JPH02114250A - slide projector - Google Patents

Abstract

PURPOSE:To project an image at desired projecting magnification without an troublesome operation by setting the focal distance of a zoom lens so that the image on a slide film may be projected at the projecting magnification which is read based on the read magnification and a detected projecting distance. CONSTITUTION:A reading means 103 reads the projecting magnification recorded in a recording area corresponding to each frame of the slide film and a range- finding means 104 detects the projecting distance corresponding to the distance to a projection screen. A focal distance setting means 105 sets such focal distance of the zoom lens that the image on the slide film is projected at the projecting magnification based on the read projecting magnification and the detected projecting distance. A lens driving means 102 drives the room lens 101 so that the set focal distance can be obtained. Thus, the image on the slide film can be automatically projected at the desired magnification without the troublesome operation.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a slide projector that projects an image on a slide film onto a projection screen.

B. Prior art In a conventional slide projector, 1. For example, when you want to project an object at a desired projection magnification, such as life size (actual size) or 1/2 times, the projection screen is moved until the desired magnification is obtained. This was done by manually changing the focal length of the projection lens while looking.

Problems to be solved by the C8 invention However, with this method, the operation is cumbersome and
In addition to the lack of accuracy, if the actual size of the object is unknown, it is impossible to project the object at the desired projection magnification.

A technical object of the present invention is to enable projection of an object of unknown size at a desired projection magnification without any troublesome operations.

01 Means for Solving the Problems To explain with reference to FIGS. 1(a) and 1(b), which are diagrams corresponding to the claims, the present invention provides a zoom lens 101 and a method for driving the zoom lens 101 to a predetermined focal length. The present invention is applied to a slide projector that includes a driving means 102 and projects an image on a set slide film.

The invention of claim 1 provides, as shown in FIG. 1(a),
A reading means 103 reads the projection magnification recorded in the recording area corresponding to each frame of the slide film, a distance measuring means 104 detects the projection distance corresponding to the distance to the projection screen, and the read projection magnification and detection and a focal length setting means 105 for setting the focal length of the zoom lens such that the image on the slide film is projected at the projection magnification based on the projected projection distance, thereby solving the above technical problem. .

Further, the invention of claim 2 provides, as shown in FIG. 1(b),
A reading unit 203 that reads parameters for calculating a projection magnification recorded in a recording area corresponding to each frame of a slide film, a calculation unit 204 that calculates a projection magnification based on the read parameters, and a distance to a projection screen. A distance measuring means 104 detects a projection distance corresponding to the projection distance, and a focal length of the zoom lens is set so that the image on the slide film is projected at the projection magnification based on the calculated projection magnification and the detected projection distance. Focal length setting means 1
05, thereby solving the above technical problem.

E1 Effect (1) The invention reading means 103 of claim 1 reads the projection magnification recorded in the recording area corresponding to each frame of the slide film, and the distance measuring means 104 reads the projection magnification corresponding to the distance to the projection screen. Detect projection distance.

The focal length setting means 105 sets the focal length of the zoom lens such that the image on the slide film is projected at the projection magnification based on the read projection magnification and the detected projection distance. The lens driving means 102 drives the zoom lens 101 to achieve the set focal length. Due to this.

To automatically project an image on a slide film at a desired projection magnification without any troublesome operations.

(2) The invention reading means 203 of claim 2 reads the parameters for projection magnification calculation recorded in the recording area corresponding to each frame of the slide film, and the calculation means 204 projects the projection magnification based on the read parameters. The magnification is calculated. Based on the calculated projection magnification and the projection distance detected by the distance measuring means 104, the focal length of the zoom lens 101 is calculated in the same manner as described above.

F. Example An embodiment of the present invention will be described with reference to FIGS. 2 to 5.

In FIG. 2 showing the overall configuration, a distance measuring circuit 2 and an information reading device 3 are connected to the CPUI. The distance measuring circuit 2 calculates the distance (
The information reading device 3 reads the projection magnification E recorded on the slide mount 20 (FIG. 3(a)) on which the slide film 21 is mounted and inputs it to the CPUI. do.

Here, the projection magnification E is the ratio between the size of the subject image obtained on the projection screen when the slide film 21 is projected and the size of the subject on the slide film 21. The slide film 21 is provided with an information recording area in the margin of each frame, and information regarding the projection magnification E is encoded and imprinted on the information recording area by an imprinting device in the camera during photographing. In a conventional slide film, the portion other than the exposure area is covered by the slide mount 20, so that the information recorded in the information recording area cannot be read as it is. Therefore, in order to make this information readable, in this embodiment, before mounting, information regarding the projection magnification E recorded in the information recording area of the film is read.
The information is written on the slide mount 20.

That is, as shown in FIG. 3(a), the slide mount 20 on which the slide film 21 is mounted is provided with a storage area at the bottom of its surface, in which one ground contact 22 and ten electrical contacts are stored. 23 are provided.

These electrical contacts 23 are each connected to the ground contact 22 via a fuse 24, as shown in FIG. 3(b).

A reading device (not shown) reads information regarding the projection magnification E from the information recording area of the slide film 21, and according to this information, predetermined fuses among the ten fuses 24 are cut, and their electrical contacts 23 and ground contacts are cut. 22, information regarding the projection magnification E is written. Since there are 10 electrical contacts 23, it is possible to write 10 bits of information using this method.

The above-mentioned information reading device 3 reads the thus written information regarding the projection magnification E and inputs it to the CPU 1 prior to projection.

The CPUI determines the focal length f of the projection lens LE as shown below based on the input projection distance and projection magnification E.
Calculate.

Now, as shown in FIG. 4, the distance from the slide film 21 on the slide mount 20 set at a predetermined position to the front principal point of the projection lens LE is a, and the projection lens L
Let b be the distance from the rear principal point of E to the projection screen SC. Since the distance between the front and rear principal points is sufficiently smaller than the projection distance, the projection distance can be expressed as L=a+b (1). Also, the projection magnification E is E = b
/ a ... (2), and from equations (1) and (2), a=L/ (1+E) ... (3)
b=EL/ (1+E) ・ (4)
is obtained. Furthermore, from the imaging formula, 1/f = (1/a) + (1/b) - (5) holds, so from equations (3), (4), and (5), f = E
L/(1+E)' (6), and the focal length f can be expressed by the projection magnification E and the projection distance. Based on this formula (6), the CPUI
A focal length f such that the image on the slide film 21 is projected at a projection magnification E is calculated.

The CPU also includes a motor drive circuit 4 for a zooming motor 11 and a focusing motor 12, and an alarm device 5.
are connected. The motor drive circuit 4 drives the projection lens (zoom lens) LE to a predetermined focal length using the motor 11 in response to a zooming signal output from the CPUI based on the above-mentioned focal length f, and also responds to a focusing signal. The projection lens L is rotated by the motor 12.
E is driven to a predetermined focus position. The alarm device 5 is a CPU
In response to a command from I, a buzzer sound is generated to issue a warning as described later.

In the configuration of the above embodiment, the motor drive circuit 4 and the zooming motor 11 serve as the drive means 102, and the information reading device 3 serves as the reading means 103.

The distance measuring circuit 2 constitutes a distance measuring means 104, and the CPU constitutes a focal length setting means 105.

Next, the control procedure by the CPU 1 will be explained based on the flowchart in FIG.

After turning on the power to the slide projector and setting the slide mount 20 at a predetermined projection position, the program shown in FIG. The distance measuring circuit 2 is activated to read the projection distance, and the process proceeds to step S3. In step S3, it is determined whether an error has occurred. If it is impossible to read the projection magnification E or the projection distance, it is determined that an error has occurred and the process proceeds to step S8, where the alarm device 5 generates a buzzer sound to issue an alarm, and the projection lens L is adjusted to a predetermined focal length f. If the focal length of E is set as the driving destination focal length, the process proceeds to step S6 (error processing).

If it is determined in step S3 that there is no error, step S4
Then, the focal length f of the projection lens LE is calculated based on the read projection magnification E and the projection distance according to the above equation (6). Next, the process advances to step S5, and it is determined whether an error has occurred.

If the calculated focal length f is outside the focal length range of the projection lens LE, it is determined that an error has occurred, error handling is performed in step S9, and the process proceeds to step S6. That is, the alarm device 5 generates a buzzer sound to issue a warning, and if the focal length f is smaller than the focal length at the wide-angle end of the projection lens LE, the focal length at the wide-angle end is set as the driving light focal length, and the focus If the distance f is larger than the focal length at the telephoto end of the projection lens LE, the focal length at the telephoto end is set as the driving light focal length. Furthermore, if it is determined in step S5 that there is no error, the process directly advances to step S6.

In step S6, a zooming signal is output, and the projection lens LE is controlled by the motor 11 via the motor drive circuit 4 so that the focal length f calculated in step S4 or the focal length f set in step S8 or S9 is achieved. drive In other words, zooming is performed. After that, in step S7, the projection ratio RIA obtained in step S12 is
A focusing signal based on L is output, and the projection lens LE is driven to a predetermined focusing position by the motor 12 via the motor drive circuit 4 to perform focusing, and then the process is terminated.

According to the above procedure, the focal length of the projection lens LE is calculated based on the projection magnification E read from the slide mount 20 and the projection distance obtained by the distance measuring circuit 2, and the projection lens LE is adjusted so as to have this focal length. Since the LE is driven, the slide film 21 can be moved without any troublesome operations.
The above image can be projected onto a projection screen SC- with a desired projection magnification E.

Note that the method of writing the information regarding the projection magnification E recorded in the margin area of the slide film 21 onto the slide mount 20 is not limited to the embodiment.5 For example, as shown in FIG. A magnetic track 51 may be formed on the slide film 21, and information on the slide film 21 may be written onto this magnetic trunk 51. Moreover, a bar code may be used instead of this magnetic track 51.

Furthermore, as shown in FIG. 6(b), instead of writing information on the slide film 21'2 onto the slide mount 20, a hole 52 is formed on the surface of the slide mount 20 in a portion of the slide film 21 located in the information recording area. The information recording area may be opened to expose the information recording area, and the information recorded there may be read by the information reading device 3. Furthermore, the information in the information recording area of the slide film 21 may be recorded on a separate device from the slide mount 20, such as an IC card, and this information may be read by the information reading device 3. As described above, various methods can be considered for making it possible to read the information recorded on the film in the camera during photography when it is mounted, but the information reading device 3 needs to be configured to be compatible with each method.

Furthermore, although the example above has been shown in which the projection magnification E is recorded on the slide film 21, the following information may also be recorded as a parameter for calculating the projection magnification E. I do it.

■Reference projection magnification E preset on the slide projector side. In the case where the coefficient for the screen size WSC on the projection screen SC is 2, the projection magnification E can be calculated using the following formula within the CPUI.

E=EoXK Furthermore, in the case of (2), the projection magnification E may be similarly calculated using the following equation.

E=WSC/WFL Here, WFL is the screen size on the slide film 21, and this value is set in advance in the CPUI.

Furthermore, although the above example has shown an example of converting film taken in a camera into a slide film, it is not limited to this.
For example, the present invention can be applied to the case where the output of computer graphics is made into a slide film and the film is projected. In this case as well, by recording information regarding the projection magnification on, for example, a slide mount, projection can be performed at a desired projection magnification.

Effects of the G9 Invention According to the invention of claim 1, the projection magnification recorded corresponding to each frame of the slide film is read, the distance to the projection screen (projection distance) is detected, and the read projection magnification and Since the focal length of the zoom lens is set so that the image on the slide film is projected at this projection magnification based on the detected projection distance, the desired projection magnification can be recorded in advance on, for example, the slide mount. By doing so, even if the actual size of the subject is unknown, projection can be performed at the desired projection magnification without any troublesome operations.

Further, according to the invention of claim 2, the parameters for calculating the projection magnification recorded corresponding to each frame of the slide film are read, the projection magnification is calculated based on this parameter, and the projection magnification is used to calculate the projection magnification. Since the focal length is set in the same manner as described above, the same effect as described above can be obtained.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are complaint correspondence diagrams. 2 to 5 show an embodiment of the present invention, FIG. 2 is a block diagram showing the overall configuration of the slide projector according to the present invention, FIG. 3(a) is a diagram showing the slide mount 20, FIG. 3(b) is a diagram showing the structure of the information writing section,
FIG. 4 is a diagram showing the relative relationship among the slide film, projection lens, and projection screen, and FIG. 5 is a flowchart showing the processing procedure. FIGS. 6(a) and 6(b) are diagrams showing two modified examples of the information reading method, respectively. 1: CPU 2: Distance measuring circuit 3: Information reading device 4: Motor drive circuit 20 Ni-Ride mount 21 Ni-Ride film 101: Zoom lens 102: Driving means 103: Reading means 104: Distance measuring means 105: Focal length setting means LE : Projection lens SC: Projection screen (a) (b) Figure 3 Patent applicant Fuyu Ki Nagai Patent attorney Nikon Co., Ltd. Figure 5 (a) (shi) Figure 6

Claims (1)

[Claims] 1) A slide projector that projects an image on a set slide film, comprising a zoom lens and a driving means for driving the zoom lens to a predetermined focal length, comprising: reading means for reading a projection magnification recorded in a recording area corresponding to each frame; a distance measuring means for detecting a projection distance corresponding to a distance to a projection screen; and the read projection magnification and the detected projection. 2) a slide projector comprising: a focal length setting means for setting a focal length of a zoom lens such that an image on the slide film is projected at the projection magnification based on the distance; 2) a zoom lens; A slide projector for projecting an image on a set slide film, the slide projector comprising a driving means for driving the zoom lens to achieve a predetermined focal length, the image being recorded in a recording area corresponding to each frame of the slide film. reading means for reading parameters for calculating projection magnification; calculation means for calculating projection magnification based on the read parameters; distance measuring means for detecting a projection distance corresponding to the distance to the projection screen; and a focal length setting means for setting a focal length of a zoom lens such that an image on the slide film is projected at the projection magnification based on the projection magnification determined by the projection magnification and the detected projection distance. slide projector.