JPS6134536A - Recording device - Google Patents

Abstract

PURPOSE:To detect accurately a density of an original picture without providing a large number of detecting means in the direction intersecting the scanning direction. CONSTITUTION:Detected optical information of the density condition of an original picture by means of photodetector element 21 is impressed upon a holding circuit 104 after it is converted into electric signals at a detecting circuit. The circuit 104a of the circuit 104 selectively holds the densest signal and the circuit 104b selectively holds the lightest signal. Output of the circuits 104a and 104b are impressed upon a differential amplifier 105 and a control output corresponding to the output difference is led out. The control output is impressed upon a circuit 101 controlling the intensity of illumination of a lighting lamp 4 as an illumination intensity controlling signal through a gate 106. A reference power source 107 which applies a control voltage, under which the lamp 4 exerts prefixed reference intensity of illumination, across the circuit 101 is connected with the other input of the gate 106.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording device for recording information on a document onto a recording medium 1, and in particular, recording in a controlled state according to the condition of the document is difficult. It is related to the device.

Reprint of specification (no change in content) In conventional recording devices, such as electronic copying devices, the illuminance of the document illumination lamp remains at the value determined at the time the device was designed. Therefore, users have controlled the exposure amount by manually adjusting the opening amount of the lens aperture or exposure slit each time depending on the density state of the original document. This manual adjustment is troublesome for the user, and furthermore, it is difficult to obtain a copy with the desired density in just a few times; be. This not only takes time for the user, but also wastes copy paper.

JP-A-6-1-3453G (2) Therefore, a method has been proposed in which the density of the original is detected and the exposure amount and the like are set in accordance with the detected value.

However, when detecting the density of the original, there is a possibility that the density of the original cannot be detected accurately with one detection element depending on the location where the detection element is arranged.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a recording apparatus capable of accurately detecting the density of an original image and automatically setting optimal recording conditions.

That is, the present invention includes a detection means for detecting the density of an original image, a scanning means for exposing and scanning the original image by reciprocating relative to the original image, and a scanning means for detecting the density of the original image by the detection means. There is provided a recording apparatus characterized in that it has a moving means for moving the detecting means in a direction intersecting the moving direction of the scanning means during the movement by the voice scanning means.

In order to facilitate understanding of the present invention, the entire apparatus will first be described as a typical embodiment of an electronic copying apparatus. The surface of the drum L is a photosensitive surface, and the direction of the arrow in the figure (clockwise)
It is arranged in the middle of the machine box so that it can be rotated by means such as a motor. The document is placed on a document table glass 2 that constitutes a document placement surface on the top surface of the machine case, and the document table glass 2 is fixed to a document table 3. The document table 3 has a motor, clutch,
It is connected to the machine box by means such as pulleys and wires, and further via means such as slide rails or rollers, so that it can move smoothly in the left and right directions in the drawing. The home position of the document table 3 is at the position indicated by the chain double-dashed line (symbol 3') in the figure, and the document is first placed in the direction of the document table (
At symbol A), the left end of the document platen glass 2 moves to a position where it passes over the document exposure area (the document exposure start position indicated by the solid line in the figure), and then it is reversed and starts moving to the left (symbol B). When the document table 3 moves in the direction B, the process elements operate so that the document image is formed on the photosensitive surface on the surface of the drum 1. At this time, the original is illuminated by the illumination lamp 4, and its image is formed on the imaging section 7 on the surface of the drum 1 via the mirror 5 and the in-mirror lens 6. The surface of the drum 1 is uniformly charged by a negative charger 9 and then transferred to an imaging section 7.
When the image is formed as described above, the static eliminator 1
The charge is removed by □0, and then the entire surface is exposed by a full-surface exposure lamp 11, and an electrostatic latent image is formed on the drum surface.

Next, the liquid is developed by the developing electrode 16 of the developing device 14, and the remaining liquid is squeezed out by the aperture charger 17. Aperture charger 1
The visible image on the drum l from which the liquid has been squeezed by the transfer charger 18 is transferred onto the copy paper 12 fed from the paper feed section 8 . The copy paper 12 onto which the visible toner image has been transferred is then separated from the drum surface by a separating section 13.
The image is guided to the fixing section 15, fixed, and then discharged onto the tray 19. On the other hand, the remaining toner on the drum surface is cleaned by a blade cleaner 20 pressed against the drum surface, making it possible to cycle the method again. After the document table 3 moves in the B direction by the required document exposure distance, it is immediately reversed, reaches the original home position, and stops there. In the vicinity of the document exposure section, there is a photodetection element 21 fixedly disposed on the main body with its detection surface facing the document exposure section. The detection element 21 detects the reflected light of the original image illuminated by the illumination lamp 4 during movement from the aforementioned home position to the original exposure start position. At this point the process elements are inactive so no image appears on the drum. Detection element 21
The amount of exposure during actual document exposure can be controlled by the output from. In this method, the original density is detected during a part of the reciprocating movement of the original table, and the original is exposed in the subsequent steps at an exposure state that is optimal for the original density, which may result in a reduction in copying speed. This is an effective method.

The configuration, control means, etc. of the above-mentioned photodetecting element will be described below.

A conventionally known photoelectric conversion element can be used as the above-mentioned photodetection element. In the case of Figure 1, Figure 2 (
As shown in a), the photodetecting element 21 detects document information in the shaded area 102a of the document 102 on the document table.

(a) in the figure shows a case where the original is small, and the original is detected over the entire area in the moving direction. If the document is larger than the distance from the document table's home position to the document exposure start position, as shown in FIG. 102
The document information of a' is detected, and only a part of the document in the moving direction is detected.

In the case of these figures (a) and (b), the entire document information is detected using a part of the document.

Therefore, this method is extremely economical and effective when considering output adjustment, assembly man-hours, etc. since only one detection element is required for a document whose entire document information can be determined from only a portion thereof.

FIG. 3 shows a control circuit in this case.

Optical information obtained by continuously detecting the shading state of the original image by the photodetecting element 21 is further converted into an electrical signal by the detection circuit 103. The document information converted into electrical signals in this manner is applied to the holding circuit 104, which is composed of a first holding circuit 104a and a second holding circuit. This first holding circuit 104a selects the signal with the highest density (original information signal when the light detection element receives the least amount of light) from among the density information of the original sent from the detection circuit 103. It consists of a peak hold circuit that holds . The second holding circuit 104b is composed of a peak holding circuit that selects the signal with the lowest concentration (original information signal when the most amount of light is received by the photodetecting element) and holds it. That is, the above-mentioned holding circuit 104 selects the highest value and the lowest value of the document density within one scan of the document and holds them respectively.

Reference numeral 105 indicates a differential amplifier, and since the outputs of the first and second holding circuits 104a and 104b are applied to its inputs, the first . The control output is derived according to the difference in the outputs of the second holding circuits. Such control output is
The signal is applied as an illuminance control signal to the illuminance control circuit 101 that controls the illuminance of the illumination lamp 4 via the gate IO6. Further, to the other input of this game) 106, a control voltage is applied so that the illumination lamp 4 emits a predetermined reference illuminance.
Reference power source 107 for applying to the illuminance control circuit 101
is applied. That is, a control signal is sent to the control terminal 108 of the gate 106 to apply the output of the differential amplifier 105 to the illuminance control circuit 101 when the document table 3 moves in the direction of arrow B, and when the document table 3 moves in the direction of arrow A. When moving in the direction of , the output of the reference power source 107 is
The outputs of the differential amplifier 105 and the reference power source 107 are selectively applied to the illuminance control circuit 101 by applying a control signal such as that applied to the illuminance control circuit 101.

Such a control signal is set by, for example, a copy start command signal (using this signal as a trigger signal, the document table 3 starts moving in the direction of arrow A), and a microswitch is activated when the document table 3 reaches a predetermined position. (The document table 3 starts moving in the direction of arrow B when the drive of this switch is used as a trigger signal.) This can be formed by the output signal of a flip-flop that is reset by the output of the switch.

As is clear from the above description, if the circuit shown in FIG. 3 is used, the document information is read when the document table 3 moves in the direction of arrow A, and when the document table 3 moves in the direction of arrow B
Based on the read information, copies can be made while controlling the copying machine. The signals in the holding circuits 104a and 104b can be cleared each time the document is scanned (each time the document table 3 completes one reciprocating movement); however, if the same copy is to be made many times, the signals are stored as they are. It is also possible. In this case, the holding circuit may be cleared only when the cover is opened, in conjunction with the opening and closing of the document cover.

FIG. 4 shows another arrangement example of the detection elements. 21-1 in FIG.
, 112-i, is detected.

If the original is larger than the original detection area, the photodetecting elements 21-1, 21-2, 21-3, and 21-1, 21-2, 21-3.
-----． 21-i is the shaded area 112-1 of the original 112'
', 112-2'.

112-3', ----, 112-i''. If the shading of the originals 112, 112' varies greatly depending on the location, one optical detector' Depending on where they are placed, it may not be possible to accurately capture the information on the manuscript. In this case, it is effective to arrange multiple pieces as shown in Figure 4 to more accurately detect the manuscript information. If desired, the number of photodetecting elements can be increased.

In the case shown in Figure 4(b), the entire area of the document cannot be detected in any case, so in this case, place the document on the document glass in advance so that the information area you most want to detect is above the detection area. Good.

FIG. 5 shows a control circuit using a plurality of photodetecting elements as shown in FIG. 4.

Each photodetector element 21-1.21-2. -----． 21-l
Correspondingly, a detection circuit having a function similar to that described in FIG. 3!・03-1.103-2, -----. 10
3-i is provided to convert the density information of the original into an electrical signal.

Furthermore, the outputs of the respective detection circuits 103-1 to 103-i are applied to integration circuits 114-1 to 114-i, and integrated by the circuits. The integrated signal is applied to a holding circuit 115 having the same function as the holding circuit 104 shown in FIG. The signal is output terminal 11
It is output from 5b. These two signals are transferred to the differential amplifier 10
5, and a signal proportional to the difference is output. This output signal allows the original exposure amount to be changed in a manner similar to that described in FIG.

When the integrating circuit 114 is used in this way, information is not recorded in the peripheral areas of the document, such as the shaded areas 112-1 and 112-i, and information is not recorded in the central area of the document, such as the shaded areas 112-1 and 112-i.
This is suitable for use when information is recorded in 12-2 to 112-(i-1).

Of course, the integration circuit 114 can be completely removed and used in the same manner as explained in FIG. 2.

In addition, the circuit shown in Figure 5 detects multiple locations on the document and compares all detected amounts, so even if there is an extremely high (or low) concentration in a part of the document, it will not be detected. It is possible to obtain the contrast of information that is averaged over the entire document without being influenced by this.

Note that in FIG. 5, parts given the same numbers as in FIG. 3 have the same structural functions.

Another example of the configuration of the detection element will be described with reference to FIG. A plurality of photodetecting elements 21-1, 21-2, ----. 21
-i reciprocates in the width direction of the original 122 (in the direction of the arrow in the figure) at a constant period and with a constant amplitude. Therefore, the detection areas 122-1, 122-2, -----. 122-i
The area becomes a meandering area as shown in the figure. This method is useful because the shading of the manuscript information varies greatly depending on the location.
It is effective when it is not possible to detect the entire document with a single detection element, and it is also characterized in that it can detect an area equivalent to almost the entire document with a relatively small number of detection elements. An embodiment for causing reciprocating vibration of the detection element shown in FIG. 6 is shown in FIG. In FIG. 7, photodetecting elements 21-1, 21-2. -----． A member 123 to which 21-1 is fixed is fixed to a slide plate 124.

The slide plate 124 is a stay 1 fixed to the main body side plate, etc.
A spring 126 is arranged so as to be slidable along the guide groove 125a of 25, and has one end fixed to the stay 125.
being pulled by. On the other hand, the member 123 is the spring 1
It is in contact with an eccentric cam 127 on the 26 side, and the cam 127 is fixed to the output shaft of a motor 128. motor 1
28 is fixedly disposed on the stay 125 by a mounting plate 129. The eccentric cam is moved back by the motor 128. As for output control from a plurality of detection elements as shown in FIG. 6, a method similar to that described in FIG. 5 can be used. Furthermore, with the method shown in Figure 6, if the amount of eccentricity of the eccentric cam is set so that the amplitude is relatively large, the above-mentioned effect can be achieved even with just one detection element, depending on the original. Needless to say.

As described in FIGS. 3 and 5, it is of course possible to control the brightness of the illumination lamp 4 that illuminates the document depending on the detected state of the document.
The brightness of the photosensitive drum 1 may be kept constant, and instead of this, the slit width of the slit light irradiated onto the photosensitive drum 1 may be controlled.

That is, as shown in FIG. 8, a slit adjusting plate 203 having a wide opening is provided in a part of the optical path of the slit light, and the slit adjusting plate 203 is adjusted so that it can rotate around point 0. In place of the illuminance control circuit 101 in FIGS. 3 and 5, this slit adjustment plate 20 is used.
It is also possible to provide an angle control circuit for controlling the angle θ of No. 3, and to use this angle control circuit to determine the angle θ of the slit adjustment plate 203 in accordance with the output of the differential amplifier 105.

Furthermore, a comparison circuit is provided that compares the output EO of the differential amplifier 105 with a predetermined reference value ESI. For example, when the output EO is smaller than the reference value ES (when the density difference in the original is small), For copying, increase the contrast above a predetermined value so that the information is clear even if the background is slightly obscured.
The angle θ of 03 may be increased).

Similarly, a second reference value ES2 may be determined in advance, and when the output EO of the differential amplifier is larger than this ES2, the contrast may be lowered than the desired value.

Further, in the above embodiment, an embodiment in which the document table moves is described, but it goes without saying that the present invention can also be applied to an embodiment in which the optical system moves.

Furthermore, in addition to controlling the amount of beam light irradiated onto the photosensitive drum, it is also possible to control the -forming charging voltage, the developing bias voltage, the voltage applied to the transfer charger, etc.

As described above, according to the present invention, since the detection means is moved in the direction crossing the scanning direction when detecting the density of the original image, the density of the original image can be accurately detected without providing a large number of detection means, and the density of the original image can be detected optimally. It is possible to set recording conditions for

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of a copying machine to which the present invention is applied, FIG. 2 is an explanatory diagram of the detection area of a document when one photodetection element is used, and FIG. 3 is the circuit shown in FIG. 2. 4 is an explanatory diagram of the detection area of a document when a plurality of the detection elements are used, FIG. 5 is a control circuit diagram for controlling recording based on the detection output in FIG. 4, and FIG. An explanatory diagram of the detection area of a document when a plurality of detection elements are used and further vibrated back and forth in the width direction of the document, FIG. 7 is a perspective view of the drive device for the photodetection element in FIG. 6, and FIG. FIG. 3 is an explanatory diagram of exposure amount control using a slit. Here, 1 is a drum, 3 is a manuscript table, 4 is an illumination lamp, 2
1 is a photodetecting element, 104 and 115 are holding circuits, 105 is a differential amplifier, and 101 is an illuminance control circuit. Patent applicant □ Canon Co., Ltd. Procedural amendment blind motion) August 29, 1985 Patent application No. 47784 of 1985 2, Invention title recording device 3, Relationship with the amended person case Patent applicant address Tokyo 3-30-2 Shimomaruko, Ota-ku Name (100
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4, Agent's residence Address: 3-30-25 Shimomaruko, Ota-ku, Tokyo 146 Date of amendment order: - July 30, 1960 (shipment date) 6: Specification and drawings subject to amendment 7; As per the attached sheet (no changes to the content)

Claims (1)

[Scope of Claims] A detection means for detecting the density of an original image; a scanning means for exposing and scanning the original image by moving back and forth relative to the original image; and for detecting the density of the original image by the detection means. A recording apparatus comprising: a moving means for moving the detecting means in a direction intersecting a direction of movement by the scanning means during the movement by the scanning means.