JP2811676B2 - Film image projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a film image projection device that projects an image such as a microfilm, and more particularly, to a focus adjustment of a projection lens thereof.

<Prior Art> Image information recorded on a microfilm is used by being enlarged and projected through a projection lens.

As a micro image projection device used when using micro film, an image recorded on the micro film is enlarged and projected on a screen (reader)
In addition to the reader function, there is an image processing apparatus that has an image processing function of performing processing such as recording a projection image from a microfilm on a recording paper or reading the image with a CCD or the like and converting the image into an electric signal.

The image recorded on the microfilm is projected by illuminating the microfilm with light from a light source and projecting the image of the microfilm by a projection lens.

Here, if the distance between the microfilm and the projection lens is always constant, it is sufficient to fix the focal point of the projection lens at a preset position. However, in the case of a micro image projection apparatus, the distance between the micro film and the projection lens may change due to the distortion of the micro film, the inclination of the film holder holding the micro film, and the like. ).

In order to avoid the complexity of manually adjusting the focus of the projection lens while watching the projected image on the screen when adjusting the focus of the projection lens, an autofocus device that automatically adjusts the focus of the projection lens has been proposed. (JP-A-62-105574).

<Problems to be Solved by the Invention> In a film image projection apparatus, when one projection lens is always used without replacement, even if the focal position shifts, it does not become so large. However, when the projection lens is replaced with a lens having a different magnification, the focal position shift becomes extremely large, and the projected image is completely out of focus.

Autofocus automatically achieves the in-focus state detected from the contrast difference or phase difference of the projected image, but if the image projected on the microfilm has no contrast, the in-focus state is achieved. Cannot be detected, so that autofocus cannot be executed.

When such a situation occurs in the above-described conventional autofocus device, it is necessary for the operator to manually adjust the focus, and the operation involved in exchanging the projection lens has become very complicated.

The present invention has been made in view of the above conventional circumstances,
It is an object of the present invention to provide a film image projector capable of maintaining an autofocus function even when a projection lens is replaced.

<Means for Solving the Problems> In order to achieve the above object, a film image projection apparatus of the present invention includes a light source for illuminating a film mounted on a film mounting unit, and a lens having a plurality of projection lenses that are detachable. A film image projection apparatus comprising: a mounting unit; a projection lens mounted on the lens mounting unit for projecting an image of the film; and an automatic focus adjustment unit for automatically adjusting the focus of the projection lens. When the projection lens is mounted on the projection lens, before the focus adjustment of the projection lens by the automatic focus adjustment means is automatically performed, the projection lens is set so that the focus of the mounted projection lens is focused on a position near the film mounting portion. It is characterized by having projection lens driving means for driving.

Further, a manual focus adjusting mechanism for adjusting the focus of the projection lens based on an operation of an operator may be provided.

Further, in addition to the above configuration, a display unit for displaying a focus adjustment direction may be provided when the focus of the projection lens is adjusted by the manual focus adjustment unit.

<Operation> When the projection lens is newly mounted, the lens driving unit focuses the projection lens at a position near the film mounting portion on which the film is mounted.

In the vicinity of the position where the projection lens is focused, there is always the image plane of the film, that is, the position where the projection lens should be focused. Therefore, even if the projection lens is replaced and newly mounted, the focus can be easily adjusted by the autofocus without any blurring of the focus.

Further, in the camera having the manual focus adjustment mechanism, when the projection lens is replaced and mounted, the focus is not completely out of focus, so that the focus can be easily adjusted while watching the image on the film.

Further, in the apparatus having the display means for displaying the focus adjustment direction, the focus adjustment direction can be recognized at a glance, so that the manual focus adjustment can be performed more quickly.

<Embodiment> FIG. 1 is a perspective view showing a micro-reader printer as an embodiment of the present invention. The reader printer is for printing a light source for image irradiation and an image projected by the light source on a lower portion 1 of a main body. Built-in printer. In addition, as shown in FIG.
Predetermined operation buttons such as a print button B ₁ , a seesaw type zoom button B ₂ , an auto focus (hereinafter referred to as AF) button B ₃ , a seesaw type manual focus button B _4,
An AF disable indicator LED2 is provided.

On the other hand, as shown in FIG. 1, an optical system described later is built in the upper part 5 of the main body, and a screen 6 for projecting an image when the optical system is in the reader mode is provided on the upper front face. Immediately below the screen 6, a film carrier loading space A is provided, and in this example, a fish film carrier 7 having a frame search function is loaded in this space A. Carrier 7 for this fish film
Can be removed from the reader / printer body by pulling in the direction of the front of the body. Although not shown, a carrier for a roll film can be loaded in the loading space A in place of the fish film carrier 7, and the carrier is selectively mounted as appropriate according to the type of microfilm to be used. With the fish film carrier 7 loaded, a projection lens 8 forming a part of a projection optical path is mounted on the central upper surface thereof.
Reference numeral 9 denotes a fish film insertion opening formed on the front surface of the carrier 7, and reference numeral 10 denotes a controller connected to the reader printer main body through a connection code. The controller has a key for designating a frame number to be searched or a frame feed key. B ₅ ··· and the like are provided.

As shown in FIG. 3, the fish film carrier 7 is provided with a X-
A Y carrier 12 and a film loading block 13 are provided. The XY carrier 12 is composed of an X-axis linear motor 14 and Y
The movable base 16 is moved in any direction on the XY plane by both motors.

The movable table 16 is provided with upper and lower two transparent film holders 17 and 18 for holding a fish film (not shown). The X-axis and Y-axis linear motors 14 and 15 move according to a search command from a control circuit described later, and
The fish film held at 17, 18 is moved in an arbitrary direction to position the designated piece on the optical path. The loading block 13 is disposed in the vicinity of the insertion slot 9, and supplies the fish film inserted from the insertion slot 9 between the film holders 17 and 18, or loads the fish film from between the film holders. ,
It has an unloading function. Further, a plate piece 19 is provided on the outer surface of the innermost right end of the casing case 11, and when the carrier 7 is loaded in the loading space A in a normal state, the plate piece 19 is moved to the reader printer main body side. It penetrates into the detection groove 20a of the provided photointerrupter 20, and the loading of the carrier can be detected. In FIG. 3,
Reference numeral 21 denotes an opening provided in the casing case 11 corresponding to an optical path for irradiating the fish film with light from a light source.

The projection lens 8 mounted on the carrier 7 has a configuration as shown in FIG. The illustrated lens 8 is a zoom lens having an autofocus (hereinafter, referred to as AF) gear 31 and a zoom gear 32 on its periphery, and is loosely inserted into a lens receiving unit 33. A lens accommodating case 35 in which a portion 34 corresponding to a projection optical path is cut out is provided on the main body of the reader printer, and the lens 8 is inserted by sliding the lens receiving unit 33 on the bottom plate of the lens accommodating case 35 in the arrow direction. Is loaded into the optical path portion 34. Although not shown, since the upper film holder 18 of the carrier for fish film is located below the case bottom plate, the lens 8 is mounted on the film holder 18 in the loaded state as described above. Become. A lens mounting detection optical switch 36 is provided on the right side wall of the housing case 35, and when the lens 8 is loaded as described above, a detection piece 37 formed by bending a part of the lens receiving unit 33 is turned on. It is detected at 36, and the presence or absence of the loaded lens can be confirmed. In the figure, 38 is an AF gear, 39 is a zoom gear, and is connected to a rotating shaft 44, 45 connected to a motor 40 having a built-in optical encoder 40a and a stepping motor 41 via timing levels 42, 43, respectively. Has been attached. Each of the gears 38, 39 has a corresponding gear 31, 32 on the lens side when the lens 8 is loaded.
Mesh. The AF gear 38 is driven during focus adjustment by a command from a control circuit described later. On the other hand, the zoom gear 39
Is driven by the operation of a zooming key provided on the front of the reader printer main body.

FIG. 5 shows a projection optical system inside the microreader printer. In the figure, 46 is a light source, 47 is a concave mirror, 48a, 48b
Is a condenser lens, and 49 is an illumination mirror. The light emitted from the light source 46 irradiates the fish film F sandwiched between the transparent film holders 17 and 18 via the condenser lens 48b. The light transmitted through the film F passes through the projection lens 8 and reaches the first mirror 51 where the light path is bent.
This mirror 51 is rotatable, the light reflected by the mirror being selectively switched in two directions. In the first direction, a reader optical path that is reflected by the half mirror 52 and reaches the screen 6 and a focus detection optical path that passes through the half mirror 52 and passes through the second reflection mirror 53 to the focus detector 54 are formed. . The second direction is the third mirror 55, the fourth mirror 56,
A printer optical path that reaches the photosensitive drum 58 via the fifth mirror 57 is formed.

As shown in FIG. 6, the first mirror 51 is supported by a horizontal axis 59 at the center in the vertical direction. The horizontal axis 59 is connected to a rocking mechanism such as a motor (not shown). The rocking of the mechanism selectively switches the optical path between the two directions described above. Is subjected to scanning exposure.

As long as the focus detector 54 is of the TTL (Through The Lens) type, it may be either one that detects a focused state based on a contrast difference, a phase difference, or the like. In this embodiment, as shown in FIG. , Half mirror 6 with 2/3 transmittance
1 and 1/2 half mirror 62 and 3 two-dimensional CCD 63a,
b, c, and employs a configuration for detecting a focused state from a contrast difference. The light receiving surface of the CCD 63c is a projection lens 8
Is placed at a position equidistant from the projection lens 8 and the screen 6, and the light receiving surfaces of the CCDs 63a and 63b are placed at a predetermined distance before and after the plane to be imaged. The detection operation of the focus detector 54 will be described later.

FIG. 8 shows a control circuit for controlling the operation of the micro reader printer. This circuit consists of two CPUs (AF7 CPU
1, RP control CPU 72) and ROMs 73, 74, RA connected to each CPU
It comprises M75, 76, I / O ports 77, 78, and input / output devices 79-89, 91 connected to each I / O port. Although only 12 input / output devices are shown in the figure, there are other devices such as a carrier control device and an exposure control device. The AF CPU RAM
A backup power supply 90 is connected to 75. The illustrated focus detection mechanism 79 includes a circuit for driving the CCDs 63a to 63c and a circuit for sending the light receiving signal of the CCD to the I / O port. The lens moving mechanism 80 and the first mirror swing mechanism 82 include driving means such as a stepping motor and a circuit for detecting the positions of the lens and the mirror. Encoder output shaping circuit 81 is AF
This is a circuit for shaping and amplifying the encoder output of the motor 40 for use. The printer control mechanism 83 includes a mechanism for operating a series of devices at a predetermined timing to print an image on the fish film using the photosensitive drum 58. The search state detection circuit 84 includes a film movement motor (X-axis linear motor 14).
And a circuit for monitoring the movement of the Y-axis linear motor 15), and outputs a search start signal and a search end signal when any of the motors 14, 15 starts moving and stops. The lens replacement detection circuit 85 is a circuit for shaping and amplifying the detection signal of the optical switch 36 shown in FIG. 4. The film carrier detection circuit 86 is a circuit for shaping and amplifying the detection signal of the photo interrupter 20 shown in FIG. print button detection circuit 87, a zoom button detection circuit 88, AF button detection circuit 89, a focus button detection circuit 91 print button respectively B _1, the zoom button B _2, AF button B _3, the switch in conjunction with the focus button B _4-one A circuit for detecting off.

FIG. 9 is a flowchart for explaining a control procedure of the RP control CPU 72 of the control circuit. First, when the power is turned on while the film carrier 7 is loaded in the loading space A and the projection lens 8 is at a predetermined projection position, the flow proceeds to steps S1, S2, S3, S4, S5, S6, and S1. Circulate. At this time the AF button B ₃ is pressed (YES in step S1), the resets the flag F _1, F ₂ (the step S8) AF start signal
The data is transmitted to the AF CPU 71 (step S10). AF
The CPU 71 starts automatic focus adjustment. RP in parallel with this
The control CPU 72 detects that the projection lens 8 is mounted on the optical switch 36 until the AF CPU 71 ends the automatic focus adjustment (step S11), and the photo interrupter 20 mounts the film carrier 7 on the photo interrupter 20. detects that has (step S12), the zoom button detection circuit detects that no depressed zoom button B ₂ (step S13), and
Further, while confirming that the search state detecting circuit detects that the film search is not being performed (step S14), the process circulates through steps S11 → S12 → S13 → S14 → S15 → S16 → S17 → S11. Then, when the AF CPU 71 ends the automatic focus adjustment,
Upon receiving a signal to that effect from the CPU (step S17),
Proceed to the next step S18. At this time, if no print button still depressed, the flag F ₂ is the remains reset, a _{F 1 = 0, F 2 =} 0, the flow step
The process returns from S18 to S1, and circulates between S1, S2, S3, S4, S5, S6, and S1. When the print button is pressed during this cycle,
The flow proceeds from S6 to S7 to perform a predetermined print operation. On the other hand, in the flow leading to S8 → S18, i.e., while the AF CPU71 is performing automatic focusing, the print button in step S15 is determined to have been pressed, sets the flag F ₂ to 1 at step S30 I do. Thereby, step S18
Based on the determination result in step, the flow proceeds from step S18 to step S7, and after AF is completed, a predetermined print operation is performed.

On the other hand, if the projection lens 8 is replaced while the AF CPU 71 is executing the automatic focus adjustment, since the focal length differs depending on the newly provided lens, it is meaningless to continue the current focus adjustment operation any further. It is. Therefore, in this case, the flow proceeds from step S11 to S19, where the AF CP
A focus adjustment stop signal is given to U71 to stop the automatic focus adjustment operation. Then, when a new lens is set (YES in step S20), a lens movement signal is transmitted to the AF CPU 75 (step S21), and on condition that the film carrier is mounted in the predetermined space A ( Step S22),
After the lens movement by the lens movement signal is completed, the automatic focus adjustment operation is started again.

Also, in the case where the carrier for the film is changed from the one for the fish film to the one for the roll film during the automatic focusing as well as the replacement of the projection lens, the current automatic focusing operation is further continued. That is pointless. Therefore, in that case, the flow shown in FIG. 9 proceeds from step S12 to step S25, and the automatic focus adjustment is stopped. When a new carrier is loaded (YE in step S23)
S), on condition that a fish film is present in the carrier (YES in step S24), the focus adjustment operation is started again.

Further, when the zoom button is pressed or the search for the frame image is started during the automatic focus adjustment, the automatic focus adjustment is stopped for the same meaning as described above (steps S26 and S2).
8) After waiting for the zooming process and the search process to end (steps S27 and S29), the automatic focus adjustment operation is restarted.

On the other hand, if the print button is pressed during auto focus adjustment, the print should generally be performed after the focus adjustment is completed. The printing is not stopped, and the printing is continued after the automatic focus adjustment is completed. This operation is as described above. However, in this case,
For example, when the contrast of the film image located in the projection optical path is unable autofocus low, the flow proceeds from step S16 to S31, sets the flag F ₁ for storing that the focus adjustment impossible In step S32, a display to that effect is made on the display LED2, and in steps S18 to S1.
To return to the focus adjustment standby state. Step S32
Is displayed next time the AF button is pressed.
Is to be revoked. Thus, AF
If the print operation is not possible, the print operation is not performed even if the print button is pressed. However, focus adjustment standby state (circulation between steps S1 → S2 → S3 → S4 → S5 → S6 → S1)
If the print button is pressed during the flow, the flow proceeds to step S6
The process proceeds to S7, where a predetermined print operation is performed. In this case, since the operator gives a print instruction after knowing that the AF focus adjustment is impossible by the display, the print button is usually pressed after performing the focus adjustment manually. .

The above operation is performed under the condition that the AF button is pressed. However, according to the program, even if the AF button is not pressed, the lens can be changed (step S2 → S2
0 → S22), carrier exchange (Step S3 → S23)
→ S24) or the zoom button is pressed (step S4 → S2
7) Further, the film search ends ((Step S5 → S
29) Then, automatic focus adjustment is automatically performed.

Next, a control operation performed by the AF CPU 71 will be described.
FIG. 10 is a flowchart illustrating this control procedure.

When the AF CPU 71 receives the lens movement signal from the RP control CPU 72 (step S33), the AF motor 40 is operated in one preset direction (step S34), and in this embodiment, the AF motor 40 is used to adjust the focus of the projection lens 8. The AF gear 38 is driven so that the movable lens moves to the screen side. The AF motor 40 includes a code plate for speed control and position control, and an encoder 40a including a photo interrupter. The output from the photo-interrupter is sent to the AF CPU 71 as a shaped pulse signal, and the number of rising edges of the pulse for a predetermined time and the number of rising edges of the pulse after the motor 40 are operated are counted. The moving speed and the moving position of the gear 38 (that is, the moving speed and the moving position of the lens for focus adjustment) can be detected. Incidentally, while t ₁ ~t ₂ shown in FIG. 11 state motor 40 is rotating at a constant speed, t ₂ ~ is rotated AF gear 38 to the end of its movable range (i.e., lens focus The state of the pulse sent to the AF CPU 71 in a state in which the motor 40 cannot rotate any more (moving to the end of the adjustable range) is shown. When the pulse reaches the end of the pulse, the number of rising edges of the pulse disappears.
U71 determines that the moving speed of the lens is zero. in this way,
When the lens moves to the end on the screen side within the focus adjustable range and the rotation speed of the motor 40 is determined to be zero (step S35), the operation of the motor 40 is stopped (step S3).
6), the pulse number L which is the value of the counter indicating the lens position
After resetting to zero (step S37), the above-described step S
Operate the motor 40 in the direction opposite to the direction of Step 34 (Step S3
8) Move the lens to the film F side opposite to the screen. The operation of the motor 40 is determined based on the presence or absence of the output of the encoder 40a (step S39).
Count the number of pulses obtained from (Step S4
0), when the count L reaches 100, the operation of the motor 40 is stopped (steps S41 and S42).

Here, L = 100 is set as a count number having the following meaning in the present invention. That is, as shown in FIG. 12, since the film F is sandwiched between the lower film holder 17 and the upper film holder 18, the lower surface α of the upper film holder 18 and the upper surface There is always a point between the side surfaces β where the projection lens 8 must be focused. Therefore, after replacing the projection lens 8 with another projection lens 8, if the focus of the projection lens 8 is adjusted so as to focus on an arbitrary point between the lower surface α and the upper surface β, this focus Since there is not so much difference between a point to be originally focused (a surface on which the image of the film F is present), it is possible to prevent a projection image from being blurred due to a large defocus of the projection lens with respect to the object point. In addition, the contrast of the projected image can be set to such a level that the AF can be reliably performed.
Accordingly, in the present invention, the focus is automatically set between the surfaces α and β after the replacement of the projection lens to realize the AF operation. In the present embodiment, the lens is moved from the screen side and L = 100.
When this occurs, the projection lens focuses on the lower surface α of the upper film holder 18. Above AF CPU71
Steps S33 to S42 performed in step S33 constitute AF control means for detecting that the projection lens has been replaced and focusing the replaced projection lens at a predetermined position between the film holders.

On the other hand, when the lens movement signal is not received in the step S33, the manual focusing of the projection lens 8 or the
The following processing is performed to perform AF. First, it is determined the operation whether the manual focus button B ₄ (step S43), if there is a manual focus button operation (movement of the lens to the screen side) the operation direction (+) direction or (-) direction ( It is determined whether the lens has moved to the film side (step S44). As a result, if the operation direction of the manual focus button is the (-) direction, the AF motor 40 is driven forward (step S45), and the operation of the motor 40 is confirmed by the output of the encoder 40a (step S46). ,
In response to the motor operation, the count L is incremented by one (step S47). On the other hand, if the operation direction of the manual focus button is the (+) direction, the motor 40 is driven in reverse rotation (step S51), and the operation of the motor 40 is confirmed by the output of the encoder 40a (step S52). , The count L is decremented by one (step S53). Any of the above process is continued until the operation of the manual focus button B ₄ is released (step S48), when this operation is canceled to stop the operation of the motor 40 (step S42).

If it is confirmed that the manual focus button B ₄ at the step S43 has not been operated, RP control CP
It is determined whether an AF start signal has been received from U72 (step S49), and if a signal has been received, an AF routine is executed (step S50).

FIG. 13 is a flowchart showing the AF routine of step S50 in detail.

First, the first mirror 51 is swung so as to form an optical path for the focus adjustment detection system, and is set so as to project the approximate center of the image projected on the screen 6 to the focus detector 54 as shown by E in FIG. . Thereafter, the light receiving outputs of all the pixels of each of the CCDs 63a to 63c of the focus detector 54 are detected, the maximum value Lmax and the minimum value Lmin are searched for in each of the CCDs 63a to c, and the difference Cs is obtained (step S54).

Cs = Lmax−Lmin (1) Here, the Cs value of the CCD 63a is Csa, and the Cs value of the CCD 63b is Csb, CC
The Cs value of D63c is defined as Csc.

Next, each of the Csa, Csb, and Csc is set in advance, and the necessary minimum contrast Csm stored in the ROM 73.
Compare with in (step S55). Csa, Csb, Csc is Csmin
If smaller, it means that a low-contrast image has been detected or no image has been detected, and automatic focusing cannot be performed. In this case, it is checked whether L is equal to 100 by looking at L stored in the RAM 75 (step S68). As a result, if L = 100, as described above, α
Despite being in a state in which AF can not be performed at a low contrast despite the state in which focus is achieved on the surface and AF can be performed, an AF impossible signal is transmitted to the control CPU 72 to end the operation (step S69).
In this embodiment, the AF impossible signal 2 shown in FIG. 2 is turned on by this AF impossible signal to indicate the lens moving direction.

On the other hand, if L ≠ 100 in the comparison in step S68, it is determined whether this L is larger or smaller than 100 (step S7).
0). As a result, if L is smaller than 100, the AF motor 40 is driven to rotate forward (step S71), and the focus adjusting lens of the projection lens 8 is moved to the film side, and the
While checking the operation of the motor 40 based on the presence or absence of the output of 40a (step S72), L is added one by one (step S7).
3) When L = 100, the motor is stopped (steps S74 and S75). On the other hand, if L is greater than 100, A
Operate the F motor 40 in the opposite direction to the above (step S
76) The focus adjusting lens of the projection lens 8 is moved to the screen side opposite to the above, and L is subtracted one by one while checking the operation of the motor 40 based on the presence or absence of the output of the encoder 40a (step S77) (step S77). In step S78), when L = 100, the motor is stopped (steps S79 and S75). As described above, when L = 100 is achieved, the operation of the motor 40 is stopped, an AF disable signal is transmitted to the control CPU 72, and the operation is terminated (step S69).

As described above, when the AF is not possible, the position of the projection lens 8 set in advance (L = 100 (plane α) in the present embodiment, but not limited to this, any position within the focus adjustment range) But possible) because you have to focused, thereafter when the operator focusing in manual focus button B _4, a short period of time since L = 100 is in the vicinity of the point to connect the original focus Focus can be adjusted. In the present embodiment, in order to move the focus from the plane α to the point where the focus should be originally focused, a certain direction in which the focus adjusting lens should be moved is displayed by the arrow of the AF impossible display 2. The adjustment operation is very easy.

As a result of the determination in step S55, Csa, Csb, and Csc are set to Cs
If it is larger than min, the focus can be adjusted by AF. In this case, the AF shown in step S19 etc. in FIG.
It is determined whether or not the stop signal has been transmitted from the control CPU 72 (step S56), and if this signal has been received, the AF operation is terminated, while if this signal has not been received, Csa, Csb,
Perform the AF operation by comparing Csc with each other (step S5
7). Here, as a result of the comparison of the Cs values, which Cs value becomes the maximum means that an image is formed on the light receiving surface of the CCD that gives the maximum Cs value. FIG. 15 schematically shows the relationship between the CCDs 63a to 63c of the focus detector 54 and the states of focusing, front focus, and rear focus. FIG. 16 illustrates the characteristics of the Cs value of each CCD in the states of FIGS. 15 (a), (b) and (c). From this figure, in the focused state of FIG. 15 (a), the Cs value of each CCD is Csc> Csa, Csa = Csb, and the back focus state (the state of defocusing to the rear side) in FIG. ), Csa <Csb, and Csa> Csb in the front focus state (state in which the front side is out of focus) in FIG.

Therefore, as a result of the comparison in step S57, Csc> Csa and Csa =
In the case of Csb, there is no need for AF because it is in focus,
The treatment ends as it is.

Also, if Csa ≠ Csb as a result of the comparison in step S57, C
The sizes of sa and Csb are compared (step S58), and if Csa> Csb, the front focus state is determined, and if Csa <Csb, the rear focus state is determined. If the result of this determination is that the camera is in the front focus state, the AF CPU 71 reads out distance information (N ₂ as the number of output pulses of the encoder) preset for focusing from the ROM 73 and sends the information to the lens moving mechanism 80. It sends a signal to move the motor 49 the lens of the projection lens 8 by normal rotation to distance the screen side determined by N ₂ (step S59, S61).

On the other hand, the determination result, in the case of rear focus state, a flag F ₃ indicating that the driving direction of the motor 40 is opposite to the front focus state (step S85), AF for CPU71 distance information N ₂
Is read from the ROM 73 and the signal is sent to the lens moving mechanism 80 to drive the motor 40 in the reverse direction to rotate the lens of the projection lens 8.
Moving the determined distance film side with N ₂ (step
S86, S60). The operation of the motor 40 as described above is performed by the encoder.
It is confirmed by the presence or absence of the output of 40a (step S61), and N (N ₂ ) set in step S60 is subtracted one by one to obtain N =
It continues to 0 (steps S62 and S63), and when N = 0 is achieved, the motor 40 is stopped (step S64). Then, check the flag F ₃ (step S65), step S60
The L value indicating the lens position of the projection lens 8 is corrected by adding or subtracting Ns (N ₂ ) set in the above according to the driving direction of the motor 40 (steps S66 and S87). The flag F ₃ Then in the clear (step S67), and repeats the above series of processing returns to step S56 and subsequent flow. By repeating a series of processes in this way, the focal position of the projection lens
The focus position will be approached by N _2, and the focus state will be achieved sequentially, and the AF flow will end from step S57.

Further, in the determination in step S57, Csa = Csb = C
In the case of sc (that is, a contrast exceeding the required minimum contrast is obtained, but the imaging position of the projection lens 8 is much farther than the screen equivalent surface, and the image is out of focus at all) With the operation of the motor 40, L sequentially stored in the RAM 75 is compared with 100 to determine whether it is larger or smaller than 100 (step S80). Is shifted in the screen side or the film side. As a result of this determination, if L <100, the AF CPU 71 stores the distance information (N ₁ as the number of encoder output pulses) set in advance in the ROM 73 to obtain the contrast difference between Csa, Csb, and Csc. from sends the signal to the lens moving mechanism 80 is read, moving the lens of the projection lens 8 the motor 40 is rotated forward to distance the screen side determined by N ₁ (step S81, S82). On the other hand, the result of the determination, when the L> 100 is a flag F ₃ indicating that the driving direction of the motor 40 is contrary to the above (step S8
3) AF for CPU71 distance information N ₁ and sends the signal to the lens moving mechanism 80 reads from the ROM 73, to move the lens of the projection lens 8 by reverse rotation of the motor 40 to the distance film side determined by N ₁ ( Steps S84 and S82). The operation of the motor 40 as described above is confirmed by the presence or absence of the output of the encoder 40a (step S61), and the N set in step S82.
(N ₁ ) is decremented _one by one and is continued until N = 0 (steps S62 and S63), and when N = 0 is achieved, the motor 40 is stopped (step S64). Then, check the flag F ₃ (step S65), the addition or subtraction to correct the L value according to Ns (N ₁₎ set in step S82 in the driving direction of the motor 40 (step S66, S87). Thereafter, the flag F ₃ is cleared (step S67), the flow returns to step S56 and subsequent flow. Such a series of processes are repeated distance information N ₁ at a time, in step S57 Csa, Csb, obtained contrast difference between Csc, transits to the AF flow described above when the AF becomes ready Become.

In the above-described embodiment, N ₁ and N ₂ are set to predetermined constant values. However, these values are obtained from the focus detection mechanism 79 (defocus amount in the case of the phase difference method, and contrast information in the case of the contrast method). (Size). In the above embodiment, the position where the lens of the projection lens is stopped is fixed (L = 100). However, since the rotation angle of the focus ring per unit for focus adjustment differs depending on the type of lens, May be determined and changed accordingly.

As described above, the present invention has been described with reference to a microreader having a printer function for printing a document image, that is, a so-called microreader printer, but the present invention is not limited to such a microreader. Instead of the printer function, the present invention is also applicable to a microreader having an image processing function such as an image scanner function of reading a document image and outputting an image signal, that is, a so-called microreader scanner.

<Effect of the Invention> According to the present invention, when the projection lens is replaced, the focal point of the projection lens is set to a preset position between the film holders by the lens driving means, so that the focal position of the replacement projection lens is changed. The focal point can be set at or near the focal point, and the image obtained by the replacement projection lens will not be blurred at all. Therefore, the autofocus can be performed without any trouble even by the replacement projection lens.

[Brief description of the drawings]

FIG. 1 is a perspective view of a reader printer to which one embodiment of the present invention is applied, FIG. 2 is a front view of the operation panel, FIG. 3 is a partially cutaway perspective view of the film holder, and FIG. FIG. 5 is an exploded perspective view of the lens drive system, FIG. 5 is a configuration diagram of the optical path, FIG. 6 is a perspective view of the optical path switching mirror, FIG. 7 is a view showing the arrangement of the CCD of the focus detector, FIG. FIG. 9 is a configuration diagram of the control circuit, FIG. 9 is a flowchart illustrating the operation of the RP control CPU of the control circuit, FIG. 10 is a flowchart illustrating the operation of the AF control CPU of the control circuit, and FIG.
FIG. 12 is a diagram showing an output pulse from an encoder. FIG. 12 is a diagram showing a relationship between a focal position of a projection lens and a film holder. FIG. 13 is a flowchart for explaining the operation of an AF control CPU of a control circuit. FIG. 15 is a diagram showing a detection area of a screen equivalent surface, FIG. 15 is a schematic diagram showing a relationship between a CCD of a focus detector and focusing, a front focus and a rear focus, and FIG. 16 is a characteristic diagram showing a magnitude of contrast. is there. 8 is a projection lens, 40 is an AF motor, 46 is a light source, 71 is AF
CPU and F are microfilms.

Claims (3)

(57) [Claims] 1. A light source for illuminating a film mounted on a film mounting portion, a lens mounting portion to which a plurality of projection lenses are detachable, and a projection lens mounted on the lens mounting portion to project an image of the film. And a film image projection apparatus comprising: an automatic focus adjustment unit that automatically adjusts the focus of the projection lens. When the projection lens is mounted on the mounting unit, the focus adjustment of the projection lens by the automatic focus adjustment unit is performed. A film image projection apparatus, comprising: a projection lens driving unit that drives a projection lens so that a focal point of a mounted projection lens is focused on a position near a film mounting portion before the projection is automatically performed. 2. A film image projection apparatus according to claim 1, further comprising a manual focus adjustment mechanism for adjusting the focus of said projection lens based on an operation of an operator. 3. The film image projection apparatus according to claim 2, further comprising display means for displaying a focus adjustment direction when the focus of the projection lens is adjusted by said manual focus adjustment means.