On the other hand, when the discriminating unit 1 4 detects the fact that no film sensitivity data is recorded on the film cartridge, the output signal (2a...6a) of the manual setting device 1 5a is outputted.Thus, the display unit 1 9 displays the film sensitivity data according to the output of the discriminating unit 14.

Fig. 3 is a block diagram showing a second embodiment of the invention. In this embodiment, in addition to the film sensitivity, the shutter speed or aperture value is displayed.

In Fig. 3, a drive circuit 1 8a receives shutter speed or aperture value data from the exposure calculation control circuit 17, film sensitivity data from the selector 16, and a signal from the discriminating unit 1 4. A film sensitivity displaying switch S1 is operated by the photographer to select which of the photographing data, namely, the shutter speed, aperture value, or film sensitivity, should be displayed on a display unit 1 9a. the switch S1 is turned on to display the film sensitivity.

The display unit 1 9a may be a segmenttype display in which numeral segments are turned on or off (illuminated or extinguished) selectively, according to the output signal of the discriminating unit 14, to display not only digits but also a decimal point, which is needed for displaying aperture values, F1.4 for instance. The display units 1 9 and 1 9a are different from each other in that, while the diaplay unit 1 9 in Fig. 2 displays only digits, the display unit 1 9a in Fig. 3 displays also a decimal point. However, the display unit 1 9 in Fig. 2 may be replaced by the display unit 19a.

Fig. 4 is a circuit diagram showing the second embodiment of Fig. 3 in more detail.

In Fig. 4, the recording areas 3 and 5 on the cartridge of the film 13, being coated with the insulating material, are insulated from the recording areas 1 and 7. In Fig. 4, P1 through P7 designate contact pins which are provided in the film chamber of the camera and positioned to contact the recording areas 1 through 7, respectively. These contact pins P1 through P7 form the reading unit 1 5. The pins P1 and P7 are connected to the input terminals of the discriminating unit 14. The pin P7 is further connected to the negative terminal of a battery (not shown), and the pin P1 is further connected to the positive termi nal of the battery through a resistor R1 and to the control terminal CONT of the selector 1 6.

The selector 1 6 includes an inverter 1 61 for inverting the output signals of the discriminating unit 14, and logic circuits 1 62 through 165, each including two AND gates and one OR gate. Accordingly, when the discriminating unit 1 4 outputs a "1" signal, the selector 1 6 supplies only the signals of the contact pins P2 through P6 to the exposure calculation control circuit 17, and when the discriminating unit 14 outputs a "0" signal, the selector 1 6 supplies only the output signal of the manual setting device 1 5a to the circuit 17.

The manual (film sensitivity) setting device 15a includes positive edge-triggered D-type flip-flops F2 through F6, logic circuits 1 52 through 1 56 which each include two AND gates and one NOR gate, NAND gates 1 57 and 253, NOR gates 158, 159, 250 and 251, OR gate 252, AND gates 254, 255 and 256, resistors R2 and R3, and switches S2 and S3. The manual setting device 15a functions as an up-down counter. The relationships between the states of the recording areas 2 through 6 and the film sensitivities are the same as those in Fig. 5, under the condition that the output signals of the recording areas 2, 3, 4, 5 and 6 are read as the output signals 2a, 3a, 4a, 5a and 6a of the manual setting unit.

Each time the switch S2 is turned on, the content of the counter is incremented by one, while each time the switch S3 is turned on, the content of the counter is decremented by one. As is apparent from Fig. 5, higher count values correspond to lower film sensitivities and vice versa.

The exposure calculation control circuit 1 7 provides signals representing shutter speeds and aperture values at the output terminals AO, A4, A3, A2 and A6.

The drive circuit 18a includes a ROM 181 for driving the display unit 1 9a with the output signals of the exposure calculation control unit 1 7 as addresses, logic circuits 182, 183, 1 84 and 186 which each include two AND gates and one OR gate, the switch S1 for selecting one of the output of the exposure calculation control circuit and the output of the selector 16, and an inverter 1 87 receiving the switching signal of the switch S1. The drive circuit 1 8a receives signals from the discriminating unit 14, the selector 16, and the exposure calculation control circuit 1 7.

Figs. 6, 7 and 8 are tables correlating input signals AO, Al, A2, A3, A4, A5 and A6 to the ROM 181 with display contents of the display unit 19a. The display contents in Figs.

6, 7 and 8 are aperture values, shutter speeds and film sensitivities, respectively. In Figs. 6, 7 and 8, the symbol "X" designates a bit which may be either "1" or "O".

When the input signals Al is "1", the aperture value or shutter speed is displayed on the display unit 1 9a as indicated in Fig. 6 or 7. When the input signal Al is "0", the film sensitivity is displayed on the display unit 1 9a as indicated in Fig. 8. When the input signal Al is "1" and the input signal AO is "1", the aperture value is displayed on the display unit 19a as indicated in Fig. 6. When the input signal Al is "1" and the input signal AO is "0", the shutter speed is displayed on the display unit 1 9a as indicated in Fig. 7.

When the switch S1 is turned off, the input signal Al to the ROM 181 is raised to "1", and the output signals A2, A3, A4 and A6 of the exposure calculation control circuit 1 7 are applied directly as the input signals A2, A3, A4 and A6 to the ROM 1 81. Therefore, according to the content of the input signal AO, an aperture value indicated in Fig. 6 or a shutter speed in Fig. 7 is displayed on the display unit 19a. When, on the other hand, the switch S1 is turned off, the input signal Al of the ROM 181 is set to "0", and the film sensitivity is displayed on the display unit 19a.

The operation of the display device thus constructed will be described.

In the case where the film sensitivity, etc., are recorded on the cartridge 13, the recording areas 1 and 7 are electrically connected to each other, and therefore the output of the inverter 161 is raised to "1", as a result of which only the left-hand one of the AND gates in each of the logic circuits 162 through 166 is opened. Under this condition, the contact pins P2 through P6 detect the film sensitivity recorded on the film cartridge to provide output signals, which are applied through the AND gates thus opened to the exposure calculation control circuit 1 7. As a result, in the circuit 17, an exposure value is automatically calculated according to the film sensitivity recorded on the film cartridge.

In this case, a signal "0" is applied to the inverter 161, and therefore the left-hand one of the AND gates in each of the logic circuits 16a through 1 66 is closed. Accordingly, even if the film sensitivity is attempted to be set manually, it will not be delivered to the exposure calculation control circuit 1 7. On the other hand, in the case where the film sensitivity, etc., are not recorded on the film cartridge, the recording areas 1 and 7 are not connected to each other. Therefore, the output of the inverter 161 is set to "O". As a result, only the right-hand one of the AND gates in each of the logic circuits 1 62 through 1 66 is opened.Accordingly, a signal corresponding to the film sensitivity manually set is applied through the selector 1 6 to the exposure calculation control circuit 17, where an exposure value is calculated according to the film sensitivity manually set.

The switches S2 and S3 are operated to manually set the film sensitivity. The content of the counter is incremented by turning on and off the switch S2 and decremented by turning on and off the switch S3. Thus, a desir-ed film sensitivity can readily be set by suitably operating the switches S2 and S3.

The manual film sensitivity setting device using the switches S2 and S3, unlike the conventional device using a dial, contributes to miniaturization of the camera body due to the elimination of the dial, which requires a reiatively large space.

When the film cartridge contains no recorded data, the output of the inverter 1 61 is "0", and therefore the left-hand one of the AND gates in each of the logic circuits 1 62 through 166 is closed. Accordingly, no data from the contact pins P1 through P6 is supplied to the exposure calculation control circuit 17.

When the switch S1 is turned off, the aperture value or shutter speed is displayed on the display unit 19a. When the switch S1 is turned on, the film sensitivity is displayed on the display unit 19a.

The discriminating unit 14 supplies signals to the drive circuit 18a. The signals are used to turn on and to turn off a second segment separately provided in the display unit 1 9a. It is assumed that the output "0" of the discriminating unit 14 turns off the second segment and the output "1" turns it on. In this case, it can be detected from the second segment being turned off that the film sensitivity displayed on the display unit 1 9a has been automatically set. Similarly, it can be detected from the second segment being turned on that the film sensitivity displayed on the display unit 1 9a has been manually set.

Accordingly, the photographer can readily determine by observing the second segment whether or not the film sensitivity of the loaded film has been automatically read.

As is apparent from the above description, the invention has the effect that the film sensitivity can be easily read not only when the film sensitivity is recorded on the film cartridge but also when the film sensitivity is manually set.

Claims

1. In a camera having manual setting means for manually setting a film sensitivity and reading means for reading film sensitivity data provided on a film cartridge, a display device comprising: means for discriminating whether film sensitivity data is recorded on a film cartridge loaded in said camera; means for selecting one of an output of said manual setting means and an output of said reading means according to an output of said discriminating unit; a display unit for displaying digits according to said output selected by said selecting means; and drive circuit means for driving said display unit according to said output selected by said selecting means.

2. The display device as claimed in claim 1, further comprising film sensitivity data switch means coupled to said drive circuit means for selecting one of data representing a film sensitivity and data representing one of a camera shutter speed and aperture value, said film sensitivity, shutter speed or aperture value being displayed on said display unit according to said data selected by said switch.

3. The display device as claimed in claim 1 or claim 2, wherein said display unit comprises a further segment in addition to segments for displaying digits, said further segment being turned on or off according to an output of said discriminating unit.

4. The display device as claimed in any one of the preceding claims, wherein said manual setting means comprises counter means and switch means for selectively incrementing and decrementing a count of said counter means.

5. The display device as claimed in any one of the preceding claims, wherein said reading means comprises means for sensing the presence and absence of conductive areas provided in predetermined locations on said film cartridge.

6. A display device in a camera substantially as hereinbefore described with reference to and as shown in the accompanying drawings.