JPH09211739A - Microfilm camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate irregularities in the feeding of a film and to improve photographic picture quality by making the selection of transmission gear ratios in proportion to the size reduction factors of plural photographic lenses possible, in a belt type transmission. SOLUTION: In a microfilm, the rotation of an original feeding roller 202A at a position nearer to an original ejecting side is transmitted to the belt type transmission by a belt 206 and further, the rotation of the output shaft 210 of the transmission is transmitted to a cassette driving mechanism by a belt 212, to drive the cassette. A dial as a switching operator facing the rear side of a cover is fixed at the top end of a switching shaft 222. Three graduations of 1/50, 1/44 and 1/24 are imparted to the dial and positioned to graduations on a casing side, to selectively press tension rollers 230A, 230B and 230C against a corresponding belt 228C respectively. Consequently, three groups of belt type clutch mechanisms are constituted and one of three groups is connected to obtain a fixed transmission gear ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microfilm camera for photographing a document on a microfilm cassette containing a roll film by a slit exposure method.

[0002]

2. Description of the Related Art A microfilm camera for photographing a document original on a roll film by a slit exposure method is known which uses a cassette containing a roll film.

In this cassette, in addition to a supply reel and a take-up reel on which the roll film is wound from both ends, a photographing roller around which the roll film is wound is accommodated. Then, the roll film wound around the photographing roller is exposed inside the photographing opening provided in the cassette, and the image of the original is transferred onto the roll film through the photographing opening.

On the other hand, in an optical system for reducing an image of an original to form an image on a film, a photographing lens having a different reduction ratio is usually provided exchangeably. For example, a plurality of photographing lenses having a reduction ratio of 1/24 to 1/50 are prepared, and one of them is selected and used.

In this way, when changing the photographing reduction ratio, it is necessary to change the feed speed of the roll film. That is, the film feed speed needs to be a speed obtained by adding the reduction ratio to the document feed speed. For example, if the reduction ratio of the taking lens is 1/24, the film feeding speed is also 1 / of the document feeding speed.
Set to 24.

As a method of changing the film feed speed,
Conventionally, two methods have been used. One method (first method) is to prepare a camera head for accommodating a photographing lens and a film separately for each different photographing lens, and a gear type transmission having a reduction ratio corresponding to the photographing lens in each camera head. Is built in. When changing the reduction ratio, the entire camera head is changed. Needless to say, a rotational driving force having a constant rotational speed that is interlocked with the document feeding mechanism is input to this transmission.

Another method (second method) is to provide an independent film feeding motor separate from the document feeding mechanism, and change the speed of this motor according to the reduction ratio of the taking lens.

[0008]

In the first method, not only is it necessary to prepare a separate camera head for each photographing lens, but it is also necessary to incorporate a speed reducer and a film feed mechanism in each camera head. However, the size of each camera head is large, which is inconvenient to handle, and the size of the entire apparatus is large. Further, the speed reducer using a normal spur gear has a problem that uneven rotation due to periodic tooth contact is unavoidable and uneven film feeding occurs to deteriorate the image quality of a photograph. For this reason, it is necessary to use a special gear that removes uneven rotation.

In the second method, since it is necessary to control the speed ratio between the original feeding motor and the film feeding motor with high accuracy, there is a problem that the motor and the control device are complicated and expensive.

In these various conventional rotary type micro film cameras, the feeding speed of the original is always kept constant and the photographing reduction ratio is usually switched within the range of 1/24 to 1/50. Then, I could change the film feed speed within the range of about twice. However, the applicants of the present application are considering changing the document feeding speed in accordance with the photographing reduction ratio.

That is, when the reduction ratio is small, for example, 1/24, the original is fed at high speed (for example, 60 m / min), and when the reduction ratio is large, for example, 1/50, the original is fed at low speed (for example, 1).
5 m / min). By doing so, the captured image density can be increased and the image quality can be kept high even if the reduction ratio is large, and the processing speed can be increased when the reduction ratio is small.

In this case, the feed rate of the film varies from the variation range of the reduction ratio (about twice) to the variation range of the document feed rate (60 /
15 = 4 times), and it is necessary to change within a range of about 8 times. That is, in the conventional case, it is sufficient to switch the film feeding direction within the speed change range of about 2 times, whereas it is necessary to cope with the speed change range of about 8 times.

In order to change in the speed range of about 8 times in the second method, an extremely expensive encoder and speed detecting mechanism are required. Further, the rotation unevenness of the motor becomes large especially at low speed.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is not necessary to prepare a plurality of large camera heads, it is easy to handle, suitable for downsizing of the apparatus, and film feeding. An object of the present invention is to provide a microfilm camera which can improve image quality by eliminating unevenness and which does not require a complicated and expensive control device.

[0015]

According to the present invention, an object of the present invention is to provide a document feeding motor for driving a document feeding roller for feeding a document in a micro camera for photographing a document image on a roll film housed in a cassette by a slit exposure method, and a document feeding motor. An optical system for forming an image on a roll film is provided so as to be replaceable, and a belt type transmission for transmitting the rotation of the document feeding roller to a cassette drive mechanism. This is achieved by a microfilm camera characterized in that a gear ratio proportional to the reduction ratio of the taking lens can be selected.

The belt type transmission used here can be constituted by a plurality of sets of belt clutch mechanisms which intermittently transmit rotation by tension pulleys. In this case, the reduction ratio of each belt clutch is made proportional to the reduction ratio of each photographic lens for replacement, and one tension pulley corresponding to the photographic lens to be used is selected by the switching operator to select one belt clutch mechanism. Only one is configured to transmit rotation.

Since it is necessary for the gear ratio selected by the belt type transmission to correspond to the reduction ratio of the taking lens, if there is an error in the combination of this gear ratio and reduction ratio, a warning should be issued. It is good to report the error. A lock mechanism that restricts the mounting of each shooting lens at the mounting and dismounting part of the shooting lens is provided, and when the gear ratio changes, only the shooting lens that corresponds to the gear ratio can be mounted, and the inappropriate mounting of the shooting lens is prevented. Good. For document feeding, the speed of the document feeding motor may be changed according to the reduction ratio of the photographing lens.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing the outer appearance of a microfilm photographing apparatus using one embodiment of the present invention, and FIG.
Is a conceptual diagram of this photographing device, FIG. 3 is a side view showing the internal structure, FIG. 4 is a plan view, FIG. 5 is a view taken in the direction of arrow V in FIG. 4 for showing the optical system of the microfilmer, and FIG. Fig. 7 is a perspective view of the system, Fig. 7 is a plan view of the belt type transmission, Fig. 8 is a side view of the same, Fig. 9 is an exploded perspective view of a switching operation portion, and Fig. 10 is a view showing a rotation transmission system path.

1 to 4, reference numeral 10 is a scanner, 1
2 is an auto feeder (auto document feeder, abbreviated as ADF), 14 is a microfilmer to which the present invention is applied, 16 is a turn unit, and 18 is a stacker. The auto feeder 12 is detachably attached to the front of the scanner 10. The microfilmer 14 has a housing 20 formed in an L shape in plan view (FIG. 4).
0 surrounds the rear surface and the left side surface of the scanner 10. 2 to 4, reference numeral 22 denotes a multi sorter, which can be replaced with the turn unit 16.

1 and 4, reference numeral 24 is a control unit, which is composed of a display 26 and a keyboard 28. The control unit 24 is for performing status display and condition input / setting for controlling the entire apparatus. For example, for the scanner 10, selection of reading conditions
Settings such as selection / setting of a shooting mode are performed for the microfilmer 14.

In FIG. 2, 30 is a personal computer (P
C, workstation WS may be used), image information and attribute information read by the scanner 10 are input,
The image is subjected to predetermined image processing and stored in a storage device such as the magneto-optical disk 32. It also outputs to a printer (not shown) as needed. It can also be transferred to another computer or image processing apparatus.

The scanner 10 includes an auto feeder 12 to 1
It has a conveying means for horizontally and linearly feeding the documents (original documents) 34 taken in one by one toward the rear. First, the document 34 is read by a barcode reader (BCR) 36, which is a barcode attached to a predetermined position of the document 34. This bar code determines the condition setting based on the document format number, etc.
It includes information for automatically selecting the reading conditions of the CR 42 and the image scanner 44 from preset modes.

In this mode, for example, the image cut-out position, single-sided / double-sided reading discrimination, on / off discrimination of the scanner 10,
And so on. This read data is PC
It is sent to the (WS) 30, and the PC (WS) 30 sends an instruction number for the PC to the imprinter 40 described later. The barcode reader 36 may be an OCR (optical character reader) that reads characters instead of the barcode.

Document 34 is then patch reader 38 (FIG. 3).
Pass through. The patch reader 38 detects switching information of marks such as a blip attached when photographing a microfilm. For example, large / medium / small classification data can be distinguished by the type of partition plate inserted between documents. To detect. The patch reader 38 may detect information for automatically switching on / off of the scanner 10. These data are transferred as document or page attribute information to the external PC (WS) 30 via the data transfer interface.

The document 34 is then transferred to the imprinter (IMP) 4
Numbered by 0. For example, an instruction number output by the PC (WS) 30 to the output of the barcode reader 30 or a number indicating the order of the documents 34 set by the control unit 24 is added. Next, OCR42 is document 34
The document number or the like attached to is read and sent to the PC (WS) 30. This data is stored in the memory as document or page attribute information together with the image information read by the image scanner 44, which will be described later.
(WS) 30.

Image scanners (CCD) 44 and 44
And has a CCD line sensor. That is, for images on the front surface and the back surface of the document 34 moving at a constant speed,
Each line sensor is arranged so as to be orthogonal to the image moving direction, and the image is continuously read as the document 34 moves (moves in the sub-scanning direction). That is, the image is read by the slit exposure method.

In the CCD 44, the instruction input from the control unit 24 and the PC (WS) 3 in advance are used.
The image of a partial area of the document is cut out from 0 according to the input instruction, and transferred to the PC (WS) 30 via the interface together with the attribute information of the image. In addition, the mode is automatically selected from the format number of the document 34 read by the BCR 36, the cutting position, single-sided / double-sided, scanner on / off, etc. are determined, and the image is read according to the determination result. To do. Furthermore, conditions such as the cut-out position instructed by the PC (WS) 30 are obtained based on the document format number detected by the BCR 36, and the image data is displayed together with other attribute information in the PC (WS) 3
You may make it transfer to 0.

When this apparatus is used as a scanner, a turn unit 16 is connected to the rear surface of the scanner 10 as shown in FIG. The turn unit 16 makes a U-turn of the document 34 discharged from the rear surface of the scanner 10 upward, and feeds the upper portion inside the scanner 10 in the reverse direction.
Then, the stacker 1 provided on the upper front surface of the scanner 10
Collect in 8. The stacker 18 includes a path stacker 46 (FIG. 1) that reverses and stacks documents that have undergone normal image reading processing in the same order, and a reject stacker 48 that separates and stacks documents 34 that need to be reprocessed when an error occurs.
(Fig. 1) and. The reject stacker 48 can also be used to divide the processed documents into two groups and classify and collect only one of the groups.

On the connection surface between the turn unit 16 and the scanner 10, a separable joint (not shown) is provided for transmitting the driving force of the conveying roller in the scanner 10 to the turn unit 16 side. Therefore, in the state of FIG. 2A in which the turn unit 16 is connected to the scanner 10, the document can be conveyed at the same speed in the scanner 10 and the turn unit 16. Documents that are too thick to be transported in the turn unit 16 are collected in the straight stacker 50.

A multi-sorter 22 may be connected instead of the turn unit 16. The multi-sorter 22 sorts and stacks the processed documents 34 discharged from the scanner 10 and stacks thick documents on the straight stacker 5 as well.
Collect at 0A.

The above construction is of the scanner type shown in FIG. 2A. However, when a microfilm photographing function is added to this apparatus, the microfilm camera or microfilmer according to the embodiment of the present invention is used. 14
Is interposed between the scanner 10 and the turn unit 16. FIG. 2B shows the structure of the scanner / microfilmer type in this way. As described above, the microfilmer 14 has the L-shaped housing 20 in plan view, and the housing 20 houses an optical system for guiding images on both the front and back surfaces of the document 34 to the microfilm.

As shown in FIGS. 4 to 6, this optical system is long in the direction orthogonal to the conveying direction of the document 34 (direction of arrow A in FIG. 6) and is diagonally opposed to the front and back surfaces.
The mirror 52 and the second mirror 54, and both mirrors 52, 5
The third that simultaneously reflects the front and back images shown in FIG.
A mirror 56, a fourth mirror 58 and a fifth mirror 60,
It has two sets of taking lenses 62, 62.

The photographing lenses 62, 62 face the microfilm cassettes 64, 64.
66, which is housed in a car and runs at a constant speed
(FIG. 6) is photographed by the slit exposure method. For this reason, as shown in FIG.
The images on the front surface and the back surface are imaged side by side in the width direction of the film 66 (duplex imaging method).

When the front and back surfaces of the document 34 are simultaneously lined up in the width direction of the film with the microfilm 14 (duplex photographing method), these mirrors 5 are used.
2 to 60 simultaneously capture images on both the front and back sides of the document 34, but if duo photography is used, the document 34
Only one of the front side and the back side is photographed within the half width of the film 66. That is, when only the front side is photographed by the duo photographing method, the second mirror 54 is removed and the photographing is performed within the half width below the film 66.

The taking lenses 62, 62 can be replaced from the top surface of the housing 20. That is, a lid 20A (FIG. 1) that opens and closes above the projection lens 62 is provided on the upper surface of the housing 20, and the photographing lens 6 is opened by opening the lid 20A.
2, 62 can be attached and detached from above. Belt type transmission 2
The rotation of the output shaft 210 of 08 is the cassette drive mechanism 2 described later.
The belt 212, which will be described later in more detail in FIG. 14, is displaced laterally from the taking lens 62 in a plan view as shown in FIGS.

Here, the cassettes 64, 64 are inserted from the front into a loading chamber 67 that opens vertically in two steps on the front of the housing 20, that is, on the left front of the stacker 18. This loading chamber 6
7 is covered with a cover 68 after the cassettes 64, 64 are loaded to prevent external light from entering the loading chamber 67. Thus, by arranging the cassettes 64 in upper and lower two stages and simultaneously photographing the images of the same document, two microfilms can be simultaneously photographed, which is efficient. Of course, only one cassette 64 can be loaded so that only one microfilm can be photographed.

Reference numerals 100 and 100 are mark photographing lenses which are disposed adjacent to the sides of the photographing lenses 62 and 62. The optical axes of these lenses 100, 100 are inclined with respect to a line perpendicular to the film 66 in the film length direction, that is, the film running direction. Also, on this optical axis, for example, L
A digital image generator 102 (see FIG. 6) including an ED (light emitting diode) array is arranged in the film width direction.

The digital image generator 102 generates a one-dimensional image which changes in synchronism with the traveling speed of the film 66, and the image is taken on the traveling film 66 through the lens 100. Therefore, in addition to the above-mentioned search mark, other data can be imprinted on the film 66 adjacent to or over the image of the document.

Next, a mechanism for controlling the feeding speed of the film 66 will be described. The film 66 is fed by the document feeding motor 200 provided in the scanner 10. That is, as shown in FIGS.
The original feeding roller 202 within 0 is rotated at a predetermined speed.
Further, the rotation of the motor 200 is transmitted to other devices connected to the scanner 10, for example, the auto feeder 12, the micro filmer 14, the turn unit 16 and the like through a joint, and the document feed roller 20 in each device.
Rotate 2.

The joint between the scanner 10 and the microfilmer 14 is shown at 204 in FIG.
The joint 204 may have a structure in which a pin protruding in the radial direction is provided on one of opposing shafts, and a grooved pipe engaging with the pin is fixed to the other shaft. The document feed roller 202 in each device
Is belt driven.

In the microfilmer 14, the rotation of the document feed roller 202A (FIGS. 3, 5, 7, and 8) near the document discharge side is transmitted to the belt type transmission 208 by the belt 206. The rotation of the output shaft 210 of the transmission 208 is
Further, the belt 212 is used to drive the cassette drive mechanism 214.
(FIGS. 5 and 10), the cassette 64 is driven.
Here, the cassette drive mechanism 214 is the upper and lower cassettes 64,
The image pickup roller 21 in the cassette 64 is accommodated in the cassette 64.
6 and two reels 218 (FIG. 10) on the winding side and the supplying side are rotationally driven.

The belt type transmission 208 is located below the cassette 64 as shown in FIGS.
0, a switching shaft 222, and the output shaft 210 described above. A pulley 220A fixed to the input shaft 220 and a pulley 202B fixed to the document feeding roller 202A are orthogonal to each other, and a belt 206 is wound around them. As shown in FIG. 7, a guide roller 224 and a tension roller 226 are in rolling contact with the belt 206 to apply a predetermined tension to the belt 206.

On the input shaft 220, three pulleys 220B, 220C and 220D having the same diameter are arranged above the pulley 220A in this order.
Are fixed (Fig. 8). Three pulleys 210A, 210B, 210C facing the pulleys 220B, 220C, 220D are fixed to the output shaft 210.
The diameters of these three pulleys 210A, 210B and 210C are decreasing in order. These three sets of pulleys 220B
And 210A, 220C and 210B, 220D and 210C
And the belts 228A, 228B, 228C, respectively.
Is wrapped around with slack.

As shown in FIG. 7, the switching shaft 222 is eccentric to one side of the plane connecting the input shaft 220 and the output shaft 210. Each belt 228A is attached to the switching shaft 222,
Three tension rollers 230A, 230B and 230C pressed by 228B and 228C are attached at equal intervals as seen from the axial direction. That is, four discs 232 are fixed to the switching shaft 222, and two adjacent discs 2 are attached.
Between the tension rollers 230A and 230, respectively.
B and 230C are held. The tension rollers 230A, 230B, and 230C are the switching shaft 22.
2 is movable in the radial direction and is biased in the outer radial direction by a spring. Each disc 232 has three belts 2
28A, 228B, and 228C are also prevented.

The lid 20A is provided on the upper end of the switching shaft 222.
A dial 234 as a switching operator facing the lower side of the is fixed. This dial 234 has 3 scales 1 /
50, 1/44, and 1/24 are attached to the housing 20.
By aligning with a side scale (not shown), the tension rollers 230A, 230B, 230C can be selectively pressed against the corresponding belts 228A, 228B, 228C. As a result, three sets of belt type clutch mechanisms are formed, and by connecting one of these, a predetermined gear ratio can be obtained.

The belt 228C pressed by the tension roller 230C selected at a reduction ratio of 1/24 has a small diameter on the output shaft 210 side pulley 210C as shown in FIG.
The tension side and the slack side of the belt 228C may contact each other. Therefore, in this embodiment, a guide roller 240 shown in FIGS. 7 and 8 is added.

When the photographing lenses 62, 62 are replaced in this apparatus, the lid 20A of the housing 20 is opened and the lenses 62, 62 having different reduction ratios are replaced from above. And dial 2 to the reduction ratio of this newly loaded lens 62,62.
Adjust the scale of 34. For example, if the new lens 62 has a reduction ratio of 1/24, the scale of the dial 234 is adjusted to 1/24.

Then, the switching shaft 222 rotates, the tension roller 230C is pressed against the belt 228C, and the other tension rollers 230B and 230A have belts 228B and 228B.
The pressing force on 228A is released. Therefore, the tension roller 230C, the belt 238C, and the pulley 220
Only the belt type clutch mechanism formed by D and 210C is connected, and the other two sets of belt type clutch mechanisms are disengaged.
Therefore, the film 64 is fed to the cassette 64 at a speed corresponding to the reduction ratio of 1/24, and the photographing roller 216 is rotated.

When the taking lens 62 is loaded, it is desirable to provide a warning means 242 (FIG. 10) so as to issue a warning when the gear ratio of the belt type transmission 208 is wrongly selected. For example, a bar code indicating a reduction ratio is attached to the photographic lens 62, and the reduction ratio is detected by a bar code reader when it is loaded, while the switching shaft 2 is used.
It is possible to determine the suitability of the combination by detecting the rotational position of 22 and comparing both.

When changing the document feeding speed, the rotation speed of the document feeding motor 200 may be changed. This motor 2
Instead of changing the speed of 00, a transmission (not shown) may be interposed between the motor 200 and the document feeding roller 202. The rotation of the document feed roller 202 in the scanner 10 is transmitted to the document feed roller 202A of the microfilmer 14, and the document feed roller 202A drives the cassette drive mechanism 214 via the belt type transmission 208. If the feeding speed changes, the feeding speed of the film 66 and the rotation speed of the photographing roller also change in proportion at the same time. Therefore, even if the document feeding speed changes, it is possible to cope with the change without changing the gear ratio of the belt type transmission 208.

The present invention is not limited to the one in which the rotation of the document feed roller is directly transmitted to the belt type transmission 208, and the rotation is taken out from another rotating portion having substantially the same speed as the document feed roller to form a belt type transmission. Including what to convey. The belt type transmission uses a plurality of sets of belt type clutches, but it is a transmission that changes one belt around pulleys with different diameters, a transmission that changes the belt winding position around a conical pulley, etc. May be.

[0052]

As described above, according to the invention of claim 1, the gear ratio of the belt type transmission for transmitting the rotation of the document feeding roller to the cassette drive mechanism can be selected in proportion to the reduction ratio of the photographing lens used. It was done.

Therefore, it is only necessary to change the speed of the transmission when exchanging the taking lens, and the handling is easy. Further, it is not necessary to prepare a plurality of large-sized devices such as a camera head, and it is sufficient to prepare a plurality of types of taking lenses, which is suitable for downsizing of the entire apparatus. Further, the belt type transmission does not have uneven rotation like the gear type transmission, but rather has a function of absorbing the uneven rotation, so that uneven feeding of the film is reduced and the image quality of the photograph can be improved.

Since the cassette drive mechanism is driven by the rotating portion at the same speed as the original feed roller, it is not necessary to use a complicated and expensive control device as in the case where a separate motor for driving the cassette is provided. , The configuration becomes simple.

The belt type transmission used here is provided with a plurality of sets of belt clutch mechanisms corresponding to the reduction ratio, and one of the tension rollers is selected by a switching operator to press one belt and press one belt. The structure may be such that only the belt clutch is connected (Claim 2). In this case, the gear ratio of each set can be accurately set, and the film feed speed can be managed with high accuracy.

It is preferable to provide a warning means for detecting an error in the combination of the selected gear ratio and the reduction ratio of the photographing lens used, because the error can be easily confirmed (claim 3).
It is more convenient if the document feeding motor can change the document feeding speed according to the reduction ratio of the photographing lens. For example, when the reduction ratio is as high as 1/50, the document feeding speed is reduced to enable high-density image recording, and when the reduction ratio is as small as 1/25, the document feeding speed is increased to perform processing. You can increase the speed.

[Brief description of drawings]

FIG. 1 is a perspective view of a microfilm photographing apparatus using an embodiment of the present invention.

FIG. 2 is a conceptual diagram of this photographing device.

FIG. 3 is a side view showing its internal structure.

FIG. 4 is a plan view thereof.

5 is a view on arrow V in FIG. 4 showing an optical system of a microfilmer.

FIG. 6 is a perspective view of this optical system.

FIG. 7 is a plan view of a belt type transmission.

FIG. 8 is a side view of the belt type transmission.

FIG. 9 is an exploded perspective view of a switching operation unit.

FIG. 10 is a diagram showing a rotation transmission path.

[Explanation of symbols]

10 Scanner 12 Auto Feeder (ADF) 14 Micro Filmer as Micro Film Camera According to the Present Invention 24 Control Unit 34 Document (Document) 64 Micro Film Cassette 66 Roll Film 200 Document Feed Motor 202, 202A Document Feed Roller 208 Belt Type Speed Change Machine 210 Output shaft 214 Cassette drive mechanism 220 Input shaft 222 Switching shaft 228A, B, C Belt 230A, B, C Tension roller 234 Dial as switching operator

Claims (4)

[Claims] 1. A micro camera for photographing a document image on a roll film housed in a cassette by a slit exposure method, and a document feed motor for driving a document feed roller for feeding a document, and an optical system for forming a document image on the roll film. The system is provided with a taking lens that is replaceable, and a belt type transmission that transmits the rotation of the document feeding roller to a cassette drive mechanism, and the belt type transmission has a gear ratio proportional to the reduction ratio of the taking lens. A micro film camera characterized by being selectable. 2. A belt type transmission having a plurality of sets of belt clutch mechanisms having a gear ratio proportional to a reduction ratio of each of the replacement photographing lenses and intermittently transmitting rotation by a tension pulley, and the plurality of sets of belt clutches. 2. The microfilm camera according to claim 1, further comprising a switching operator that selectively presses one of the tension pulleys of the mechanism against a corresponding belt. 3. The microfilm camera according to claim 1, further comprising warning means for detecting an error in a combination of a gear ratio selected by the belt type transmission and a photographing lens mounted therein and issuing a warning. 4. The microfilm camera according to claim 1, wherein the document feeding motor is capable of changing the document feeding speed in accordance with the reduction ratio of the loaded photographing lens.