JPH0373681A - Still video camera - Google Patents

Abstract

PURPOSE:To eliminate the need for integrating a rapidly writable buffer memory in a camera by delaying the operation speed of a solid image pickup element as compared with a normal operation speed in accordance with the writing operation speed of a memory at the time of transferring image information to the memory. CONSTITUTION:The writing operation speed information of a semiconductor memory in a memory card 14 is read out. The frequency dividing ratio of a frequency divider 16 is selectively controlled by a control unit 7 based upon the writing speed information inputted from the memory card 14. A driving circuit 11, a signal processing circuit 12, an A/D converter 13, and the memory card 14 are driven by a timing signal outputted from a timing generator 10 based upon the frequency dividing output outputted from the frequency divider 16 and the image information of a CCD 4 is transferred and recorded to/in the semiconductor memory in the memory card 14 based upon the address information obtained from the memory card 14. Consequently, it is unnecessary to include an expensive buffer memory in a camera.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a still video camera, and in particular to a technology for driving a solid-state image sensor in a still video camera that records electrical image signals output from a solid-state image sensor in, for example, a semiconductor memory. Regarding.

<Prior Art> In recent years, in place of conventional film-type cameras, cameras have been developed that convert an optical image signal from a subject into an electrical image signal using a solid-state image sensor, and store the electrical image signal in an external memory equivalent to a film. A still video camera has been developed,
Electrical image signals stored in external memory can be played back and viewed on a monitor, or printed as hard copies.

Magnetic disks are generally used as external memory for such still video cameras, but the method of magnetically recording on magnetic disks requires a mechanism to drive the rotation of the magnetic disk in the camera, resulting in increased size and cost. This is unavoidable and is causing a delay in its widespread use not only for commercial use but also for consumer use.

In view of this, a method has been proposed in which an electrical image signal obtained by a solid-state image sensor is converted into a digital signal and stored in a semiconductor memory (see, for example, Japanese Patent Laid-Open No. 10784/1984). .

In such a still video camera, an optical image signal of a subject obtained through an optical system is transferred to a solid-state image sensor, such as a CCD.
is converted into an electrical image signal by CCD after signal processing.
The signal corresponding to one pixel is A/D converted by an A/D converter, and the resulting digital image signal is recorded on a memory card with a built-in semiconductor memory that can be freely attached to and detached from the camera. . Note that these series of operations are performed in synchronization with a predetermined tie.

This method of recording on a memory card with built-in semiconductor memory does not require a drive mechanism like that required for magnetic disks, making the camera smaller and lighter.

Cost reduction can be achieved.

<Problems to be Solved by the Invention> However, in conventional still video cameras that record digital image data in the semiconductor memory of a memory card, C.
OD electrical image signal output operation speed (about 10 per pixel)
Since the write operation speed of the semiconductor memory of a memory card (approximately 10 Onsec or more) is slower than that of a memory card (approximately 10 Onsec or less), the camera has a built-in buffer memory that can perform high-speed writing, and the electrical image signal from the COD is temporarily recorded in this buffer memory. After that, image information is recorded from the buffer memory onto the memory card in accordance with the writing speed of the semiconductor memory of the memory card. For this reason,
This requires expensive buffer memory, which hinders the cost reduction of cameras using memory cards.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a still video camera that can record image information in a memory with a slow writing speed without intervening a buffer memory.

shall be.

<Means for Solving the Problems> Therefore, the present invention converts an optical image signal of a subject obtained by an optical lens into an electric image signal by a solid-state image sensor, and converts the electric image signal into an electric image signal by an A/D converter. In a still video camera configured to record a digital image signal obtained by /D conversion in a low-speed writing memory that is detachably connected to the camera body, the operating speed of the solid-state image sensor is The structure includes a solid-state image sensor operating speed control means that switches the operation speed when recording to the memory and slows down the speed when recording to the memory in accordance with the writing speed of the memory.

<Operation> According to this configuration, during photographing, the solid-state image sensor operating speed control means drives the solid-state image sensor at the same operating speed as in the past, and optical image information is recorded. Then, when recording the recorded image information in a memory having a slow writing speed, the solid-state imaging device operation speed control means slows down the electric image signal output operation speed of the solid-state imaging device in accordance with the writing speed of the memory.

This makes it possible to accurately record image information in a low-speed writing memory without using a buffer memory.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 1 showing the system configuration of a first embodiment of a still video camera according to the present invention, optical lenses 1. An optical system composed of an aperture 2, a shutter 3, and the like forms an optical image on a light receiving surface of a CCD 4 as a solid-state image sensor. The aperture 2 and shutter 3 are
The drive is controlled via each drive circuit 8.9 in accordance with the exposure amount calculated by the control unit 7 based on the amount of light inputted via the D converter 6.

The CCD 4 is driven by a drive circuit 11 to which a tying signal from a timing generator 10 is input, and photoelectrically converts the optical image formed on the light receiving surface and outputs it as an analog signal. The analog signal from the CCD 4 is input to a signal processing circuit 12 and subjected to signal processing including correlated double sampling processing, and then converted to digital image data by an A/D converter 13. The digital image data from the A/D converter 13 is written to a low-speed writing memory card 14 using, for example, a semiconductor memory, which is detachably connected to the camera body. The signal processing circuit 12. Each operation of the A/D converter 13 and the memory card 14 is performed according to a timing signal from the timing generator 10, similarly to the CCD 4.

The output from the original oscillation circuit 15 at a predetermined frequency is directly input to the timing generator 10 during photographing, and the output from the original oscillation circuit 15 is input when recording the optical image formed on the CCD 4 to the memory card 14. The control unit 7 is configured to switch and control the two changeover switches 17 and 18 so that the output of the frequency divided by the frequency divider 16 is input, and the operating speed of the CCD 4 is changed between the shooting speed and the memory card 14. Switching is controlled when recording information. Then, the control unit 7 selectively controls the frequency division ratio of the frequency divider 16 based on the write speed information of the memory card 14 given from the memory card 14 .

Next, the COD operation speed switching control operation will be explained according to the flowchart of FIG.

First, step 1 (indicated by 81 in the figure, the same applies below)
Now, write operation speed information of the semiconductor memory of the memory card 14 is read. As a method for inputting the operating speed information, for example, a method may be employed in which a notch is formed on the peripheral edge of the memory card 14 and the shape of the notch in the memory card is changed according to the operating speed, or a method in which the operating speed information is stored in the nonvolatile memory of the memory card 14. One possible method is to leave it alone.

In step 2, the CCD 4 starts operating in preparation for photographing. That is, preparation for exposure is performed by sweeping out the dark current. During such COD driving, the two changeover switches 17 and 18 are controlled to be connected to the contact A side by the control unit 7, and the original oscillation circuit 15 is connected to the timing generator 1.
Connected directly to 0.

Therefore, the CCD 4 is driven by a timing signal from the timing generator 15 based on the oscillation frequency of the original oscillation circuit 15, and is driven at the conventional normal operating speed.

In step 3, the exposure amount is calculated based on the amount of light input from the light receiving sensor 5 via the A/D converter 6, and the aperture value and shutter speed are determined.

In step 4, the aperture 2 is driven and controlled via the drive circuit 8 to the aperture value determined based on the calculated exposure amount.

In step 5, the operation of the CCD 4 is stopped.

In step 6, the shutter 3 is driven and controlled via the drive circuit 9 at the shutter speed determined based on the exposure amount calculated in step 3 to perform exposure and photograph the subject.

In step 7, the changeover switches 17 and 18 are switched to the contact B side, and the output of the original oscillation circuit 15 is divided by the frequency divider 16 and input to the timing generator 10. The frequency division ratio of the frequency divider 16 is determined by the memory card 14 inputted from the memory card 14.
control unit 7 based on the writing speed information of
The selection is controlled by That is, the frequency division ratio is set so that the output cycle of the timing signal from the timing generator 10 based on the output frequency from the frequency divider 16 is equal to or larger than the write cycle (operating speed) of the memory card 14. Control selection.

In step 8, the drive circuit 11. Signal processing circuit 12. The A/D converter 13 and the memory card 14 are operated to transfer and record the image information on the CCD 4 to the semiconductor memory in the memory card 14 based on the address information from the memory card 14.

In this way, if the image information transfer operation speed of the CCD 4 is varied according to the write operation speed on the memory card 14 side,
When recording image information in an external semiconductor memory, there is no need to incorporate an expensive buffer memory into the camera.

Next, a second embodiment shown in FIG. 3 will be described.

This embodiment shows a memory card in which a circuit section for determining the oscillation frequency of the original oscillation circuit when recording image information is built into the memory card. Incidentally, the same parts as in the first embodiment shown in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, the original oscillation circuit 21 configured as shown in FIG.
It is connected via the contact point A of 2. Also, memory card 2
4 also has a built-in oscillation time constant circuit 24A that sets an oscillation time constant different from that of the oscillation time constant circuit 23, and is connected to the original oscillation circuit 2 through contact B of the changeover switch 22.

The oscillation time constant circuit 24 in the memory card 24
The time constant of A is determined by the write operation speed of the semiconductor memory in the memory card 24.

To explain the operation of this embodiment, during photographing, the control unit 7 controls the changeover switch 22 to be connected to the contact A side. As a result, the oscillation time constant circuit 23 is connected to the original oscillation circuit 21, the oscillation frequency output similar to the conventional one is input to the timing generator 10, and the timing signal from the timing generator 10 based on this is used to operate at the normal operating speed. The CCD 4 is driven and controlled.

On the other hand, when transferring image information from the CCD 4 to the memory card 24, the control unit 7 switches the changeover switch 22 to the contact B side. As a result, the oscillation time constant circuit 24A in the memory card 24 is connected to the original oscillation circuit 21, and an oscillation frequency output based on this time constant is input to the timing generator 10.

Therefore, from the timing generator 10, the memory card 2
A timing signal matching the write operation speed of the semiconductor memory 4 is output, and the operation speed of the CCD 4 is controlled to be slow in accordance with the write operation speed of the memory card 24.
Image information is directly transferred and recorded from the CD 4 to the memory card 24.

According to this embodiment, in addition to eliminating the need for a buffer memory, the number of changeover switches can be reduced by one, so that the camera can be further simplified.

Incidentally, if the CCI) 4 has a variable speed electronic shutter function, the shutter 3 and its drive circuit 9 become unnecessary as shown in FIG. In such a configuration, the original oscillation frequency is switched when the CCD 4 is exposed to light and the charges in the photosensitive area are sent to the transfer path.

<Effects of the Invention> As explained above, according to the present invention, the operating speed of the solid-state image sensor is made slower than the normal operating speed in accordance with the write operation speed of the memory when image information is transferred to the memory. Therefore, it is no longer necessary to incorporate a high-speed writable buffer memory into the camera, which was necessary in the past. Furthermore, even if the number of pixels in the solid-state image sensor of a camera increases and the operation becomes faster, conventional memory can be used.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the still video camera of the present invention, FIG. 2 is a flowchart illustrating control of changing the operating speed of the solid-state image sensor in the same embodiment, and FIG. FIG. 4 is a circuit diagram of an original oscillation circuit applied to the above embodiment, and FIG. 5 is a block diagram showing a third embodiment of the present invention. 1... Optical lens 2... Aperture 3... Shutter 4... CCD 7... Control unit) 10... Tie selection generator 11... Drive circuit 13... A/D Converter 14.24...
・Memory card 15.21... Original oscillation circuit 1
6... Frequency divider 17.18.22... Selector switch

Claims (1)

[Claims] An optical image signal of the subject obtained by an optical lens is converted into an electrical image signal by a solid-state image sensor, and the electrical image signal is A/D converted by an A/D converter, and the resulting digital image signal is sent to the camera body. In a still video camera configured to record in a removably connected low-speed writing memory, the operating speed of the solid-state image sensor is switched between when shooting and when recording to the memory, and when recording to the memory. A still video camera characterized in that it is provided with a solid-state image sensor operation speed control means that slows down the operation speed in accordance with the writing speed of the memory.