Abstract:
This invention is directed to an electrophotographic copying machine capable of copying small originals such as ID cards. The copying machine includes a recording medium carrier having a cover by which a recording medium is placed within the carrier at a first location before the copying operation is begun and guide rails along which the enclosed recording medium is then driven for the imposition of a uniform charge and a latent image to a second location where the cover is opened and the recording medium is removed and developed while the carrier is returned to the first location.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrophotographic copying machine adapted to copy in an efficient manner an original of relatively small size such as an ID card (Identity card), a driver&#39;s license, a membership card and so on. 
     2. Description of the Prior Art 
     In the conventional ID cards or the like the photos of the possessors are laminated to the cards. 
     It has been generally difficult for the conventional electrophotographic apparatus to copy an original of very small size. 
     SUMMARY OF THE INVENTION 
     One of the objects of the present invention is therefore to provide an electrophotographic copying machine best adapted to copy an original of a relatively small size. 
     Another object of the present invention is to provide a photocopying machine of the type described and which is simple in construction and compact in size. 
     A further object of the present invention is to provide a photocopying machine of the type described and which is reliable in operation even after it has been used for a long time. 
     Still another object of the present invention is to provide a photocopying machine of the type described and capable of copying at a very high speed. 
     Briefly stated, an electrophotographic copying machine of the present invention generally comprises an original holder means, original illumination means, means for forming an electrostatic latent image of an original upon a precharged recording medium, first transport means for transporting the recording medium through said latent image forming means, developing means for developing the latent image on the recording medium into a visible image, second transport means for transporting the recording means through said developing means, and means for controlling the operations of said original holder means, said latent image forming means, said first and second transport means and, said developing means. 
     The above and other objects, features and advantages of the present invention will become more apparent from the following description of one preferred embodiment thereof taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal sectional view of one preferred embodiment of the present invention; 
     FIG. 2 is a perspective view of a recording medium carrier; 
     FIG. 3 is a side view thereof in its initial or start position; 
     FIG. 4 is a perspective view illustrating a recording medium retaining or gripping means; 
     FIGS. 5 and 6 are views used for the explanation of the step of drying a developed recording medium; 
     FIG. 7 is a front view of a control panel; 
     FIG. 8 is a block diagram of an exposure control system; 
     FIG. 9 is a circuit diagram thereof; 
     FIG. 10 is a view used for the explanation of the control of the recording medium detecting signal; 
     FIG. 11 is a view used for the explanation of control means; 
     FIG. 12 illustrates a time sequence thereof; 
     FIG. 13 illustrates the developing and rising tanks and the manner in which they may be moved during the developing process. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, upon an original holder 1 is placed an original (not shown) such as an ID card, and a cover 3&#39; of a recording medium carrier 3 which is pivoted at 3&#34; for opening place therein a recording medium 4 of the substantially same size as that of the original. The set position of the recording medium 4 is controlled by means of positioning pins 5 (See FIG. 2). Below the carrier 3 is disposed a mount 8 upon which are mounted a photocell such as a CdS cell 6 and a lamp 7 in such a way that light emitted from the lamp 7 is reflected by the undersurface of the recording medium 4 back to the CdS cell 6 whereby an indicating lamp 9 on a control panel a (See FIG. 7), for indicating that the carrier 3 is ready to start, is turned on. A start switch 10 on the control panel a is so interlocked with the indicating lamp 9 that when the latter is turned on the start switch 10 may be turned on (See FIG. 10). 
     Upon depression of the start switch 10 the carrier 3 is moved from its initial or first position in the direction indicated by A, and an arrow indicating lamp 66 is turned on. The carrier 3 is moved along guide rails 13 by a tension wire 11 moved by the rotation of a drum 12. 
     As shown in FIG. 2, a pressure plate 14 is disposed below the cover 3&#39; of the carrier 3, and a pair of intermediate members 16 which together with cover 3&#39; form a holder for a recording medium are disposed along both side edges of the carrier 3 and are loaded with springs 17 so as to be normally upwardly rotated about shafts 15, but the upward rotation of these members 16 is prevented by means of plate cams 19 in engagement with rollers 18 of the intermediate members 16 while the carrier 3 is advanced. The plate cams 19 also serve as guide means. 
     Referring back to FIG. 1, when the carrier 3 is advanced below corona discharge means 20 the surface of the recording medium 4 is charged. Thereafter the carrier 3 is stopped in the exposure station where the optical image of the original 2 which is illuminated by a light source such as a halogen lamp 21 is focussed upon the recording medium 4 through mirrors 22 and 23, a lens 24 and a mirror 25 so that the electrostatic latent image is formed. The quantity of light emitted from the source 21 is controlled in a suitable manner by an exposure control system to be described hereinafter. 
     The carrier 3 is advanced again to the end of the forward stroke, that is, the second position, and stopped. The rollers 18 of the intermediate members 16 of the carrier 3 are released from the undersurface of a point cam plate 26 so that the front side of the intermediate members 16 are opened about the shaft 15 and the carrier cover 3&#39; is also raised because it is coupled to the intermediate members 16. The rollers 18 are transferred from the undersurfaces of the plate cams 19 to those of the point cam plates 26 as the carrier 3 is advanced. 
     As shown in FIG. 3 a roller 29 is released from a cam 28 when the carrier 3 is started from its initial or first position so that a lever 30 which is formed integral with the roller 29 is caused to swing downwardly about a pivot pin 32 under the force of a spring 31, thereby causing the positioning pins 5 to move downwardly. As a result the recording medium 4 is released from the positioning pins 5 but is securely held in the correct position by the pressure plate 14. 
     When the carrier 3 is stopped at the second position a finger 33 which is a recording medium retaining means is rotated about a pin 35 in the counterclockwise direction toward a finger 34 which is held in a predetermined position by a stopper 36, thereby catching the leading edge of the recording medium 4. The finger 34 is loaded with a spring 37 so as to be normally biased toward the finger 33. 
     As the leading edge of the recording medium 4 is gripped or caught by the pair of fingers 34 and 33 in the manner described above the drum 12 starts to rotate in the opposite direction so that the carrier 3 starts the return stroke. The rollers 18 of the intermediate members 16 are advanced along the inclined surfaces 38 of the plate cams 19. In this case the intermediate members 16 and the carrier cover 3&#39; are not completely closed. When the rollers 18 reach the intersection between the point plates 26 and the plate cams 19, they push the point plates 26 downwardly about a pivot pin 39 and move to the undersurfaces of the plate cams 19 so that the carrier cover 3&#39; and the intermediate members 16 are completely closed. Then the point plates 26 are turned to their initial position under the force of springs. The carrier 3 is returned by a distance longer than the length of the recording medium 4 so that the latent image formed upon the recording medium 4 which is retained by the pair of fingers 33 and 34 which are retaining or gripping means may be prevented from being damaged by the contact with the inner surface of the carrier cover 3&#39;. In the return stroke the carrier 3 is not stopped at the exposure station but is directly returned to the initial or first position. Immediately the carrier 3 is stopped the pins 5 are pushed upwardly by the cam 28 so as to receive the next recording medium. The positioning pins 5 have been retracted in order to permit the return stroke of the carrier 3 while the recording medium 4 is retained by the pair of fingers 33 and 34. 
     When the carrier 3 is returned from the second position toward its initial position by a distance longer than the length of the recording medium retained in position by the pair of fingers 33 and 34, the shaft 35 is further rotated until the recording sheet 4 is brought into contact with the developing liquid in a developing liquid tank or developer 45. As shown in FIG. 4 the rotation of a reversible motor 47 is transmitted to the shaft 35 through a segment gear 46 and a gear 41. Therefore when the gear 41 is disengaged from the segment gear 46 the rotation of the shaft 35 is interrupted. Stoppers 44 are provided in order to determine the position of the gear 41 when it is released from the segment gear 46, and a spring 43 is provided in order to impart some resistance to the rotation of the shaft 35. 
     The gear 41 is disengaged from the segment gear 46 when the recording medium 4 is brought into contact with the developing liquid in the developer tank 45, and then the segment gear 46 is meshed with an idler gear 53 so that a gear 48 and a cam 49 are rotated to actuate a microswitch 50, thereby de-energizing the reversible motor 47. 
     As the gear 48 is rotated, a curling preventive plate 52 carried by a shaft 51 carrying the gear 48 is also rotated so as to press the back surface of the recording medium 4 in contact with the developing liquid, thereby preventing the upward movement of the recording medium 4 away from the developing liquid surface under the hydrostatic pressure thereof and also ensuring the uniform contact of the recording medium 4 with the developing liquid. This arrangement is advantageous especially when the thickness of the recording medium is of the order of 100 μ. 
     After a suitable developing time, the developer tank 45 is displaced along bars 54 away from the recording medium 4 and a tank 45&#39; containing rinsing liquid (which is generally the carrier liquid of the developing liquid) is moved toward the recording medium 4 along bars 54 to rinse the latter. The rinsing liquid tank 45&#39; is similar in construction to the developer tank 45 (see FIG. 13). 
     After a suitable rinsing time, the reversible motor 47 is rotated in the opposite direction so that the curling preventive plate 52 is returned to its initial vertical position. Thereafter the segment gear 46 meshes with the gear 41 so that the shaft 35 is rotated in the opposite direction. As a result the fingers 33 and 34 are returned to their initial positions while retaining the recording medium 4. During this return stroke, the fingers 33 and 34 are stopped as shown in FIG. 5 so that air from a blower 55 flows substantially in parallel with the surfaces of the recording sheet 4. The recording medium 4 is therefore swung as shown in FIG. 5 and dried. 
     After a suitable drying time, the segment gear 46 is further rotated so that the finger 34 is stopped by the stopper 36 and the finger 33 is further rotated and stopped. The segment gear 46 is stopped when a microswitch 42 is actuated by a cam 40 so that the reversible motor 47 is stopped. As the finger 33 is moved away from the finger 34, the recording medium 4 is released and dropped upon a conveyor belt 56 (a third position) disposed below the second position of the first transport means or the carrier 3 as the latter is returned to the initial position. Thereafter the recording medium 4 is discharged into a tray 57 by the conveyor belt 56. 
     The developing liquid is forced into the developer 45 (FIG. 1) through a hose 60 from a developing liquid storage tank 64 as a pump 59 is driven by a motor 58, and the developing liquid overflowing from the developer 45 is returned to the storage tank 64 through a hose 61. 
     When a decrease in concentration of the developing liquid is detected by a toner concentration detector 62, toner is automatically supplied into the storage tank 64 from a toner tank 63. A rinsing liquid storage tank 65 similar in construction to the developing liquid storage tank 64 is provided, but is not provided with means such as the toner concentration detector 62 and the toner tank 63. 
     Referring to FIGS. 2 and 3, the pressure plate 14 is loaded with a spring 14&#39; and is provided with an aperture 14&#34; (through which is transmitted the light emitted from the light source 6 in order to detect whether the recording medium 4 is placed upon the carriage 3 or not). 
     In the present embodiment, the pair of recording medium retaining fingers 33 and 34 have been described as being rotated in a vertical plane, but it will be understood that they may be rotated in a horizontal plane toward the developing station where the recording medium is developed by a magnet brush developing process. Furthermore the present invention is also useful in a system in which the image developed upon the recording medium is transferred to a recording paper so that the recording medium may be used repetitively, and any suitable process for forming an electrostatic latent image may be employed. 
     Next the exposure control system will be described. The quantity of exposure light may be varied by about 30% by an exposure selection switch SW on the control panel shown in FIG. 7. The exposure control system is shown in block diagram in FIG. 8. The output signal of a detecting circuit including light detecting means such as a photosensitive element is intergrated by an integrating circuit, and the output signal of the integrating circuit is compared by a comparator with a reference signal representing the quantity of exposure light set by the exposure selection switch. Therefore when the exposure light reaches a predetermined quantity, the comparator gives a stop signal to a control circuit. Thus the correct exposure may be always ensured regardless of the degradation of aging of the light source. 
     Next, referring to FIG. 9 there is illustrated one embodiment of the exposure control system of the present invention, wherein light received from the lamp is converted into electric current by a photosensitive element SB1 such as a solar cell and electric current is converted into voltage by means of an operational amplifier Q1. The values of variable resistors RV1 and RV2 are so selected that the output voltage V1 of the operational amplifier Q1 is almost equal to the power source voltage even when the intensity of light emitted from the lamp is maximum. The output voltage V1 of the operational amplifier Q1 is integrated by an operational amplifier Q2 the operating condition of which is determined by RV3, R3, C1 and C2. The output voltage V2 integrated by the operational amplifier Q2 is compared by an operational amplifier Q3 with one of the reference voltages V5, V6 and V7 which are set by RV5, RV6 and RV7. One of the reference voltages V5, V6 and V7 is applied through a selection switch SW2 to the operational amplifier Q3. When the output voltage V2 of the operational amplifier Q2 coincides with the reference voltage V7, a transistor Q4 is conducted in response to the ouput voltage V3 of the operational amplifier Q3. When the transistor Q4 is cut off, a unijunction transistor Q5 is oscillated at a frequency determined by a capacitor C3 and resistors R11 and R12 so that a triac Q7 coupled through a power transformer PT is turned on, thereby turning on the lamp. However when the transistor Q4 is turned on the oscillation of the transistor Q5 is interrupted so that the lamp is turned off. Thereafter the microswitch Ca2 is opened, the capacitor C1 and C2 in the integrating circuit Q2 are discharged for the next exposure control. 
     The sequence of the steps in photocopying operation is controlled by control means shown in FIG. 11 and FIG. 12 as comprising program cams A and B, cams mounted upon the drum 12 and a group of microswitches actuable by the cams on the drum. The cams carried by the same shaft are driven by a main motor, and the program cams A and B are rotated in one direction only through clutches CL1 and CL4, respectively. The cams on the drum may be rotated in both directions through clutches CL2 and CL3. The control means further comprises cams which may rotate in both directions through clutches CL5 and CL6 and which drive the developing and rinsing chambers. FIG. 12 illustrates the time sequence of the switches actuated by the cams. 
     As described hereinbefore the photocopying machine in accordance with the present invention comprises an original holder 1, means 20, 21-25 for forming an electrostatic latent image, the developing means 45 and the carrier 3. A latent image is formed on the forward stroke of the carriage upon which is placed the recording medium 4, and at the end of the forward stroke the recording medium 4 is retained by the retaining means 33 and 34 and moved toward the developing means as the retaining means is rotated. After development and rinsing, the recording medium is released from the retaining means and is discharged from the photocopying machine. Since a recording medium of small size may be smoothly transported through the photocopying machine the photocopying machine of the present invention is best adapted for copying an original of samll size such as an ID card. 
     Furthermore when the wet developing process is employed, the developed recording medium is retained by the retaining means and dried by air flowing substantially in parallel with the surfaces of the recording medium while the recording medium is swung. Therefore the air flows so as to directly take away the developing liquid on the recording medium and the developing liquid is also separated from the recording medium as the latter swings. Therefore one air flow may accomplish two functions so that a synergistic drying effect may be obtained. Thus the drying time may be reduced to almost half of the drying time required when the recording medium is not swung at all. 
     The exposure control system may ensure the uniform exposure so that the uniform image quality may be ensured regardless of the degradation or aging of the lamp.