That which is claimed is:
1. A voltage regulator comprising a regulation MOS transistor with low serial resistance, one of whose terminals receives a supply voltage while its other terminal is connected to the output of the regulator, and an amplifier whose output drives the gate of the transistor as a function of the difference between a reference voltage and a feedback voltage, the regulator comprising:
a switch having one of its terminals connected to the gate of the regulation transistor while its other terminal is taken to a potential for turning the regulation transistor off, and means to control the switch, monitoring the output of the regulator, laid out to close the switch when the output voltage of the regulator is higher than a first threshold that is higher than the nominal value of the output voltage.
2. A regulator according to claim 1, wherein the switch control means are laid out in order to compare the output voltage of the regulator or a voltage proportional to the output voltage with the reference voltage.
3. A regulator according to claim 2, wherein the switch control means comprise a comparator whose output delivers a signal for closing the switch, the comparator receiving the reference voltage at one input and the output voltage or a voltage proportional to the output voltage at another input.
4. A regulator according to claim 3, wherein the comparator has a switch-over hysteresis chosen so that the switch is reopened when the output voltage becomes lower than a second threshold that is lower than the first threshold and higher than the nominal value of the output voltage.
5. A regulator according to one of the claims 1 to 4, wherein the regulation transistor is a PMOS transistor and the turning-off potential is the supply voltage.
6. A regulator according to claim 5, wherein the amplifier comprises an output stage comprising a gate resistor with a value that is too great for the current flowing through the gate resistor to be capable, on its own, of swiftly turning off the regulation transistor when the supply voltage increases rapidly.
7. A regulator according to claim 6, wherein the switch is a PMOS transistor having a drain-source resistance in the on state that is far lower than the gate resistance of the output stage of the amplifier.
8. A mobile telephone comprising a battery and radio circuits powered by the battery by means of a voltage regulator according to one of the claims 1 to 7.
9. A method to prevent or limit the appearance of overshooting at the output of a voltage regulator when the supply voltage of the regulator increases rapidly, the regulator comprising a regulation MOS transistor with high gate capacitance, the gate of which is driven by an amplifier delivering a current which, by itself, is insufficient to swiftly turn off the regulation transistor, the method comprising a step in which there is provided a switch connected between the gate of the regulation transistor and a potential for turning off the regulation transistor, and a step in which the switch is closed when the output voltage of the regulator becomes higher than a first threshold higher than the nominal value of the output voltage, so as to temporarily help the amplifier turn off the regulation transistor.
10. A method according to claim 9, comprising a step in which the switch is reopened when the output voltage of the regulator becomes smaller than a second threshold that is between the nominal value of the output voltage and the first threshold.
11. A method according to one of the claims 9 and 10, in which the switch is driven by a comparator receiving, at input, a reference voltage from the regulator and a voltage proportional to the output voltage of the regulator.
12. A method according to one of the claims 9 to 11, wherein the regulation transistor is a PMOS transistor and the turning-off potential is the supply voltage.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A camera system, comprising:
an imaging optical system configured to form an optical image of a subject;
an imaging component configured to convert the optical image into an image signal and to cyclically acquire images of the subject based on a photography condition;
a display component having first and second display regions that allow a plurality of the images acquired by the imaging component to be displayed side by side;
a condition input component with which the photography condition can be inputted;
a condition adjustment component configured to adjust the photography condition to a preset first photography condition in a first cyclical period and to adjust a second photography condition inputted to the condition input component at a different timing from the timing at which the photography condition is adjusted to the first photography condition; and
a display control component configured to control the display component to cyclically display at least part of a first image cyclically acquired in the first cyclical period by the imaging component under the first photography condition as a reference image in the first display region and to cyclically display at least part of a second image cyclically acquired by the imaging component at a different timing from that of the first image as a comparative image in the second display region,
wherein the condition adjustment component is configured to adjust the photography condition to the first photography condition in the first cyclical period and the photography condition to the second photography condition in a second cyclical period that is the same as the first cyclical period, and
wherein the display control component is arranged to continue to display the most recent reference image on the display component until a newer reference image is acquired.
2. The camera system according to claim 1, wherein
the display control component is arranged to continue to display the most recent comparative image on the display component until a newer comparative image is acquired.
3. The camera system according to claim 2, wherein
the display control component is arranged to enlarge the reference image in the first display region more than another portion of the first image.
4. The camera system according to claim 3, wherein
the display control component is arranged to enlarge the comparative image in the second display region more than another portion of the second image.
5. The camera system according to claim 4, wherein
the reference image and the comparative image are in a relationship of linear symmetry based on the center lines of the images acquired by the imaging component.
6. The camera system according to claim 1, wherein
the display control component is arranged to continue to display the most recent reference image on the display component until a newer reference image is acquired.
7. The camera system according to claim 6, wherein
the display control component is arranged to continue to display the most recent comparative image on the display component until a newer comparative image is acquired.
8. The camera system according to claim 7, wherein
the display control component is arranged to enlarge the reference image in the first display region more than another portion of the first image.
9. The camera system according to claim 8, wherein
the display control component is arranged to enlarge the comparative image in the second display region more than another portion of the second image.
10. The camera system according to claim 9, wherein
the reference image and the comparative image are in a relationship of linear symmetry based on the center lines of the images acquired by the imaging component.
11. The camera system according to claim 1, wherein
the display control component is arranged to enlarge the reference image in the first display region more than another portion of the first image.
12. The camera system according to claim 11, wherein
the display control component is arranged to enlarge the comparative image in the second display region more than another portion of the second image.
13. The camera system according to claim 12, wherein
the reference image and the comparative image are in a relationship of linear symmetry based on the center lines of the images acquired by the imaging component.
14. The camera system according to claim 1, wherein
the reference image and the comparative image are in a relationship of linear symmetry based on the center lines of the images acquired by the imaging component.