JPH04170852A - Picture reader - Google Patents

Abstract

PURPOSE:To prevent out-of-focus in an optical system even if the state of an original picture changes by operating an automatic focus control means again when prescribed output can be obtained from a discrimination means discriminating the secular change state of the original picture after the operation of the automatic focus control means. CONSTITUTION:A maximum value extraction means 106 extracts the maximum value of sharpness, which can be obtained from a sharpness detection means 105, while it changes the focus position of an image pickup lens 103. When a difference between the maximum value of sharpness at the ON-time of copy start and sharpness obtained by a comparison means 108 comparing sharpness after automatic color balance adjustment is more than a prescribed value (DELTAS), a control means 109 permits a focus adjustment means 110 to execute an AF operation again. Thus, automatic focus control can be executed again even if a state change occurs in an original by the sudden irradiation of light quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device having an automatic focus adjustment function.

[Prior Art] A film reading device has been known as one of this type of image reading device.

When using this film reading device, the film is stored in a special storage case or the like, and when the film is taken out and read by the film reading device, a sudden amount of light is irradiated onto the film. In particular, regarding color film, A
A control sequence is determined to perform automatic color balance adjustment after performing the F operation. The reason for this is that since it takes a considerable amount of time from when the lamp is turned on until the lamp becomes stable, the AF operation is executed within this waiting time, thereby shortening the first copy time.

[Problems to be Solved by the Invention] However, in the above conventional example, since a sudden amount of light is applied after the film is inserted, the film itself may be deformed (that is, warped) depending on the state of the film, making it difficult to focus. There was a drawback that the parts could be misaligned.

SUMMARY OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to provide an image reading device configured so that the optical system does not become out of focus even if the state of the original image changes due to irradiation with a large amount of light.

[Means for Solving the Problems] The present invention provides an image reading device that irradiates light onto a document image to activate an automatic focus adjustment means of an optical system, in which image reading is started after the automatic focus adjustment means is activated. The apparatus further includes a determining means for determining a change state of the document image over time, and a control means for operating the automatic focus adjusting means again when a predetermined output is obtained from the determining means.

Here, it is preferable that an image formed on a film is used as the original image, and that the determining means determines the magnitude of the physical deformation state of the film.

Another embodiment of the image reading device according to the present invention includes an imaging lens that forms a projected image of a transparent original, an imaging element that photoelectrically converts the image formed by the imaging lens, and an output of the imaging element. a sharpness detection means for inputting a signal to detect the sharpness of an image in an AF image reference area; a focus adjustment means for adjusting the focus by moving the imaging lens; and a focus adjustment means for adjusting the focus by moving the imaging lens; maximum value extraction means for extracting the maximum value of sharpness obtained from the sharpness detection means; storage means for storing the maximum value of sharpness; The apparatus includes a comparison means for comparing stored sharpness levels, and a control means for operating the focus adjustment means again in response to the output of the comparison means.

[Function] According to the present invention, even if the state of the document changes due to irradiation with a sudden amount of light and the reading device goes out of focus, automatic focus adjustment can be performed again.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Mitane Yu FIG. 1 is a block diagram showing one embodiment of the present invention.

In this figure, reference numeral 103 is an imaging lens that forms an image of the transparent original 102 illuminated by an illumination means lot.

104 is an image sensor for photoelectrically converting the image formed by the image pickup lens 103.

105 detects the sharpness of the image in the AF image reference area based on the image signal of one area among the plurality of predetermined AF image reference areas obtained by photoelectric conversion by the image sensor 104. This is sharpness detection means.

106, while changing the focal position of the imaging lens 103,
This is a maximum value extraction means for extracting the maximum value of sharpness obtained from the sharpness detection pressure means 105.

107 is a backup memory, and maximum value extraction means 1
06 is stored.

Reference numeral 10111 is a comparison means that compares the maximum sharpness value at the time of copy start instruction and the sharpness after automatic color balance adjustment.

109 is a control means, and if the difference in sharpness obtained by the comparison means 108 is greater than a certain value (ΔS), the focus adjustment means 110 causes the AF operation to be redone.

FIG. 2 is a flowchart showing the flow of the control sequence of this embodiment.

First, after turning on the power, the boat is initialized in step 1.

Next, in step 2, it is determined whether or not there is a copy start instruction, and if there is, the lamp is turned on. After that, AF operation and automatic color balance adjustment are performed.

In the next step 3, it is determined whether there is a difference in sharpness (see Figure 3), and if there is, the AP operation is re-executed; if not, the film is read in step 4,
This sequence ends.

Here, FIG. 3 is a diagram showing changes in lens extension amount ΔX and sharpness P. 301 in the figure is a change in sharpness during AF. Moreover, 302 is the sharpness read with the same lens extension amount as when the sharpness of 301 was the maximum after automatic color balance adjustment.

It is determined whether or not to re-execute the AF operation based on the difference between the respective sharpness levels s and s'.

FIG. 4 is a flowchart showing a second embodiment of the present invention.

First, in step 21 after turning on the power, the boat is initialized.

In the next step 22, the number of copies is set, and it is determined whether or not there is a copy start instruction, and if so, the lamp is turned on. After that, AF operation and automatic color balance adjustment are performed.

In the next step 33, it is determined whether there is a difference in sharpness, and if there is, the AF operation is re-executed;
Perform film reading. After reading the film, if the initialized counter is not "O", the difference in sharpness is compared again and the film is read. After this, the sequence ends when the counter becomes zero.

Note that the circuit configuration of this embodiment is the same as that of the first embodiment.

FIG. 5 is a block diagram showing the third embodiment. In this figure, 503 is an imaging lens that forms an image of the transparent original 502 illuminated by the illumination means 501.

504 is an imaging element for photoelectrically converting the image formed by the imaging lens 503.

505 is means for detecting film warpage based on the image signal photoelectrically converted by the image sensor 504.

506 is a comparison means.

507 is a control means, which sends a control signal to the focus adjustment means 508 based on the data sent from the comparison means 506.

FIG. 6 is a flowchart showing the control procedure of the third embodiment.

First, in step 31, after the power is turned on, each part is initialized.

In step 32, if there is a copy start instruction, the lamp is turned on and AF operation and automatic color balance adjustment are performed.

In the next step 33, it is determined whether or not the film has warped. If there is warpage, the AF operation is re-executed and the film is read. If there is no warpage, reading of the film in step 34 is performed as is, and the sequence ends.

According to this embodiment, by providing another sensor to determine warpage of the film and re-executing the AF operation depending on the situation, it is possible to eliminate out-of-focus of the film reading device.

[Effects of the Invention] As explained above, according to the present invention, even if the state of the document changes due to irradiation with a sudden amount of light and the reading device goes out of focus, automatic focus adjustment can be performed again. It becomes possible to perform proper image reading.

Furthermore, when the present invention is applied to a film reading device,
It is possible to eliminate out-of-focus of the film reading device due to warping of the film.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart showing the control procedure of the first embodiment, FIG. 3 is a magnification diagram showing the relationship between lens extension amount and sharpness, and FIG. 4 is a flowchart showing the control procedure of the second embodiment, FIG. 5 is a block diagram showing the third embodiment, and FIG. 6 is a flowchart showing the control procedure of the second embodiment.
3 is a flowchart showing the control procedure of the embodiment. 101... Illuminating means, 102... Transparent original, 103... Imaging lens, 104... Imaging element, 105... Sharpness detection means, 106... Maximum value extraction means, 107... Backup memory, 108... Comparison means, 109... Control means, 110... Focus adjustment means, 501... Illumination means, 502... Transparent original, 503... Imaging lens, 504... Image sensor, 505... Film warpage detection means, 506... Comparison means, 507... Control means, 508... Focus adjustment means. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1) In an image reading device that activates an automatic focus adjustment means of an optical system by irradiating light onto an original image, the original An image reading device comprising: a determining means for determining a temporal change state of an image; and a control means for operating the automatic focus adjusting means again when a predetermined output is obtained from the determining means. 2) The image reading device according to claim 1, wherein an image formed on a film is used as the original image, and the determining means determines the magnitude of a physical deformation state of the film. 3) an imaging device that photoelectrically converts an image formed by the imaging lens; a sharpness detection unit that receives an output signal from the imaging device and detects the sharpness of an image in an AF image reference area; a focus adjustment means for adjusting the focus by moving a lens; a maximum value extraction means for extracting the maximum value of sharpness obtained from the sharpness detection means while changing the focal position by the focus adjustment means; storage means for storing a maximum value; comparison means for comparing the sharpness after automatic color balance adjustment with the sharpness stored in the storage means; and reactivating the focus adjustment means in response to the output of the comparison means. An image reading device comprising a control means for controlling the image reading device.